Improved Finite Element Model to Predict the Reverse Loading Behavior of Autofrettaged A723 and HB7 Cylinders

Ideal isotropic or kinematic hardening is often utilized in order to simplify the modeling of the loading and reverse loading behavior of materials when using finite element analysis. Unfortunately, this simplification can result in significant error if the material exhibits the Bauschinger effect (BE), which is the loss of strength of the material upon reverse loading. The error associated with this simplification is further compounded in heavily autofrettaged, Cr-Mo-V, thick walled cylinders due to the fact that the Bauschinger effect and the reverse loading strain hardening exponent are a strong function of the initial applied plastic strains, which can vary significantly throughout the wall of the cylinder.