Degradation Characteristic of CFRP by Heat Cycle

Abstract

A heat cycle test equipment was designed and assembled, and it was used to perform the fatigue test of CFRP as one of the environmental element tests for evaluating the durability of composite materials in thermal environments. The main results obtained are as follows.
(1) For CFRP, lowering of flexure strength was most remarkable in the environment comparable to the condition on the fracture critical curve of stress-temperature, when subjected to heat cycle fatigue under creep stress.
(2) The maximum degradation was found when the high temperature side of the heat cycle temperature range was near T_g.
(3) The degradation of CFRP with heat cycle fatigue indicated the following behaviors depending upon the combination of stress and temperature range.
(a) Type showing a remarkable degradation in the early stage.
(b) Type showing a gradual degradation.
(c) Type showing little degradation in the early stage.