THERMAL, HYGROSCOPIC AND IRRADIATION EXPANSION OF COMPOSITE-MATERIALS

Formulae relating the effective thermal or hygroscopic expansion coefficients of composite materials to the elastic constants and expansion coefficients of the component phases and effective elastic constants of the aggregate were first presented in 1967-8 by several authors. Those results have since been generalized. The present letter reports the apparently unobserved fact that these relationships can always be case into a form which shows that the effective thermal expansion properties of a given composite can be related to the effective hygroscopic exapnsion when the thermal and hygroscopic behavior of the constituting materials are known, without any knowledge being required of the elastic properties of either the constituents or composite.