The Effects of Matrix Plasticity on the Thermal Deformation of Continuous Fiber Graphite/Metal Composites

Abstract

The thermal deformation behavior of very low expansion, unidirectional and angle- ply metal matrix composites is investigated. The theoretical investigation accounted for the plastic flow in the matrix material resulting from residual thermal stresses and ex posure to thermal cyclic environment. Results indicate that the thermal deformation behavior varies significantly in accordance with the stress state of the matrix material. Plasticity in the matrix material causes large thermal strains and hysteresis loops that are not predicted by the elastic analysis. The effects of plasticity can be minimized, however, by increasing the yield stress of the matrix material and preconditioning the composite consistent with the operating temperatures. This paper also includes test data substantiating the elastoplastic effects of matrix material as predicted by analysis.