Fatigue Life Assessment Via Ply-By-Ply Stress Analysis Under Biaxial Loading

Abstract

A new modelling approach for calculating the stress redistributions due to matrix cracking within the fatigue life of a slightly non-symmetric composite is presented. Thereby, a ply-by-ply stiffness degradation model and an analytical engineering approach allowing the layer-wise calculation of lamina stresses are applied. The result is a single lamina-based S-N curve of the critically stressed layer (predominant fibreparallel stresses) indicating the overall laminate failure under fatigue loading. Using experimentally fatigue loaded tube specimens under biaxial loading provides the fatigue damage information (crack densities depending on the biaxial stress ratio) adopted in the modelling approach. The application and a validation of the modelling approach are shown.