Prediction of static and fatigue damage progress in composites

Soft X-ray photograph of fatigue
damage near a hole of CFRP cross-ply
laminate

Although the fatigue property of CFRPs are superior to metals, various damage occurs before fatigue failure. Long-term durability must be guaranteed in actual structures, and prediction of high-cycle fatigue damage is essential for durability evaluation. We have developed a simulation code to predict high-cycle fatigue damage of composite laminates by using a layer-wise finite-element model with cohesive elements connecting layers, and by applying the fatigue damage law based on the damage mechanics to the cohesive elements. In addition, a damage monitoring technique using FBG optical fiber sensors has been applied to CFRP laminates subjected to cyclic loading.