A Cumulative Fatigue Damage Model for Gas Turbine Engine Disks Subjected to Complex Mission Loading

Abstract

The objective of a continuing research program is to develop a low cycle fatigue (LCF) damage model which accurately evaluates the life exhaustion of military gas turbine engine disks subjected to complex loading spectra. This paper reports the results of the first phase of the effort and specifically concerns “cold region” disk bolt holes. A simple cycle LCF model is developed which accounts for nonlinear material behavior and the presence of local surface residual stresses due to machining. Nonlinear cumulative damage is clearly observed in specimen and component testing and is successfully modeled by a “double damage” principle in which an initial crack length need not be known explicitly. Testing of full-scale components under complex loading is used to verify the models.