On Thermal Hardening and Uniform Fields in Two-Phase Composite Materials

Abstract

The effect of uniform thermal changes on the position of yield surfaces in the overall stress space is described for two-phase fibrous and particulate composite materials with an elastic-plastic matrix. An auxiliary uniform strain field is used to evaluate this effect in an exact manner. The thermal change is shown to cause a rigid-body translation of all local branches of the yield surface in the overall stress space, in the direction of the overall stress associated with the uniform strain field. In a similar way, the contribution of a thermal change to the overall strain is evaluated from the solution of a mechanical loading problem, in terms of an equivalent overall stress increment, and a uniform isotropic strain change. Such connections between mechanical and thermal loads in inelastic analysis of composites have been described in [1–4]; their applications in processing of composite laminates appear in [5].