Characterisation and modelling of the cured shapes of arbitrary layup bistable composite laminates

Asymmetric laminates can have a bistable response to loading, making them of particular interest for applications requiring a large deflection with relatively small and removable energy input. After nearly 30 years of research effort the effects of ply orientation and laminate geometry on the room-temperature shapes of such laminates are well understood and the temperature dependent deformations of laminates of arbitrary layup can be quantitatively predicted. With attention switching to the design of mechanisms incorporating bistable laminates for actuation there is an increasing importance placed on the accuracy and the sensitivity of modelling techniques to predict out-of-plane deflections. This paper presents the results of a novel experimental investigation to map the surface profiles of a series of arbitrary layup laminates. It is concluded that while existing modelling techniques are successful in accurately predicting room-temperature shapes, the sensitivity of solutions to imperfections is significant.