On Evaluation Method of Damage Development for CFRP Laminates under Low Impact Energy (1st Report, Estimation of Residual Strength based on Static Bending Test after Occurrence of Damage)

Abstract

Compression after impact (CAI) test has been applied as a representative method of the evaluation for the residual strength of CFRP laminates after the occurrence of cracks or delamination. As it has several problems such as the accuracy of load measurement, the strength dependency on attachment of specimen and so on, we have proposed an evaluation method of the static bending test without the special attachment instead of the compression test after impact. We used ultrasonic microscope and SEM to observe the damage states in CFRP laminates under the impact test with low energy and the static test. From these results, we have proposed three-point static bending test method, which can determine the equivalent static bending load for arbitrary impact load. It is recognized that the residual strength after the occurrence of damage can be evaluated by the proposed method. The method, which is presented, is more convenient than the conventional method like CAI.