Finite Element Analysis Of The Slow Crack GrowthProcess

Abstract

A nonlinear finite element analysis, based on the incremental theory of plasticity with isotropic hardening rule, has been performed for the process of slow crack growth in center-cracked specimens made of 2024-T3 aluminum alloy. With experimental data relating the applied stress and the crack size taken as input, it is found that the plastic energy and the crack size are linearly related during the entire process of slow crack growth. Moreover, the linear relation between the plastic energy and the crack size, replacing the experimental applied stress vs. crack size curve, may also be taken as the input and generate a crack resistance curve which is in excellent agreement with the experimental result. This finding enables one to establish a fracture law which can be used to identify the onset of slow crack growth and the onset of fast fracture. Also, a non-self-similar crack growth process has been analyzed for a cracked specimen subjected to monotonically increasing biaxial and shear loading until the point of fast fracture is reached. The orientation and the amount of crack growth are determined by the equivalent maximum opening stress criterion and the linear relation between the plastic energy and the crack size, respectively.