Environmentally-induced expansion of heterogeneous media

Relationships between effective expansion behavior and effective elastic constants for composite materials have been known for many years. In the present work composites are considered for which more than one environmental variable (e.g., temperature and relative humidity) cause expansions. A simple direct method to relate effective expansions due to different causes is developed. It is shown that most of the previous elasticity-expansion behavior results are gotten as corollaries, and the applicability of these relationships is broadened.