Material Models for the Finite Element Analysis of Materials Exhibiting a Pronounced Bauschinger Effect

Realistic material models have been developed on the basis of the experimental investigation of reverse loading with actual Bauschinger effect and implemented into a two-dimensional finite element computer program. The developed program is capable of treating the elastoplastic deformation behavior of thick-walled cylinders during both loading and unloading phases. Strain hardening may occur during loading, and reverse yielding may occur during unloading at a yield strength significantly reduced due to the Bauschinger effect. Three different models for the reverse hardening are presented. Strain hardening during reverse yielding may have a different slope than for forward loading, and it may also be nonlinear. The intended application is for autofrettage analysis of thick-walled cylinders. Being a numerical solution, it will also be very useful for finite element analysis of residual stress experimental procedures and also in the determination of more accurate stress intensity factors for autofrettaged cylinders that had undergone reverse yielding due to the Bauschinger effect.