The paper concerns with analytical description of the phenomena observed in stress drop tests, namely, negative increment in plastic and creep deformation due to the sudden decrease in the acting stresses while the net stress remains positive. The model is developed in terms of the synthetic theory of irrecoverable deformation which has been generalized by introducing interplay between the deformation properties of material in the direction of acting load and opposite to it.
EFFECT OF SURFACE ROUGHNESS ON CHARACTERISTICS OF SQUEEZE FILM BETWEEN POROUS...IAEME Publication
In investigation aims to analyse the effect of transverse surface roughness on the squeeze film performance between porous rectangular plates. The associated differential equation is stochastically averaged making use of stochastic averaging method of Christensen and Tonder for transverse surface roughness. The equation is solved with appropriate boundary conditions to obtain the pressure and consequentlythe load bearing. The graphical results suggest that the bearing suffers because of transverse surface roughness. However the situation is slightly better in the case of
negatively skew roughness. Further variance (-ve) makes the situation furtherimproved even if moderate values of porosity are involved
Acta Mater 57 (2009) 559 Investigation Of The Indentation Size EffectDierk Raabe
Investigation of the indentation size effect through the measurement of the geometrically necessary dislocations beneath small indents of different depths using EBSD tomography
Prediction of joint strength and effect of the surface treatment on the singl...Filipe Giesteira
A two-component high-ductility adhesive (acrylic and catalyst based), SikaFast® - 5211 NT, was used to bond single overlap joints with mild steel adherends and 25 mm of overlap. One joint configuration used treated bonding surfaces while the other was did not employ treatment of the adherend surfaces, with the aim of studying the influence of the material surface treatment. The specimens were tensile tested in a INSTRON® universal testing machine and the non-treated surface have shown a strength four times lower than the treated surface. Several analytical methods were used to predict joint strength, with two methods achieving reasonably accurate failure load predictions.
Predicting the Nonlinear Material Behaviour under Monotonic and Cyclic loadin...IJERA Editor
Nonlinearity naturally arises in a true, rigorous mathematical formulation of physical problems. One of the most
common nonlinearity is the material nonlinearity where the stress-strain response behaves nonlinearly. The main
objective of this paper is to predict the material nonlinearity with the use of constitutive material model. To this
end, the specimen is modeled with the eight nodded solid elements. One end of the specimen is fixed while the
prescribed displacement is specified at the other end. The Chaboche model parameters are fitted first by
matching the experimental stress-strain curve [4] with the finite element simulations. After that the response of
the specimen is predicted when subjected to different displacement amplitudes i.e. completely reversed loading,
cyclic tension loading and fluctuating ramp loading
Dynamic Relaxation (DR) method is presented for the analysis of geometrically linear laterally loaded, rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse shear deformations. A computer program has been compiled. The convergence and accuracy of the DR solutions of isotropic, orthotropic, and laminated plates for elastic small deflection response are established by comparison with different exact and approximate solutions. The present Dynamic Relaxation (DR) method shows a good agreement with other analytical and numerical methods used in the verification scheme. It was found that: The convergence and accuracy of the DR solution were dependent on several factors which include boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR small deflection program using uniform meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads in a fairly good accuracy.
A comprehensive literature review on different theories of laminated plates have been
reviewed and discussed thoroughly. It has been found that there are two main theories of
laminated plates which are known as linear and nonlinear theories. The two theories are
depending on the magnitude of deformation resulting from loading the given plates. The
difference between the two theories is that the deformations are small in the linear theory,
whereas they are finite or large in the nonlinear theory.
In comparisons between FEM and different numerical methods it has been found that
FEM can be considered of acceptable accuracy, and can also be applied to different
complicated geometries and shapes.
EFFECT OF SURFACE ROUGHNESS ON CHARACTERISTICS OF SQUEEZE FILM BETWEEN POROUS...IAEME Publication
In investigation aims to analyse the effect of transverse surface roughness on the squeeze film performance between porous rectangular plates. The associated differential equation is stochastically averaged making use of stochastic averaging method of Christensen and Tonder for transverse surface roughness. The equation is solved with appropriate boundary conditions to obtain the pressure and consequentlythe load bearing. The graphical results suggest that the bearing suffers because of transverse surface roughness. However the situation is slightly better in the case of
negatively skew roughness. Further variance (-ve) makes the situation furtherimproved even if moderate values of porosity are involved
Acta Mater 57 (2009) 559 Investigation Of The Indentation Size EffectDierk Raabe
Investigation of the indentation size effect through the measurement of the geometrically necessary dislocations beneath small indents of different depths using EBSD tomography
Prediction of joint strength and effect of the surface treatment on the singl...Filipe Giesteira
A two-component high-ductility adhesive (acrylic and catalyst based), SikaFast® - 5211 NT, was used to bond single overlap joints with mild steel adherends and 25 mm of overlap. One joint configuration used treated bonding surfaces while the other was did not employ treatment of the adherend surfaces, with the aim of studying the influence of the material surface treatment. The specimens were tensile tested in a INSTRON® universal testing machine and the non-treated surface have shown a strength four times lower than the treated surface. Several analytical methods were used to predict joint strength, with two methods achieving reasonably accurate failure load predictions.
Predicting the Nonlinear Material Behaviour under Monotonic and Cyclic loadin...IJERA Editor
Nonlinearity naturally arises in a true, rigorous mathematical formulation of physical problems. One of the most
common nonlinearity is the material nonlinearity where the stress-strain response behaves nonlinearly. The main
objective of this paper is to predict the material nonlinearity with the use of constitutive material model. To this
end, the specimen is modeled with the eight nodded solid elements. One end of the specimen is fixed while the
prescribed displacement is specified at the other end. The Chaboche model parameters are fitted first by
matching the experimental stress-strain curve [4] with the finite element simulations. After that the response of
the specimen is predicted when subjected to different displacement amplitudes i.e. completely reversed loading,
cyclic tension loading and fluctuating ramp loading
Dynamic Relaxation (DR) method is presented for the analysis of geometrically linear laterally loaded, rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse shear deformations. A computer program has been compiled. The convergence and accuracy of the DR solutions of isotropic, orthotropic, and laminated plates for elastic small deflection response are established by comparison with different exact and approximate solutions. The present Dynamic Relaxation (DR) method shows a good agreement with other analytical and numerical methods used in the verification scheme. It was found that: The convergence and accuracy of the DR solution were dependent on several factors which include boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR small deflection program using uniform meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads in a fairly good accuracy.
A comprehensive literature review on different theories of laminated plates have been
reviewed and discussed thoroughly. It has been found that there are two main theories of
laminated plates which are known as linear and nonlinear theories. The two theories are
depending on the magnitude of deformation resulting from loading the given plates. The
difference between the two theories is that the deformations are small in the linear theory,
whereas they are finite or large in the nonlinear theory.
In comparisons between FEM and different numerical methods it has been found that
FEM can be considered of acceptable accuracy, and can also be applied to different
complicated geometries and shapes.
The convergence and accuracy of the Dynamic Relaxation (DR) solutions for elastic
large deflection response are established by comparison with various exact and approximate
solutions. New numerical results are generated for uniformly loaded square laminated plates
which serve to quantify the effects of shear deformation, length to thickness ratio, number of
layers, material anisotropy and fiber orientation.
It was found that linear analysis seriously over predicts deflection of plates. The shear
deflection depends greatly on a number of factors such as length to thickness ratio, degree of
anisotropy and number of layers. As the degree of anisotropy increases, the plate becomes
stiffer and when it is greater than a critical value, the deflection becomes virtually
independent on the degree of anisotropy. It was also found that deflection of plates depends
on the angle of orientation of individual plies and the size of load applied.
Linear And Nonlinear Analytical Modeling of Laminated Composite Beams In Thre...researchinventy
The large current development of aerospace and automotive technologies is based on the use of composite materials which provide significant weight savings compared to their mechanical characteristics. Correct dimensioning of composite structures requires a thorough knowledge of their behavior in small as in large deflection.This work aims to simulate linear and nonlinear behavior of laminates composites under threepoint bending test. The used modelization is based on first-order shear deformation theory (FSDT), classical plate theory (CPT) and Von-Karman’s equations for large deflection. A differential equation of Riccati, describing the variation of the deflection depending on the load, was obtained. Hence, the results deduced show a good correlation with experimental curves
Literature Review of Experimental Study on Load Bearing Masonry WallIOSRJMCE
Masonry load bearing wall subjected to vertical concentric and eccentric loading may collapse through instability. In this Paper the buckling behavior of masonry load bearing wall of different slenderness ratio were investigated by many researcher has been reviewed via testing a series of scale masonry wall subjected to concentric and eccentric vertical loading. The influence of nonlinear behavior of interface element, slenderness ratio and various end conditions have been investigated together with the effect of different end eccentricity of vertical load.
Dynamic Relaxation (DR) method is presented for the geometrically nonlinear laterally loaded,
rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse
shear deformation. A computer program has been compiled. The convergence and accuracy of the DR
solutions for elastic large deflection response are established by comparison with various exact and
approximate solutions. New numerical results are generated for uniformly loaded square laminated
plates which serve to quantify the effects of shear deformation, length to thickness ratio, number of
layers, material anisotropy and fiber orientation.
It was found that linear analysis seriously over predicts deflection of plates. The shear
deflection depends greatly on a number of factors such as length to thickness ratio, degree of
anisotropy and number of layers. As the degree of anisotropy increases, the plate becomes stiffer and
when it is greater than a critical value, the deflection becomes virtually independent on the degree of
anisotropy. It was also found that deflection of plates depends on the angle of orientation of individual
plies and the size of load applied.
A composite material can be defined as a combination of two or more materials that
gives better properties than those of the individual components used alone. In contrast to
metallic alloys, each material retains its separate chemical, physical, and mechanical
properties. The two constituents are reinforcement and a matrix. The main advantages of
composite materials are their high strength and stiffness combined with low density when
compared to classical materials. Micromechanical approach is found to be more suitable for
the analysis of composite materials because it studies the volume proportions of the
constituents for the desired lamina stiffness and strength.
First order orthotropic shear deformation equations for the nonlinear elastic bending response of rectangular plates are introduced. Their solution using a computer program based on finite differences implementation of the Dynamic Relaxation (DR) method is outlined. The convergence and accuracy of the DR solutions for elastic large deflection response of isotropic, orthotropic, and laminated plates are established by comparison with various exact and approximate solutions. The present Dynamic Relaxation method (DR) coupled with finite differences method shows a fairly good agreement with other analytical and numerical methods used in the verification scheme.It was found that: The convergence and accuracy of the DR solution is dependent on several factors including boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR large deflection program using uniform finite differences meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads. All the comparison results for simply supported (SS4) edge conditions showed that deflection is almost dependent on the direction of the applied load or the arrangement of the layers
Examples of Homogenization Techniques in the Material Modeling Under the Effe...Sardasht S. Weli
Explosions become a very attractive research area in the last decades.
This is due to the increase of accidental and intentional explosions.
Historical structure were not designed and built against the extreme loading events.
Homogenization Techniques were developed to assess the masonry response.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The effects of boundary conditions and lamination arrangements
(i.e. stacking sequence and orientation of a lamina) were found to be important
factors in determining a suitable exact, analytical or semi – analytical method
for analyzing buckling loads on laminated plates. It was also found that: as the
derivative order of shear deformation increases, the accuracy of stresses, strains,
buckling loads … etc. increases and it doesn't need shear correction factors.
“ Study of Sesmic Analysis of Masonry Wall Structure”IJERA Editor
Earthquakes are natural trouble under which disasters are mainly caused by damage or collapse of the structure and other man-made structures. When an earthquake occurs natural period of vibration is more on heavy loaded building and less in light loaded building. If the building is light weighted, i.e. steel is less then economy of structure is also achieved. Hence it is necessary to find out natural/fundamental time period when mass changes with different type of brick masonry and concrete masonry.This is necessary because IS 1893:2002 does not incorporate the effect of mass in a formula which they have mentioned for brick masonary structure. Thedesign will also analyze with ETAB software.
A Food Monitoring System Based on Bluetooth Low Energy and Internet of ThingsIJERA Editor
A Food Monitoring System Based on Bluetooth Low Energy(BLE) and Internet of Things(IoT)have provided a plethora of benefits to a variety of commercial industries, including the agricultural, biomedical, cosmetics, environmental, food manufacturing, military, pharmaceutical, regulatory,and various scientific research fields. In this System there exists a gas sensor which is used to detect the gases evolved from the food, temperature sensor to detect the temperature of the food storage area and the humidity sensor to check the humidity. The collected data from the test samples is transferred to the application through Bluetooth using Bluetooth Low Energy(BLE) or Internet of Things(IoT) based on the range of the server. The system uses a GSM/GPRS public wireless network for remote data transfer The combination of internet of things technology, GSM / GPRS public wireless network technology and Internet significantly reduces the cost of the system, with leading limitless scope of tracking recognition, which enhances the comprehensive performance of the system greatly.Advances have improved productattributes, uniformity, and consistency as a result of increases in quality control capabilities afforded by A Food monitoring system based on Bluetooth Low Energy(BLE) and Internet of Things of all phases of industrial manufacturing processes. This paper is a review of some of the more important and modern applications that have been of greatest benefit to the humankind
The convergence and accuracy of the Dynamic Relaxation (DR) solutions for elastic
large deflection response are established by comparison with various exact and approximate
solutions. New numerical results are generated for uniformly loaded square laminated plates
which serve to quantify the effects of shear deformation, length to thickness ratio, number of
layers, material anisotropy and fiber orientation.
It was found that linear analysis seriously over predicts deflection of plates. The shear
deflection depends greatly on a number of factors such as length to thickness ratio, degree of
anisotropy and number of layers. As the degree of anisotropy increases, the plate becomes
stiffer and when it is greater than a critical value, the deflection becomes virtually
independent on the degree of anisotropy. It was also found that deflection of plates depends
on the angle of orientation of individual plies and the size of load applied.
Linear And Nonlinear Analytical Modeling of Laminated Composite Beams In Thre...researchinventy
The large current development of aerospace and automotive technologies is based on the use of composite materials which provide significant weight savings compared to their mechanical characteristics. Correct dimensioning of composite structures requires a thorough knowledge of their behavior in small as in large deflection.This work aims to simulate linear and nonlinear behavior of laminates composites under threepoint bending test. The used modelization is based on first-order shear deformation theory (FSDT), classical plate theory (CPT) and Von-Karman’s equations for large deflection. A differential equation of Riccati, describing the variation of the deflection depending on the load, was obtained. Hence, the results deduced show a good correlation with experimental curves
Literature Review of Experimental Study on Load Bearing Masonry WallIOSRJMCE
Masonry load bearing wall subjected to vertical concentric and eccentric loading may collapse through instability. In this Paper the buckling behavior of masonry load bearing wall of different slenderness ratio were investigated by many researcher has been reviewed via testing a series of scale masonry wall subjected to concentric and eccentric vertical loading. The influence of nonlinear behavior of interface element, slenderness ratio and various end conditions have been investigated together with the effect of different end eccentricity of vertical load.
Dynamic Relaxation (DR) method is presented for the geometrically nonlinear laterally loaded,
rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse
shear deformation. A computer program has been compiled. The convergence and accuracy of the DR
solutions for elastic large deflection response are established by comparison with various exact and
approximate solutions. New numerical results are generated for uniformly loaded square laminated
plates which serve to quantify the effects of shear deformation, length to thickness ratio, number of
layers, material anisotropy and fiber orientation.
It was found that linear analysis seriously over predicts deflection of plates. The shear
deflection depends greatly on a number of factors such as length to thickness ratio, degree of
anisotropy and number of layers. As the degree of anisotropy increases, the plate becomes stiffer and
when it is greater than a critical value, the deflection becomes virtually independent on the degree of
anisotropy. It was also found that deflection of plates depends on the angle of orientation of individual
plies and the size of load applied.
A composite material can be defined as a combination of two or more materials that
gives better properties than those of the individual components used alone. In contrast to
metallic alloys, each material retains its separate chemical, physical, and mechanical
properties. The two constituents are reinforcement and a matrix. The main advantages of
composite materials are their high strength and stiffness combined with low density when
compared to classical materials. Micromechanical approach is found to be more suitable for
the analysis of composite materials because it studies the volume proportions of the
constituents for the desired lamina stiffness and strength.
First order orthotropic shear deformation equations for the nonlinear elastic bending response of rectangular plates are introduced. Their solution using a computer program based on finite differences implementation of the Dynamic Relaxation (DR) method is outlined. The convergence and accuracy of the DR solutions for elastic large deflection response of isotropic, orthotropic, and laminated plates are established by comparison with various exact and approximate solutions. The present Dynamic Relaxation method (DR) coupled with finite differences method shows a fairly good agreement with other analytical and numerical methods used in the verification scheme.It was found that: The convergence and accuracy of the DR solution is dependent on several factors including boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR large deflection program using uniform finite differences meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads. All the comparison results for simply supported (SS4) edge conditions showed that deflection is almost dependent on the direction of the applied load or the arrangement of the layers
Examples of Homogenization Techniques in the Material Modeling Under the Effe...Sardasht S. Weli
Explosions become a very attractive research area in the last decades.
This is due to the increase of accidental and intentional explosions.
Historical structure were not designed and built against the extreme loading events.
Homogenization Techniques were developed to assess the masonry response.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The effects of boundary conditions and lamination arrangements
(i.e. stacking sequence and orientation of a lamina) were found to be important
factors in determining a suitable exact, analytical or semi – analytical method
for analyzing buckling loads on laminated plates. It was also found that: as the
derivative order of shear deformation increases, the accuracy of stresses, strains,
buckling loads … etc. increases and it doesn't need shear correction factors.
“ Study of Sesmic Analysis of Masonry Wall Structure”IJERA Editor
Earthquakes are natural trouble under which disasters are mainly caused by damage or collapse of the structure and other man-made structures. When an earthquake occurs natural period of vibration is more on heavy loaded building and less in light loaded building. If the building is light weighted, i.e. steel is less then economy of structure is also achieved. Hence it is necessary to find out natural/fundamental time period when mass changes with different type of brick masonry and concrete masonry.This is necessary because IS 1893:2002 does not incorporate the effect of mass in a formula which they have mentioned for brick masonary structure. Thedesign will also analyze with ETAB software.
A Food Monitoring System Based on Bluetooth Low Energy and Internet of ThingsIJERA Editor
A Food Monitoring System Based on Bluetooth Low Energy(BLE) and Internet of Things(IoT)have provided a plethora of benefits to a variety of commercial industries, including the agricultural, biomedical, cosmetics, environmental, food manufacturing, military, pharmaceutical, regulatory,and various scientific research fields. In this System there exists a gas sensor which is used to detect the gases evolved from the food, temperature sensor to detect the temperature of the food storage area and the humidity sensor to check the humidity. The collected data from the test samples is transferred to the application through Bluetooth using Bluetooth Low Energy(BLE) or Internet of Things(IoT) based on the range of the server. The system uses a GSM/GPRS public wireless network for remote data transfer The combination of internet of things technology, GSM / GPRS public wireless network technology and Internet significantly reduces the cost of the system, with leading limitless scope of tracking recognition, which enhances the comprehensive performance of the system greatly.Advances have improved productattributes, uniformity, and consistency as a result of increases in quality control capabilities afforded by A Food monitoring system based on Bluetooth Low Energy(BLE) and Internet of Things of all phases of industrial manufacturing processes. This paper is a review of some of the more important and modern applications that have been of greatest benefit to the humankind
Custom Angle Ceiling fan can be used to regulate air flow only into areas where we need air flow, by changing the angles. (i.e.) both swiveling and tilting of the ceiling fan down-rod. The reason for the innovation of this mechanism is that, we found several areas, where the ceiling fans were installed at the wrong locations on the ceiling. Normally, the rooms are designed, according to personal wish, only after concreting the roof slab. Therefore, the hooks for hooking up the ceiling fan are to be placed during the concreting process of roof slab. But, they might not be in the correct position to blow air into all areas of the room. This is the case where, Custom angle ceiling fan can be used. The relevance of this mechanism lies in, reducing the power wastage in conditions like, fans blowing air, where it is not required.
Soft Computing Technique for the Control of Triple-Lift Luo ConverterIJERA Editor
Positive output Luo converters are a series of new DC-DC step-up (boost) converters, which were developed from prototypes using voltage lift technique. These converters perform positive to positive DC-DC voltage increasing conversion with high power density, high efficiency and cheap topology in simple structure. They are different from other existing DC-DC step-up converters with a high output voltage and small ripples. Triple lift LUO circuit is derived from positive output elementary Luo converter by adding the lift circuit three times. Due to the time varying and switching nature of the Luo converters, their dynamic behaviour becomes highly nonlinear. The classical control methods employed to design the controllers for Luo converters depend on the operating point so that it is very difficult to select control parameters because of the presence of parasitic elements, time varying loads and variable supply voltages. Conventional controllers require a good knowledge of the system and accurate tuning in order to obtain the desired performances. A fuzzy logic controller is a soft computing technique which neither requires a precise mathematical model of the system nor complex computations. The performances of the Triple-lift Luo converter with fuzzy logic controller are evaluated under line and load disturbances using Matlab-Simulink based simulation. The results are presented and analyzed.
Dynamic Evolving Neuro-Fuzzy Inference System for Mortality Prediction IJERA Editor
In this paper we propose a dynamic evolving neuro-fuzzy inference system (DENFIS) to forecast mortality. DENFIS is an adaptive intelligent system suitable for dynamic time series prediction. An Evolving Cluster Method (ECM) drives the learning process. The typical fuzzy rules of the neuro- fuzzy systems are updated during the learning process and adjusted according to the features of the data. This makes possible to capture the changes in the mortality evolution at the basis of the so called longevity risk
Design, Construction and Experiment on Imbert Downdraft Gasifier Using South ...IJERA Editor
The solid fuel must be converted to gas fuel or liquid fuel for application to internal combustion engine or gas turbine. Gasification is a technology to convert solid fuel into combustible gas. Gasification system generally consists of a gasifier, cyclone, spray tower and filter. This study is purposed to design, construction, and experiment of gasification system. The imbert downdraft gasifier was designed with 42 kg/h for the maximum capacity of fuel consumption, 90 cm for height, 26.8 cm for main diameter and 12 cm for throat diameter. The gasifier was constructed from stainless steel material of SUS 304. Biomass and low rank coal from South Sumatera, Indonesia was used as fuel. The result of the experiment showed that combustible gas was produced after 15 minutes operation in average. The air fuel ratio of low rank coal was 1.7 which was higher than biomass (1.1). Combustible gas stopped producing when the fuel went down below the throat of gasifier.
Papercrete Bricks An Alternative Sustainable Building MaterialIJERA Editor
A large amount of non-renewable resources is consumed by the construction industry throughout the world. Everyday tons of waste papers are discarded as landfill or dump sites than those recycled. It is learnt that it takes about fifteen trees to make a ton of paper which means that 720 million trees are used once and then buried as landfills each year. In order to address these issues it has become imperative to push the boundaries of research in the field of innovative sustainable construction materials. This study is one such kind of efforts. Papercrete is a new composite material comprising of waste papers and cement. In this investigation, an attempt is made to produce an alternative material using waste papers. This could help eradicate a few of the environmental hazards caused by the construction industry. But there is no proper code for the mix proportioning of papercrete bricks. Therefore, a mix proportion of [Cement: Paper : Sand] 1:1.15:1.3 was chosen on trial and error basis. All the necessary engineering properties are studied and compared with the conventional bricks and discussions on its potential uses are made.
Enhancement of Single Moving Average Time Series Model Using Rough k-Means fo...IJERA Editor
In the last decade, real–time audio and video services have gained much popularity, and now occupying a large portion of the total network traffic in the Internet. As the real-time services are becoming mainstream the demand for Quality of Service (QoS) is greater than ever before. It is necessary to use the network resources to the fullest, to satisfy the increasing demand for QoS. To solve this issue, we need to apply a prediction model for network traffic, on the basis of network management such as congestion control and bandwidth location. In this paper, we propose an integrated model that combines Rough K-Means (RKM) clustering with Single Moving Average (SMA) time series model to improve prediction loading packets of network traffic. The single moving average time series prediction model is used to predict loading of packets volume in real network traffic. Further, clustering granules obtained by using rough k-means is used to analyze the network data of each year separately. The proposed model is an integration of the prediction results that were obtained from conventional single moving average prediction model with centriods of clusters that obtained from rough k-means clustering. The model is evaluated using on line network traffic data that has been collected from WIDE backbone Network MSE, RMSE and MAPE metrics are used to examine the results of the integrated model. The experimental results show that the integrated model can be an effective way to improve prediction accuracy achieved with the help of rough k-means clustering. A Comparative result between conventional prediction model and our integrated model is presented.
Performance Study of Tube Settlers ModuleIJERA Editor
The water treatment plant plays an important role for supplying and purifying potable water. The present study is aimed to emphasize the performance of tube settler unit. A pilot scale model of sedimentation tank is prepared & installed for performance measurement. In conventional sedimentation tank the detention time required is 2-4 hrs. In view of increasing demand of water for society, a modification is used in water treatment plant i.e. high rate settling. The detention time is reduced up to 10-15 min. which is very less as compare to conventional sedimentation tank. The average efficiency of turbidity removal is 70-80% in modified unit as compare to conventional tube settler unit.
Multi resolution defect transformation of the crack under different anglesIJRES Journal
It is used to analyze the crack of different angles by the method of finite element. In the same material, the same crack is applied different angles, crack with 15 degree Angle differences, and applying Ⅰ type load on the material. The effective elastic modulus under the different angles of crack are obtained by finite element. With comparative judgment method, it provides the relationship between the modulus of elasticity and crack different angles, and a method crack material defects of transformation. On based on the transformation of energy equivalent principle, there are a lot of crack defects of materials for different degrees of defects, so as to simplify the material crack, provide a simple way for material fatigue analysis.
Failure waves in glass were first observed in tests some 30 years ago, with a wave velocity of 1.5-2.5 km/s. In spite of the long time since then, some essential questions concerning failure waves remained unanswered. These are: 1) what is the formation mechanism of failure waves; 2) what is the propagation mechanism of failure waves; and 3) what are the kinetics of the failure process? In the past failure wave researchers assumed that material damage starts from the boundary. But in a recent experimental work on glass [9] the investigators observed that the glass starts to fail within the material behind the shock front, and not from the boundary. This seemingly small change in the way failure waves are started makes it possible to predict the mechanics of failure wave formation and propagation, using existing failure models for brittle materials. We’re using here a dynamic failure model for brittle materials that we’ve developed in recent years [10]. To get a failure wave that lags behind the shock front, we assume in that the rate of damage accumulation behind the shock front decreases exponentially with distance from the boundary. This is a plausible assumption because opening pores and cracks would become more difficult with distance from the boundary. And indeed, using this assumption we get a failure wave that propagates slower than the shock and at an approximately constant velocity.
Application of CAD and SLA Method in Dental ProsthesisIDES Editor
Placement of dental implants requires precise
planning that accounts for anatomic limitations and
restorative goals. Diagnosis can be made with the assistance
of computerized tomographic scanning, but transfer of
planning to the surgical field is limited. Precise implant
placement no longer relies upon so called mental-navigation
but rather can be computer guided, based on a three
dimensional prosthetically directed plan. Recently, novel CAD/
CAM techniques such as stereolithographic rapid prototyping
have been developed to build surgical guides in an attempt to
improve precision of implant placement. The purpose of this
paper is to discuss the use of scanning equipments to transfer
clinically relevant prosthetic information which can be used
for fabrication of stereolithographic medical models and
surgical guides. The proposed method provides solid evidence
that computer-aided design and manufacturing technologies
may become a new avenue for custom-made dental implants
design, analysis, and production in the 21st century.
Modeling and Analysis of Laminated Composite Beams using Higher Order TheoryIDES Editor
The present study deals with the assessment of
higher order theory of laminated beams under static
mechanical loads. The theory has been presented for general
lay-up of the laminate. The displacement field is expressed in
terms of only three primary displacement variables by
satisfying exactly the conditions of zero transverse shear stress
at the top and bottom and its continuity at layer interfaces.
The governing equations of motion and boundary conditions
are derived using virtual work. The number of primary
displacement unknowns is three, which is independent of the
number of layers and equal in number to the ones used in the
first order shear deformation theory. Higher order theory thus
preserves the computational advantage of an equivalent single
layer theory. The Third order theory and First order shear
deformation theory are assessed by comparison with the exact
two-dimensional elasticity solution of the simply-supported
beam. A theory is good only if it yields accurate results for all
kinds of loads and for any lay-up of the beam. For this purpose,
parametric studies for composite laminates and sandwich
beams are conducted.
Implementation Of Geometrical Nonlinearity in FEASTSMTiosrjce
Analysis of the structures used in aerospace applications is done using finite element
method. These structures may face unexpected loads because of variable environmental situations.
These loads could lead to large deformation and inelastic manner. The aim of this research is to
formulate the finite elements considering the effect of large deformation and strain. Here total
Lagrangian method is used to consider the effect of large deformation. After deriving required
relations, implementation of formulated equation is done in FEASTSMT(Finite Element Analysis of
Structures - Substructured and Multi-Threading). .Newton-Raphson method was utilized to solve
nonlinear finite element equations. The validation is carried out with the results obtained from the
Marc Software.
CROSS-CORRELATION OF STRESSES IN THE TRAN REINFORCEMENT UNDER SHEAR LOAD AND ...IAEME Publication
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CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
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Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
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• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
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Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
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This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
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Peculiarities of irrecoverable straining in stress-drop test
1. Andrew Rusinko . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -6) March 2017, pp.15-21
www.ijera.com DOI: 10.9790/9622-0703061521 15 | P a g e
Peculiarities of irrecoverable straining in stress-drop test
Andrew Rusinko
Óbuda University, Népszínház St. 8, Budapest, Hungary, H-1081
ABSTRACT
The paper concerns with analytical description of the phenomena observed in stress drop tests, namely, negative
increment in plastic and creep deformation due to the sudden decrease in the acting stresses while the net stress
remains positive. The model is developed in terms of the synthetic theory of irrecoverable deformation which
has been generalized by introducing interplay between the deformation properties of material in the direction of
acting load and opposite to it.
Keywords: negative creep, stress drop test, synthetic theory of irrecoverable deformation
I. INTRODUCTION
Plastic or creep deformation under
variable stresses is of great interest due to the rise
of such phenomenon as negative (reverse) creep,
which grows out of the competence of the classical
theories of plastic/creep deformation, is widely
studied in the literature in terms of both theoretical
modeling and experimental researches.As an
example, nuclear fuel cladding tubes are subject, in
service, to complex multiaxial loading that
undergoes sudden change. An accurate description
of the strain response due to varying stresses is
essential in reliably predicting the accumulated
plastic strains in the cladding. Direct extrapolations
of the creep behavior under constant load to
describe creep due to varying loads would result in
strains significantly different from those observed,
mainly due to negative creep transients following
load drops (Murty, & Yoon, 1979).
The negative creep is of great importance
due to it contradicts the hypothesis of creep
potential (Rabotnov, 1969), according to which the
creep rate is a single-valued function of acting
stresses independently of the way these stresses
have been reached. In contrast to this, the reverse
creep occurs in the direction opposite to what is
predicted in terms of this theory.Fig. 1
demonstrates schematically strain-time diagram in
the course of stress drop test. Many theories have
been developed to explain the behavior patterns
observed in stress-drop tests (SDT). If to omit
minor details in the interpretation of the processes
governing creep in SDT, they confirm that: (a)
dislocation creep is the dominant mechanism; (b)
high plastic anisotropy is a source of the energy
inducing processes occurring in material; (c) the
response is dictated by a competition between the
rates of recovery and hardening processes.
Fig. 1. Strain-time diagram in the stress-drop test; 1-2: creep portion under stress, 2-3: negative
contraction due to stress-drop , 3-4: negative creep (applied stress remains positive!), 4-5: creep delay
(incubation period) , 5-6: accelerating (inverse) creep , from point 6: steady state creep
corresponding to stress. For the case of small stress drop, 3-4 portion is absent and only portions 4-5-6
are observed after the stress drop.
RESEARCH ARTICLE OPEN ACCESS
2. Andrew Rusinko . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -6) March 2017, pp.15-21
www.ijera.com DOI: 10.9790/9622-0703061521 16 | P a g e
With instantaneous and time-dependent
negative plastic deformation, the following
approaches can be distinguished.LRIS (Long range
internal stress), Composite model (Kassner et al.,
2009,2015). Mughrabi (1983) developed/advanced
the concept of relatively high (long-range internal)
stresses in association with heterogeneous
dislocation substructures (e.g., cell/subgrain walls,
dipole bundles, persistent slip bands walls, etc.). He
presented the simple case where “hard” (high
dislocation density walls, etc.) and “soft” (low
dislocation density channels, or cell interiors)
elastic-perfectly-plastic regions are compatibly
sheared. Each component yields at different
stresses and it is suggested that the “composite” is
under a heterogeneous stress-state with the high-
dislocation density regions having the higher stress.
As soft and hard regions are unloaded in parallel,
the hard region eventually places the soft region in
compression while the stress in the hard region is
still positive. That is, a backstress is created. The
plasticity occurs on reversal due to “reverse”
plasticity in the soft region. The concept of
heterogeneous stresses has also been widely
embraced for monotonic deformation (Borbély et
al. 1997, 2000) including elevated-temperature
creep deformation.Non-Backstress
explanation.Sleeswyk et al. (1978) proposed a
different approach; when analyzing the hardening
features in several metals at ambient temperature,
he adopted an Orowan-type mechanism (long-
range internal stresses or “back-stresses” not
especially important) with dislocations easily
reversing their motion (across cell). He suggested
gliding dislocations, during work-hardening,
encounter increasingly effective obstacles and the
stress necessary to activate further dislocation
motion or plasticity continually increases. On
reversal of the direction of straining from a
“forward” sense, the dislocations will easily move
past those, non-regularly-spaced, obstacles that
have already been surmounted. Thus the flow stress
on reversal is relatively low. Lloyd and McElroy
(1974) shears the same opinion, considering only
the unbowing of dislocation segment, immobilized
in a bowed out configuration, toward a new
configuration at reduced stress. Another
observation (Davies, & Wilshire, 1971) says that
the instantaneous specimen contraction on
decreasing the stress is greater than would be
expected from the elastic modulus is a consequence
of runback of dislocation pile-ups.
The aim of this paper is to model the
plastic and creep deformation of material due to the
stress drop as shown in Fig. 1. Here, we focus our
attention upon 2-3-4 portion in the strain-time
diagram, i.e. negative increment in plastic and
creep deformation caused by . The
implementation of the problem takes place in terms
of the synthetic theory by means of its
generalization for the discussed issue.
II. ORDINARY CREEP
DEFORMATION IN TERMS OF
THE
SYNTHETIC THEORY
The creep rate of material in uniaxial tension at
point 2 in Fig. 1 is calculated as follows (Rusinko,
A., & Rusinko, K., 2009,2011)
(
1
)
(
2
)
where is the creep limit of material.
Consider the quantities in the formulae
above. is strain intensity rate which is an
average measure of the plastic shifts developing
within one slip system (microlevel of material). A
macrodeformation is expressed through the
components of strain rate vector in the Ilyushin
three-dimensional strain deviator space, while the
loading is expressed by stress vector in the stress
deviator space. For the case of uniaxial tension we
have two vectors and
. The integration in Eq. (1) gives the rule
how to calculate deformation on the macrolevel of
material: one has to sum (integrate) all the
microstrains developed within activated slip
systems. The magnitude of can be found from
the constitutive equation
(3)
where is defect intensity, an average measure of
the defects of crystalline grade induced by
irrecoverable deformation:
(
4
)
3. Khushbu Nagori . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -5) March 2017, pp.66-69
www.ijera.com DOI: 10.9790/9622-0703061521 17 | P a g e
where is the measure of material hardening,
which expressed via the distance from the origin of
coordinate to the plane tangential to loading (yield)
surface (the position of a plane is defined via
and its normal unit vector , i.e. by angles , ,
and ). The boundary values of , , and are
(Rusinko, A., & Rusinko, K., 2011)
(
5
)
(
6
)
The second term on the right hand side of
(4) is referred to as rate-integral which accounts for
the loading rate and its influence upon the
development of plastic deformation:
(7)
III. GENERALIZATION OF THE
SYNTHETIC THEORY
We establish a law that governs how
plastic/creep strain in one direction affects the
material hardening in the opposite direction. In
terms of the synthetic theory, this question sound
like “How does a plastic straining, which is
modeled by the movements of planes with
normals at the endpoint of stress vector , affect
the plane distances with opposite normals ,
?
According to Eq. (4), for normals is
.
(8)
Therefore, the question posed above can be
rephrased as: “How to set the relation between
and as well as between and ?”
Eq. (7) gives the rate integral for normals
as
(
9
)
Since the rate hardening of material in initial
loading does not exert any influence upon that in
the subsequent loading of opposite sign, we say
that if is positive, then is set to be zero and
vice versa:
If , or if , .
(10)
To reflect the influence of upon , the
following formula is proposed
(11)
Summarizing, Eq. (4) becomes
(12)
The non-zero value of from (11) by
no means represents any defects generated in the
course of inelastic deformation because the planes
with normals are not at the endpoint of vector
, while the magnitude of is directly related to
the value of irrecoverable strain. Therefore, the
main postulate of the synthetic theory that
irrecoverable deformation is modeled by the planes
shifted by stress vector remains intact. The only
aim of Eq. (11) is to establish, via Eq. (12), the
relationship between the plastic deformation
induced by loading in one direction and the degree
of hardening relative to the opposite-sign-loading.
Indeed, the growth of defect intensity leads to
the decrease in the distance in Eq. (12) that
symbolizes the softening of material with respect to
the loading of opposite sign.
The softening of material expressed by
Eq. (12) is in full harmony with Sleeswyk’s (1978),
Lloyd’s and McElroy’s (1974) opinion that
dislocations easily reverse their motion in the
direction opposite to the initial plastic flows. In
other words, less stresses are needed to induce
irrecoverable deformation in the opposite
direction.In addition, formula (12) correlates with
the notions of effective and backward stresses and
their interplay with the dislocation behavior
(Kassner et al., 2009), Mughrabi (1983), Evans
(1985). Really, internal stresses defining the
effective stresses and eventually the degree of
material softening in reversal loading directly
depend on the number of defects and stress field
around them raised in the direct loading. The same
situation is observed in Eq. (12) where terms
and stand for the number of defects and the
lattice distortion caused by their presence.
4. Khushbu Nagori . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -5) March 2017, pp.66-69
www.ijera.com DOI: 10.9790/9622-0703061521 18 | P a g e
Consider the domain that is the mirror
reflection of that from (5):
(13
)
The defect intensity and plane distance ,
according to Eqs. (8)-(12), are
an
d
(1
4)
where stands for
.
Intermediate remarks.To model portions 2-3 and 3-
4 from Fig. 1, we need to give the following
preliminary reasoning. Since both of them are of
compressive nature, they can be modeled only by
means of planes with normal vectors . The
occurrence of negative plastic strain increment (2-
3) is possible only if the stress increment vector
reaches and moves a set of planes with negative
normals . The description of reverse(negative)
creep under the constant stress (3-4) also
can be modelled only by the manipulations with
planes with normals . It is feasible only if
, i.e. if the planes with negative normals
get over the origin of coordinates. Therefore, the
initial stress vector must be of such magnitude that
the plane distances from the first formula in (14) at
are negative.
Special attention must be paid for the rate integral
due to it stands for the regulation of time-
dependent strain for the planes with normals .
To model the reverse creep, it is immediately clear
that the requirement that be positive is needed.
The fact that the negative creep can be observed
only if it is preceded by negative plastic
deformation means that a material needs to obtain
some compressive strain energy which then can be
released in the form of time-dependent deformation
(negative creep).
IV. STRESS DROP
Because of stressdrop , the rate integral ,
according to Eq. (7), yields the following form
(Fig. 2)
(15)
To meet the condition , the magnitude of
must be greater than implying
that from (15) becomes negative. Then,
according to Eq. (10), we obtain that
(16
)
As the stress vector shortens due to the stress drop,
the planes with normals are no more at its
endpoint and they stop producing inelastic
deformation. This, in turn, means that there is no
defect increment in positive direction, and Eq. (4)
remains unchangeable until increments in defect
intensity occur. This is possible if planes with
normals are shifted by vector . For the
rest planes Eq. (14) holds true.
Let us designate through the length of stress
vector when it reaches the first plane with negative
normal. Since this plane is perpendicular to the
stress vector, , it is distanced from the origin
as
(17)
Therefore, to calculate the , we use Eq. (12)
where (i) the left-hand-side is ; (ii) is
given by (14) at and ; (iii) is from
Eq. (16) at and . As a result,
(1
8)
(1
9)
Summarizing, the occurrence of negative plastic
strain increment is possible if the magnitude of
is positive and the stress is less than .
These conditions, in the view of Eq. (19), can be
met if
5. Khushbu Nagori . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -5) March 2017, pp.66-69
www.ijera.com DOI: 10.9790/9622-0703061521 19 | P a g e
(20)
If , the fulfillment of the second inequality
in (20) provides that of the first one.
According to Eq. (3), the increments in defect- and
strain intensity are related to each other as
(21)
It is worthwhile to remind once more that, in terms
of the synthetic theory, the increase in defects and,
consequently, in strain intensity is obtained only if
the stress vector translates planes on its endpoint,
i.e. .
Therefore, the defect intensity increment, relatively
to the defects at point 2, is determined as
(22
)
where is given by (16) and stands for the
plane distance at point 2 given by Eq. (14) at
. The domains of angles , , and where
are
(23)
Beyond (we designate this range through )
the planes are not reached by the vector ,
i.e. , and, consequently, do
not take part in plastic deforming. Decompose
into two parts, :
(25)
(26)
includes the planes which is not reached by
, but moved during the creep on 1-2 portion
when . includes the planes which did
not move during the whole process ( ), from
point 0 to point 2.
Fig. 2. Rate integral vs. time plot at .
It is clear that there is no defect intensity increment
within , i.e. Eq. (14) must be applied to calculate
for the range (25)-(26).
The defect intensity distribution at point 3
is
(2
7)
6. Khushbu Nagori . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -5) March 2017, pp.66-69
www.ijera.com DOI: 10.9790/9622-0703061521 20 | P a g e
where denotes the defect intensity at point 2
given by Eq. (14) at .
Now, the plane distance due to the stress drop is
(28)
The increment in the compressive plastic strain
vector component ( ) is calculated by the
integration of the strain intensity increment given
by Eqs. (21) and (22) within boundaries (23):
(2
9)
V. NEGATIVE (REVERSE) CREEP
Rate integral for behaves as (Fig. 2)
(30
)
It is easy to see that for due to
vs. time curve constructed via (30) never cuts the
time-axis.
Inspect the strain rate intensity for . First of
all, it is clear that the creep strain can develop only
from the domain (23) or its sub-domain, where the
planes are located on the endpoint of at
, and . Therefore, the
formulae for and , according to Eqs. (11)
and (30), take the form as follows
,
(
3
1
)
Further, Eqs. (3) and (31) give as
(3
2)
The domain of the positive values of is
(33)
(34)
Special attention must be paid to the
relation between the domains of non-zero and
. In order to avoid a situation when the creep
deformation develops on the planes which are not
at the endpoint of the stress vector, we require that
range (33) be not greater than that from (23) taken
at , i.e. . To meet this condition,
the following restriction must be imposed
(35)
If this inequality holds true, the planes from the
domain
(36)
do not take part in the development of reverse
creep.
To calculate the negative creep strain rate vector
component ( ), Eq. (1), together with Eqs. (32)
and (34), must be utilized. As a result, we have
(3
7)
7. Khushbu Nagori . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -5) March 2017, pp.66-69
www.ijera.com DOI: 10.9790/9622-0703061521 20 | P a g e
The analysis of the formulae above gives that the
is a decreasing function of time and at
the instant of time ( ) when . This
is in a full agreement with portion 3-4 in Fig. 1.
VI. COMPARISON OF THE MODEL
AND EXPERIMENTAL RESULTS
My goal here is:
a) to calculate plastic contraction due to the stress
drop,
b) to plot negative creep diagram,
The results obtained in terms of the synthetic model
will be compared with experimental data obtained
in uniaxial tension for Ti3SiC2 alloy (Radovic et al.,
2003).
The following series of parameters are needed: (i)
experiment parameters, (ii) material constants, (iii)
model constants. The first column in Table 1
contains the parameters of experiment on Ti3SiC2
conducted by Radovic et al. (2003). The second
column shows the constants of the synthetic theory
via which the analytical diagrams are constructed
(Figs. 3 and 4).
First of all, we read from Fig. 3 the value of the
specimen contraction due to the stress drop:
. According to the Hooke
law, an elastic contraction caused by the would
be . This
fact implies the onset of plastic contraction due to
the stress drop, which can be calculated as
. By utilizing Eq. (29), I have obtained the plastic
contraction 5.644 , which deviates from
the experiment only by 8.9%.
Table 1.Calculation parameters
Material and experiment parameters Model constants
Stress 40 B 0.3163
Stress drop -20 0.00453
Temperature 1150 38200
Young modulus ; (Barsoum et al., 1999) 325 502000
Creep limit ; 3.0
k 3.0The creep activation energy ; (Radovic et
al., 2003)
4.58×105
To utilize the formulae derived for
negative creep, we need to determine the value of
the creep limit. We take creep limit at a given
temperature as the value of tensile stress resulting
in the strain rate of .Therefore, can
be read from the experimental line in Fig. 3 if
to prolong it to the indicated value.
To calculate steady state creep rate, we use
formulae obtained by Rusinko (Rusinko, A., &
Rusinko, K., 2011):
(4.1
.83)
(4.1
.84)
The model line in Fig. 3, which is obtained via the
formulae above, shows good agreement with the
experimental data.Theoretical stress ~ time plot for
the negative creep portion (Fig. 4) is constructed as
(4.1.85)
where is defined by Eq. (37). The value of the
deformation at the beginning of negative creep
( ) we have read from the experimental curve
( )
8. Khushbu Nagori . Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -5) March 2017, pp.66-69
www.ijera.com DOI: 10.9790/9622-0703061521 2 | P a g e
Fig. 3. vs. plot for Ti3SiC2 alloy at 1150 ; □ – experiment (Radovic et al., 2003), line – model result.
( is steady-state creep rate).
Fig. 4. Negative creep diagram of Ti3SiC2 alloy at 1150 , ; □ – experiment (Radovic et al., 2003),
line – model result.
V. CONCLUSION
In terms of the synthetic theory, a model has
been developed for phenomena accompanying stress-
drop tests such as a) stress-drop induced plastic
contraction, which is recorded in spite of the fact that the
net stress remains positive and b)negative creep. These
results have been achieved by introducing a relation
between the deformation properties of materials for
opposite directions, e.g. tension-compression.It is
possible due to the basic features of the synthetic theory:
a) the uniformed approach to the modeling of permanent
deformation independently of instantaneous (plastic) or
temporary (creep) deformation to be considered, and
b) the intimate connection between the macro-
deformation and the defect structure on the micro-
level of material. Model results, plastic contraction
due to the stress-drop and negative creep diagram,
show good agreement with experimental data.
REFERENCES
[1] Cadek,J. (1987). The back stress concept in
power law creep of metals: a review. Materials
Science and Engineering, 94: 79-92.
[2] Davies, P. W., & Wilshire, B. (1971). On
internal stress measurement and the mechanism
of high temperature creep. Scripta
Metallurgica, 5: 475-478.
[3] Evans, R. W., Roach, W. J. F., & Wilshire, B.
(1985). A re-interpretation of r and h
measurementsduring creep. Materials Science
and Engineering, 73: L5-L8.
[4] Kassner, M. E., Geantil, P., Levine, L. E., &
Larson, B. C. (2009). Backstress, the
Bauschinger effect and cyclic deformation.
In Materials Science Forum, 604: 39-51. Trans
Tech Publications.
[5] Lloyd, G. J., & McElroy, R. J. (1974). On the
anelastic contribution to creep. Acta
Metallurgica, 22: 339-348.
[6] Mughrabi, H. (1983). Dislocation wall and cell
structures and long-range internal stresses in
deformed metal crystals. Acta
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