Fatigue life prediction of composite laminates incorporating 3D stress analysis

The multidirectional(MD) composite laminates subjected to in-plane loading are in the three dimensional stress state due to the presence of interlaminar stresses. A quasi-3D finite element model consisting of plate elements, spring elements and rigid elements was established which, together with the fatigue damage models of unidirectional laminate, is used to construct a fatigue life estimation procedure for MD laminates with arbitrary stacking sequences. This is an integration of stress analysis, static strength analysis, cumulative damage analysis and the material property degradations. The application of the procedure for two T300/QY8911 composite laminates demonst ates good agreement of fatigue life prediction with the experiments.