Fatigue behavior of laminated composites with a circular hole under in-plane uniaxial random loading

A modified fiber failure fatigue model is presented to evaluate the behavior of laminated composites with a central circular hole under in-plane uniaxial random/block loading. The analytical model presented is based on minimum strength model and fiber failure criterion under static loading available in the literature. The analysis starts with the determination of location of a characteristic curve around the hole and the stress state along the characteristic curve under in-plane uniaxial fatigue loading. Number of cycles to failure and location of failure are determined under given fatigue loading condition. Based on ply-by-ply analysis, ultimate fatigue failure and the corresponding number of cycles are determined. Degradation of material strength as a function of applied number of cycles is considered in the model presented. Random loading case is analyzed based on rainflow counting technique. Analytical predictions are compared with the experimental results for uniaxial block loading.