Characterization of the post-necking strain hardening behavior using the virtual fields method

The ability to map plastic deformation around high strain gradient microstructural features is central in studying phenomena such as fatigue and stress corrosion cracking. A method for the visualization of plastic deformation in electron back-scattered diffraction (EBSD) data has been developed and is described in this article. This technique is based on mapping the intragrain misorientation in polycrystalline metals. The algorithm maps the scalar misorientation between a local minimum misorientation reference pixel and every other pixel within an individual grain. A map around the corner of a Vickers indentation in 304 stainless steel was used as a test case. Several algorithms for EBSD mapping were then applied to the deformation distributions around air fatigue and stress corrosion cracks in 304 stainless steel. Using this technique, clear visualization of a deformation zone around high strain gradient microstructural features (crack tips, indentations, etc.) is possible with standard EBSD data.

Misorientation mapping for visualization of plastic deformation via electron back-scattered diffraction.

A new mean stress corrected strain energy model is proposed for fatigue life prediction of metals. Specifically, a mean stress sensitivity parameter is incorporated into modify the dissipated strain energy by introducing two mean stress correction factors. The prediction accuracy of the proposed model is compared with those of Walker, Smith–Watson–Topper, Morrow, and generalized damage parameter models by using 13 experimental data sets. All data points for each material are, respectively, fitted into a single mean stress corrected strain energy-life curve. More accurate predictions are achieved by the proposed model for all data sets with lower model prediction errors than others.

Mean stress effect correction in strain energy-based fatigue life prediction of metals:

Measurement of true stress–strain curves and evolution of plastic zone of low carbon steel under uniaxial tension using digital image correlation

Identification of post-necking stress–strain curve for sheet metals by inverse method

A procedure for determining the true stress-strain curve over a large range of strains using digital image correlation and finite element analysis

Mean stress effect on fatigue strength of stainless steel

Strain-based modeling of fatigue crack growth – An experimental approach for stainless steel

Loading sequence effect on fatigue life of Type 316 stainless steel

True stress-strain curves of cold worked stainless steel over a large range of strains

Masahiro Kawakubo

Papers

A procedure for determining the true stress-strain curve over a large range of strains using digital image correlation and finite element analysis

Mean stress effect on fatigue strength of stainless steel

Strain-based modeling of fatigue crack growth – An experimental approach for stainless steel

Loading sequence effect on fatigue life of Type 316 stainless steel

True stress-strain curves of cold worked stainless steel over a large range of strains