Fatigue analysis of transport aircraft structures using advanced cyclic plasticity models - an assessment

Strain-life methodologies have routinely been used in the aeronautical industry for many years for fatigue analysis of aircraft. The Masing plasticity model is frequently used to track hysteresis loops for fatigue damage assessment. However, for load spectra containing sparsely spaced severe overloads (common to transport aircraft), the validity of the Masing model is questionable due to its inability to capture transient material behaviour. In this paper, four advanced cyclic plasticity models are assessed. A genetic optimisation algorithm was used to optimise model parameters. The optimised models were used to simulate the fatigue lives for 21 load spectra for P-3C Orion aircraft. A comparison was made between the test lives and the numerical lives based on their statistical distributions. Based on the present optimisation process the multicomponent Armstrong Frederick model with threshold provided the best fatigue damage calculation.