A Simplified Transient Hardening Formulation for Modeling Stress–Strain Response Under Multiaxial Nonproportional Cyclic Loading

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Nicholas R. Gates ◽  
Ali Fatemi
Keyword(s):  
Cyclic Plasticity ◽  
Accurate Estimation ◽  
Strain Response ◽  
Multiaxial Loading ◽  
Loading Conditions ◽  
Stress Strain ◽  
Material Constants ◽  
Modeling Stress ◽  
Incremental Step

Accurate estimation of material stress–strain response is essential to many fatigue life analyses. In cases where variable amplitude loading conditions exist, the ability to account for transient material deformation behavior can be particularly important due to the potential for periodic overloads and/or changes in the degree of nonproportional stressing. However, cyclic plasticity models capable of accounting for these complex effects often require the determination of a large number of material constants. Therefore, an Armstrong–Frederick–Chaboche style plasticity model, which was simplified in a previous study, was extended in the current study to account for the effects of both general cyclic and nonproportional hardening using a minimal number of material constants. The model was then evaluated for its ability to predict stress–strain response under complex multiaxial loading conditions by using experimental data generated for 2024-T3 aluminum alloy, including a number of cyclic incremental step tests. The model was found to predict transient material response within a fairly high overall level of accuracy for each loading history investigated.

scholarly journals Stress-strain response in gears tooth root due to low cycle fatigue

2019 ◽  
Vol 287 ◽  
pp. 02002
Author(s):  
Marina Franulovic ◽  
Kristina Markovic ◽  
Zdravko Herceg
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Material Model ◽  
Strain Response ◽  
Tooth Root ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Main Research ◽  
Damage Initiation

Gears are mechanical components which experience high dynamic loading during their exploitation period. Therefore, their load carrying capacity together with life expectancy are often the main research interest in various studies. The research presented in this paper is focused on the materials response in spur gears tooth root, with the attention given to the repeated overloads during gears operation. In order to simulate low cycle fatigue by using numerical modeling of stress - strain relationship within material, the material model which takes into account isotropic and kinematic hardening is used here. Material response of specimens produced out of steel 42CrMo4 in different loading conditions is used for the calibration of material model, which is then applied to simulate damage initiation and materials stress - strain response in gears tooth root. The results show that materials response to the given loading conditions non-linearly change through the loading cycles.

scholarly journals Stress-Strain Response Determination during Incremental Step Tests and Variable Loadings on Flat Specimens

Technologies ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 53 ◽  
Author(s):  
Domen Šeruga ◽  
Marko Nagode ◽  
Jernej Klemenc
Keyword(s):  
Strain Response ◽  
Variable Loading ◽  
Stress Strain ◽  
Damage Prediction ◽  
Stress Signal ◽  
Loading Tests ◽  
Sufficient Magnitude ◽  
Response Determination ◽  
Incremental Step ◽  
Initial Cracks

For stress-strain response simulations and damage prediction of cyclically loaded mechanical components, it is crucial to determine both the stress-strain and durability curves of the materials sued. Round and flat specimens can be used for this purpose, either following standard recommendations for their geometry or by designing a special geometry which enables special requirements, such as initial cracks of various shapes, attachment of an extensometer, special grips for raised temperatures, and so on. However, especially in the case of flat specimens having a slender shape, buckling can occur before the stress or strain values reach a sufficient magnitude in compression. To avoid this, an anti-buckling support can be attached to the specimen, which prevents the occurrence of buckling. In turn, friction occurs between the specimen and the anti-buckling support, which affects the measurement of the stress. If a special sensor is attached under the anti-buckling support, the friction force can be measured and subtracted from the stress signal, leaving only the stress-strain response of the material under investigation. In this study, two materials were investigated during incremental step and variable loading tests: The aluminium alloy AlMgSi0.5 and a biodegradable polylactide.

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