Families of Hygrothermally Stable Asymmetric Laminated Composites

Abstract

Necessary and sufficient material-independent conditions are derived for hygrothermal stability of a laminated composite plate with plies made of the same specially orthotropic material based on classical lamination theory. The minimum number of plies required to obtain an asymmetric hygrothermally stable stacking sequence is proven to be five, and families of stable laminates are identified for six, seven, and eight plies. A sensitivity analysis demonstrates the robustness of hygrothermally stable solutions to small errors in ply orientation. A finite element analysis of geometric and ply orientation imperfections was performed to verify the robustness of the classical lamination theory results. Hygrothermally stable asymmetric laminate specimens were fabricated to confirm the analytical predictions.