On the integration of stresses in large deformations plasticity

Discusses an alternative formulation for the incremental determination of s tresses in strain measures that can be used to replace the stress rates cur rently employed, The formulation is based on Doyle-Hill generalized definit ion of strain, the corresponding conjugate stresses and an isotropic hypere lastic constitutive equation. When used to analyze the simple shear deforma tion the proposed formulation avoids the pathologies usually observed (osci llations, pressure build up, path dependence). The origin and importance of these pathologies is then discussed in relation to different materials beh avior It is shown that the incremental procedure used together with the log arithmic definition of strain is the most convenient but that other approxi mations may be used in well defined particular situations. The numerical al gorithms proposed are detailed in an Appendix.