Fatigue damage of quasi-isotropic composite laminates under tensile loading in different directions

The purpose of this work is to investigate fatigue damage of quasi-isotropic laminates under tensile loading in different directions. Low cycle fatigue tests of [0/−60/60]s laminates and [30/−30/90]s laminates were carried out. Material systems used are AS4/Epoxy and AS4/PEEK. The fatigue damage of [30/−30/90]s is very different from that of [0/−60/60]s. The experimental results are compared with the result obtained from the method for determining strain energy release rate components proposed by the authors. The analytical results were in good agreement with the experimental results. It is proved that the failure criterion based on the strain energy release rate is an appropriate approach to predict the initiation and growth of delaminations under cyclic loading.