The Development of an Analytical Prediction Technique for Variable Amplitude Fatigue Crack Propagation

The development of a fatigue crack-growth predictive technique for variable amplitude loading, initiated under previous NADC support, was continued. Attention was focused on a simple version of the general model. This provided a crack growth predictive formula for constant amplitude loading. Comparisons with experimental results and a semiempirical crack-growth law ahow that the prediction is quite realistic. The work has also indicated how improvements in the general model can be made to cope with more realistic service conditions. The further steps required to develop an efficient model that can cope with both variable amplitude loading and environmental effects are outlined. (Author)