Analysis of Fatigue and Crack Growth in Carbon-Fiber Epoxy Matrix Composite Laminates

A study of high frequency fatigue in carbon-fiber reinforced composites has been undertaken. A comparison has been made between the fatigue behavior of crossply (0° / 90°) and angleply (± 45°) carbon/epoxy unnotched and notched laminates. Additionally, a micromechanical analysis of fracture surfaces performed by scanning electron microscopy was carried out to evaluate the micromechanisms that occurred during fatigue. Experimental observations indicate that fatigue damage consists of a combination of matrix cracks, longitudinal splitting, fiber fracture, and delamination. In order to minimize the effects of residual strain due to temperature rise, a method is proposed for determining real fatigue strength at the level of variable load not lower than the fatigue limit, at which residual strains are minimal.