Numerical Simulation of Static and Dynamic Shadow Patterns Using an Atomistic Description of Crack Initiation and Propagation

摘要

In this paper we model crack propagation from an atomistic point of view. We seek to understand the phenomenology of crack propagation in a decreasing stress field. Our objective is to better understand the interpretations and implications of optical measurements (Kalthoff, Beinert, and Winkler, 1977a) of stress intensities. Our computational method is to use the simplest interatomic potential which captures the important features of real interactions and structure of cracks from a discrete point of view. In our atomistic approach the fracture criterion is not independently specified but rather follows, along with all other macroscopic constitutive quantities, from the interparticle forces. We developed a model to estimate the average strength of the stress singularity from a direct simulation of the shadow pattern using the strain distribution around the crack tip. We applied this model to the steady state propagation of a crack in a finite strip and obtained good agreement with Nilsson's (1972, 1973) corresponding continuum solution. (ERA citation 10:010228)