Creep Rupture of Multidirectional Polymer Composite Laminates — Influence of Time-Dependent Damage

Evolution of various damage modes with time, in multidirectional laminates of a polymer composite (Hexcel F263-7/T300) subjected to a constant load, was experimentally studied and correlated to experimental creep rupture results to understand the influence of the former on the latter. Influence of various parameters, such as stress, temperature, thickness of inner plies, and outer-ply constraint, on damage evolution was evaluated. Observed damages include transverse (also referred in the literature as matrix cracks) cracking due to in-plane stresses, vertical cracking due to out-of-plane normal stress, delamination due to interlaminar stresses, splitting, and fiber fracture. The sequence of evolution of these damages varied with laminate stacking sequence, stress, and temperature. These damages significantly influenced one another and the creep rupture time.