A practical methodology for elastic-plastic fatigue crack growth

摘要

A practical methodology is being developed to characterize elastic-plastic fatigue crack growth (EPFCG) behavior. The methodolgy will be implemented in engineering software for crack growth analysis and life prediction of advanced resulable aerospace propulsion systems. The correlating parameter upon which the methology is based is the range of the J-integral, DELTA J. Existin J solutions are summarized, and robust methods for developing new J solutions under various loading configurations are introduced and validated. Some practical crack growth algorithms required to translate a J calculation into a quantitation of EPFCG life are highlighted. Crack cosure plays a significant role in the engineering characterization of EPFCG rates, and simple algorithms to estimate cosure stresses are described. Other algorithms address the tearing-fatigue interaction near final instability and the estimation of required material properties. Early results from experimental verification tests are reported.