Design of multistable composites for application in adaptive structures

During the manufacturing process and operating conditions of multilayered fibre-reinforced composites with variable fibre orientations, residual stresses build up due to the directional expansion of the unidirectionally reinforced single layers. Dependent on the laminate lay-up, these inhomogeneous residual stresses, which are primarily caused by thermal effects, moisture absorption and chemical shrinkage, can lead to large multistable out-of-plane deformations in the case of unsymmetric laminates. Instead of avoiding these laminateʹs curvatures, they can be advantageously used for technical applications such as novel adaptive structures. In order to adjust the laminate deformations to technical requirements, a dimensioning tool based on a modified stability analysis in combination with a novel optimisation procedure has been developed and experimentally verified. Based on the theoretical investigations, an adaptive prototype of a multistable composite with integrated smart alloys has been designed and manufactured.