MANUFACTURING-INDUCED DISTORTION IN A SHORT GLASS FIBRE REINFORCED COMPOSITE STRUCTURE

摘要

Short fibre reinforced composites have become an attractive material for many applications in various fields of industry. For example, short glass fibre reinforced polymers are being used to make automobile and bus side panels and doors, metro seats and water jet skis. During manufacturing residual stresses develop because of the anisotropy of the material properties, cure shrinkage of the resin, and the temperature variation during manufacturing. These residual stresses can lead to undesirable shape distortions, called warping, when the part is released from the mould. Warping can be severe, leading to assembly problems for components that require a precise dimension shape. The objective of this work is to investigate and analyse the effect of anisotropy of the thermo-elastic properties, cure shrinkage of the resin, and temperature variation on the process-induced distortion of glass/polyester composite structures. First, the experimental program conducted to evaluate the elastic properties, the coefficients of thermal expansion, and the chemical shrinkage strains of the composite material will be presented. The properties of the gelcoat, used to guarantee a good quality surface finish, are also evaluated. Then, a finite-element model developed using a commercial code is used to analyse the shape distortion of simple corner like structures. Finally, the manufacturing-induced distortion of a real part, a bus engine door, is predicted using the model.