THERMAL STRESSES IN FIBRE REINFORCED COMPOSITES

A theoretical analysis is made of the dimensional changes, stresses and plastic flow accompanying an allotropic transformation in one component of a fibre composite, taking into account the simultaneous stress relaxation which occurs. The theory predicts the transformation dimensional changes observed experimentally under various temperature cycling conditions and provides an estimate of the stresses. Extending the theory to include the effect of a variation in temperature, several categories of coefficients of thermal expansion are obtained, none of which correspond to the rule of mixtures. The predicted transition from one coefficient of expansion to another during continuous cooling is confirmed experimentally and the resulting dimensional changes verified. © 1969.