Thermal Expansion of Graphite-Epoxy Composites

The thermal expansion behavior of unidirectional, balanced angle‐ply, and complex laminated graphite‐epoxy composites, is studied. The expansion coefficient of the unidirectional composites is determined as a function of fiber orientation and is found to follow the simple equation $${\alpha }_{\theta }{\mathrm{=\alpha }}_L\hspace{0.17em}{\cos }^2{\mathrm{\theta +\alpha }}_T\hspace{0.17em}{\sin }^2\theta$$ . Results obtained on angle‐ply composites are in agreement with the predictions based on Halpin and Pagano's analysis. The applicability of the same approach to a panel of more complex construction is discussed. Hysteresis effects, observed in this panel, may be caused by interlayer stress relaxation.