A critical evaluation of dynamic fracture simulations using cohesive surfaces

TL;DR

This paper critically evaluates dynamic fracture simulations using cohesive surfaces, highlighting how different cohesive laws influence crack behavior and the importance of length scales in modeling.

Contribution

It provides a comparative analysis of elastic and rigid cohesive laws in dynamic fracture simulations and discusses their effects on crack branching and elastic properties.

Findings

Elastic cohesive laws cause crack branching at high velocities.

Rigid cohesive laws do not alter elastic response or produce branching.

Cohesive surface spacing acts as an important length scale in simulations.

Abstract

Finite element calculations of dynamic fracture based on embedding cohesive surfaces in a continuum indicate that the predictions are sensitive to the cohesive law used. Simulations were performed on a square block in plane strain with an initial edge crack loaded at a constant rate of strain. Cohesive laws that have an initial elastic response were observed to produce spontaneous branching at high velocity, but to modify the linear elastic properties of the body. As a consequence the cohesive surface spacing cannot be refined arbitrarily and becomes an important length scale in the simulations. Cohesive laws that are initially rigid do not alter the linear elastic response of the body. However, crack branching behavior was not observed when such a cohesive relation was implemented using a regular finite element mesh.