FATIGUE DAMAGE EVALUATION IN CFRP WOVEN FABRIC COMPOSITIES THROUGH DYNAMIC MODULUS MEASUREMENTS

摘要

Damage development during tension-tension fatigue loading is non-destructively evaluated in terms of a damage function formulated using a dynamic elastic modulus which continuously varies with an increasing fatigue damage caused by the progressive accumulation of cracks in CFRP woven fabric composites. The dynamic elastic modulus is a function of a number of cycles alone because of the stress independency, and it forms the same cubic curve for different stress levels or stre ratios, which decreases monotonously. On the other hand, the damage function is a monotonously increasing cubic one, from which the damage development in composites during cyclic loading is presented as a function of a number of cycles. The damage function is also applied for the remaining lifetime of CFRP composites subjected to two-stress level fatigue loadings and the prediction is experimentally verified.