A New Cumulative Fatigue Damage Model for Short Glass Fiber-Reinforced Polyamide 66

Fatigue damage of short glass fiber-reinforced composite is a quite complex phenomenon, and a large research effort is being spent on it these days. Furthermore, fatigue damage in such materials, fatigue damage kinetic exhibits three stages, namely: (i) matrix microcracking and damage initiation, (ii) coalescence and propagation of microcracks and (iii) macroscopic cracks propagation up to material failure. The proposed model is based on the stiffness degradation rule of short glass fibers-reinforced polyamide 66. This new versatile phenomenological fatigue damage model attempts to predict fatigue damage growth in its three stages. The characteristics of damage growth and accumulation of short glass fiber-reinforced polyamide 66 under fatigue bending loading were studied in this paper. Experimental data from bending fatigue tests were used to identify the model parameters. Results showed that this model is capable of describing the three stages of damage evolution of theses composite materials. Furthermore, the predicted fatigue life is in good agreement with the experimental ones.