Modeling the Failure Behavior of CFRP Laminates Subjected to Combined Thermal and Mechanical Loadings

This paper proposes a theoretical approach to predict the failure behavior of laminated carbon fiber reinforced polymer (CFRP) under combined thermal and mechanical loadings. Two types of CFRP Laminates i.e. CCF300/BA9916 and T700/BA9916 are investigated and TGA tests in both nitrogen and oxidation environments at different heating rates are carried out to obtain the thermal decomposition kinetic parameters of polymer matrix and carbon fiber. Based on the thermal decomposition behavior and a multi-level structure model the thermal physical properties mechanical properties and thermal deformations of the laminated composites at high temperatures are obtained. Then substituting thermally degraded properties into constitutive equations of composite materials as macroscopic defects the damage mode and failure strength of the laminated composite under thermo-mechanical loadings is obtained. Predicted elastic properties and failure strength are compared with experimental results as well as previous models. Effects of heating rates and heating environments through rigorous physical model are considered in the present work. It is found that the heating rate significantly affects the thermal and mechanical properties the higher the heating rate the less degraded are the thermo-mechanical properties and failure strength at a given temperature. Young's modulus and failure strength of T700/BA9916 are higher than those of CCF300/BA9916 at high temperatures due to the higher volume fraction of carbon fibers which are less weakened in thermal environment