Study of zero CTE (coefficients of thermal expansion) of graphite/epoxy composites

The design of composite with very low coefficients of thermal expansion (CTE) is presented in this paper. The magnitude of the CTE of a composite laminate is usually coupled with the mechanical properties. In this paper, the thermomechanical properties of multidirectional laminates, consisting of plies with arbitrary orientations and stacking sequences, are obtained by the laminate theory. Tests are performed to determine the thermomechanical properties of unidirectional composite laminates and to verify the analytical results for a variety of composite laminates. These tests measure the elastic moduli, Poisson's ratios, and CTEs. In order to provide the required accuracies for measuring low CTEs, a differential dilatometer is used. All test results agree with the analytical predictions. 6 figs.