A Simple Crack Closure Model for Prediction of Fatigue Crack Growth Rates under Variable Amplitude Loading

摘要

A model for the prediction of growth rates of fatigue cracks in aluminum alloys is presented. It is based on an approximate description of crack closure behavior and can be used to predict effects of crack growth acceleration and retardation observed experimentally under variable amplitude loading. The model accounts for load interaction effects and for plane strain to plane stress transition. A computer program was developed for analysis of fatigue crack growth, and was used to analyze the effect for certain parameter variations in a flight simulation load spectrum on the crack growth rate. Model predictions of growth rates were in agreement with test data for 7075-T6 thin sheet.