A constitutive approach to fracture simulation based on augmented virtual internal bond method

摘要

The K-dominant zone, which is a small area surrounding the fracture tip, has been the interesting focus of the fracture mechanics. In the traditional linear elastic fracture mechanics(LEFM), a stress intensity factor is used to characterize the stress field of the K-dominant zone and a separate fracture criterion is used to predict the fracture behaviors. However, when using LEFM to simulate fracture propagation, the computation of stress intensity factor is a tough problem. The LEFM is actually a phenomenological methodology. The fracture behaviors are determined by material microstructure. The augmented virtual internal bond(AVIB) is a constitutive model based on microstructure. Its constitutive relation is derived from the micro bond potential, which contains the micro fracture mechanism. Hence, the so-called fracture criterion is implicitly built in the constitutive relation. In this paper, the AVIB constitutive model is used in the K-dominant zone while the usual linear elastic constitutive model is used in the rest zone to simulate fracture propagation. By this method, the computation of stress intensity factor is avoided. When and how fracture propagation is completely governed by the AVIB constitutive relation. It provides an efficient approach to fracture simulation.