THERMAL-EXPANSION OF ISOTROPIC MULTIPHASE COMPOSITES AND POLYCRYSTALS

Sharp bounds on the effective thermal expansion coefficients of isotro pic multiphase composites and isotropic polycrystals are obtained by u sing classical variational principles and the translation method. Our bounds are appreciably narrower than the known Schapery-Rosen-Hashin b ounds. Conditions are formulated that guarantee a one-to-one correspon dence between the bulk modulus and thermal expansion coefficient of a polycrystal. All of our results can be readily applied to the poroelas ticity problem. Generalizations of the results to treat anisotropic co mposites comprised of anisotropic phases are discussed. (C) 1997 Elsev ier Science Ltd.