On the finite element analysis of fatigue crack closure—1. Basic modeling issues

A model for the elastic-plastic finite element simulation of fatigue crack growth and crack closure is presented and evaluated. Results show that careful attention must be given to a series of critical decisions about mesh and model design if the analysis is to be reliable. Of particular concern is the mesh refinement along the crack line and the extent of crack growth beyond initial crack lengths or notch sizes. Possible criteria which would insure valid results are suggested. The choice of a crack advance scheme is considered, and several possible schemes are shown to give similar but not identical results. A particular scheme is endorsed for its stability and economy. Crack opening stresses determined by the finite element method are shown to be consistent with a number of simple analytical models, giving special attention to the effects of stress ratio and maximum stress.