Systematic analysis of bistable anti-symmetric composite cylindrical shells and variable stiffness composite structures in hygrothermal environment

This paper systematically studies the effect of temperature and moisture on bistable anti-symmetric composite cylindrical shells and variable stiffness composite structures in the hygrothermal environment. Based on the classical laminate theory, together with the principle of minimum potential energy, an analytical model is developed to predict the bistable behavior of those bistable anti-symmetric composite cylindrical shells in the hygrothermal environment. Finite element simulates the change of curvature of bistable anti-symmetric composite cylindrical shells. An experiment of temperature and moisture was presented to measure the principal curvatures and twisting curvatures in the hygrothermal environment. The numerical and experimental methods are employed for predicting and verifying the theoretical results. The temperature and moisture have prominent effects on the bistable anti-symmetric composite cylindrical shells. In order to optimize shell's shape for being used in some particular situations, a novel approach that may control the bistable shell's curvatures by adjusting the temperature or moisture are presented. For the moisture variation take a long time to affect the structure curvature, the twisting curvature is eliminated by adjusting the temperature to the given value. Finally, the change of variable stiffness composite structures in the process of moisture absorption is discussed, and the load-displacement test of variable stiffness composite structures is carried out at the maximum saturation value.