Analysis of bi-stability and residual stress relaxation in hybrid unsymmetric laminates

Unsymmetric bi-stable composite laminates are receiving interests in adaptive and deployable structures. The low load-bearing capacity and the residual stress relaxation of such laminates are significant limitations for application. The hybridization of unsymmetric composite laminates has potential to solve the problem. In this paper, the hybrid bi-stable laminates are investigated by analytical, finite element and experimental techniques. The curvature decrease of hybrid laminates along with the residual stress relaxation in the polymer matrix is investigated. The critical snap-through loads of hybrid laminates are numerically and experimentally studied. The improved critical load of hybrid laminate and the limited over time reducing of critical load are discussed. Comparisons of cured shape and critical loads between hybrid and pure bi-stable laminates show that the hybridization enable to accomplish both the high load-bearing capacity, the large shape change and the limited response to the residual stress relaxation in the polymer matrix.