Multistable composite plates with piecewise variation of lay-up in the planform

The non-linear out-of-plane displacements of partially unsymmetric laminates are modelled using both finite element analysis and an analytical method. Attention is focused on the effects that thermal stresses have on the potential multiple shapes of a composite structure. The paper extends previous analytical models which could only take into account "free-free" boundary conditions. The shape functions that model the out-of-plane displacements are modified to include variations of the curvatures within the domain. The new analytical formulation is compared with literature and finite element analysis for a square plate and then it is tested for laminates with piecewise variation of lay-up in the planform. The results are validated against finite element analysis and experimental tests and a good correlation is obtained. Finally, a parametric study is made on the effect of changing the fibres orientation and the laminate thickness. The results confirm that it is possible to introduce bi-stable composites within structures to obtain systems that are both flexible and stiff depending on the loading environment. (c) 2008 Elsevier Ltd. All rights reserved.