Prediction of fibre rearrangement and thermal expansion behaviour of deformed woven-fabric laminates

Forming woven-fabric composites into parts consisting of double-curvature shells leads to complex redistribution and reorientation of fibres in the composite. The thermo-mechanical behaviour of woven-fabric composites in the moulded part is highly dependent on this rearrangement. The paper presents the results of a study on the prediction of the forming-induced fibre rearrangement and the complex thermal expansion behaviour of deformed woven-fabric laminates. It is proposed that the thermo-mechanical properties of deformed fabric composites (non-orthogonal structure) can be characterized by a sub-plies laminate composed of four fictional unidirectional plies. Based on the sub-plies model, a workable approach is developed to analyse the thermal expansion properties of general woven-fabric laminates with any arbitrary in-plane shearing deformation. The equivalent on-axis thermal expansion coefficients of the constituent plies in the sub-plies model, which include the fibre undulation effect, are also determined. The orthogonal and various specimens made of 8-harness satin fabric composite, subjected to different in-plane shearing deformations before moulding, were tested from 21 °C to 177 °C to verify the proposed model. The predicted results are in good agreement with experimental data.