Residual strength and damage mechanisms of laminated carbon fiber reinforced polymer under thermal environments and laser irradiations

It is interesting to compare the residual strength of laminated carbon fiber reinforced polymer under thermal environments with finite heating rate, and laser irradiation with rapid heating rate. In these two conditions, heating rates are varied in two orders of magnitude, and thermally-induced damage mechanisms are quite different, which may influence the performance of residual strength. Systematic experiments are performed to obtain the tensile failure behavior of laminated carbon fiber reinforced epoxy composites at different temperatures with a heating rate of about 10(2)degrees C/min. In comparison, composite samples are subjected to laser irradiations of different power densities and then tested for residual strengths, the laser induced heating rate is above 10(4)degrees C/min. Experimental results indicate that the residual strength decreases with the increase of heating temperatures and laser power densities, however the damage mechanisms for conventional heating are thermal pyrolysis, oxidation and delamination, whereas the main damage mechanisms for laser irradiation are thermal pyrolysis and fiber ablation. The experimentally obtained residual strength and modulus are also compared with those predicted by theoretical model. POLYM. ENG. SCI., 58:2311-2319, 2018. (c) 2018 Society of Plastics Engineers