Characteristics of damage and fracture process of carbon fiber reinforced plastic under loading-unloading test by using AE method

The purpose of present paper is to estimate the damage of carbon fiber reinforced plastic (CFRP) by using a new factor of acoustic emission (AE) and secant modulus during loading-unloading test. Acoustic emission signal and fracture process were monitored by AE measurement system and video microscope in real time during the test. In the investigation of fracture process with AE amplitude distributions, high amplitude signal, middle amplitude signal and low amplitude signal correspond to fiber breaking, debonding and matrix cracking, respectively. Felicity ratio and secant modulus were studied during the sequential loading-unloading test. It is concluded that this factor is to be a good indicator to predict the damage condition and final fracture time.