Multiaxial fatigue damage evaluation of bonded repair and efficient performance evaluation of a composite wing section

Abstract

Technology gaps exist for design and certification of bonded repair of large composite structures under multiaxial loading. They are 1) consideration of delamination failure without including the matrix cracking-induced stress concentration at a ply interface; 2) use of test data from a simple geometry for the failure prediction of a complex repaired configuration with a multiaxial stress state and spatial variation of the local stress ratio; 3) pre-assumed failure modes without including the multiaxial stress state-driven damage initiation and progression; and 4) lack of a rational modeling approach for the damage evaluation of a full-scale structure to balance the computational efficiency and solution accuracy. Our primary goal of this study is to extend our modeling capability for a bonded composite structure subjected to multiaxial loading and to demonstrate a global-local modeling capability for the high-fidelity damage evaluation at a critical location of a full-scale composite wing section. Multiaxial tests for a scarf repaired component are performed via the bi-axial cruciform apparatus while a capability demonstration is conducted using the strain survey test of a full-scale wing section via the developed test rig. After verification of the global response prediction, the developed global-local modeling strategy is used to evaluate the damage progression at a critical location with a detected initial defect.