Prediction of the crack density evolution in multidirectional laminates under fatigue loadings

An innovative procedure is proposed for the prediction of the crack density evolution in multidirectional laminates subjected to cyclic loadings. The crack initiation and propagation phases are treated separately and described by means of a master S-N curve and a Paris-like curve, respectively. A damage-based multiscale strategy is adopted for the prediction of multiple crack initiation, accounting for the statistical distribution of fatigue strength and crack propagation resistance within a ply. The procedure has been implemented in a Matlab® code for the simulation of the fatigue damage evolution in multi-directional symmetric laminates. Comparisons with experimental results taken from previous works show a very good agreement.