Progressive fatigue damage simulation method for composites

The main objective of this work is to show the ability of solid finite element-based techniques to accurately predict the onset and progression of matrix cracks and delaminations in composites under fatigue loading. The specific objectives are: (a) to develop fatigue failure simulation method for multi-directional carbon/epoxy laminate articles in a finite element code; and (b) to correlate the failure predictions with test data. The failure prediction models presented in this work use stress-based fatigue failure criteria combined with fatigue damage accumulation and are not based on initial flaw assumptions. The verification test articles include 88-ply IM7/8552 carbon/epoxy composite laminate coupons with wavy plies, and 16-ply IM7/8552 carbon/epoxy open-hole tensile coupons. Available stress–strain relations and failure progression algorithm are built in finite element models; and fatigue material properties are used to predict fatigue damage onset and progression. The fatigue model predictions and subsequent test correlations are presented.

► Damage progression algorithm based on fatigue element failure and damage accumulation.
► 3D solid finite element-based fatigue failure models verified by tests.
► Interaction of fatigue matrix-ply cracking and delaminations.
► Fatigue failure properties established in short beam shear and curved beam tests.
► Unique insight in damage modes by 3D Computed Tomography visualization.