Elastic-Plastic Analysis of a Propagating Crack under Cyclic Loading

Fatigue cracks have been experimentally shown to close at positive stresses during constant-amplitude load cycling. The crack-closure phenomenon is caused by residual plastic deformations remaining in the wake of an advancing crack tip. This paper is concerned with the development and application of a two-dimensional finiteelement analysis to predict crack-closure and crack-opening stresses during specified histories of cyclic loading. An existing finite-element computer program which accounts for elastic-plastic material behavior under cyclic loading was modified to account for changing boundary conditions—crack growth and intermittent contact of crack surfaces. This program was subsequently used to study the crack-closure behavior under constantamplitude and simple block-program loading. a [B]