Acoustic emission monitoring of low-cycle fatigue behavior of glass-mat FRP in various temperature environments.

Abstract

Acoustic emission (AE) monitoring of fatigue damage processes of glass-mat FRP was made in low-cycle fatigue tests a three environmental temperatures such as -20°C, 25°C, and 120°C. The AE signal was measured in the ring-down mode with an AE measuring system connected with a personal computer. It was found at all temperatures tested here that three are three regions where a certain feature can be recognized in the ring-down rate count with the development of fatigue damage. That is, in the first region, the AE rate count is the largest at the first cycle and then it will shake down. The second region is one in which the AE rate count at the shake-down state will be approximately stable during comparatively large cycles due to the testing conditions and finally in the third, it will increase abruptly just before fatigue failure of the specimen takes place. As a result of the measured data, it was shown that the AE counts in each region have a correlation not only with low-cycle fatigue life but also with fatigue failure mode under each temperature environment.