An experimental investigation of non-elastic deformation of fibrous reinforcements in composites manufacturing

Many manufacturing processes that have been developed to produce fibre-reinforced polymer composites require compression of the fibrous reinforcement. When modelling these processes, the common approach taken in the published literature has been to assume that the deformation is non-linear elastic. However, research has demonstrated that viscoelastic behaviour as well as permanent deformation occur. Observations of stress relaxation and hysteresis have been made, which are typical indicators of non-elastic deformation. For this study a series of experiments were conducted using two types of glass fibre reinforcements to investigate these non-elastic effects, and to establish their relative importance. The aim has been to determine the proportion of each type of deformation, and the influence of important manufacturing process parameters. Permanent deformation has been shown to be very significant in all situations, and must be considered in the development of a comprehensive reinforcement deformation model.