This document discusses fatigue analysis and design based on stress. It begins by introducing stress and fatigue, and the relationship between them. It then discusses stress-life (S-N) curves, which relate cyclic stress levels to the fatigue life of a material. It describes how to generate S-N curves through stress-life and fatigue limit testing. It also addresses notch effects, mean stress effects, and how to analyze combined proportional loads in fatigue testing and analysis.
This document provides an overview of fatigue failure resulting from variable loading. It discusses three main fatigue life methods: the stress-life method, strain-life method, and fracture mechanics method. The stress-life method is based on stress levels and is most commonly used for high-cycle fatigue predictions, while the strain-life method considers localized plastic deformation and is better for low-cycle applications. The fracture mechanics method assumes a crack is already present and is used to predict crack growth. Key concepts discussed include fatigue testing methods, S-N diagrams, endurance limits, stress concentrations, and cumulative damage.
This document summarizes Test Method E 647 for measuring fatigue crack growth rates. It describes the test method, which involves cyclic loading of precracked specimens to determine the rate of crack growth expressed as a function of stress-intensity factor range (DK). Several specimen configurations are provided, and crack growth rates are considered a function of DK and force ratio (R). The test method standardizes how crack growth rate data can be generated and compared to characterize a material's resistance to stable crack extension under cyclic loading conditions.
IRJET-Fatigue Life Estimation of Machine ComponentsIRJET Journal
This document discusses fatigue life estimation of machine components. It begins with an introduction to fatigue failure, which occurs when fluctuating stresses cause cracks or fractures over many load cycles, even when maximum stresses are below ultimate strength. It then describes three main approaches to estimating fatigue life: stress-life, strain-life, and fracture mechanics. The majority of the document focuses on applying the stress-life approach using a stress-strain diagram to determine the number of cycles before failure based on applied stresses. It provides equations for calculating alternating and mean stresses under different loading types and for determining an equivalent stress under combined loading. The document concludes by outlining the procedural steps to use these methods and equations to estimate the fatigue life of a machine component.
Numerical modeling of the welding defect influence on fatigue life of the wel...inventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Three stress analysis methodologies were used to analyze stresses in a mild steel specimen with an eccentric hole under tension: theoretical analysis using equations, computational analysis using FEA software, and experimental analysis using strain gauges. Each method agreed the maximum stress occurred in the hole area, with the second highest in the net area and lowest in the gross area. Theoretical and experimental results differed by an average of 10%, theoretical and computational by 5.1%, and computational and experimental by 4.8%. Retesting revealed a bending moment induced by the testing machine, requiring averaging of results. Overall the different methodologies correlated well.
This document provides an overview of tensile testing. It discusses tensile specimens, testing machines, stress-strain curves, and key mechanical properties measured by tensile tests such as strength, ductility, and elastic modulus. Tensile tests are used to select materials, ensure quality, compare new materials/processes, and predict behavior under other loads. Stress-strain curves are generated by applying tension to a specimen and recording the resulting force and elongation. Important aspects of the curves, like yield strength and plastic deformation, are defined.
This document describes the ASTM E647 standard test method for measuring fatigue crack growth rate. The test involves cyclic loading of pre-cracked specimens to grow cracks over time. Crack length is measured as a function of cycles to determine the crack growth rate, which is expressed in terms of the stress intensity factor range (ΔK). Specimen geometry and testing procedures are specified to accurately measure crack growth rates and determine material properties like the threshold stress intensity factor range (ΔKth) below which cracks do not propagate. Sources of error are also discussed since precision is important but difficult to achieve given variability in materials, testing apparatus, and measurement techniques.
Diseno en ingenieria mecanica de Shigley - 8th ---HDes
descarga el contenido completo de aqui http://paralafakyoumecanismos.blogspot.com.ar/2014/08/libro-para-mecanismos-y-elementos-de.html
This document provides an overview of fatigue failure resulting from variable loading. It discusses three main fatigue life methods: the stress-life method, strain-life method, and fracture mechanics method. The stress-life method is based on stress levels and is most commonly used for high-cycle fatigue predictions, while the strain-life method considers localized plastic deformation and is better for low-cycle applications. The fracture mechanics method assumes a crack is already present and is used to predict crack growth. Key concepts discussed include fatigue testing methods, S-N diagrams, endurance limits, stress concentrations, and cumulative damage.
This document summarizes Test Method E 647 for measuring fatigue crack growth rates. It describes the test method, which involves cyclic loading of precracked specimens to determine the rate of crack growth expressed as a function of stress-intensity factor range (DK). Several specimen configurations are provided, and crack growth rates are considered a function of DK and force ratio (R). The test method standardizes how crack growth rate data can be generated and compared to characterize a material's resistance to stable crack extension under cyclic loading conditions.
IRJET-Fatigue Life Estimation of Machine ComponentsIRJET Journal
This document discusses fatigue life estimation of machine components. It begins with an introduction to fatigue failure, which occurs when fluctuating stresses cause cracks or fractures over many load cycles, even when maximum stresses are below ultimate strength. It then describes three main approaches to estimating fatigue life: stress-life, strain-life, and fracture mechanics. The majority of the document focuses on applying the stress-life approach using a stress-strain diagram to determine the number of cycles before failure based on applied stresses. It provides equations for calculating alternating and mean stresses under different loading types and for determining an equivalent stress under combined loading. The document concludes by outlining the procedural steps to use these methods and equations to estimate the fatigue life of a machine component.
Numerical modeling of the welding defect influence on fatigue life of the wel...inventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Three stress analysis methodologies were used to analyze stresses in a mild steel specimen with an eccentric hole under tension: theoretical analysis using equations, computational analysis using FEA software, and experimental analysis using strain gauges. Each method agreed the maximum stress occurred in the hole area, with the second highest in the net area and lowest in the gross area. Theoretical and experimental results differed by an average of 10%, theoretical and computational by 5.1%, and computational and experimental by 4.8%. Retesting revealed a bending moment induced by the testing machine, requiring averaging of results. Overall the different methodologies correlated well.
This document provides an overview of tensile testing. It discusses tensile specimens, testing machines, stress-strain curves, and key mechanical properties measured by tensile tests such as strength, ductility, and elastic modulus. Tensile tests are used to select materials, ensure quality, compare new materials/processes, and predict behavior under other loads. Stress-strain curves are generated by applying tension to a specimen and recording the resulting force and elongation. Important aspects of the curves, like yield strength and plastic deformation, are defined.
This document describes the ASTM E647 standard test method for measuring fatigue crack growth rate. The test involves cyclic loading of pre-cracked specimens to grow cracks over time. Crack length is measured as a function of cycles to determine the crack growth rate, which is expressed in terms of the stress intensity factor range (ΔK). Specimen geometry and testing procedures are specified to accurately measure crack growth rates and determine material properties like the threshold stress intensity factor range (ΔKth) below which cracks do not propagate. Sources of error are also discussed since precision is important but difficult to achieve given variability in materials, testing apparatus, and measurement techniques.
Diseno en ingenieria mecanica de Shigley - 8th ---HDes
descarga el contenido completo de aqui http://paralafakyoumecanismos.blogspot.com.ar/2014/08/libro-para-mecanismos-y-elementos-de.html
Effect of V Notch Shape on Fatigue Life in Steel Beam Made of High Carbon St...IJMER
The present work includes study effect of V notch shape with various angle orientation and
depths on fatigue life behavior in steel beam made of High Carbon Steel alloy AISI 1078 which has a wide
application in industry. Fatigue life of notched specimens is calculated using the fatigue life obtained from
the experiments for smooth specimens (reference) and by use Numerical method (FEA).The fatigue
experiments were carried out at room temperature, applying a fully reversed cyclic load with the
frequency of 50 Hz and mean stress equal to zero (R= -1), on a cantilever rotating-bending fatigue testing
machine. The stress ratio was kept constant throughout the experiment. Different instruments have been
used in this investigation like Chemical composition analyzer , Tensile universal testing machine
,Hardness tester , Fatigue testing machine and Scanning Electron Microscope (SEM).The results show
that there is acceptable error between experimental and numerical works
Thesis - Design a Planar Simple Shear Test for Characterizing Large Strange B...Marshal Fulford
This document presents the results of a finite element analysis of a tensile loaded shear sample used to characterize the large strain behavior of sheet metals. The analysis validated that the gauge section experiences a state of simple shear. Additional simulations examined the effects of mesh sensitivity, fillets in the gauge section corners to reduce stress concentrations, and a smaller gauge section aspect ratio. The tensile loaded shear sample was concluded to produce a simple shear state in the gauge section.
Experimental and numerical analysis of elasto-plastic behaviour of notched sp...IJERA Editor
The objective of the work was to estimate the elasto-plastic stress and strain behaviour at the root of the notch of
an Al 6061 plate undergoing tensile and compressive cyclic loading by both experimental and numerical
methods. This attempt to measured initial elasto-plastic stresses experimentally then verified by numerically.
The various Kt values such as 2, 4 and 6 specimens were subjected to tensile test using a computerised universal
testing machine. Numerical approach associated with body discretization and developed finite element model
with sufficient degree of freedom to analyses elasto-plastic analysis of notched specimen. Experimental results
show that analysis of three Kt notched specimens had similar behaviour of elasto-plastic behaviour but different
magnitude. The experimental results compare well with the numerical results which are obtained during finite
element analysis of notched specimens.
This document provides an introduction to fatigue, including:
- Fatigue occurs when a component is subjected to fluctuating stresses and fails at a stress lower than its static strength.
- It accounts for 90% of mechanical failures and occurs suddenly without warning.
- Three factors are needed for fatigue failure: a maximum stress, stress variation, and sufficient number of cycles.
- Fatigue testing involves subjecting specimens to cyclic stresses and recording the number of cycles until failure to generate an S-N curve.
The document discusses steps involved in developing S-N curves to characterize fatigue life of materials. It describes testing various stress levels on specimen groups and recording the cycle count at failure. The data is then plotted on a stress vs log life graph to develop the S-N curve. It also discusses factors that influence fatigue behavior like microstructure, size effects, surface finish and mean stress effects. Different models used to represent S-N curves in approximations are presented, including the tri-slope and Basquin models. Equations for determining allowable stress levels for a given fatigue life are also provided.
1) A monotonic tension test subjects a specimen to increasing tensile force until fracture to obtain its stress-strain behavior. For larger strains, true stress and strain must account for changes in specimen dimensions rather than engineering stress and strain.
2) Cyclic strain-controlled testing better characterizes fatigue behavior by directly controlling and measuring strain. Hysteresis loops provide the cyclic stress-strain response.
3) The strain-life approach relates the fatigue life of notched components to the life of unnotched specimens experiencing the same strain levels. It assesses fatigue damage directly based on local strain measurements.
OPTIMIZATION AND FATIGUE ANALYSISOF A CRANE HOOK USING FINITE ELEMENT METHODijmech
Stress analysis plays an important role in the design of structures like crane hook under loading conditions.
Crane hook is a reliable lifting component being used in industries. Structure failure of crane hook occurs
because of the stress induced due to repetitive loading and unloading conditions. In this study, solid
modeling of crane hook having trapezoidal cross-section referring to one of its existing design is done
using SOLIDWORKS. Further, analyses are carried out in ANSYS Workbench and nCode DesignLife. The
lengths of two parallel sides of the cross-section of crane hook are varied and different candidates are
obtained for loading capacity of 30 ton on the basis of Mass, total Displacement and Von-Mises stress.This
is done to reduce weight and balance economy. Further, out of these candidates, best candidates are
considered and fatigue analysis is performed on these candidates.
This document discusses fatigue, which is damage that accumulates in materials due to repetitive loading below the yield point. It can lead to failure even though a single application of the load would not. The document covers:
- Fatigue crack initiation from flaws where stresses concentrate and growth of intrusions/extrusions resembling cracks
- S-N curves that relate stress amplitude and cycles to failure through empirical testing
- Factors like mean stress, stress ratio, and variability that affect fatigue behavior
- Miner's law for estimating cumulative damage from variable loading
- The Paris law relating crack growth rate to the stress intensity factor range
This document discusses various concepts related to stress and strain. It begins by explaining the three main types of loads - tension, compression, and shear. It then provides diagrams demonstrating these different types of loads. The document goes on to define engineering stress and strain and discuss their units. Several mechanical properties are also defined, including yield strength, ultimate tensile strength, and elongation. Finally, the document discusses various tests used to determine mechanical properties, including tensile, compression, hardness, and impact tests.
Design against fluctuating loads, stress concentration, Goodman and Modified Goodman Diagrams, Factors affecting stress concentration, Use of charts for finding stress concentration facotrs
The document summarizes an experiment that performed tensile tests on samples of 2024 aluminum and 1018 steel to determine material properties. Two measurement methods were used - one that measured displacement directly with a laser and one that used the testing machine's crosshead measurement. The laser method proved more accurate for determining properties that depend on strain like Young's modulus and strain hardening exponent. Tables of results show the laser method yielded values closer to published data. Direct strain measurement improved accuracy over using the crosshead displacement.
Predicting fatigue using linear – finite element analysisSowmiya Siva
Graphler Technology is one of the fastest-growing product design companies in India . Our FEA Consulting services hold great promise for the future trends of Commercial Furniture’s using ANSI/BIFMA. We have a team of experts specialized in CAD Conversion Services, Engineering animation services and also in Product Animation Services
Studies on factors influencing the behavior of bolted flanged jointseSAT Journals
Abstract This article aims to study the parameters influencing the overall behavior of bolted flanged joints. Three dimensional finite ele-ment analysis has been extensively used to study the performance of bolted joints for eccentric tensile loading. Pretension in the bolt is modeled using ANSYS pretension element (PRETS179) which can be used on solid or line element types. Surface-to-surface contact elements are used to account for the contact pressure at various flange interfaces. The parameters considered for the study are bolt load, contact pressure between flanges and washers, flange opening and strains in the bolt. The effect of prel-oad on various parameters is studied. This paper illustrates the behavior of bolted flanged joints in entirety and brings out the effect of prying action on the bolted flanged joint. Index Terms— Bolt Load , Bolted joint, Contact Elements, Contact Pressure, External load, Pretension, Strains
Photoelastic Stress Analysis of Bell Crank Lever: A ReviewIRJET Journal
The document discusses photoelastic stress analysis of a bell crank lever. It provides background on photoelasticity, which uses properties of light to determine stress and strain fields in loaded components. The document then reviews using photoelastic methods like a polariscope to analyze stresses in a bell crank lever model made of a photoelastic material. Results from the experimental photoelastic analysis are shown to be in close agreement with numerical finite element analysis, with maximum stresses occurring at the fulcrum of the lever. The summary provides an overview of the key points discussed in the document regarding photoelastic stress analysis of a bell crank lever.
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.
Analysis of Stress Distribution in a Curved Structure Using Photoelastic and ...IOSR Journals
1) The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2) Photoelasticity is used to experimentally determine stress distribution in models of the curved structure with and without circular and elliptical stress relievers. Finite element analysis is then used to validate the experimental photoelastic results.
3) The study found that an elliptical stress reliever with its major axis normal to the load more effectively reduced stress concentration at the inner boundary of the curved structure compared to a circular stress reliever.
1. The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2. It introduces circular and elliptical stress relievers in the low stress region to reduce weight without affecting strength. The elliptical stress reliever with major axis normal to loading reduced stress intensity by 2% compared to the original structure.
3. Results from photoelastic experiments matched well with finite element analysis simulations. The experimental method provided precise stress values regardless of geometric complexity, while finite element analysis was less time consuming and helped optimize the stress reliever geometry.
Analysis of Stress Distribution in a Curved Structure Using Photoelastic and ...IOSR Journals
1. The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2. It introduces circular and elliptical stress relievers in the low stress region to reduce weight without affecting strength. The elliptical stress reliever with major axis normal to loading reduced stress intensity by 2% compared to the original structure.
3. Results from photoelastic experiments matched well with finite element analysis simulations. The experimental method provided precise stress values regardless of geometric complexity, while finite element analysis was less time consuming and helped optimize the stress reliever geometry.
This document summarizes a senior project analyzing the ultimate strength of aircraft structures through testing and analysis. A group of students analyzed and tested beams with different cross-sectional shapes to study local buckling effects on strength, following methods from a paper by their advisor Dr. Todd Coburn. The project involved analyzing critical cross-sections using plastic bending analysis and Cozzone's method. It also developed a hybrid procedure accounting for material non-linearity, flange stability, and other factors influencing ultimate strength. The procedure determines strain distributions and calculates ultimate moments based on stress-strain curves for each section element.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
Effect of V Notch Shape on Fatigue Life in Steel Beam Made of High Carbon St...IJMER
The present work includes study effect of V notch shape with various angle orientation and
depths on fatigue life behavior in steel beam made of High Carbon Steel alloy AISI 1078 which has a wide
application in industry. Fatigue life of notched specimens is calculated using the fatigue life obtained from
the experiments for smooth specimens (reference) and by use Numerical method (FEA).The fatigue
experiments were carried out at room temperature, applying a fully reversed cyclic load with the
frequency of 50 Hz and mean stress equal to zero (R= -1), on a cantilever rotating-bending fatigue testing
machine. The stress ratio was kept constant throughout the experiment. Different instruments have been
used in this investigation like Chemical composition analyzer , Tensile universal testing machine
,Hardness tester , Fatigue testing machine and Scanning Electron Microscope (SEM).The results show
that there is acceptable error between experimental and numerical works
Thesis - Design a Planar Simple Shear Test for Characterizing Large Strange B...Marshal Fulford
This document presents the results of a finite element analysis of a tensile loaded shear sample used to characterize the large strain behavior of sheet metals. The analysis validated that the gauge section experiences a state of simple shear. Additional simulations examined the effects of mesh sensitivity, fillets in the gauge section corners to reduce stress concentrations, and a smaller gauge section aspect ratio. The tensile loaded shear sample was concluded to produce a simple shear state in the gauge section.
Experimental and numerical analysis of elasto-plastic behaviour of notched sp...IJERA Editor
The objective of the work was to estimate the elasto-plastic stress and strain behaviour at the root of the notch of
an Al 6061 plate undergoing tensile and compressive cyclic loading by both experimental and numerical
methods. This attempt to measured initial elasto-plastic stresses experimentally then verified by numerically.
The various Kt values such as 2, 4 and 6 specimens were subjected to tensile test using a computerised universal
testing machine. Numerical approach associated with body discretization and developed finite element model
with sufficient degree of freedom to analyses elasto-plastic analysis of notched specimen. Experimental results
show that analysis of three Kt notched specimens had similar behaviour of elasto-plastic behaviour but different
magnitude. The experimental results compare well with the numerical results which are obtained during finite
element analysis of notched specimens.
This document provides an introduction to fatigue, including:
- Fatigue occurs when a component is subjected to fluctuating stresses and fails at a stress lower than its static strength.
- It accounts for 90% of mechanical failures and occurs suddenly without warning.
- Three factors are needed for fatigue failure: a maximum stress, stress variation, and sufficient number of cycles.
- Fatigue testing involves subjecting specimens to cyclic stresses and recording the number of cycles until failure to generate an S-N curve.
The document discusses steps involved in developing S-N curves to characterize fatigue life of materials. It describes testing various stress levels on specimen groups and recording the cycle count at failure. The data is then plotted on a stress vs log life graph to develop the S-N curve. It also discusses factors that influence fatigue behavior like microstructure, size effects, surface finish and mean stress effects. Different models used to represent S-N curves in approximations are presented, including the tri-slope and Basquin models. Equations for determining allowable stress levels for a given fatigue life are also provided.
1) A monotonic tension test subjects a specimen to increasing tensile force until fracture to obtain its stress-strain behavior. For larger strains, true stress and strain must account for changes in specimen dimensions rather than engineering stress and strain.
2) Cyclic strain-controlled testing better characterizes fatigue behavior by directly controlling and measuring strain. Hysteresis loops provide the cyclic stress-strain response.
3) The strain-life approach relates the fatigue life of notched components to the life of unnotched specimens experiencing the same strain levels. It assesses fatigue damage directly based on local strain measurements.
OPTIMIZATION AND FATIGUE ANALYSISOF A CRANE HOOK USING FINITE ELEMENT METHODijmech
Stress analysis plays an important role in the design of structures like crane hook under loading conditions.
Crane hook is a reliable lifting component being used in industries. Structure failure of crane hook occurs
because of the stress induced due to repetitive loading and unloading conditions. In this study, solid
modeling of crane hook having trapezoidal cross-section referring to one of its existing design is done
using SOLIDWORKS. Further, analyses are carried out in ANSYS Workbench and nCode DesignLife. The
lengths of two parallel sides of the cross-section of crane hook are varied and different candidates are
obtained for loading capacity of 30 ton on the basis of Mass, total Displacement and Von-Mises stress.This
is done to reduce weight and balance economy. Further, out of these candidates, best candidates are
considered and fatigue analysis is performed on these candidates.
This document discusses fatigue, which is damage that accumulates in materials due to repetitive loading below the yield point. It can lead to failure even though a single application of the load would not. The document covers:
- Fatigue crack initiation from flaws where stresses concentrate and growth of intrusions/extrusions resembling cracks
- S-N curves that relate stress amplitude and cycles to failure through empirical testing
- Factors like mean stress, stress ratio, and variability that affect fatigue behavior
- Miner's law for estimating cumulative damage from variable loading
- The Paris law relating crack growth rate to the stress intensity factor range
This document discusses various concepts related to stress and strain. It begins by explaining the three main types of loads - tension, compression, and shear. It then provides diagrams demonstrating these different types of loads. The document goes on to define engineering stress and strain and discuss their units. Several mechanical properties are also defined, including yield strength, ultimate tensile strength, and elongation. Finally, the document discusses various tests used to determine mechanical properties, including tensile, compression, hardness, and impact tests.
Design against fluctuating loads, stress concentration, Goodman and Modified Goodman Diagrams, Factors affecting stress concentration, Use of charts for finding stress concentration facotrs
The document summarizes an experiment that performed tensile tests on samples of 2024 aluminum and 1018 steel to determine material properties. Two measurement methods were used - one that measured displacement directly with a laser and one that used the testing machine's crosshead measurement. The laser method proved more accurate for determining properties that depend on strain like Young's modulus and strain hardening exponent. Tables of results show the laser method yielded values closer to published data. Direct strain measurement improved accuracy over using the crosshead displacement.
Predicting fatigue using linear – finite element analysisSowmiya Siva
Graphler Technology is one of the fastest-growing product design companies in India . Our FEA Consulting services hold great promise for the future trends of Commercial Furniture’s using ANSI/BIFMA. We have a team of experts specialized in CAD Conversion Services, Engineering animation services and also in Product Animation Services
Studies on factors influencing the behavior of bolted flanged jointseSAT Journals
Abstract This article aims to study the parameters influencing the overall behavior of bolted flanged joints. Three dimensional finite ele-ment analysis has been extensively used to study the performance of bolted joints for eccentric tensile loading. Pretension in the bolt is modeled using ANSYS pretension element (PRETS179) which can be used on solid or line element types. Surface-to-surface contact elements are used to account for the contact pressure at various flange interfaces. The parameters considered for the study are bolt load, contact pressure between flanges and washers, flange opening and strains in the bolt. The effect of prel-oad on various parameters is studied. This paper illustrates the behavior of bolted flanged joints in entirety and brings out the effect of prying action on the bolted flanged joint. Index Terms— Bolt Load , Bolted joint, Contact Elements, Contact Pressure, External load, Pretension, Strains
Photoelastic Stress Analysis of Bell Crank Lever: A ReviewIRJET Journal
The document discusses photoelastic stress analysis of a bell crank lever. It provides background on photoelasticity, which uses properties of light to determine stress and strain fields in loaded components. The document then reviews using photoelastic methods like a polariscope to analyze stresses in a bell crank lever model made of a photoelastic material. Results from the experimental photoelastic analysis are shown to be in close agreement with numerical finite element analysis, with maximum stresses occurring at the fulcrum of the lever. The summary provides an overview of the key points discussed in the document regarding photoelastic stress analysis of a bell crank lever.
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.
Analysis of Stress Distribution in a Curved Structure Using Photoelastic and ...IOSR Journals
1) The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2) Photoelasticity is used to experimentally determine stress distribution in models of the curved structure with and without circular and elliptical stress relievers. Finite element analysis is then used to validate the experimental photoelastic results.
3) The study found that an elliptical stress reliever with its major axis normal to the load more effectively reduced stress concentration at the inner boundary of the curved structure compared to a circular stress reliever.
1. The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2. It introduces circular and elliptical stress relievers in the low stress region to reduce weight without affecting strength. The elliptical stress reliever with major axis normal to loading reduced stress intensity by 2% compared to the original structure.
3. Results from photoelastic experiments matched well with finite element analysis simulations. The experimental method provided precise stress values regardless of geometric complexity, while finite element analysis was less time consuming and helped optimize the stress reliever geometry.
Analysis of Stress Distribution in a Curved Structure Using Photoelastic and ...IOSR Journals
1. The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2. It introduces circular and elliptical stress relievers in the low stress region to reduce weight without affecting strength. The elliptical stress reliever with major axis normal to loading reduced stress intensity by 2% compared to the original structure.
3. Results from photoelastic experiments matched well with finite element analysis simulations. The experimental method provided precise stress values regardless of geometric complexity, while finite element analysis was less time consuming and helped optimize the stress reliever geometry.
This document summarizes a senior project analyzing the ultimate strength of aircraft structures through testing and analysis. A group of students analyzed and tested beams with different cross-sectional shapes to study local buckling effects on strength, following methods from a paper by their advisor Dr. Todd Coburn. The project involved analyzing critical cross-sections using plastic bending analysis and Cozzone's method. It also developed a hybrid procedure accounting for material non-linearity, flange stability, and other factors influencing ultimate strength. The procedure determines strain distributions and calculates ultimate moments based on stress-strain curves for each section element.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
Low power architecture of logic gates using adiabatic techniquesnooriasukmaningtyas
The growing significance of portable systems to limit power consumption in ultra-large-scale-integration chips of very high density, has recently led to rapid and inventive progresses in low-power design. The most effective technique is adiabatic logic circuit design in energy-efficient hardware. This paper presents two adiabatic approaches for the design of low power circuits, modified positive feedback adiabatic logic (modified PFAL) and the other is direct current diode based positive feedback adiabatic logic (DC-DB PFAL). Logic gates are the preliminary components in any digital circuit design. By improving the performance of basic gates, one can improvise the whole system performance. In this paper proposed circuit design of the low power architecture of OR/NOR, AND/NAND, and XOR/XNOR gates are presented using the said approaches and their results are analyzed for powerdissipation, delay, power-delay-product and rise time and compared with the other adiabatic techniques along with the conventional complementary metal oxide semiconductor (CMOS) designs reported in the literature. It has been found that the designs with DC-DB PFAL technique outperform with the percentage improvement of 65% for NOR gate and 7% for NAND gate and 34% for XNOR gate over the modified PFAL techniques at 10 MHz respectively.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
1. CONTENTS
INTRODUCTION
1
STRESS – LIFE (S-N)
2
DESIGN S-N CURVES WITH ULTIMATE
TENSILE STRENGH
4
NOTCH EFFECT
5
MEAN STRESS EFFECT
6
COMBINED PROPORTIONAL LOADS
7
06/01/2023 1
STRESS-LIFE AND FATIGUE LIMIT
TESTING
3
2. 1 INTRODUCTION
06/01/2023 2
What is Fatigue ?
Fatigue is a localized damage process of a component produced by cyclic
loading. It is the result of the cumulative process consisting of crack initiation,
propagation, and final fracture of a component.
What is Stress ?
Stress is a physical quantity that expresses the internal forces that
neighboring particles of a continuous material exert on each other or Stress is
defined as the force per unit area of a material.
What is the relation between them ?
To treat this topic, we are going to show how fatigue analysis and design can be
based on stress, by focusing on how to establish fatigue data and determine
fatigue life based on a stress-based damage.
We have to note that cyclic stresses are the governing parameter for fatigue
failure.
3. 2 STRESS-LIFE (S-N)
06/01/2023 3
The cyclic loading applied to the specimen is defined by either a constant stress range (𝑆𝑟)
or a constant stress amplitude (𝑆𝑎).
The stress range is the algebraic difference between the maximum stress and the minimum
stress and the stress amplitude is equal to one-half of the stress range.
𝑆𝑟 = 𝑆𝑚𝑎𝑥 − 𝑆𝑚𝑖𝑛 and 𝑆𝑎= 𝑆𝑟 2
Also, S-N fatigue testing is conducted using a loading that alternate about a zero mean
stress. We call it fully reversed loading.
The mean stress is given by :
𝑆𝑚 =
𝑆𝑚𝑎𝑥 + 𝑆𝑚𝑖𝑛
2
The fatigue life of the specimen at a combination of stress amplitude and mean stress
levels is defined by the number of cycles to failure 𝑁𝑓 .
Here, the fatigue life (cycles or reversals) refers to the life required to nucleate and grow
a small crack to visible crack length.
NOTE : each cycle is equal to two reversals
4. 2 STRESS-LIFE (S-N)
06/01/2023 4
The typical relation between stress and fatigue life is
𝑆𝑎 = 𝑆′
𝑓(2𝑁𝑓)𝑏
Where b is the fatigue strength and 𝑆′
𝑓 the fatigue strength coefficient.
Plot of this relation is called S-N curves.
S–N curve can be generated for standard smooth material specimens, for individual
manufactured structural components, for subassemblies, or for complete structures.
S–N curve provides the baseline fatigue data on a given geometry, loading condition, and
material processing for use in subsequent fatigue life and strength analyses. This baseline
data can be adjusted to account for realistic component conditions such as notches,
size, surface finish, surface treatments, temperature, and various types of loading.
How to plot S-N curves for a given specimen ?
5. 3 STRESS-LIFE AND FATIGUE LIMIT TESTING
06/01/2023 5
S-N fatigue tests tends to give how much time a specimen can resist up to its complete
failure under a cyclic stress.
Tests consist of a specified number of specimen that would be subjected individually to a
specified stress level and counting how much cycle is necessary to get the failure of the
specimen.
For the same stress level, two specimens can break up at different number of cycle. Also,
observation show that we can have two specimens under different stress level and have the
same fatigue life. So the statistical nature of the fatigue must be considered.
Many statistical methods are used to conducted testing and each methods is particularly
different of the other.
S–N test methods presented by the Japan Society of Mechanical Engineers (1981),
Nakazawa and Kodama (1987), ASTM (1998), Shen (1994), Wirshing (1983), and
Kececioglu (2003) are widely used by researchers for S–N testing and fatigue life
predictions.
6. 06/01/2023 6
3 STRESS-LIFE AND FATIGUE LIMIT TESTING
It is necessary to understood requirements, limitations, and approaches to the
construction of an S–N curve.
requirements, limitations, and approaches
We are going to focuses on the median S–N test method with a small sample size
presented by the Japan Society of Mechanical Engineer.
Requirements
This method requires 14 specimens. Eight specimens are used to determine the finite
fatigue life region, and six specimens are used to find the fatigue limit.
Approaches
The curve for the finite life region is determined by testing two samples at each of four
different levels of stress amplitude and the fatigue limit is tested by the staircase method
with six specimens. The recommended test sequence is shown in Figure 4.3, in which the
number next to the data point represents the order in which the specimen is to be
tested.
The finite life region data is assumed linear in the log–log coordinates, and the data are
analyzed by the least-squares method.
7. 06/01/2023 7
3 STRESS-LIFE AND FATIGUE LIMIT TESTING
b. Design s–n curves in the finite life region
As the S-N curves have been obtained, in practice, we are considering its value is
associated with an error. So, we have to define a reliability and confidence on this value.
a. Analysis of fatigue data in the finite
life region
Analysis is based on the least-squares
method for generating a line of best fit
from the data.
.
The regression line is
𝒀 = 𝑨 + 𝑩𝑿
Where
𝑩 = 𝒊=𝟏
𝒏𝒔
(𝑋𝑖 − 𝑿)(𝑌𝑖 − 𝒀)
𝒊=𝟏
𝒏
(𝑋𝑖 − 𝑿) ²
𝑨 = 𝒀 − 𝑩𝑿
8. 06/01/2023 8
3 STRESS-LIFE AND FATIGUE LIMIT TESTING
reliability is possibility of survival of the specimen tested and confidence traduce how
much we can believe in the reliability value .
This permit to have an interval or bounds around the median S-N curves plotted earlier.
The equation of this bounds or the design S-N curves are equation is
𝒀𝑳 𝑿𝒊 = 𝒀 𝑿𝒊 − 𝑲 ∗ 𝒔
where 𝑠 is the sample standard error of 𝑌 on 𝑋𝑖, 𝐾 is a multiplier equal to 2 or 3.
Limitations
As K doesn’t depend of the sample size( K is constant), this method fail to account for the
statistical distribution of fatigue life.
To overcome this, another methodology is used : the one-side lower-bound tolerance
limit method (Lieberman, 1958) , double-sided confidence intervals approach (ASTM, 1998)
and the approximate Owen one-side tolerance limit (Shen et al., 1996).
9. 06/01/2023 9
3 STRESS-LIFE AND FATIGUE LIMIT TESTING
For double-sided confidence intervals approach (ASTM, 1998) and the approximate Owen
one-side tolerance limit (Shen et al., 1996), the value of K depends on the sample size.
c. Fatigue strength testing
The objective here is to estimate a statistical distribution of the fatigue strength at a specific
high-cycle fatigue life. The staircase method is widely used for this test.
Description
A mean fatigue limit has to be first estimated, and a fatigue life test is then conducted at a
stress level a little higher than the estimated mean. If the specimen fails prior to the life of
interest, the next specimen has to be tested at a lower stress level. If the specimen does not
fail within this life of interest, a new test has to be conducted at a higher stress level.
Therefore, each test is dependent on the previous test results, and the test continues with
a stress level increased or decreased.
To determine statistical parameters of the test results two typical data reduction are used
: techniques, the Dixon-Mood (1948) and the Zhang-Kececioglu (1998) methods.
10. 06/01/2023 10
4 DESIGN S-N CURVES WITH ULTIMATE TENSILE STRENGH
Methodology
1- estimate the ultimate tensile strength
For low and medium strength of steels with low Brinell hardness (<500 BHN), the ultimate
tensile strength of a material can be linearly approximated as :
2- estimate the fatigue strength at 1000 cycles
For low and medium strength of steels with low Brinell hardness (<500 BHN), the ultimate
tensile strength of a material can be linearly approximated as :
where 𝑆1000 is the fatigue strength at 1000 cycles based on the standard test specimens
and 𝐶𝑅 is the modifying factor at a specified reliability level.
11. 06/01/2023 11
3- estimate the fatigue limit
The fatigue limit 𝑆𝑒 can be estimated by modifying the bending fatigue limit 𝑆𝑏𝑒 with the
four factors for the type of loading (𝐶𝐿), surface finish (𝐶𝑆), size (𝐶𝐷), and reliability level
(𝐶𝑅):
4 DESIGN S-N CURVES WITH ULTIMATE TENSILE STRENGH
Note that these modifying factors are empirically based and usually range from 0.0 to 1.0
fatigue strength at a specific fatigue life can be determined by the following equation:
13. 06/01/2023 13
5 NOTCH EFFECT
Notch have effect on the fatigue Failure of a specimen.
It is dependent of a factor called fatigue strengh reduction factor and defined by
For engineering applications, the fatigue strength reduction factor can be empirically related
to the elastic stress concentration factor by a notch sensitivity factor q
Value of q is given by
14. 06/01/2023 14
5 NOTCH EFFECT
We can use relative stress gradient instead of using the Notch radius to calculate the stress
gradient effects on the fatigue strength reduction
Notch effect at intermediate and short lives
where 𝐾′𝑓 is the fatigue strength reduction factor at 1000 cycles.
Estimate of fatigue life for a notched component
Where 103 ≤ 𝑁 ≤ 106.
And using
RSG is dependent of the radius and the type of loadings.
15. 06/01/2023 15
6 MEAN STRESS EFFECT
Mean stresses have a significant effect on fatigue behavior of components.
Normal mean stresses are responsible for the opening and closing state of microcracks :
tensile normal mean stresses are detrimental and compressive normal mean stresses are
beneficial in terms of fatigue strength.
The shear mean stress does not influence the opening and closing state of microcracks,
and, not surprisingly, has little effect on crack propagation.
Gerber’s mean stress correction
There are other mean stress
correction equation.
16. 06/01/2023 16
7 COMBINED PROPORTIONAL LOADS
Previously, specimen were subjected only to a uni-axial loading,
Here, multi-axial loadings are used to conduct fatigue test of the specimen.
As for each loading we have a stress , the effective stress can be found by using the von
Mises criterion with the stresses calculated from the loads and the corresponding fatigue
strength reduction factors. For brittle materials, the maximum principal stress theory is
recommended
Approach are fully described in the textbooks Fatigue Testing and Analysis. Theory and
Practice (2004, Butterworth-Heinemann) by Yung-Li Lee, Jwo Pan, Richard Hathaway,
Mark Barkey.