Fatigue life modeling of composite laminates

In this paper fatigue in composite laminates with transverse matrix cracking is addressed in the context of damage assessment using correlation between the loss of stiffness and the applied strain instead of stress. This resulted in lower data scatter in developing a more reliable characteristic curve for the material relating damage and strain. Strain is the primary driver for damage evolution. When strain is kept constant through strain-controlled fatigue tests, no degradation in fatigue life is observed. A fatigue life model that reflects strain-damage relation is proposed for brittle composites.