A unified J-Integral-based procedure to investigate at different loading regimes the fracture by FEM simulations and image analysis

Abstract

This paper presents a robust methodology aimed at assessing the fracture toughness of materials undergoing quasi-static or dynamic loads leading to crack propagation. The proposed implementation relies on the J-Integral concept and it identically operates with data fields obtained by Finite Element modeling or fields experimentally obtained by Digital Image Correlation technique. The capability of the methodology to extract information is put into practice by simulating a FEM-based Single-Edge Notched test specimen undergoing different loading scenarios, from a simple quasi-static linear load increase up to a very aggressive loading pulse that leads to crack propagation and total failure. To do that, the simulated specimen is modeled by an isotropic damageable and pressure-dependent material model that represents a sample made of epoxy resin. The configuration parameters of the J-integral calculation algorithms and the simulation tests are subjected to an extensive parameter study to evaluate the reliability of the calculated static and dynamic energy release rate, with and without crack propagation. From this analysis, a detailed correlation between the instantaneous evolution of the fracture energy and the stress field at every material point is presented and discussed. The proposed method makes it possible to readily track the sequence of propagation and arrest of dynamic cracks.