Investigation of Finite Deformations and Shear Banding: Theory and Experiment

Abstract

An experimental method using a digital image processing technique is developed for the purpose of characterizing material behavior at large elastoplastic deformations and the associated phenomenon of localization of plastic flow into shear bands. This allows for a detailed description of the evolution of the nonuniform deformation pattern in the post-localization regime. The experimental results are utilized to calibrate a recently developed gradient-dependent constitutive equation which takes into account the effect of heterogeneous plastic flow, anisotropy and large deformations. The measured values of the gradient coefficients are of small magnitude suggesting that higher order gradients are important only in the highly inhomogeneous region as expected. Moreover, it is found that anisotropic effects become significant in the post-localization regime where the anisotropy ratio changes considerably.