Modelling the fatigue behavior of composites under spectrum loading

In this paper the results coming from modelling the fatigue life and residual strength of fiber reinforced composites subjected to variable amplitude (VA) loadings are reported. The approach is based on a recently developed two-parameter residual strength model where the damage accumulation rule relies on the "equivalent strength approach" that allows considering variable loading sequences without any simplifying assumption. The development of a numerical procedure is illustrated by a series of simulations following High-Low (H-L), Low-High (L-H) and random sequences of loadings. The analytical predictions reveal that the sequence and interaction of events has a strong influence both on the rate of damage accumulation and fatigue life.