Tensile behavior of 2D-C/SiC composites at elevated temperatures: Experiment and modeling

In this paper, on-axis tensile behavior of a coated 2D-C/SiC composite at elevated temperatures was studied experimentally and theoretically. The measured data reveals that the tensile modulus and strength increase continuously with increasing temperature till 1273 K. Contrarily, the failure strains decrease sharply at high temperatures than the counterpart at room temperature, manifesting the significant influence of thermal residual stresses (TRS) on mechanical behavior of C/SiC composites. Simulation of stress-strain response is based on a two-scale analytical model, in which the plain-weave element is idealized as a cross-ply laminate and its macroscopic mechanical parameters are evaluated by shear-lag approach. The primary calculation was concentrated on TRS of the composite. And, a new crack evolution model was introduced to describe the stochastic cracking process. The total strain response including residual strain and elastic strain from the loading-unloading-reloading conception was finally formulated through micromechanical analysis involving the influence of TRS on matrix cracking and interface debonding. Additionally, a strength model was developed for plain-weave structures by using shear-lag theory, statistical theory and rule of mixture. Both of the proposed constitutive and strength models can give accurate predictions for 2D-C/SiC composites at elevated temperatures.