LOCALIZING GRADIENT DAMAGE MODELS FOR DYNAMIC FRACTURE

Abstract

This thesis focuses on developing an improved gradient enhancement to adequately describe the dynamic fracture of quasi-brittle materials. Specifically, the model should • regularize the numerical solution; • obtain sharp localized damage profile(s) representing the development of macroscopic crack(s); • capture the strain rate effect. To this end, a 1D homogenization theory incorporating micro inertia is proposed to translate the micro processes onto the macro level. The good predictive capability of the homogenized model is demonstrated by considering the direct single pressure bar example and the spall tests of concrete. Based on the insights obtained from the 1D model, a localizing gradient damage model with micro inertia is proposed, following the generalized micromorphic framework. Considering the dynamic fracture of Polymethyl Methacrylate, the new model is shown to resolve the issues of the conventional model and the predicted solutions match the experimental data well.