In this paper, a developed three-dimensional Molecular Dynamics (MD) model for AFM-based
nanomachining is applied to study mechanical indentation and scratching at the nanoscale. The
correlation between the machining conditions, including applied force, depth, tip speed, and
defect mechanism in substrate/workpiece is investigeted. The simulations of nanoscratching
process are performed on different crystal orientations of single-crystal gold substrate, Au(100),
Au(110), and Au(111). The material deformation and deformed geometry are extracted from the
final locations of atoms, which are displaced by the rigid indenter. The simulation also allows
for the prediction of forces at the interface between the indenter and substrate. Material
properties including modulus of elasticity and hardness are estimated. It is found that properties
vary significantly at the nanoscale. In addition to the modeling, an AFM is used to conduct
actual indentation and scratching at the nanoscale, and provide measurements to which the MD
simulation predictions are compared. Due to computational time limitation, the predicted forces
obtained from MD simulation only compares well qualitatively with the experimental results.
Assessment of wear rate is an inseparable section of the saw ability of dimension stone, and an essential task to optimization in the diamond wire saw performance. This research aims to provide an accurate, practical and applicable model for predicting the wear rate of diamond bead based on rock properties using applications and performances of intelligent systems. In order to reach this purpose, 38 cutting test results with 38 different rocks were used from andesites, limestones and real marbles quarries located in eleven areas in Turkey. Prediction of wear rate is determined by optimization techniques like Multilayer Perceptron (MLP) and hybrid Genetic algorithm –Artificial neural network (GA-ANN) models that were utilized to build two estimation models by MATLAB software. In this study, 80% of the total samples were used randomly for the training dataset, and the remaining 20% was considered as testing data for GA-ANN model. Further, accuracy and performance capacity of models established were investigated using root mean square error (RMSE), the coefficient of determination (R2) and standard deviation (STD). Finally, a comparison was made among performances of these soft computing techniques for predicting and the results obtained indicated hybrid GA-ANN model with a coefficient of determination (R2) of training = 0.95 and testing = 0.991 can get more accurate predicting results in comparison with MLP models.
This paper presents a model for calculation of torsion capacity of the reinforced concrete beams using the artificial neural network. Considering the complex reaction of reinforced concrete beams under torsion moments, torsion strength of these beams is depended on different parameters; therefore using the artificial neural network is a proper method for estimating the torsion capacity of the beams. In the presented model the beam's dimensions, concrete compressive strength and longitudinal and traverse bars properties are the input data, and torsion capacity of the reinforced concrete beam is the output of the model. Also considering the neural network results, a sensitivity analysis is performed on the network layers weight, and the effect of different parameters is evaluated on the torsion strength of the reinforced concrete beams. According to the sensitivity analysis, properties of traverse steel have the most effect on torsion capacity of the beams.
The document discusses using modal analysis and frequency response functions (FRF) to analyze the state of wall elements. Modal analysis involves exciting wall elements and measuring their response over time. The FRF relates the input excitation signal to the output response signal and can reveal differences between intact and damaged wall elements. The author uses software to perform experimental modal analysis on various wall materials like bricks. Frequency response functions are obtained and displayed for intact and damaged bricks in different directions. The results show differences in the FRFs that could help diagnose the state of wall elements nondestructively.
Wire electrical discharge machining (WEDM) is a specialized thermal machining process
capable of accurately machining parts of hard materials with complex shapes. Response surface
methodology (RSM) with central composite design is selected for experimentation. In the present
work, four factors are taken as input parameters, and the effect of these parameters on MRR are
studied. The influence of the input parameters on response in WEDM process has been examined.
The input parameters are Pulse on time (Ton), Pulse off time (Toff), Servo voltage (SV) and peak
current (IP). The experiments have been performed on high chromium high carbon steel with a wire
of diameter 0.2 mm and the obtained data has been analyzed with the help of RSM using design
expert software. The work piece material was a high carbon high chromium (HCHCr) die steel with
excellent wear resistance, hot toughness and good thermal shock resistance. The experiments shows
that Pulse on time (Ton), Pulse off time (Toff), Servo voltage (SV) and peak current (IP) influence
MRR. Results show that machining speed increases with increase in the pulse on-time and the pulse
off-time increases as the number of discharges within given period of time decreases. Moreover,
there is not much influence of servo voltage on MRR and it increases very slightly with increase in
peak current. Also, as the Ton increases the MRR increases and as Toff increases MRR decreases.
This is because as Ton increases number of sparks per unit time increases and as Toff increases the
sparks per unit time decreases.
The purpose of this paper is to perform a structural optimization of a flat thermoplastic plate (tile). This task is developed computationally through the interface between an optimization algorithm and the finite element method with the goal of minimizing the equivalent stress with specified target stress of 2 MPa when applied with a load intensity of 1000N. A 300 x 300 x 20 mm thermoplastic plate was selected for the optimization, which was performed with a tool in MATLAB R2012b known as genetic algorithm accompanied with static analysis in ANSYS 15. The results produced the optimum equivalent stress (δopt) of 2.136 MPa with the optimum dimensions of 305 x 302 x 20 mm. Also, the dimensions of the plate with the optimum value of the equivalent stress were discovered to be within the lower and upper bound dimensions of the plate. The thermoplastic plate object of the optimization was a square plate of 300 x 300mm, and 20 mm thick with isotropic properties and a particular load and boundary conditions were applied on the entire plate.
This document discusses the modelling and characterization of 3D printed cellular structures. Three different cellular structures were designed and fabricated using fused deposition modelling of ABSplus material. Experimental compression tests were performed on the structures to determine their mechanical properties. Finite element analyses were also conducted and found to correlate well with the experimental results. A mesh sensitivity study was performed to assess the influence of mesh properties on the modelling outcomes. The document presents a methodology for analyzing the energy absorption properties of 3D printed cellular structures through both experimental testing and numerical simulation.
This document reviews the use of ANSYS finite element analysis software to model reactive powder concrete (RPC). It discusses how ANSYS can be used to perform various types of structural analyses, including static, modal, transient dynamic and buckling analyses. The review then describes how RPC specimens were modeled and meshed in ANSYS, and the results obtained, including stress contours showing higher shear stresses at connections. It concludes RPC behaves in an elasto-plastic manner initially, then is plastic dominated, and that fiber reinforcement improves its shear strength through fiber pullout and dowel action.
Poster: Tailoring the Mechanical Environment of Scaffolds with Computer Aided...Matthew Wettergreen
ABSTRACT
Tailoring the Mechanical Environment of Scaffolds with Computer Aided Design and Rapid Prototyping
Wettergreen MA, Bucklen BS, Mikos AG, Liebschner MAK
Department of Bioengineering, Rice University, Houston, TX 77005
While porous scaffolds have shown success in stimulating tissue growth, the random organization of the microarchitecture results in regions exhibiting large variability in mechanical properties. Stress profiles on the scaffold surface depend upon the volume fraction and may vary wildly, presenting regions, which may be unsuitable for cell attachment and viability. If a regular/repeatable architecture is provided, the mechanical environment can be predetermined. We and others have previously demonstrated that rapid prototyping can be utilized to create scaffolds with designed, repeated architecture. The goal of this study was to evaluate a library of CAD designed architectures for tissue engineering. Regular polyhedra based on the Archimedean and Platonic solids and architectures taken from current literature were compared against randomized architecture using finite element analysis. The results demonstrated that for a specific material volume fraction but varying spatial distribution, Young’s Modulus may vary by two orders of magnitude, thus illustrating the dependence of strength upon architecture. Additionally, the stress profile for the designed architectures exhibit peaks at specific stress levels and scaffolds with grossly dissimilar geometry exhibited similar stress profiles. Scaffolds with tailored mechanical properties may be assembled from the unit architectures. The scaffolds may be fabricated from any desired material using rapid prototyping and negative molding and may be helpful for treating defects which require the scaffold to bear mechanical loading.
Assessment of wear rate is an inseparable section of the saw ability of dimension stone, and an essential task to optimization in the diamond wire saw performance. This research aims to provide an accurate, practical and applicable model for predicting the wear rate of diamond bead based on rock properties using applications and performances of intelligent systems. In order to reach this purpose, 38 cutting test results with 38 different rocks were used from andesites, limestones and real marbles quarries located in eleven areas in Turkey. Prediction of wear rate is determined by optimization techniques like Multilayer Perceptron (MLP) and hybrid Genetic algorithm –Artificial neural network (GA-ANN) models that were utilized to build two estimation models by MATLAB software. In this study, 80% of the total samples were used randomly for the training dataset, and the remaining 20% was considered as testing data for GA-ANN model. Further, accuracy and performance capacity of models established were investigated using root mean square error (RMSE), the coefficient of determination (R2) and standard deviation (STD). Finally, a comparison was made among performances of these soft computing techniques for predicting and the results obtained indicated hybrid GA-ANN model with a coefficient of determination (R2) of training = 0.95 and testing = 0.991 can get more accurate predicting results in comparison with MLP models.
This paper presents a model for calculation of torsion capacity of the reinforced concrete beams using the artificial neural network. Considering the complex reaction of reinforced concrete beams under torsion moments, torsion strength of these beams is depended on different parameters; therefore using the artificial neural network is a proper method for estimating the torsion capacity of the beams. In the presented model the beam's dimensions, concrete compressive strength and longitudinal and traverse bars properties are the input data, and torsion capacity of the reinforced concrete beam is the output of the model. Also considering the neural network results, a sensitivity analysis is performed on the network layers weight, and the effect of different parameters is evaluated on the torsion strength of the reinforced concrete beams. According to the sensitivity analysis, properties of traverse steel have the most effect on torsion capacity of the beams.
The document discusses using modal analysis and frequency response functions (FRF) to analyze the state of wall elements. Modal analysis involves exciting wall elements and measuring their response over time. The FRF relates the input excitation signal to the output response signal and can reveal differences between intact and damaged wall elements. The author uses software to perform experimental modal analysis on various wall materials like bricks. Frequency response functions are obtained and displayed for intact and damaged bricks in different directions. The results show differences in the FRFs that could help diagnose the state of wall elements nondestructively.
Wire electrical discharge machining (WEDM) is a specialized thermal machining process
capable of accurately machining parts of hard materials with complex shapes. Response surface
methodology (RSM) with central composite design is selected for experimentation. In the present
work, four factors are taken as input parameters, and the effect of these parameters on MRR are
studied. The influence of the input parameters on response in WEDM process has been examined.
The input parameters are Pulse on time (Ton), Pulse off time (Toff), Servo voltage (SV) and peak
current (IP). The experiments have been performed on high chromium high carbon steel with a wire
of diameter 0.2 mm and the obtained data has been analyzed with the help of RSM using design
expert software. The work piece material was a high carbon high chromium (HCHCr) die steel with
excellent wear resistance, hot toughness and good thermal shock resistance. The experiments shows
that Pulse on time (Ton), Pulse off time (Toff), Servo voltage (SV) and peak current (IP) influence
MRR. Results show that machining speed increases with increase in the pulse on-time and the pulse
off-time increases as the number of discharges within given period of time decreases. Moreover,
there is not much influence of servo voltage on MRR and it increases very slightly with increase in
peak current. Also, as the Ton increases the MRR increases and as Toff increases MRR decreases.
This is because as Ton increases number of sparks per unit time increases and as Toff increases the
sparks per unit time decreases.
The purpose of this paper is to perform a structural optimization of a flat thermoplastic plate (tile). This task is developed computationally through the interface between an optimization algorithm and the finite element method with the goal of minimizing the equivalent stress with specified target stress of 2 MPa when applied with a load intensity of 1000N. A 300 x 300 x 20 mm thermoplastic plate was selected for the optimization, which was performed with a tool in MATLAB R2012b known as genetic algorithm accompanied with static analysis in ANSYS 15. The results produced the optimum equivalent stress (δopt) of 2.136 MPa with the optimum dimensions of 305 x 302 x 20 mm. Also, the dimensions of the plate with the optimum value of the equivalent stress were discovered to be within the lower and upper bound dimensions of the plate. The thermoplastic plate object of the optimization was a square plate of 300 x 300mm, and 20 mm thick with isotropic properties and a particular load and boundary conditions were applied on the entire plate.
This document discusses the modelling and characterization of 3D printed cellular structures. Three different cellular structures were designed and fabricated using fused deposition modelling of ABSplus material. Experimental compression tests were performed on the structures to determine their mechanical properties. Finite element analyses were also conducted and found to correlate well with the experimental results. A mesh sensitivity study was performed to assess the influence of mesh properties on the modelling outcomes. The document presents a methodology for analyzing the energy absorption properties of 3D printed cellular structures through both experimental testing and numerical simulation.
This document reviews the use of ANSYS finite element analysis software to model reactive powder concrete (RPC). It discusses how ANSYS can be used to perform various types of structural analyses, including static, modal, transient dynamic and buckling analyses. The review then describes how RPC specimens were modeled and meshed in ANSYS, and the results obtained, including stress contours showing higher shear stresses at connections. It concludes RPC behaves in an elasto-plastic manner initially, then is plastic dominated, and that fiber reinforcement improves its shear strength through fiber pullout and dowel action.
Poster: Tailoring the Mechanical Environment of Scaffolds with Computer Aided...Matthew Wettergreen
ABSTRACT
Tailoring the Mechanical Environment of Scaffolds with Computer Aided Design and Rapid Prototyping
Wettergreen MA, Bucklen BS, Mikos AG, Liebschner MAK
Department of Bioengineering, Rice University, Houston, TX 77005
While porous scaffolds have shown success in stimulating tissue growth, the random organization of the microarchitecture results in regions exhibiting large variability in mechanical properties. Stress profiles on the scaffold surface depend upon the volume fraction and may vary wildly, presenting regions, which may be unsuitable for cell attachment and viability. If a regular/repeatable architecture is provided, the mechanical environment can be predetermined. We and others have previously demonstrated that rapid prototyping can be utilized to create scaffolds with designed, repeated architecture. The goal of this study was to evaluate a library of CAD designed architectures for tissue engineering. Regular polyhedra based on the Archimedean and Platonic solids and architectures taken from current literature were compared against randomized architecture using finite element analysis. The results demonstrated that for a specific material volume fraction but varying spatial distribution, Young’s Modulus may vary by two orders of magnitude, thus illustrating the dependence of strength upon architecture. Additionally, the stress profile for the designed architectures exhibit peaks at specific stress levels and scaffolds with grossly dissimilar geometry exhibited similar stress profiles. Scaffolds with tailored mechanical properties may be assembled from the unit architectures. The scaffolds may be fabricated from any desired material using rapid prototyping and negative molding and may be helpful for treating defects which require the scaffold to bear mechanical loading.
Multiscale Modeling Approach for Prediction the Elastic Modulus of Percolated...ijtsrd
In this study the effective elastic modulus of cellulose nanocrystal CNC network is evaluated using multiscale method and micromechanical analysis. For this purpose, the elastic modulus of CNC water phases are randomly assigned to a two dimensional 2D checkerboard structure and the elastic response is evaluated. In addition, the effect of having a different number of phases CNC, water and interface is evaluated by assigning a discreet and continuous distribution of elastic modulus to checkerboard structure. When the number of phases increases dramatically, the distribution of phases is continuous and is defined with Weibull distribution. The results show that for two phase materials CNC and water when the microstructure has organized pattern the rule of the mixture and numerical model provide the same effective modulus, however when the microstructure is completely random, the self consistent micromechanical model should be used. Also, this study suggests 50 volume fraction as the percolation threshold for the CNC network with 10 GPa effective elastic modulus. The results from percolated multiphase network reveal that for microstructures with 4 phases and above, the percolated network converge to 35 GPa. Mehrdad Bor | Jim Huang "Multiscale Modeling Approach for Prediction the Elastic Modulus of Percolated Cellulose Nanocrystal (CNC) Network" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26553.pdfPaper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/26553/multiscale-modeling-approach-for-prediction-the-elastic-modulus-of-percolated-cellulose-nanocrystal-cnc-network/mehrdad-bor
A review study of mechanical fatigue testing methods for small scale metal ma...Alexander Decker
This document reviews mechanical fatigue testing techniques for small-scale metal materials. It begins by discussing the increased focus on materials behavior at the micro and nano scales due to growing MEMS/NEMS applications. It then classifies fatigue testing techniques for small-scale materials, including uniaxial tension-tension, dynamic bending, and uniaxial tension-compression. Specific techniques are described in more detail, such as using piezoelectric actuators to enable load-controlled uniaxial cyclic loading of thin films. The document also examines fatigue properties of materials tested with these techniques, like studying crack growth rates in nickel alloy cantilever beams under dynamic bending.
A new proposed approach for moment capacity estimation of ferrocement members...Pouyan Fakharian
Ferrocement composites are widely used as a novel method for many different structural purposes recently. The uniform distribution and the high surface area-to-volume ratio of the reinforcement of such composites would improve the crack-arresting mechanism. Given these properties, ferrocement is an ideal option as a replacement for some traditional structures methods. In members with axially loaded reinforced concrete ferrocement composite, it would be the best alternative to use ferrocement members. Lack of sufficient research in this approach is the cause of not well defining this field for RC structures. This study has aimed to evaluate the moment capacity of ferrocement members using the GMDH method. Mechanical and geometrical parameters including the width of specimens, total depth specimens, compressive strength of ferrocement, ultimate strength of wire mesh and volume fraction of wire mesh are considered as inputs to predict the moment capacity of ferrocement members. For evaluating this model, mean absolute error (MAE), root mean absolute error (RMAE), normalized root mean square error (NRMSE) and mean absolute percentage error (MAPE) were carried out. The results conducted that the GMDH model is significantly better than some previous models and comparable to some other methods. Moreover, a new formulation for moment capacity of ferrocement members based on GMDH approach is presented. Finally, Sensitivity analysis is operated to understand the influence of each input parameters on moment capacity of ferrocement members.
- The document discusses buckling analysis of a fiber-filled plastic push rod component used in clutch release cylinders.
- It performs nonlinear buckling analysis using both isotropic and anisotropic material models, coupled with injection molding simulations to model fiber orientation.
- The results show that accounting for anisotropy induced by the molding process, as predicted by the Moldflow simulation, improves the accuracy of the buckling load prediction compared to experimental data over using a traditional isotropic material model.
Maneuverable postbuckling of microscale plate like mechanical metamaterials w...TalalSalem5
Architected, structural materials have been reported with promising enhancement of mechanical performance
using the structural method (e.g., mechanical metamaterials MM) and the material method (e.g., composite
materials). Here, we develop the extensible, plate-like mechanical metamaterials at the microscale using the
functionally graded materials (FGM-MM) and the carbon nanotubes (CNT-MM) to obtain the advanced structural
materials with good maneuverability over the postbuckling response. Theoretical models are developed to
investigate the postbuckling response of the FGM-MM and CNT-MM subjected to the bilateral constraints, and
numerical simulations are carried out to validate the theoretical results. The theoretical models are used to
investigate the maneuverability of the postbuckling behaviors with respect to the material properties (i.e., the
FGMs and CNTs) and geometric properties (i.e., the corrugated microstructures). The findings show that the
corrugation in the MM and composition in the FGMs and CNTs assist in tuning the buckling mode transitions. The
reported CNT-MM and FGM-MM provide a novel direction for programming the mechanical response of the
artificial materials.
When a ductile material with a crack is loaded in
tension, the deformation energy builds up around the crack tip
and it is understood that at a certain critical condition voids are
formed ahead of the crack tip. The crack extension occurs by
coalescence of voids with the crack tip. The “characteristic
distance” (Lc) defined as the distance b/w the crack tip & the void
responsible for eventual coalescence with the crack tip. Nucleation
of these voids is generally associated with the presence of second
phase particles or grain boundaries in the vicinity of the crack tip.
Although approximate, Lc assumes a special significance since it
links the fracture toughness to the microscopic mechanism
considered responsible for ductile fracture. The knowledge of the
“characteristic distance” is also crucial for designing the size of
mesh in the finite element simulations of material crack growth
using damage mechanics principles. There is not much work
(experimental as well as numerical) available in the literature
related to the dependency of “characteristic distance” on the
fracture specimen geometry. The present research work is an
attempt to understand numerically, the geometry dependency of
“characteristic distance” using three-dimensional FEM analysis.
The variation of “characteristic distance” parameter due to the
change of temperature across the fracture specimen thickness was
also studied. The work also studied the variation of “characteristic
distance”, due to the change in fracture specimen thickness.
Finally, the ASTM requirement of fracture specimen thickness
criteria is evaluated for the “characteristic distance” fracture
parameter. “Characteristic distance” is found to vary across the
fracture specimen thickness. It is dependent on fracture specimen
thickness and it converges after a specified thickness of fracture
specimen. “Characteristic distance” value is also dependent on the
temperature of ductile material. In Armco iron material, it is
found to decrease with the increase in temperature.
Regression model for analyzing the dgs structures propagation characterisitcseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
International Journal of Computational Engineering Research(IJCER) ijceronline
nternational Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
This paper addresses the fracture toughness ( ), or also known as critical stress intensity Factor, according to
conditions of Lineal Elastic Fracture Mechanics (LEFM). The characterization of the mechanical properties in
tensile and fracture toughness of structural steel pipes API-5L used in hydrocarbons transportation was
performed. For fracture toughness, the material was tested through fatigue crack propagation on standardized
compact specimen (CT) according to ASTM E-399 norm. A thickness (B) equal to and a crack size (a) equal
to 0.5w were used. With the porpoise of establishing the adequate conditions at the crack tip, the specimens were
subjected to fatigue pre-cracking by application of repeated cycles of load in tensile-tensile and constant load
amplitude with a load ratio of R = 0.1. The experimental Compliance method was used based on data obtained
from load vs. Crack Mouth Opening Displacement (CMOD). The results show a Stress Intensity factor of 35.88
MPa√m for a 25 mm crack size specimen. The device used for testing is a MTS-810 machine with capacity of
100KN and 6 kHz sampling rate, which meets the conditions of the ASTM E-399 standard. The cracking
susceptibility of steel is influenced by the size, morphology and distribution of non-metallic inclusions,
thermochemical interaction with the environment and microstructure.
IRJET- A Review on Finite Element Modelling and Numerical Study of Precast St...IRJET Journal
This document reviews several studies that used finite element modeling and analysis to study precast structural elements. It summarizes 14 studies that used software like ABAQUS and ANSYS to model precast concrete connections, walls, beams, and slabs. The studies considered different modeling techniques, load cases, material properties, and analyses like nonlinear static and dynamic analyses. They analyzed parameters like stresses, cracks, deformations, load-displacement responses, and effectiveness of different connection designs. In general, the studies demonstrated that finite element modeling is useful for analyzing precast concrete elements and understanding their behavior.
Analysis and characterization of dendrite structures from microstructure imag...eSAT Journals
This document presents a method for 3D characterization and analysis of dendrite structures from microstructure images of magnesium alloys. Serial sectioning is used to acquire 300 microstructure images from a magnesium-aluminum alloy sample. The images are preprocessed using filtering and segmentation. A algorithm is developed to determine the volume fractions of dendrite structures across slices using image analysis techniques. The results show 80% alpha-Mg dendrite matrix and 12.9% beta-Mg17Al12 phase, which is close to values from the Scheil-Gulliver solidification model. The proposed automated method provides accurate 3D quantification of dendrite structures from microstructure images.
Analysis of Stress Concentration of Laminated Composite Plate With Circular Holeijiert bestjournal
Composite materials are finding a wide range of applications in structural design,especially for lightweight structure that have stringent stiffness and strength requirements. They are attractive replacement for metallic materials for many structural applications. By finding efficient composite str ucture design that meets all requirements of specific application. This is achieved by tailoring of material properties through selective choice of orientation,no. of stacking sequence of layers that make up composite material. Composites are used more and more often for load carrying and safety structures in all kind of applications foe aviation and space technology,for vehicles etc. Composite materials have been introduced progressively in automobiles,followingpolymer materials,a few of which have be en used as matrices. It is interestingto examine the relative masses of different materials which are used in theconstruction of automobiles. Even thoughthe relative mass of polymer - based materials appears low,one needs to take intoaccount that the specif ic mass of steel is about 4 times greater than that of polymers.This explains the higher percentage in terms of volume for the polymers.
This document summarizes a study that used finite element analysis to analyze the micromechanical behavior of fiber-reinforced polymer composites with different fiber materials (Hexply Im7-8552, Kelvar, and Carbon T300) embedded in an epoxy resin matrix. A unit cell model was developed and analyzed under tensile loading to evaluate engineering properties like modulus and Poisson's ratio for various fiber volume fractions. Interfacial stresses at the fiber-matrix interface were also estimated. Results from the finite element analysis were validated against theoretical models. The study aims to predict the mechanical behavior and properties of unidirectional fiber composites subjected to longitudinal tensile loading.
Fractal characterization of dynamic systems sectional imagesAlexander Decker
This document discusses using fractal analysis to characterize sectional images of dynamic systems. It simulates three systems - a hollow sphere, transmissibility ratio, and Lorenz weather model. For each system, it generates the governing equations, simulates the surface, takes 200 sectional images by passing a plane through the surface, and uses fractal disk dimension to characterize the roughness of each image. It finds the hollow sphere surface is smoothest, transmissibility ratio is rougher, and Lorenz weather model is roughest, indicating fractal analysis can distinguish linear from nonlinear system surfaces. The study demonstrates fractals' potential for image characterization in engineering applications.
A design and simulation of optical pressure sensor based on photonic crystal ...prjpublications
This document describes the design and simulation of an optical pressure sensor based on photonic crystals in the sub-micron range. Two designs of the pressure sensor are proposed and modeled. The first uses a two-dimensional square lattice photonic crystal with rods in air and a waveguide carved between two dielectric slabs. The second uses a two-dimensional hexagonal lattice photonic crystal with holes in a dielectric slab and a waveguide. Applied pressure moves the upper slab, changing the waveguide dimension and altering the transmission spectrum in a way that corresponds to the pressure level. The designs were simulated using the Finite Difference Time Domain method with the MEEP software tool.
Las llanuras del Pacífico de Costa Rica incluyen las llanuras del Tempisque, Tárcoles, Parrita, Térraba y Coto Colorado. Son más pequeñas y angostas que las llanuras del Caribe, con una estación seca dominante. Se dedican principalmente a la ganadería de carne y el cultivo de productos como banano, café, palma africana y frutas. Limitan al este con la Cordillera Volcánica Central y al oeste con el Océano Pacífico.
El documento describe 5 llanuras en Costa Rica. Cada llanura se caracteriza por su ubicación geográfica, actividades económicas principales como la agricultura, ganadería y turismo, así como las ciudades más importantes. Las llanuras presentan climas adecuados para el cultivo de diferentes productos agrícolas y desarrollo de la ganadería de carne. También son zonas de atracción turística por sus playas y parques naturales.
El documento describe las características geográficas de Colombia, incluyendo los diferentes tipos de relieve como las unidades montañosas, valles, llanuras y sistemas periféricos. También se mencionan los recursos hídricos, flora y fauna del territorio colombiano. El propósito es conocer y comparar el relieve, la hidrografía y el clima de las diferentes regiones de Colombia, así como identificar las relaciones entre las comunidades y su entorno geográfico.
La región Caribe de Colombia incluye los departamentos de Atlántico, Bolívar, Cesar, Córdoba, La Guajira, Magdalena, Sucre y las Islas de San Andrés, Providencia y Santa Catalina. Es la única región de Suramérica con costas en el Mar Caribe y el Océano Pacífico. Sus principales fuentes económicas son la ganadería, la agricultura, la minería y el turismo. Algunos de sus principales atractivos turísticos son la Sierra Nevada de Santa Marta, el Parque
Policy-based routing (PBR) on Juniper NetScreen firewalls allows routing decisions to be based on various packet attributes like source/destination addresses, ports, and protocols. This provides flexibility to redirect traffic in different ways, such as sending all HTTP traffic through a transparent proxy server or distributing traffic across multiple internet connections. The configuration involves creating extended ACLs to match traffic, match groups to group ACLs, action groups to define routing actions, policies to combine matches and actions, and binding policies to interfaces or virtual routers. Keeping PBR configurations simple and leaving room for future policies is recommended.
Multiscale Modeling Approach for Prediction the Elastic Modulus of Percolated...ijtsrd
In this study the effective elastic modulus of cellulose nanocrystal CNC network is evaluated using multiscale method and micromechanical analysis. For this purpose, the elastic modulus of CNC water phases are randomly assigned to a two dimensional 2D checkerboard structure and the elastic response is evaluated. In addition, the effect of having a different number of phases CNC, water and interface is evaluated by assigning a discreet and continuous distribution of elastic modulus to checkerboard structure. When the number of phases increases dramatically, the distribution of phases is continuous and is defined with Weibull distribution. The results show that for two phase materials CNC and water when the microstructure has organized pattern the rule of the mixture and numerical model provide the same effective modulus, however when the microstructure is completely random, the self consistent micromechanical model should be used. Also, this study suggests 50 volume fraction as the percolation threshold for the CNC network with 10 GPa effective elastic modulus. The results from percolated multiphase network reveal that for microstructures with 4 phases and above, the percolated network converge to 35 GPa. Mehrdad Bor | Jim Huang "Multiscale Modeling Approach for Prediction the Elastic Modulus of Percolated Cellulose Nanocrystal (CNC) Network" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26553.pdfPaper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/26553/multiscale-modeling-approach-for-prediction-the-elastic-modulus-of-percolated-cellulose-nanocrystal-cnc-network/mehrdad-bor
A review study of mechanical fatigue testing methods for small scale metal ma...Alexander Decker
This document reviews mechanical fatigue testing techniques for small-scale metal materials. It begins by discussing the increased focus on materials behavior at the micro and nano scales due to growing MEMS/NEMS applications. It then classifies fatigue testing techniques for small-scale materials, including uniaxial tension-tension, dynamic bending, and uniaxial tension-compression. Specific techniques are described in more detail, such as using piezoelectric actuators to enable load-controlled uniaxial cyclic loading of thin films. The document also examines fatigue properties of materials tested with these techniques, like studying crack growth rates in nickel alloy cantilever beams under dynamic bending.
A new proposed approach for moment capacity estimation of ferrocement members...Pouyan Fakharian
Ferrocement composites are widely used as a novel method for many different structural purposes recently. The uniform distribution and the high surface area-to-volume ratio of the reinforcement of such composites would improve the crack-arresting mechanism. Given these properties, ferrocement is an ideal option as a replacement for some traditional structures methods. In members with axially loaded reinforced concrete ferrocement composite, it would be the best alternative to use ferrocement members. Lack of sufficient research in this approach is the cause of not well defining this field for RC structures. This study has aimed to evaluate the moment capacity of ferrocement members using the GMDH method. Mechanical and geometrical parameters including the width of specimens, total depth specimens, compressive strength of ferrocement, ultimate strength of wire mesh and volume fraction of wire mesh are considered as inputs to predict the moment capacity of ferrocement members. For evaluating this model, mean absolute error (MAE), root mean absolute error (RMAE), normalized root mean square error (NRMSE) and mean absolute percentage error (MAPE) were carried out. The results conducted that the GMDH model is significantly better than some previous models and comparable to some other methods. Moreover, a new formulation for moment capacity of ferrocement members based on GMDH approach is presented. Finally, Sensitivity analysis is operated to understand the influence of each input parameters on moment capacity of ferrocement members.
- The document discusses buckling analysis of a fiber-filled plastic push rod component used in clutch release cylinders.
- It performs nonlinear buckling analysis using both isotropic and anisotropic material models, coupled with injection molding simulations to model fiber orientation.
- The results show that accounting for anisotropy induced by the molding process, as predicted by the Moldflow simulation, improves the accuracy of the buckling load prediction compared to experimental data over using a traditional isotropic material model.
Maneuverable postbuckling of microscale plate like mechanical metamaterials w...TalalSalem5
Architected, structural materials have been reported with promising enhancement of mechanical performance
using the structural method (e.g., mechanical metamaterials MM) and the material method (e.g., composite
materials). Here, we develop the extensible, plate-like mechanical metamaterials at the microscale using the
functionally graded materials (FGM-MM) and the carbon nanotubes (CNT-MM) to obtain the advanced structural
materials with good maneuverability over the postbuckling response. Theoretical models are developed to
investigate the postbuckling response of the FGM-MM and CNT-MM subjected to the bilateral constraints, and
numerical simulations are carried out to validate the theoretical results. The theoretical models are used to
investigate the maneuverability of the postbuckling behaviors with respect to the material properties (i.e., the
FGMs and CNTs) and geometric properties (i.e., the corrugated microstructures). The findings show that the
corrugation in the MM and composition in the FGMs and CNTs assist in tuning the buckling mode transitions. The
reported CNT-MM and FGM-MM provide a novel direction for programming the mechanical response of the
artificial materials.
When a ductile material with a crack is loaded in
tension, the deformation energy builds up around the crack tip
and it is understood that at a certain critical condition voids are
formed ahead of the crack tip. The crack extension occurs by
coalescence of voids with the crack tip. The “characteristic
distance” (Lc) defined as the distance b/w the crack tip & the void
responsible for eventual coalescence with the crack tip. Nucleation
of these voids is generally associated with the presence of second
phase particles or grain boundaries in the vicinity of the crack tip.
Although approximate, Lc assumes a special significance since it
links the fracture toughness to the microscopic mechanism
considered responsible for ductile fracture. The knowledge of the
“characteristic distance” is also crucial for designing the size of
mesh in the finite element simulations of material crack growth
using damage mechanics principles. There is not much work
(experimental as well as numerical) available in the literature
related to the dependency of “characteristic distance” on the
fracture specimen geometry. The present research work is an
attempt to understand numerically, the geometry dependency of
“characteristic distance” using three-dimensional FEM analysis.
The variation of “characteristic distance” parameter due to the
change of temperature across the fracture specimen thickness was
also studied. The work also studied the variation of “characteristic
distance”, due to the change in fracture specimen thickness.
Finally, the ASTM requirement of fracture specimen thickness
criteria is evaluated for the “characteristic distance” fracture
parameter. “Characteristic distance” is found to vary across the
fracture specimen thickness. It is dependent on fracture specimen
thickness and it converges after a specified thickness of fracture
specimen. “Characteristic distance” value is also dependent on the
temperature of ductile material. In Armco iron material, it is
found to decrease with the increase in temperature.
Regression model for analyzing the dgs structures propagation characterisitcseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
International Journal of Computational Engineering Research(IJCER) ijceronline
nternational Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
This paper addresses the fracture toughness ( ), or also known as critical stress intensity Factor, according to
conditions of Lineal Elastic Fracture Mechanics (LEFM). The characterization of the mechanical properties in
tensile and fracture toughness of structural steel pipes API-5L used in hydrocarbons transportation was
performed. For fracture toughness, the material was tested through fatigue crack propagation on standardized
compact specimen (CT) according to ASTM E-399 norm. A thickness (B) equal to and a crack size (a) equal
to 0.5w were used. With the porpoise of establishing the adequate conditions at the crack tip, the specimens were
subjected to fatigue pre-cracking by application of repeated cycles of load in tensile-tensile and constant load
amplitude with a load ratio of R = 0.1. The experimental Compliance method was used based on data obtained
from load vs. Crack Mouth Opening Displacement (CMOD). The results show a Stress Intensity factor of 35.88
MPa√m for a 25 mm crack size specimen. The device used for testing is a MTS-810 machine with capacity of
100KN and 6 kHz sampling rate, which meets the conditions of the ASTM E-399 standard. The cracking
susceptibility of steel is influenced by the size, morphology and distribution of non-metallic inclusions,
thermochemical interaction with the environment and microstructure.
IRJET- A Review on Finite Element Modelling and Numerical Study of Precast St...IRJET Journal
This document reviews several studies that used finite element modeling and analysis to study precast structural elements. It summarizes 14 studies that used software like ABAQUS and ANSYS to model precast concrete connections, walls, beams, and slabs. The studies considered different modeling techniques, load cases, material properties, and analyses like nonlinear static and dynamic analyses. They analyzed parameters like stresses, cracks, deformations, load-displacement responses, and effectiveness of different connection designs. In general, the studies demonstrated that finite element modeling is useful for analyzing precast concrete elements and understanding their behavior.
Analysis and characterization of dendrite structures from microstructure imag...eSAT Journals
This document presents a method for 3D characterization and analysis of dendrite structures from microstructure images of magnesium alloys. Serial sectioning is used to acquire 300 microstructure images from a magnesium-aluminum alloy sample. The images are preprocessed using filtering and segmentation. A algorithm is developed to determine the volume fractions of dendrite structures across slices using image analysis techniques. The results show 80% alpha-Mg dendrite matrix and 12.9% beta-Mg17Al12 phase, which is close to values from the Scheil-Gulliver solidification model. The proposed automated method provides accurate 3D quantification of dendrite structures from microstructure images.
Analysis of Stress Concentration of Laminated Composite Plate With Circular Holeijiert bestjournal
Composite materials are finding a wide range of applications in structural design,especially for lightweight structure that have stringent stiffness and strength requirements. They are attractive replacement for metallic materials for many structural applications. By finding efficient composite str ucture design that meets all requirements of specific application. This is achieved by tailoring of material properties through selective choice of orientation,no. of stacking sequence of layers that make up composite material. Composites are used more and more often for load carrying and safety structures in all kind of applications foe aviation and space technology,for vehicles etc. Composite materials have been introduced progressively in automobiles,followingpolymer materials,a few of which have be en used as matrices. It is interestingto examine the relative masses of different materials which are used in theconstruction of automobiles. Even thoughthe relative mass of polymer - based materials appears low,one needs to take intoaccount that the specif ic mass of steel is about 4 times greater than that of polymers.This explains the higher percentage in terms of volume for the polymers.
This document summarizes a study that used finite element analysis to analyze the micromechanical behavior of fiber-reinforced polymer composites with different fiber materials (Hexply Im7-8552, Kelvar, and Carbon T300) embedded in an epoxy resin matrix. A unit cell model was developed and analyzed under tensile loading to evaluate engineering properties like modulus and Poisson's ratio for various fiber volume fractions. Interfacial stresses at the fiber-matrix interface were also estimated. Results from the finite element analysis were validated against theoretical models. The study aims to predict the mechanical behavior and properties of unidirectional fiber composites subjected to longitudinal tensile loading.
Fractal characterization of dynamic systems sectional imagesAlexander Decker
This document discusses using fractal analysis to characterize sectional images of dynamic systems. It simulates three systems - a hollow sphere, transmissibility ratio, and Lorenz weather model. For each system, it generates the governing equations, simulates the surface, takes 200 sectional images by passing a plane through the surface, and uses fractal disk dimension to characterize the roughness of each image. It finds the hollow sphere surface is smoothest, transmissibility ratio is rougher, and Lorenz weather model is roughest, indicating fractal analysis can distinguish linear from nonlinear system surfaces. The study demonstrates fractals' potential for image characterization in engineering applications.
A design and simulation of optical pressure sensor based on photonic crystal ...prjpublications
This document describes the design and simulation of an optical pressure sensor based on photonic crystals in the sub-micron range. Two designs of the pressure sensor are proposed and modeled. The first uses a two-dimensional square lattice photonic crystal with rods in air and a waveguide carved between two dielectric slabs. The second uses a two-dimensional hexagonal lattice photonic crystal with holes in a dielectric slab and a waveguide. Applied pressure moves the upper slab, changing the waveguide dimension and altering the transmission spectrum in a way that corresponds to the pressure level. The designs were simulated using the Finite Difference Time Domain method with the MEEP software tool.
Las llanuras del Pacífico de Costa Rica incluyen las llanuras del Tempisque, Tárcoles, Parrita, Térraba y Coto Colorado. Son más pequeñas y angostas que las llanuras del Caribe, con una estación seca dominante. Se dedican principalmente a la ganadería de carne y el cultivo de productos como banano, café, palma africana y frutas. Limitan al este con la Cordillera Volcánica Central y al oeste con el Océano Pacífico.
El documento describe 5 llanuras en Costa Rica. Cada llanura se caracteriza por su ubicación geográfica, actividades económicas principales como la agricultura, ganadería y turismo, así como las ciudades más importantes. Las llanuras presentan climas adecuados para el cultivo de diferentes productos agrícolas y desarrollo de la ganadería de carne. También son zonas de atracción turística por sus playas y parques naturales.
El documento describe las características geográficas de Colombia, incluyendo los diferentes tipos de relieve como las unidades montañosas, valles, llanuras y sistemas periféricos. También se mencionan los recursos hídricos, flora y fauna del territorio colombiano. El propósito es conocer y comparar el relieve, la hidrografía y el clima de las diferentes regiones de Colombia, así como identificar las relaciones entre las comunidades y su entorno geográfico.
La región Caribe de Colombia incluye los departamentos de Atlántico, Bolívar, Cesar, Córdoba, La Guajira, Magdalena, Sucre y las Islas de San Andrés, Providencia y Santa Catalina. Es la única región de Suramérica con costas en el Mar Caribe y el Océano Pacífico. Sus principales fuentes económicas son la ganadería, la agricultura, la minería y el turismo. Algunos de sus principales atractivos turísticos son la Sierra Nevada de Santa Marta, el Parque
Policy-based routing (PBR) on Juniper NetScreen firewalls allows routing decisions to be based on various packet attributes like source/destination addresses, ports, and protocols. This provides flexibility to redirect traffic in different ways, such as sending all HTTP traffic through a transparent proxy server or distributing traffic across multiple internet connections. The configuration involves creating extended ACLs to match traffic, match groups to group ACLs, action groups to define routing actions, policies to combine matches and actions, and binding policies to interfaces or virtual routers. Keeping PBR configurations simple and leaving room for future policies is recommended.
This document contains the presentation from 3M's Chairman and CEO at their 2016 Investor Day. The presentation highlights that 3M will continue executing on their key strategies of portfolio management, investing in innovation, and business transformation to drive efficient growth. 3M announced new 2016-2020 financial objectives targeting organic growth of 2-5%, free cash flow conversion of 100%, EPS growth of 8-11%, and ROIC of 2-5%. The presentation outlines how 3M will continue outperforming markets by leveraging their fundamental strengths and winning with customers.
EFFECT OF THE PROCESS PARAMETERS ON GEOMETRICAL CHARACTERISTICS OF THE PARTS ...IAEME Publication
This document reviews the direct metal deposition (DMD) process and the effects of various process parameters on the geometrical characteristics of parts produced. It discusses how the laser power, beam diameter, scanning speed, powder flow rate, and other parameters influence characteristics like clad height, width, roughness, and dilution. Several studies that developed models and conducted experiments relating parameters to outcomes are summarized. In general, increasing laser power or powder flow rate tends to increase clad height and deposition rate while increasing scanning speed decreases these. Optimal surface roughness requires intermediate parameter values.
This document reviews the direct metal deposition (DMD) process and the effects of various process parameters on the geometrical characteristics of parts produced. It discusses how the laser power, beam diameter, scanning speed, powder flow rate, and other parameters influence characteristics like clad height, width, roughness, and dilution. Several studies that developed models and experiments to relate parameters to outcomes are summarized. In general, increasing laser power or powder flow rate tends to increase clad height while increasing scanning speed decreases height. Process maps and models have been created but further research is still needed to better understand and control the complex interactions in the DMD process.
A review study of mechanical fatigue testing methods for small scale metal ma...Alexander Decker
This document reviews mechanical fatigue testing techniques for small-scale metal materials. It begins by discussing the importance of characterizing the mechanical properties of materials used in micro-electromechanical systems. It then classifies and describes various fatigue testing techniques for small-scale materials, including uniaxial tension-tension testing, dynamic bending, and uniaxial tension-compression. Specific examples of how each technique has been used to test materials like copper thin films, carbon nanotube wires, and nickel alloy cantilever beams are provided. The document concludes by discussing factors to consider when developing testing methods for materials at the micro and nano scales.
Computational Nano Technology and Simulation Techniques Applied to Study Silv...IRJET Journal
This document discusses computational nanotechnology methods for simulating silver nano dots. It describes three types of nanotechnologies: wet, dry, and computational. Computational nanotechnology uses computer algorithms and simulations to model nanostructures and devices. The document focuses on using software tools like Quantum Dot Lab and molecular dynamics simulations to model the structure, properties, and dynamics of silver quantum dots at the nanoscale. These computational methods allow for faster, more accurate analysis compared to experimental techniques alone. The simulations provide insights into the charged states, light emission, and movement of atoms in silver nano dots over time.
An Overview of Clearance Optimization in Sheet Metal Blanking ProcessIJMER
Abstract: This document prescribes a model investigation the effect of potential parameters influencing the blanking
process and their interaction. The blanking process optimization carried out by using Design of Experiment (DOE), Finite
Element Method (FEM) with ANSYS Package, Simulation with ABAQUS-Explicit software, Blank soft Software and Neural
Network Simulation in order to achieve the intended model objectives.
Keywords: Blanking Process, DOE, FEM, Optimum Clearance and Simulation.
This document discusses optimization of clearance in sheet metal blanking processes. It investigates how parameters like clearance, tool wear, and sheet thickness affect blanking results. The blanking process is modeled using finite element analysis and design of experiments to understand interactions. An optimum clearance is defined as the point where the crack propagation direction coincides with the diagonal line between punch and die contact points, resulting in clean separation. The document outlines algorithms to predict blanking forces, crack initiation and geometry based on clearance and other factors.
Design Modification of Failure Mode Effect Analysis of Vibrating Feeder used ...ijsrd.com
Vibratin feeder technology is common in material handling applications in numerous industries. This review paper examines a problem with fatigue in the support structure of a specific type of vibrating feeder. It also reviews the theory behind vibrating feeder technology and considerations that engineers who design them need to be aware of. The finite element method is used to replicate a fatigue problem in the support structure and various design configurations are then analyzed to reduce the risk of the conditions that caused the fatigue. The results are reviewed and recommendations are made to improve the design and modify the component dimensional parameters vibrating feeder.
Nano Scale Surface Characterization of Poly Ethyleneterephthalate Silicon Rub...ijtsrd
Atomic force microscopy has been used to investigated the surface properties of different materials, in this paper it is used to measure the surface roughness and surface adhesive force of three different membrane samples Poly ethyleneterephthalate PET , Silicon Rubber SR and PET SRcopolymers. This analytical method allows images representing the topography and adhesive force Phase image of the surface to be captured simultaneously at a molecular nanometer resolution. The distribution of hydrophilic polar groups and the surface roughness on the investigated surfaces ofthese membrane samples influences the subsequent processing of polymeric membrane manufacture as well as their performance. From the results a clear distinction was observed between the three samples in both images the topography surface roughness images and adhesive force images. Promising result were obtained for the PET SRcopolymer samples to be a good candidate in membrane separation applications. This study may also help to explain the differences in membrane performances and efficiency during applications in the separation process. Dr. Abduelmaged Abduallah | Dr. Kamal M. Sassi | Dr. Mustafa T. Yagub "Nano-Scale Surface Characterization of Poly (Ethyleneterephthalate) - Silicon Rubber Copolymers using Atomic Force Microscopy" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-4 , June 2021, URL: https://www.ijtsrd.compapers/ijtsrd43688.pdf Paper URL: https://www.ijtsrd.comengineering/chemical-engineering/43688/nanoscale-surface-characterization-of-poly--ethyleneterephthalate--silicon-rubber-copolymers-using-atomic-force-microscopy/dr-abduelmaged-abduallah
Establishing empirical relations to predict grain size and hardness of pulsed...drboon
SS 304L, an austenitic Chromium-Nickel stainless steel offering the optimum combination of corrosion resistance, strength and ductility, is favorable for many mechanical components. The low carbon content reduces susceptibility to carbide precipitation during welding. In case of single pass welding of thinner section of this alloy, pulsed current micro plasma arc welding was found beneficial due to its advantages over the conventional continuous current process. The paper focuses on developing mathematical models to predict grain size and hardness of pulsed current micro plasma arc welded SS304L joints. Four factors, five level, central composite rotatable design matrix is used to optimize the number of experiments. The mathematical models have been developed by response surface method. The adequacy of the models is checked by ANOVA technique. By using the developed mathematical models, grain size and hardness of the joints can be predicted with 99% confidence level. Contour plots are drawn to study the interaction effect of pulsed current micro plasma arc welding parameters on fusion zone grain size and hardness of SS304L steel.
Establishing empirical relations to predict grain size and hardness of pulsed...drboon
SS 304L, an austenitic Chromium-Nickel stainless steel offering the optimum combination of corrosion resistance, strength and ductility, is favorable for many mechanical components. The low carbon content reduces susceptibility to carbide precipitation during welding. In case of single pass welding of thinner section of this alloy, pulsed current micro plasma arc welding was found beneficial due to its advantages over the conventional continuous current process. The paper focuses on developing mathematical models to predict grain size and hardness of pulsed current micro plasma arc welded SS304L joints. Four factors, five level, central composite rotatable design matrix is used to optimize the number of experiments. The mathematical models have been developed by response surface method. The adequacy of the models is checked by ANOVA technique. By using the developed mathematical models, grain size and hardness of the joints can be predicted with 99% confidence level. Contour plots are drawn to study the interaction effect of pulsed current micro plasma arc welding parameters on fusion zone grain size and hardness of SS304L steel.
Influence of process parameters on MRR in EDM of AISI D2 Steel: a RSM approachMohan Kumar Pradhan
Response Surface Methodology (RSM) is used to investigate the
effect of three controllable input variables namely: discharge current, pulse duration,
and pulse off time on material removal rate (MRR) in EDM process. To study the
proposed second-order polynomial model for MRR, a central composite design is
used to estimation the model coefficients of the three factors, which are believed to
influence the MRR in EDM process. Experiments were conducted on AISI D2 tool
steel with copper electrode. The response is modeled using RSM on the experimental
data. The significant coefficients are obtained by performing analysis of variance
(ANOVA) at 5% level of significance. It is found that discharge current, pulse duration,
and pulse off time and few of their interactions have significant effect on the MRR.
The model sufficiency is very satisfactory as the coefficient of determination (R2) is
found to be 97.6%.
Effect of the welding process parameter in mmaw for joining of dissimilar metalsIAEME Publication
This document discusses optimizing welding parameters for joining dissimilar metals using manual metal arc welding and an artificial neural fuzzy interface system. Experimental results were analyzed using regression analysis to develop mathematical models relating welding current, voltage, speed, and electrode angle to weld strength and metal deposition rate. An artificial neural network was trained on the experimental data and used to predict the optimal parameters to achieve the highest weld strength. Validation experiments showed the artificial neural fuzzy interface system successfully optimized the welding parameters.
IRJET- A Fault Diagnosis in Aluminium Honeycomb Structure using Vibration Tec...IRJET Journal
This document summarizes a study on detecting damage in aluminum honeycomb structures using vibration analysis and finite element modeling. Artificial damage was introduced during manufacturing. Natural frequencies were measured experimentally using an FFT analyzer and compared to ANSYS simulations. Frequency changes between the damaged and undamaged structures were used to locate and quantify damage by plotting contour lines from normalized frequency data. The goal was to identify damage location and severity to improve safety for applications like aircraft and ships.
Analytical Model Of An Induction Motor Taking Into Account The Punching Proce...Ashley Carter
This document presents an analytical model for calculating the operating parameters of an induction motor that accounts for changes in the material properties of the laminated core caused by the punching process. The model determines an equivalent width and properties for a uniformly damaged zone near cut edges based on magnetic property measurements of samples with different widths. These equivalent properties are then used in an analytical circuit model to calculate motor losses and efficiency. The results show good agreement with measurements and demonstrate the importance of accounting for size-dependent material changes induced during manufacturing.
Identification of Material Parameters of Pultruded FRP Composite Plates using...Subhajit Mondal
This document summarizes research that used finite element model updating to identify material parameters of pultruded fiber reinforced plastic (FRP) composite plates. Researchers conducted experimental modal testing on an FRP plate to measure its vibration responses. They then used an inverse eigensensitivity method to update a finite element model of the plate, adjusting the model's in-plane elastic parameters until its responses matched experimental data. This allowed them to estimate the plate's actual elastic properties nondestructively. The technique was validated using independent quasi-static tests, demonstrating its potential for structural health monitoring of pultruded FRP infrastructure.
This document summarizes an investigation into the effects of machining parameters on the surface finish and material removal rate when machining an aluminum-copper alloy (AL6351) using wire electric discharge machining (WEDM). The study uses Taguchi's design of experiments method to analyze the effects of pulse on-time, pulse off-time, and peak current. Sixteen experiments were conducted and the material removal rate and surface roughness were measured. The results were analyzed using ANOVA to determine the most significant parameters for improving surface finish and removal rate. The goal of the research was to optimize the WEDM process for machining AL6351 alloy.
High Performance Nanocomposites for Mechanical Application: Design, Preparati...Alessio Passalacqua
To effectively design polymer nanocomposites for industrial applications, it is necessary to understand the effects of nanoparticles on final proprieties of the polymers. In this project, systematic studies are carried out on the variability of the structural and mechanical properties as function of the different used nanofiller. Furthermore, the overall mission is to find a correlation between the structural and mechanical changes with the tribological proprieties of thermoplastic nanocomposite due to the inclusion of nanoparticle. This will allow to design nanocomposite materials by selecting ad hoc nanofillers in order to increase their efficiency for mechanical engineering and metal replacement applications.
Process parameter optimization of SLM process and application of Taguchi appr...ijsrd.com
Selective Laser Melting (SLM) is an emerging powder based additive layer manufacturing technology that used to fabricate three-dimensional fully functional parts from metal powders by fusing the material in a layer by layer manner as per a CAD model. The quality of SLM produced parts is significantly affected by various manufacturing parameters of SLM machine. Hence optimization of SLM process parameters is necessary in order to improve the quality of parts. The purpose of this paper is to explore the reviews for various optimization methods used for process parameter optimization of SLM process and application of Taguchi approach. This review of work can be helpful to the other researchers to carry out further work in the same era.
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
In our second session, we shall learn all about the main features and fundamentals of UiPath Studio that enable us to use the building blocks for any automation project.
📕 Detailed agenda:
Variables and Datatypes
Workflow Layouts
Arguments
Control Flows and Loops
Conditional Statements
💻 Extra training through UiPath Academy:
Variables, Constants, and Arguments in Studio
Control Flow in Studio
From Natural Language to Structured Solr Queries using LLMsSease
This talk draws on experimentation to enable AI applications with Solr. One important use case is to use AI for better accessibility and discoverability of the data: while User eXperience techniques, lexical search improvements, and data harmonization can take organizations to a good level of accessibility, a structural (or “cognitive” gap) remains between the data user needs and the data producer constraints.
That is where AI – and most importantly, Natural Language Processing and Large Language Model techniques – could make a difference. This natural language, conversational engine could facilitate access and usage of the data leveraging the semantics of any data source.
The objective of the presentation is to propose a technical approach and a way forward to achieve this goal.
The key concept is to enable users to express their search queries in natural language, which the LLM then enriches, interprets, and translates into structured queries based on the Solr index’s metadata.
This approach leverages the LLM’s ability to understand the nuances of natural language and the structure of documents within Apache Solr.
The LLM acts as an intermediary agent, offering a transparent experience to users automatically and potentially uncovering relevant documents that conventional search methods might overlook. The presentation will include the results of this experimental work, lessons learned, best practices, and the scope of future work that should improve the approach and make it production-ready.
Session 1 - Intro to Robotic Process Automation.pdfUiPathCommunity
👉 Check out our full 'Africa Series - Automation Student Developers (EN)' page to register for the full program:
https://bit.ly/Automation_Student_Kickstart
In this session, we shall introduce you to the world of automation, the UiPath Platform, and guide you on how to install and setup UiPath Studio on your Windows PC.
📕 Detailed agenda:
What is RPA? Benefits of RPA?
RPA Applications
The UiPath End-to-End Automation Platform
UiPath Studio CE Installation and Setup
💻 Extra training through UiPath Academy:
Introduction to Automation
UiPath Business Automation Platform
Explore automation development with UiPath Studio
👉 Register here for our upcoming Session 2 on June 20: Introduction to UiPath Studio Fundamentals: https://community.uipath.com/events/details/uipath-lagos-presents-session-2-introduction-to-uipath-studio-fundamentals/
zkStudyClub - LatticeFold: A Lattice-based Folding Scheme and its Application...Alex Pruden
Folding is a recent technique for building efficient recursive SNARKs. Several elegant folding protocols have been proposed, such as Nova, Supernova, Hypernova, Protostar, and others. However, all of them rely on an additively homomorphic commitment scheme based on discrete log, and are therefore not post-quantum secure. In this work we present LatticeFold, the first lattice-based folding protocol based on the Module SIS problem. This folding protocol naturally leads to an efficient recursive lattice-based SNARK and an efficient PCD scheme. LatticeFold supports folding low-degree relations, such as R1CS, as well as high-degree relations, such as CCS. The key challenge is to construct a secure folding protocol that works with the Ajtai commitment scheme. The difficulty, is ensuring that extracted witnesses are low norm through many rounds of folding. We present a novel technique using the sumcheck protocol to ensure that extracted witnesses are always low norm no matter how many rounds of folding are used. Our evaluation of the final proof system suggests that it is as performant as Hypernova, while providing post-quantum security.
Paper Link: https://eprint.iacr.org/2024/257
inQuba Webinar Mastering Customer Journey Management with Dr Graham HillLizaNolte
HERE IS YOUR WEBINAR CONTENT! 'Mastering Customer Journey Management with Dr. Graham Hill'. We hope you find the webinar recording both insightful and enjoyable.
In this webinar, we explored essential aspects of Customer Journey Management and personalization. Here’s a summary of the key insights and topics discussed:
Key Takeaways:
Understanding the Customer Journey: Dr. Hill emphasized the importance of mapping and understanding the complete customer journey to identify touchpoints and opportunities for improvement.
Personalization Strategies: We discussed how to leverage data and insights to create personalized experiences that resonate with customers.
Technology Integration: Insights were shared on how inQuba’s advanced technology can streamline customer interactions and drive operational efficiency.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/temporal-event-neural-networks-a-more-efficient-alternative-to-the-transformer-a-presentation-from-brainchip/
Chris Jones, Director of Product Management at BrainChip , presents the “Temporal Event Neural Networks: A More Efficient Alternative to the Transformer” tutorial at the May 2024 Embedded Vision Summit.
The expansion of AI services necessitates enhanced computational capabilities on edge devices. Temporal Event Neural Networks (TENNs), developed by BrainChip, represent a novel and highly efficient state-space network. TENNs demonstrate exceptional proficiency in handling multi-dimensional streaming data, facilitating advancements in object detection, action recognition, speech enhancement and language model/sequence generation. Through the utilization of polynomial-based continuous convolutions, TENNs streamline models, expedite training processes and significantly diminish memory requirements, achieving notable reductions of up to 50x in parameters and 5,000x in energy consumption compared to prevailing methodologies like transformers.
Integration with BrainChip’s Akida neuromorphic hardware IP further enhances TENNs’ capabilities, enabling the realization of highly capable, portable and passively cooled edge devices. This presentation delves into the technical innovations underlying TENNs, presents real-world benchmarks, and elucidates how this cutting-edge approach is positioned to revolutionize edge AI across diverse applications.
ScyllaDB is making a major architecture shift. We’re moving from vNode replication to tablets – fragments of tables that are distributed independently, enabling dynamic data distribution and extreme elasticity. In this keynote, ScyllaDB co-founder and CTO Avi Kivity explains the reason for this shift, provides a look at the implementation and roadmap, and shares how this shift benefits ScyllaDB users.
This talk will cover ScyllaDB Architecture from the cluster-level view and zoom in on data distribution and internal node architecture. In the process, we will learn the secret sauce used to get ScyllaDB's high availability and superior performance. We will also touch on the upcoming changes to ScyllaDB architecture, moving to strongly consistent metadata and tablets.
Must Know Postgres Extension for DBA and Developer during MigrationMydbops
Mydbops Opensource Database Meetup 16
Topic: Must-Know PostgreSQL Extensions for Developers and DBAs During Migration
Speaker: Deepak Mahto, Founder of DataCloudGaze Consulting
Date & Time: 8th June | 10 AM - 1 PM IST
Venue: Bangalore International Centre, Bangalore
Abstract: Discover how PostgreSQL extensions can be your secret weapon! This talk explores how key extensions enhance database capabilities and streamline the migration process for users moving from other relational databases like Oracle.
Key Takeaways:
* Learn about crucial extensions like oracle_fdw, pgtt, and pg_audit that ease migration complexities.
* Gain valuable strategies for implementing these extensions in PostgreSQL to achieve license freedom.
* Discover how these key extensions can empower both developers and DBAs during the migration process.
* Don't miss this chance to gain practical knowledge from an industry expert and stay updated on the latest open-source database trends.
Mydbops Managed Services specializes in taking the pain out of database management while optimizing performance. Since 2015, we have been providing top-notch support and assistance for the top three open-source databases: MySQL, MongoDB, and PostgreSQL.
Our team offers a wide range of services, including assistance, support, consulting, 24/7 operations, and expertise in all relevant technologies. We help organizations improve their database's performance, scalability, efficiency, and availability.
Contact us: info@mydbops.com
Visit: https://www.mydbops.com/
Follow us on LinkedIn: https://in.linkedin.com/company/mydbops
For more details and updates, please follow up the below links.
Meetup Page : https://www.meetup.com/mydbops-databa...
Twitter: https://twitter.com/mydbopsofficial
Blogs: https://www.mydbops.com/blog/
Facebook(Meta): https://www.facebook.com/mydbops/
QA or the Highway - Component Testing: Bridging the gap between frontend appl...zjhamm304
These are the slides for the presentation, "Component Testing: Bridging the gap between frontend applications" that was presented at QA or the Highway 2024 in Columbus, OH by Zachary Hamm.
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as “keys”). In fact, it’s unlikely you’ll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
Northern Engraving | Nameplate Manufacturing Process - 2024Northern Engraving
Manufacturing custom quality metal nameplates and badges involves several standard operations. Processes include sheet prep, lithography, screening, coating, punch press and inspection. All decoration is completed in the flat sheet with adhesive and tooling operations following. The possibilities for creating unique durable nameplates are endless. How will you create your brand identity? We can help!
AppSec PNW: Android and iOS Application Security with MobSFAjin Abraham
Mobile Security Framework - MobSF is a free and open source automated mobile application security testing environment designed to help security engineers, researchers, developers, and penetration testers to identify security vulnerabilities, malicious behaviours and privacy concerns in mobile applications using static and dynamic analysis. It supports all the popular mobile application binaries and source code formats built for Android and iOS devices. In addition to automated security assessment, it also offers an interactive testing environment to build and execute scenario based test/fuzz cases against the application.
This talk covers:
Using MobSF for static analysis of mobile applications.
Interactive dynamic security assessment of Android and iOS applications.
Solving Mobile app CTF challenges.
Reverse engineering and runtime analysis of Mobile malware.
How to shift left and integrate MobSF/mobsfscan SAST and DAST in your build pipeline.
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
"NATO Hackathon Winner: AI-Powered Drug Search", Taras KlobaFwdays
This is a session that details how PostgreSQL's features and Azure AI Services can be effectively used to significantly enhance the search functionality in any application.
In this session, we'll share insights on how we used PostgreSQL to facilitate precise searches across multiple fields in our mobile application. The techniques include using LIKE and ILIKE operators and integrating a trigram-based search to handle potential misspellings, thereby increasing the search accuracy.
We'll also discuss how the azure_ai extension on PostgreSQL databases in Azure and Azure AI Services were utilized to create vectors from user input, a feature beneficial when users wish to find specific items based on text prompts. While our application's case study involves a drug search, the techniques and principles shared in this session can be adapted to improve search functionality in a wide range of applications. Join us to learn how PostgreSQL and Azure AI can be harnessed to enhance your application's search capability.
"Frontline Battles with DDoS: Best practices and Lessons Learned", Igor IvaniukFwdays
At this talk we will discuss DDoS protection tools and best practices, discuss network architectures and what AWS has to offer. Also, we will look into one of the largest DDoS attacks on Ukrainian infrastructure that happened in February 2022. We'll see, what techniques helped to keep the web resources available for Ukrainians and how AWS improved DDoS protection for all customers based on Ukraine experience
2. 152 Computer Science & Information Technology (CS & IT)
Recently, AFM tips have been used as cutting tools for surface modification. Nanochannels,
nanoslots, and complex nanopatterns can be fabricated by directly scratching the substrate [9].
These AFM-based mechanical indentation and scratching techniques have been successfully
applied to produce complex geometries and high aspect-ratio 3D nano-objects on both flat and
curved surfaces [10]. Nanoindentation and nanoscratching are capable of fabricating complex
structures, and advances in materials, pattern transfer processes, and cost reductions of AFM
equipment have allowed these methods to become a viable but not yet scalable method for many
nanoscale devices [14]. Process throughput is low due to limited removal speed, tip-surface
approach, contact detection, desired force profile, and tool wear. Parallel fabrication using
multiple AFM tip arrays has been reported [5]. However, parallel fabrication currently does not
allow precise control over size, shape, position, or orientation of individual structures. A
fundamental understanding of substrate deformations/separations and the tip is needed to achieve
controllable nanomanufacturing [1]. Attempts have been made to study the correlation between
machining parameters, machined geometry, and surface properties for better control of AFM-based
nanomachining processes both experimentally [15-21] and computationally [22-55]. This
include experiments on few types of materials to investigate the effects of parameters such as
applied load, scratching speed, feed rate, scratching direction, tip geometry, tip angle, tip radius,
and number of scratching cycles. These parameters which also depend on material properties and
crystal orientation of the substrate, affect the depth, width, chip formation, and surface roughness
of the machined surface. Due to experimental limitations, computational models are therefore
essential to achieve a more comprehensive/complete understanding of the roles of the parameters
affecting the final nano-geometry in AFM-based nanomachining. On the other hand, a more
extensive experimental study is necessary to inform the development of accurate and realistic
predictive models. The experimental data is also needed to validate the computational models.
To address the need for computational models of AFM-based nanomachining, some efforts have
been made to model nanoindentation and nanoscratching using MD simulations [22-55]. MD
simulation presents itself as a viable alternative to the expensive traditional experimental
approach. Such a simulation was initiated in the late 1950s by Alder and Wainwright [56-57] in
the field of statistical mechanics and has been successfully applied to investigate various
phenomena at nanoscale. The advantage of MD simulation over continuum model simulation
(FE) is that it allows for a better, more detailed understanding of the ways defects are created, the
transition from elastic to plastic behavior, and crystal structure effects in materials [22].
Numerous studies have been reported on MD simulations of nanoindentaion and nanoscratching.
The effects of several parameters such as crystal orientation [41, 45, 46], indenter shape and
orientation [33, 39, 40, 44], penetration or scratching depth [37, 42, 47, 48], scratching speed [47,
48], feed (on nanoscratching) [34, 35], and temperature [25, 45, 49] have been investigated on
different types of bulk and thin film materials. In addition, mechanical properties including
Young’s modulus, friction coefficient and hardness of materials have also been reported [26, 42].
MD simulation quality depends on the accuracy of the potential energy function used. Also, the
complexity of the potential energy function directly affects computational time. The selection of
the potential function depends on material type. Various types were investigated in MD
simulations: silicon [22, 30, 31], gold [32], copper [25, 33-35], aluminum [36-38], silver [39, 40],
iron [41, 42] and nickel [43, 44]. However, MD simulation involves the interaction of a large
number of atoms as deformation occurs on an atomic scale. One major concern in MD simulation
is the high computational time required. Existing MD models are limited in the size of simulated
volume as well as time scale, inhibiting the ability to capture all important attributes for
deformation. To keep the processing time under control, most existing models of nanoindentation
use less than 100,000 atoms. The largest models of nanoindentation found in the literature contain
approximately 10 million atoms [58], which are enabled by parallel computing.
In this paper, three-dimensional MD simulations of AFM nanoindentation and nanoscratching are
performed to investigate the effects of tip speed and crystal orientation for the case of gold
material. The simulation allows for the prediction of forces at the interface between an indenter
3. Computer Science & Information Technology (CS & IT) 153
and a substrate. The material deformation and deformed geometry are extracted based on the final
locations of the atoms, which have been displaced by the rigid tool. Mechanical properties
including Young’s modulus and hardness of materials are also reported. In addition, an AFM is
used to conduct actual indentation and scratching at the nanoscale, and provide data with which to
validate MD simulation. The results of the simulation as well as the AFM data are presented and
compared.
2. METHODOLOGY
MD simulation is used to simulate the time dependent behavior of a molecular system. MD
simulations of AFM-based nanomachining in this study are implemented using LAMMPS
(Large-scale Atomic/Molecular Massively Parallel Simulator) [59, 60]. The LAMMPS code run
in parallel uses distributed memory message passing techniques and spatial decomposition of
simulation domain. The inputs required in MD simulation are initial positions and velocities of
atoms in the system along with other information such as boundary conditions, potential energy
function, time steps, etc. The outputs of the simulation include trajectories of atoms in the system,
forces, energy of the system, and other physical quantities of interest. The MD simulation model
and the potential functions used in this study are explained in the following sections.
2.1. Simulation Model
The schematic model used in the MD simulation of AFM nanoscratching is shown in Figure 1.
The simulation model consists of a single crystal gold workpiece and a three-sided pyramidal
indenter. Diamond is selected as indenter tip. The indenter tip is modeled as a rigid body. The
initial positions of atoms in the model are calculated from the default lattice position. For
example, face center cubic (fcc) structure is applied in the modeling of gold workpieces. On the
other hand, diamond structure is used for modeling of diamond indenter. The workpiece in the
MD simulation is divided into three different zones: boundary, thermostat, and the Newtonian
zones. A few layers of boundary and thermostat atoms are placed on the bottom side of the
workpiece. Fixed boundary conditions are applied to the boundary atoms. The atoms are fixed in
the position to reduce the edge effects and maintain the symmetry of the lattice. Periodic
boundary conditions are maintained along the x- and y-direction. The periodic boundary
conditions are usually employed when a simulation seek to investigate the behavior of an isolated
system, to avoid spurious edge effects and thereby simulate the behavior of a much larger crystal
system. The thermostat zone is applied to the MD simulation model to ensure that the heat
generated during the indentation process can be conducted out of the indentation region properly.
The temperature in the thermostat zone is maintained by scaling the velocities of the thermostat
atoms for each computational time step. In the Newtonian zone, atoms move according to
Newton’s equation of motion.
4. 154 Computer Science & Information Technology (CS & IT)
Figure 1. Schematic MD simulation model of AFM nanoscratching
2.2. Potential Energy Function
The motion of the atoms in the Newtonian zone is determined by the forces derived from
potential energy function and Newton’s equation of motion. The interaction of each atom can be
approximated by a potential energy function in accordance with Newtonian mechanics. The
quality of the MD simulation results depends on the accuracy of the potential energy function
used. On the other hand, the complexity of the potential energy function directly affects the
computational time [61]. The selection of the potential function depends on the type of material
used in the model. The potential energy function used for the interaction between atoms in the
gold (Au) workpiece materials is the Embedded Atom Method (EAM) potential [62]. The Morse
potential [63] is employed for the interaction between the gold workpiece and diamond indenter
tip in the MD simulations.
The Morse potential [63] is a commonly used empirical potential energy function for bonded
interactions The Morse potential energy function U can be expresses as a function of interatomic
distance r as the following formula:
U(r)=D{exp[−2a(r − re)] − 2 exp[−a(r − re)]} (1)
where r is the distance between the atoms, re is the equilibrium bond distance, D is the cohesive
energy, and is a parameter controlling the width of the potential. The single independent
variable in the equation is r. The constant parameters, re, , and D, can be determined on the basis
of the physical properties of the material. The parameters used in the Morse potential for gold are
listed in Table 1. The parameters between gold and carbon (Au-C) are calculated from the
following equations.
(2)
(3)
(4)
DAu−C = DAu × DC
aAu−C = aAu ×aC
re Au−C = re Au × re C
The EAM potential [62] is an extension of the two-body potential that has been developed for
metals. The basic approach of the EAM, which evolved from the density-function theory, is based
upon the recognition that the cohesive energy of a metal is governed not only by the pair-wise
5. Computer Science Information Technology (CS IT) 155
potential of the nearest neighbor atoms, but also by embedding energy related to the electron gas
that surrounds each atom.
Table 1. Parameters used in the Morse potential energy function
Parameter Au-Au
[64]
C-C
[25]
Au-C
D (eV)
(Å-1)
re (Å)
0.475
1.583
3.024
2.423
2.555
2.522
1.073
2.011
2.762
The interatomic force between any two atoms can be obtained from the potential energy function
(U) such that
Fij = −
¶U
¶rij
(5)
where Fij is the interatomic force between atom i and j at a distance rij from atom i. The
total force exerted on a particular atom is then calculated as the following equation.
N
Fi = F
ij
(r
ij
)
j = 1,i ¹ j
(6)
where Fi is the resultant force on atom i and N is the total number of atoms. After calculating
force on each atom, velocities and positions are calculated from Newton’s second law of motion.
In this study, material properties, Young’s modulus and hardness, are calculated using the
formulations developed by Oliver and Pharr [65]. They used data directly drawn from the load-displacement
curve and correlated the projected contact area, Ac, to the contact depth, hc, where hc
may be expresses as
hc = hmax − 0.72 Pmax
Smax
(7)
where hmax is the maximum depth of indentation, Pmax is the maximum applied load and Smax is the
slope of the unloading curve at the maximum applied load. The contact area, Ac, is thus found
from the geometry of the indenter as a function of the contact depth, hc. Once the contact area is
known, the hardness, H, is estimated from the maximum indentation load Pmax divided by the
projected contact area, i.e.
H =
Pmax
Ac
(8)
The Young’s modulus is calculated by the reduced elastic modulus, Er, which takes into account
the combined elastic effects of indenter tip and sample, as follows:
Er =
1
2
p
Ac
dP
dh
(9)
where dP/dh is the slope of tangent line at the beginning of the unloading curve and Ac is the
projected area at the maximum depth of indentation. The Young’s modulus of the sample, Es, is
then calculated from the following equation.
6. 156 Computer Science Information Technology (CS IT)
1
Er
=
2
1−n s
Es
+
2
1− ni
Ei
(10)
where Ei is the Young’s modulus of the indenter, and s and i are the Poisson’s ratios of the
sample and indenter, respectively.
2.3. Ensembles of Statistical Thermodynamics
Statistical ensembles are usually characterized by fixed values of thermodynamic variables such
as energy, E, temperature, T, pressure, P, volume, V, particle number, N, or chemical potential, μ.
One fundamental ensemble is called the microcanonical ensemble and is characterized by
constant particle number, N, constant volume, V and constant total energy, E, and is denoted as
the NVE ensemble. Other examples include the canonical, or NVT ensemble, the isothermal-isobaric
or NPT ensemble, and the grand canonical or μVT ensemble. In the current study,
microcanonical or NVE ensemble is applied in the Newtonian zone. The system is isolated from
changes in number of atoms (N), volume (V) and energy (E). It corresponds to an adiabatic
process with no heat exchange. A microcanonical molecular dynamics trajectory may be seen as
an exchange of potential and kinetic energy, with total energy being conserved.
2.4. Parallel MD Simulation
The parallel MD simulations of AFM-based nanomachining are implemented using LAMMPS
[59, 60]. The LAMMPS code run in parallel uses distributed memory message passing techniques
and spatial decomposition of simulation domain. In spatial decomposition, the simulation domain
is divided into a set of equal smaller sized domains. Each sub-domain is distributed to different
processor for calculation. Since nearby atoms are placed on same processor, only neighboring
atoms on different processor need to be communicated by Message Passing Interface (MPI).
Communication is minimized to optimal level by replicating force computations of boundary
atoms. Non-uniformity of data distribution can occur for spatial decomposition as interaction
between tool and workpiece arise. The parallel MD simulation is run on the Big Red II
supercomputer [66]. Big Red II is Indiana University's main system for high-performance parallel
computing. Big Red II combines the longstanding leadership of Cray supercomputers with IU-developed
technology. The Cray XE6/XK7 supercomputer is capable of one thousand trillion
floating-point operations per second, or one petaFLOPS, making it the fastest university-owned
supercomputer in the world.
2.5. MD Simulation Conditions
MD simulations of AFM-based nanomachining were conducted on single crystal gold with the
use of parallel computing. Table 2 gives the conditions used in the MD simulations of AFM-based
nanomachining. The dimensions of the workpiece and indenter, the depth of indentation
and the tip speeds are given. The dimensions of the workpiece are expressed in terms of the lattice
constants. The lattice constant of gold (aAu) is 4.080 Angstroms (Å).
Table 2. MD simulation conditions used in the MD simulations of AFM-based nanomachining
Workpiece material Gold (Au)
Workpiece dimension
Indent: 120aAu×120aAu×120aAu
Scratch: 160aAu×320aAu×40aAu
Crystal orientation Au: (100), (110), (111)
7. Computer Science Information Technology (CS IT) 157
Number of atoms in the
workpiece
Indent: 6,912,000 atoms
Scratch: 8,192,000 atoms
Indenter tip material Diamond
Indenter type Three sided pyramid
Indentation depth 1 - 7 nm
Nanoindentation tip
1, 10 m/s
speed
Bulk temperature 293 K
Time steps 1 fs (10-15s)
3. EXPERIMENTAL SETUP
A Veeco Bioscope AFM was used to conduct actual indent and scratch at the nanoscale, and
provides data for evaluation of the MD simulation predictions. The AFM provides resolution on
the nanometer (lateral) and angstrom (vertical) scales. A diamond probe (Bruker DNISP
indentation probe) with a spring constant of 250 N/m was used in the experiments. The indenter
tips have three-sided pyramid shapes. Nanoindentation is made by forcing the tip into the
workpiece until the required cantilever deflection is reached. The tip is then lifted to its initial
position above the workpiece. Nanoindentation can be made at various forces and rates, using the
deflection of the cantilever as a measure of the indentation force. The indentation force, F, is
directly proportional to the deflection of the cantilever can be calculated from the well-known
Hooke’s law:
F = kx (11)
where k is the cantilever stiffness or spring constant in N/m and x is the deflection of the
cantilever. Nanoscratching is performed by forcing the tip into the workpiece until the required
cantilever deflection is reached. The tip is then moved horizontally for a specified length and then
lifted to its initial position above the workpiece. The nanoindentation and nanoscratching
experiments were conducted at various applied forces and tip velocities.
4. RESULTS AND DISCUSSION
MD simulation results of AFM nanoindentation and nanoscratching are presented in this section.
All MD simulation snapshots are visualized by Atomeye [67]. The different colors shown in the
following figures represent coordination number, which is a measure of how many nearest
neighbors exist for a particular atom. For example, atoms in perfect fcc crystals have 12 nearest
neighbors and their atomic coordination number is accordingly 12. Atoms with coordination
numbers that are not 12 usually represent the location of defects and vacancies. The purpose of
using this coordination number coloring is to clearly see the defects and dislocations of atoms.
In nanoindentation process, the indenter tip moves vertically into the surface of substrate. The
atoms in the substrate are compressed beneath the tip and the deformation can be seen in the
vicinity of the tip. The material apart from the tip seems to effect very little by the motion of the
tip. MD simulation snapshots of nanoindentation are shown in Figure 2. The figure shows the
initial stage of indenter tip and workpiece material in nanoindentation followed by the movement
of the tip into the workpiece material at various time intervals. At the surrounding of contact
surface between the indenter tip and the workpiece, a material pile-up is observed. Figure 3 shows
top and cross-sectional views of MD simulation snapshots of nanoindentation. The tip is located
at the maximum indentation depth at the time of 55 ps (Figure 3 (a)), while the tip is moved to its
8. 158 Computer Science Information Technology (CS IT)
initial point at the time of 115 ps (Figure 3(b)). The elastic deformation on the top surface of the
gold workpiece undergoes elastic recovery after the tool tip was moved upward from the
workpiece. It can be seen from Figure 3 that some deformation on the surface disappeared after
the tool tip was moved up. Moreover, the depth of indentation mark and subsurface deformation
decrease after the tip was removed from the workpiece.
Figure 4 shows the MD simulation snapshots of nano-scratching with the scratching depth of 5
nm. The crystal orientation of workpiece material is Au(100) and the direction of scratching is
[100]. The scratching length is 30 nm and the tip speed is 10 m/s. The atoms in the workpiece are
compressed beneath and in front of the tip and assembled to form a small chip. The material pile-up
can be seen along the resulting groove. Several types of defects, including vacancies and
Shockley partial dislocation loops, can be observed during the simulation. The dislocation loops
are highly mobile and participate in various interactions among themselves and with other
defects. The dislocation loops on the top surface are emitted in front of the tip and generally move
out of the computation domain at a side boundary and come inside from the opposite side of
boundary, due to the periodic boundary conditions applied to all four side boundaries.
Figure 2. MD simulation snapshots of nano-indentation at various times: (a) 0 ps; (b) 10 ps; (c) 30 ps; (d)
55 ps; (e) 80 ps; (f) 115 ps
(a)
(b)
Figure 3. Top (left) and cross-sectional (right) views of MD simulation snapshots of nano-indentation: (a)
time = 55 ps; (b) time = 115 ps
9. Computer Science Information Technology (CS IT) 159
Figure 4. MD simulation snapshots of nano-scratching with a scratching depth of 5 nm.
The effect of scratching depth on material deformation was investigated. MD simulations of
nanoscratching were conducted with scratch depths varying from 1 to7 nm. Top and cross-sectional
views of MD simulation snapshots of nanoscratching at various scratching depths are
shown in Figs. 5 - 6, respectively. As the scratching depth increases, the deformation is found to
penetrate much deeper from the surface and the height of material pile-up also increases. In
addition, more dislocation loops on the top surface can be observed. With increasing depth, the
dislocations reach side boundaries sooner and re-enter from the opposite side. Some of these
partial dislocations interact with other defects to form more defects on the top surface. This
indicates that a larger computation domain is needed.
(a) (b)
(c) (d)
Figure 5. Top view of MD simulation snapshots of nanoscratching with different depths of scratch: (a) 1
nm; (b) 3 nm; (c) 5 nm; (d) 7 nm.
10. 160 Computer Science Information Technology (CS IT)
(a)
(b)
(c)
(d)
Figure 6. Cross-sectional views of MD simulation snapshots of nanoscratching with different depths of
scratch: (a) 1 nm; (b) 3 nm; (c) 5 nm; (d) 7 nm.
The effects of crystal orientation are presented. Here, the MD simulations of nanoscratching were
conducted on three different crystal orientations: Au(100), Au(110), and Au(111). The scratching
depths are 5 nm for all the three cases. Figs 7 – 9 show cross-sectional (a, b) and top (c, d) views
of different crystal orientations. Different pattern of surface and subsurface deformation can be
observed for different crystal orientations.
(a)
(b)
Figure 7. Cross-sectional (a) and top (b) views of MD simulation snapshots of nanoscratching of Au(100)
11. Computer Science Information Technology (CS IT) 161
(a)
(b)
Figure 8. Cross-sectional (a) and top (b) views of MD simulation snapshots of nanoscratching of Au(110)
(a)
(b)
Figure 9. Cross-sectional (a) and top (b) views of MD simulation snapshots of nanoscratching of Au(111)
Fig. 10 shows AFM image and cross-sectional profile of nanoindentation for different applied
forces, increasing from right to left: 65, 70, 75, 80, 85 μN. The AFM experiments were repeated
for five times (five rows shown in Fig. 10). The indentation depths increase as the applied forces
increase. The variation of indentation forces with depths of indentation at different tool tip speeds
is shown in Figure 11. It can be observed that the indentation force increases as the depth of
indentation increases. The simulation results were compared with the experimental results. Due to
the limitation on computational time, it should be noted that the tool tip speeds used in this MD
simulation are a lot higher than those used in the experiment. The typical speed used in the
experiment is approximately 5-10 μm/s. Therefore, the effect of tool tip speed on the indentation
force is also investigated in this paper. It can be observed from Figure 11 that the indentation
force increases as the tool tip speed decreases. Since the tip speed plays an important role on the
indentation force, the quantitative values of the indentation force obtained from MD simulation
are not comparable to the experimental results. However, the increasing trends of indentation
force are the same for both simulation and experimental results. AFM experiments of
nanoindentation were also carried out to investigate the effect of the tip speed. Fig. 12 shows the
experimental results of AFM nanoindentation for different applied forces and different tip speeds.
The tip speeds were increased from 1 to 10 μm/s from top to bottom rows. Fig. 12 (b) shows the
cross-sectional profile of AFM nanoindentation. The blue line represents the cross-sectional
profile for the tip speed of 1 μm/s. The red line represents the cross-sectional profile for the tip
speed of 10 μm/s. It can be seen from Fig. 12 (b) that the indentation depth increases as the tip
speed increases.
12. 162 Computer Science Information Technology (CS IT)
(a)
(b)
Figure 10. (a) AFM image of nanoindentation for different applied forces (increasing from right to left); (b)
cross-sectional profile of AFM image
v=1 m/s
v = 10 m/s
Experimental results
v = 10μm/s
Figure 11. Variation in indentation forces with depths of indentation.
13. Computer Science Information Technology (CS IT) 163
(a) (b)
Figure 12. (a) AFM image of nanoindentation for different applied forces (increasing from right to left) and
tip speeds (increasing from top to bottom); (b) cross-sectional profile of AFM image
Figure 13 shows the AFM experimental results of nanoscratching with five different depths,
namely 20, 30, 40, 50, 60 nm (increasing from right to left). As can be seen from figure 13(b), the
surface roughness varies between 0 to 20 nm across the gold substrate. In order to obtain a
meaningful result, the depths of scratch used in the experiments must be higher than 20 nm which
are ten times the depths used in the MD simulation. For this reason, the quantitative values, i.e.
forces, obtained from MD simulation are not comparable to the experimental results; only the
qualitative values are discussed here. The height of the material pile-up along the scratch groove
is found to increase as the depth of cut increases in both MD simulation and AFM experiments.
However, the material pile-up on the left side is observed to be higher than the right side which is
different from the MD simulation results. One possible explanation for the discrepancy may be
that the x-rotation of the AFM probe used in the experiment was set to 12 degree as
recommended by manufacturer. During the nanoscratching process, the pile-up material in front
of the tip increases, but not enough to form chip. Thus, no chip formation is detected in both MD
simulation and experiments for the observed depths of scratch.
(a) (b)
Figure 13. AFM experimental results of nano-scratching with five scratch depths of 20, 30, 40, 50, 60 nm
increasing from right to left: (a) AFM image of nanoscratching (b) cross-sectional profile
Figure 14 shows load-displacement curve for the case of gold material and diamond indenter tip.
As the indentation depth of the diamond tip continues to increase, the load curve continues to go
up and until its reaches a maximum depth. After reaching the specified maximum depth, the tip
begins to unload and return to it original position. The slope of the unloading curve at the
maximum load is determined and used in the calculation of hardness and Young’s modulus in Eq.
(8) and (10), respectively. Two different methods were used to calculate the contact area. In the
first method, the contact area was calculated from the geometry of the indenter as a function of
the contact depth, hc. In the second method, the contact area was estimated from the location of
displaced atoms at the interface between tip and sample. The material properties of diamond
indenter used in the calculation are Ei = 1140 GPa and i = 0.07. Table 3 shows the values of
Young’s modulus and hardness of gold obtained from the calculations.
14. 164 Computer Science Information Technology (CS IT)
Loading
Unloading
Figure 14. Load-displacement curves for the case of gold material and diamond indenter tip.
Table 3. Young’s modulus and hardness of materials at nanoscale
Young’s modulus
(GPa)
Hardness
(GPa)
Method 1
Hardness
(GPa)
Method 2
235
113.56
98.13
Comparing to the macroscale properties, the Young’s modulus of gold is approximately 57-120
GPa; while it was found to be 235 GPa from our calculation. The values of hardness obtained
from method 1 in our calculation is slightly larger than those obtained from method 2. Both
Young’s modulus and hardness in our analysis were about two to three times larger than those at
the macroscale. This discrepancy is a result of the scale differences. Bulk material typically has
constant material properties regardless of its size, but size-dependent properties are often
observed at the nanoscale. Nanoscale material has a high surface area and a large fraction of the
atoms are on its surface. This can give rise to size effects in material properties at the nanoscale.
Moreover, the defect of the material such as grain boundaries and dislocations was different at
different scales. In addition, an assumption of perfect defect-free single-crystal material was
applied in the MD simulation; while, in general, materials at macroscale were poly-crystalline and
contained several types of defects.
3. CONCLUSIONS
MD simulations of AFM-based nanoindentation and nanoscratching were conducted to
investigate the effect of indentation and scratching depth, crystal orientation and tip speed.
Material properties at the nanoscale were also extracted and compared with macroscopic
properties. Several types of defects, including vacancies and Shockley partial dislocation loops,
could be observed during the simulation. With increasing depth of scratch, the dislocations reach
side boundaries sooner and re-enter from the opposite side. Some of these partial dislocations
interact with other defects to form more defects on the top surface. Due to the periodic boundary
condition applied to all the four side boundaries, the simulation domain should be large enough to
avoid the re-entering of dislocations. For different crystal orientations, different pattern of surface
15. Computer Science Information Technology (CS IT) 165
and subsurface deformation can be observed. The effect of indentation depths and tip speeds was
investigated and found that indentation force increases as depth of indentation and tip speed
increase. Material properties, e.g. Young’s modulus and hardness, of the materials at the
nanoscale are different from those at the macroscale. Hence, due to different material properties
between nano- and macro-scale, materials at nanoscale are typically considered new types of
material. As can be seen from the presented results, these machining parameters affected the final
nano-geometry in AFM-based nanomachining. The findings from this work can be applied to the
fabrication of nanochannels/nano-fluidic devices. However, a more extensive experimental study
is necessary to better validate the computational models. This will be reported in our future work.
ACKNOWLEDGEMENTS
This research was supported in part by Lilly Endowment, Inc., through its support for the Indiana
University Pervasive Technology Institute, and in part by the Indiana METACyt Initiative. The
Indiana METACyt Initiative at IU is also supported in part by Lilly Endowment, Inc.
REFERENCES
[1] A.P. Malshe, K.P. Rajurkar, K.R. Virwani, C.R. Taylor, D.L. Bourell, G. Levy, M.M. Sundaram, J.A.
McGeough, V. Kalyanasundaram and A.N. Samant, “Tip-based nanomanufacturing by electrical,
chemical, mechanical and thermal processes,” CIRP Annals - Manufacturing Technology, Vol. 59, pp.
628-651, 2010.
[2] A. C. Fischer-Cripps, Nanoindentation, Springer, New York, 2002.
[3] A. N. Shipway, E. Katz and I Willner, “Nanoparticle Arrays on Surfaces for Electronic, Optical, and
sensor applications,” ChemPhysChem, Vol. 1(1), pp. 18–52, 2000.
[4] M. Liu, N. A. Amro, C. S. Chow and G-Y Liu, “Production of Nanostructures of DNA on Surfaces,”
Nano Letters, Vol. 2(8), pp. 863–867, 2002.
[5] P. Vettiger, M. Despont, U. Drechsler, U. Dürig, W. Häberle, M. I. Lutwyche, H. Rothuizen, R. Stutz,
R. Widmer and G. K. Binnig, “The ‘millipede’ – more than one thousand tips for future AFM data
storage,” IBM Journal of Research and Development, Vol. 44(3), pp. 323–340, 2000.
[6] C. R. Taylor, E. A. Stach, G. Salamo and A. P. Malshe, “Nanoscale dislocation Patterning by
Ultralow Load Indentation,” Applied Physics Letters, Vol. 87(7), 073108, 2005.
[7] G. F. Zheng, F. Patolsky, Y. Cui, W. U. Wang and C. M. Lieber, “Multiplexed electrical detection of
cancer markers with nanowire sensor arrays,” Nature Biotechnology, Vol. 23(10), pp. 1294-1301,
2005.
[8] X. Li, H. Gao, C. J. Murphy and K. K. Caswell, “Nanoindentation of silver nanowires,” Nano Letters,
Vol. 3, pp.1495-1498, 2003.
[9] X. Li, P. Nardi, C. W. Baek, J. M. Kim and Y. K. Kim, “Direct nanomechanical machining of gold
nanowires using a nanoindenter and an atomic force microscope,” Journal of Micromechanics and
Microengineering, Vol. 15, pp. 551-556, 2005.
[10] Y. D. Yan, T. Sun, X. S. Zhao, Z. J. Hu and S. Dong, “Fabrication of microstructures on the surface
of a micro/hollow target ball by AFM,” Journal of Micromechanics and Microengineering, Vol. 18,
035002, 2008.
[11] Y. J. Chen, J. H. Hsu and H. N. Lin, “Fabrication of metal nanowires by atomic force microscopy
nanoscratching and lift-off process,” Nanotechnology, Vol. 16, pp. 1112-1115, 2005.
[12] Y. T. Mao, K. C. Kuo, C. E. Tseng, J. Y. Huang, Y. C. Lai, J. Y. Yen, C. K. Lee and W. L. Chuang,
“Research on three dimensional machining effects using atomic force microscope,” Review of
Scientific Instruments, Vol. 80, 065105, 2009.
[13] T. Fang, C. Weng and J. Chang, “Machining characterization of nano-lithography process using
atomic force microscopy,” Nanotechnology, Vol. 11, pp. 181-187, 2000.
[14] S. Diegoli, C. A. E. Hamlett, S. J. Leigh, P. M. Mendes and J. A. Preece, “Engineering nanostructures
at surfaces using nanolithography,” Proceedings of the Institution of Mechanical Engineers, Part G:
Journal of Aerospace Engineering, Vol. 221(4), pp. 589-629, 2007.
[15] T. Sun, Y. D. Yan, J. F. Xia, S. Dong, Y. C. Liang and K. Cheng, “Research on micro machining
using AFM diamond tip,” Key Engineering Materials, Vols. 259-260, pp. 577-581, 2004.
16. 166 Computer Science Information Technology (CS IT)
[16] J. C. Huang, C. L. Li, and J. W. Lee, “The Study of Nanoscratch and Nanomachining on Hard
Multilayer Thin Films Using Atomic Force Microscope,” Scanning, Vol. 34, pp. 51-59, 2012.
[17] Y. Yan, T. Sun, Y. Liang and S. Dong, “Investigation on AFM-based micro/nano-CNC machining
system,” International Journal of Machine Tools and Manufacture, Vol. 47, pp. 1651-1659, 2007.
[18] F. Zhang, H. Zhang, Y. Yan and J. Wang, “ Research on nano-scale material removal process using
atomic force microscopy,” Key Engineering Materials, Vols. 359-360, pp. 269-273, 2008.
[19] H. Zhang, J. Kuai and F. Zhang, “Minimum thickness of cut in nanomachining using atomic force
microscopy,” 2010 International Conference on E-Product E-Service and E-Entertainment (ICEEE),
Henan, China, November 7-9, 2010.
[20] A. A. Tseng, J. Shirakashi, S. Nishimura, K. Miyashita and Z. Li, “Nanomachining of permalloy for
fabricating nanoscale ferromagnetic structures using atomic force microscopy,” Journal of
Nanoscience and Nanotechnology, Vol. 10, pp. 456-466, 2010.
[21] Z. Q. Wang, N. D. Jiao, S. Tung and Z. L. Dong, “Atomic force microscopy-based repeated
machining theory for nanochannels on silicon oxide surfaces,” Applied Surface Science, Vol. 257, pp.
3627-3631, 2011.
[22] W. C. D. Cheong and L. C. Zhang, “Molecular dynamics simulation of phase transformations in
silicon monocrystals due to nano-indentation,” Nanotechnology, Vol. 11, pp. 173-180, 2000.
[23] R. Komanduri, N. Chandrasekaran and L.M. Raff, “MD simulation of indentation and scratching of
single crystal aluminum,” Wear, Vol. 240, pp. 113-143, 2000.
[24] D. Christopher, R. Smith and A. Richter, “Atomistic modelling of nanoindentation in iron and silver,”
Nanotechnology, Vol. 12, pp. 372-383, 2001.
[25] T. Fang, C. Weng and J. Chang, “Molecular dynamics analysis of temperature effects on
nanoindentation measurement,” Material Science and Engineering, Vol. A357, pp. 7-12, 2003.
[26] X. M. Liu, Z. L. Liu and Y G Wei, “Nanoscale Friction Behavior of the Ni-film/substrate system
under scratching using MD simulation,” Tribology Letters Vol. 46, pp. 167-178, 2012.
[27] A. Gannepalli and S. K. Mallapragada, “Molecular dynamics studies of plastic deformation during
silicon nanoindentation,” Nanotechnology, Vol. 12, pp. 250-257, 2001.
[28] I. Salehinia, S.K. Lawrence and D.F. Bahr, “The effect of crystal orientation on the stochastic
behavior of dislocation nucleation and multiplication during nanoindentation,” Acta Materialia, Vol.
61, pp. 1421-1431, 2013.
[29] C. F. Sanz-Navarro, S. D. Kenny and R. Smith, “Atomistic simulations of structural transformations
of silicon surfaces under nanoindentation,” Nanotechnology, Vol. 15, pp. 692-697, 2004.
[30] T. Akabane, Y. Sasajima and J. Onuki, “Computer simulation of silicon nanoscratch test,” Materials
Transactions, Vol. 47, pp. 1090-1097, 2006.
[31] H. Okabe, T. Tsumura, J. Shimizu, L. Zhou and H. Eda, “Experimental and Simulation Research on
Influence of Temperature on Nano-Scratching Process of Silicon Wafer,” Key Engineering Materials,
Vol. 329, pp. 379-384, 2007.
[32] T. Fang, W. Chang and C. Weng, “Nanoindentation and nanomachining characteristics of gold and
platinum thin films,” Materials Science and Engineering A, Vol. 430, pp. 332-340, 2006.
[33] T. Fang and C. Weng, “Three-dimensional molecular dynamics analysis of processing using a pin tool
on the atomic scale,” Nanotechnology, Vol. 11, pp. 148-153, 2000.
[34] T. Fang, C. Weng, and J. Chang, “Molecular dynamics simulation of nano-lithography process using
atomic force microscopy,” Surface Science, Vol. 501, pp. 138-147, 2002.
[35] Y. Yan, T. Sun, S. Dong and Y. Liang, “Study on effects of the feed on AFM-based nano-scratching
process using MD simulation,” Computational Materials Science, Vol. 40, pp. 1-5, 2007.
[36] H. Yu, J. B. Adams and L. G. Hector Jr, “Molecular dynamics simulation of high-speed
nanoindentation,” Modeling and Simulation in Materials Science and Engineering, Vol. 10, pp. 319-
329, 2002.
[37] S. Jun, Y. Lee, S. Kim and S. Im, “Large-scale molecular dynamics simulations of Al(111)
nanoscratching,” Nanotechnology, Vol. 15, pp. 1169-1174, 2004.
[38] Y. Lee, J. Park, S. Kim, S. Jun and S. Im, “Atomistic simulations of incipient plasticity under Al(111)
nanoindentation,” Mechanics of Materials, Vol. 37, pp. 1035-1048, 2005.
[39] D. Mulliah, D. Christopher, S. D. Kenny and R. Smith, “Nanoscratching of silver (100) with a
diamond tip,” Nuclear Instruments and Methods in Physics Research B, Vol. 202, pp. 294-299, 2003.
[40] D. Mulliah, S. D. Kenny, R. Smith and C. F. Sanz-Navarro, “Molecular dynamics simulations of
nanoscratching of silver (100),” Nanotechnology, Vol. 15, pp. 243-249, 2004.
[41] R. Smith, D. Cristopher and S. D. Kenny, “Defect generation and pileup of atoms during
nanoindentation of Fe single crystals,” Physical Review B, Vol. 67, 245405, 2003.
17. Computer Science Information Technology (CS IT) 167
[42] C. Lu, Y. Gao, G. Y. Deng, G. Michal, N. N. Huynh, X. H. Liu and A. K. Tieu, “Atomic-scale
anisotropy of nanoscratch behavior of single crystal iron,” Wear, Vol. 267, pp. 1961-1966, 2009.
[43] Z. Lin, J. Huang and Y. Jeng, “3D nano-scale cutting model for nickel material,” Journal of Materials
Processing Technology, Vol. 192-193, pp. 27-36, 2007.
[44] Y. Gao, C. Lu, N. N. Huynh, G. Michal, H. T. Zhu and A. K. Tieu, “Molecular dynamics simulation
of effect of indenter shape on nanoscratch of Ni,” Wear, Vol. 267, pp. 1998-2002, 2009.
[45] I. Gheewala, R. Smith and S. D. Kenny, “Nanoindentation and nanoscratching of rutile and anatase
TiO2 studied using molecular dynamics simulations,” Journal of Physics: Condensed Matter, Vol. 20,
354010, 2008.
[46] Y. Liang, J. Chen, M. Chen, D. Song and Q Bai, “Three-dimensional molecular dynamics simulation
of nanostructure for reciprocating nanomachining process,” Journal of Vacuum Science and
Technology B, Vol. 27, pp. 1536-1542, 2009.
[47] J. Chen, Y. Liang, Q. Bai, Y. Tang and M. Chen, “Mechanism of material removal and the generation
of defects by MD analysis in three-dimensional simulation in abrasive processes,” Key Engineering
Materials, Vol. 359-360, pp. 6-10, 2008.
[48] Z. Lin and J. Huang, “A study of the estimation method of the cutting force for a conical tool under
nanoscale depth of cut by molecular dynamics,” Nanotechnology, Vol. 19, 11570, 2008.
[49] D. Mulliah, S. D. Kenny, E. McGee, R. Smith, A. Richter and B. Wolf, “Atomistic modeling of
ploughing friction in silver, iron and silicon,” Nanotechnology, Vol. 17, pp. 1807-1818, 2006.
[50] R. Promyoo, H. El-Mounayri, and A. Martini, “AFM-Based Nanomachining for Nano-fabrication
Processes: MD Simulation and AFM Experimental Verification,” ASME International Manufacturing
Science Engineering Conference, Erie, PA, October 2010.
[51] R. Promyoo, H. El-Mounayri, K. Varahramyan, and A. Martini, “Molecular Dynamics Simulation of
AFM-Based Nanomachining Processes,” ASME International Manufacturing Science Engineering
Conference, Corvallis, OR, June 13 – 17, 2011.
[52] R. Promyoo, H. El-Mounayri, and K. Varahramyan, “AFM-Based Manufacturing for Nano-fabrication
Processes,” TSME International Conference on Mechanical Engineering, Krabi, Thailand,
October 2011.
[53] R. Promyoo, H. El-Mounayri, and K. Varahramyan, “AFM-Based Nanoindentation Process: A
Comparative Study,” ASME International Manufacturing Science Engineering Conference, Norte
Dame, IN, June 4-8, 2012.
[54] R. Promyoo, H. El-Mounayri, K. Varahramyan, and V. Kumar, “AFM-Based Nanofabrication:
Modeling, Simulation, and Experimental Verification,” ASME International Manufacturing Science
Engineering Conference, Madison, WI, June 10 – 14, 2013.
[55] R. Promyoo, H. El-Mounayri, and K. Varahramyan, “AFM-based nanoindentation using a 3D
molecular dynamics simulation model,” Journal of Materials Science and Engineering A, Vol. 3(6),
pp. 369-381, 2013.
[56] B. J. Alder and T. E. Wainwright, 1959, Studies in molecular dynamics. I. General method, Journal
of Chemical Physics, Vol. 31, pp. 459-466, 1959.
[57] B. J. Alder and T. E. Wainwright, Studies in molecular dynamics. II. Behavior of a small number of
elastic spheres, Journal of Chemical Physics, Vol. 33, pp. 1439-1451, 1960.
[58] R. Komanduri and L. M. Raff, “A review on the molecular dynamics simulation of machining at the
atomic scale,” Proceedings Institution of Mechanical Engineers, Vol. 215 (B), pp. 1639-1672, 2001.
[59] S. J. Plimpton, S. J., “Fast parallel algorithms for short-range molecular dynamics,” Journal of
Computational Physics, Vol. 117, pp. 1-19, 1995.
[60] S. J. Plimpton, R. Pollock and M. Stevens, “Particle-mesh Ewald and rRESPA for parallel molecular
dynamics simulations,” Proc of the Eighth SIAM Conference on Parallel Processing for Scientific
Computing, Minneapolis, MN.
[61] P. Walsh, R. K. Kalia, A. Nakano and P. Vashishta, “Amorphization and anisotropic fracture
dynamics during nanoindentation of silicon nitride: A multimillion atom molecular dynamics study,”
Applied Physics Letters, Vol.77, pp.4332-4334, 2000.
[62] M. S. Daw and M. I. Baskes, “Embedded-atom method: Derivation and application to impurities,
surfaces, and other defects in metals,” Physical Review B, Vol. 29, pp. 6443-6453, 1984.
[63] P. M. Morse, “Diatomic molecules according to the wave mechanics II vibrational levels,” Physical
Review, Vol. 34, pp. 57-64, 1929.
[64] I. M. Torrens, Interatomic potentials, Academic, New York, 1972.
18. 168 Computer Science Information Technology (CS IT)
[65] W.C. Oliver, G.M. Pharr, “Measurement of hardness and elastic modulus by instrumented
indentation: Advances in understanding and refinements to methodology,” Journal of Material
Research, Vol. 19, pp. 3-20, 2004.
[66] http://rt.uits.iu.edu/bigred2/index.php
[67] J. Li, “AtomEye: an efficient atomistic configuration viewer,” Modeling and Simulation in Materials
Science and Engineering, Vol. 11, pp. 173-177, 2003.