Computation methods in residual fatigue life estimations of structural components using strain energy density method

This work is focused on computational methods and software of aircraft structural components with respect to fatigue and fracture mechanics. Computational method is based on combining singular finite elements to determine stress intensity factors for cracked structural components, with the corresponding crack growth laws that include the effect of load spectra on number of cycles or blocks up to failure. The procedure is applied to aircraft structural components. In this investigation Strain Energy Density (SED) method is used in the domain of residual fatigue life of structural components under general load spectrum up to a crack initiation and crack growth. The SED method is based on using low cycle fatigue (LCF) properties for crack initiation and crack growth analyses. To determine analytic expressions for stress intensity factors (SIF), that are necesary in crack growth analysis for residual life estimation, 6-node singular finite elements are used. Computation results are compared with the analytic ones and they agree with the experiments.