Thermally Induced Twist in Graphite-Epoxy Tubes

Abstract

This paper discusses an analytical and experimental study to investigate the thermally induced twist in laminated angle-ply graphite-epoxy tubes. Attention is focused on balanced laminates which, contrary to intuition, exhibit twist when the temperature is changed. The twisting is due to the fact that in tube a lamina with a + Φ orientation and a lamina with a − Φ orientation must be at slightly different radial positions. The lamina with the greater radial position determines the sense of the twist. Classical lamination theory does not predict this phenomenon and so a more sophisticated theory must be employed. This paper outlines such a theory, which is based on a generalized plane deformation elasticity analysis, and presents experimental data to confirm the predictions of the theory. A brief description of the experimental apparatus and procedure used to measure twist is presented.