Thermal Cycling Response of Quasi-Isotropic Metal Matrix Composites

In this study, thermal cycling response of quasi-isotropic metal-matrix composite (MMC) with a stacking sequence of [0/ ± 45/90]_s was investigated. The thermal cycles were imposed between temperatures of 316–649° C. Metallography of the samples at the edge has shown the presence of fiber-matrix debonding and ply-to-ply separation (delamination) in the 45 and 90 deg plies. The propensity for debonding was found to be greater when fibers are too close in any of these plies. Both closed form elastic analysis and linear finite element analysis using temperature dependent material properties were undertaken to evaluate the criticality of local stresses and strains in the constituent materials. Inelastic deformation around fiber-matrix interface leading to cracking in the 90 deg ply was best simulated by higher local variation in fiber volume fraction in the composite and the presence of initial process induced defect.