Study On Curing Induced Shape Distortion For Thermosetting Resin Matrix Fibre-reinforced Composites

Thermosetting Resin matrix fibre-reinforced composites will experience heating-up and cool down variety in curing process. The mismatch of thermal and curing shrinkage between reinforced fiber and polymer matrix will introduce residual stresses in composites. Improper structure or ply-up design will lead to dimensional change and warpage of composite work piece. In this thesis,factors affecting warpage of composites were studied, also methods to reduce this warpage were explored. This thesis is divided into three parts.In part one, three sorts composite lamina specimen, i.e. glass fiber/epoxy unidirectional composite, tabby composite and chopped fiber composite, were designed and made. Their curing deformations were measured. Static tension and compression experiments were carried out to determine their material parameters, e.g. stiffness of components and fiber volume fraction. The theoretical curing deformation prediction models for these three composites were suggested and they are verified by the experimental measurements.In part two, micro unit cell finite element models of unidirectional composite and orthogonal ply-up composite were built and the periodic boundary condition applied on them was specified. The curing deformation and micro scale residual stresses were calculated with these models. By adopting the thermal expansion ratio of the individual lamina obtained from the unit cell models, The warpages of asymmetrically plied laminates were forecasted.In part three, a finite element model of a typical composite blade was established. The thermal expansion parameters obtained in the chapters prior to were used to calculate the curing warpage of the blade. Factors affecting curing deformation of blade were studied. The suggestions to reduce curing warpage of blade by adjusting constitutional material and structure design were proposed.