Fatigue of Composite Materials Subjected to Variable Loadings

Abstract

In the present work, a model describing the fatigue behaviour of composite materials under spectrum loading is presented. The approach is based on a two-parameter model describing the strength degradation kinetics for fibre-reinforced materials subjected to cyclic loadings, both with constant and variable amplitudes. The point of strength of the presented approach is that it allows to consider cyclic loadings as they are, without simplifications or reductions. In particular, the analytical background of the model is based on the statements that govern the composites behaviour and focused on the issues related to this class of materials when subjected to fatigue. Then, the final step is the definition of a damage accumulation rule that goes over Miner’s rule unreliability when applied to fibre-reinforced materials. As a matter of fact, it allows to take into account the effects of different loading histories, underlining the importance of the sequence of loads application in the framework of the presented approach.