Experiments on Damage and Fracture Mechanisms in Ductile Metals Under Non-proportional Loading Paths

Abstract

The paper discusses newexperiments to study the effect of non-proportional loading paths on damage and fracture behavior of ductile metals. Specimens are taken from thin metal sheets and are tested under different biaxial loading conditions covering a wide range of stress states. In this context, a thermodynamically consistent anisotropic continuum damage model is presented based on yield and damage conditions as well as evolution laws for plastic and damage strain rates. To validate the constitutive laws and to identify material parameters different experiments with the biaxially loaded X0-specimen have been performed. 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). The results elucidate the effect of loading history on damage and fracture behavior in ductile metals.