FATIGUE FAILURE MODEL FOR FIBER-REINFORCED MATERIALS UNDER GENERAL LOADING CONDITIONS

A new model is presented which predicts the fatigue failure of fibre-reinforced materials (FRM's) under multiaxial stresses, varying minimum to maximum cyclic stress ratios and different fibre orientations with respect to the loading directions. The concept of multidirectional elementary blocks is introduced. The model predicts the fatigue failure of these and unidirectional elementary blocks, based on the establishment of a reference stress versus life line and the determination of two simple functions. This methodology reduces considerably the number of parameters to be determined experimentally. Correlation with published fatigue failure results is presented. It is shown that the model succeeds in accurately predicting fatigue failure of different unidirectional and bidirectional FRM's subjected to uniaxial and biaxial stresses and different minimum to maximum cyclic stress ratios.