Modeling of damage of ductile materials

Abstract

The paper discusses a thermodynamically consistent anisotropic continuum damage model for ductile metals. It takes into account different elastic potential functions to simulate the effect of damage on elastic material behavior. In addition, a yield condition and a flow rule describe plastic behavior whereas a damage criterion and a damage rule characterize various damage processes in a phenomenological way. To validate the constitutive laws and to identify material parameters different experiments have been performed where specimens have been taken from thin metal sheets. As an example, the X0-specimen is tested under different biaxial loading conditions covering a wide range of stress states. Results for proportional and corresponding non-proportional loading histories are discussed. During the experiments strain fields in critical regions of the specimens are analyzed by digital image correlation (DIC) technique while the fracture surfaces are examined by scanning electron microscopy (SEM). Corresponding numerical simulations have been performed and numerical results are compared with available experimental ones. In addition, based on the numerical analyses stress states as well as plastic and damage fields can be predicted allowing explanation of different damage processes on the micro-level. The results also elucidate the effect of loading history on damage and fracture behavior in ductile metals.