Experiments and numerical simulation of ductile damage and failure under low-cycle biaxial shear loading conditions with the X0-specimen

The paper deals with experimental and numerical analysis of ductile damage and failure under extremely low-cycle loading conditions. The biaxial X0-specimen is loaded in cycles causing reverse pure-shear-like conditions. Consequently, cyclic shear loading is applied whereas the stress triaxiality remains almost constant at zero. For the here discussed series at each experiment the reverse point of the applied displacements is from monotonic loading stepwise reduced leading to a different amount of loading cycles before fracture occurrence. Corresponding numerical simulations with an extended anisotropic continuum damage model are carried out and reveal different insights of the mechanisms caused by the loading history. The plastic material behavior is characterized by a hydrostatic stress sensitive Drucker-Prager yield condition with combined hardening. Furthermore, the anisotropic damage behavior is characterized by a stress-state-dependent damage condition and a damage strain tensor reflecting the damage evolution whereas stress state influences are considered as well. On the experimental side digital image correlation (DIC) enables comparison of experimental and numerical strains on the specimen surface. The numerical results for load displacement curves and strain fields agree well with the experimental data and consequently represent the material behavior in an adequate way.