Snap-through behaviour of a bistable structure based on viscoelastically generated prestress

Abstract

A novel form of shape-changing bistable structure has been successfully developed through the use of viscoelastically generated prestress. Bistability is achieved through pairs of deflecting viscoelastically prestressed polymeric matrix composite (VPPMC) strips, which are orientated to give opposing cylindrical configurations within a thin, flexible resin-impregnated fibreglass sheet. This arrangement enables the structure to ‘snap through’ between one of two states by external stimulation. Deflection from the VPPMC strips occurs through compressive stresses generated from the non-uniform spatial distribution of nylon 6,6 fibres undergoing viscoelastic recovery. In this study, snap-through behaviour of the bistable structure is investigated both experimentally and through finite element (FE) analysis. By using experimental results to calibrate FE parameter values, the modelling has facilitated investigation into the development of bistability and the influence of modulus ratio (fibreglass sheet: VPPMC strip) on the snap-through characteristics. Experimental results and FE simulation show good agreement with regard to snap-through behaviour of the bistable structure and from this, the bistability mechanisms are discussed