Actor-initiated snap-through of unsymmetric composites with multiple deformation states

Abstract

Composites with an unsymmetric lay-up are generally characterized by warpage phenomena due to residual stresses caused in the manufacture process or during operating conditions. For special classes of unsymmetric, fibre-reinforced and textile reinforced composites more than one stable deformation state occurs due to the residual stresses caused by thermal effects, moisture absorption and chemical shrinkage. In the case of the existence of bistable equilibrium states a snap-through from one stable deformation state to the second state is possible, which can be initiated by forces and moments generated by adapted actors. Thus, novel adaptive structure can be developed, which enable a shape adaption only by a short actor impuls. This paper focuses on the formulation of theoretical fundamentals for the design of those novel adaptive structure. A non-linear calculation method is presented, which serves as a basis for the prediction of warpage and for the determination of mono- and multistable deformation states of unsymmetric composites. Based on various parameter studies, which reflect the possibilities of the design of multistable laminates, first prototypes of adaptive structures with multiple stability states have been developed and successfully tested.