On fatigue damage accumulation and material degradation in composite materials

Phenomenological aspects of fatigue damage accumulation and material degredation in composite materials are examined. A damage variable is introduced to define phenomenologically the degree of damage, and a fatigue damage accumulation model is developed in which a power-law relationship between the rate of damage development, fatigue stress level, and the current level of damage is proposed. Evaluation of the model for a random short-fiber SMC (sheet moulding compounds) materials indicates good correlation between the present model and experimental results. The model can be used to assess the behavior of materials degradation and fatigue damage development in composite materials.