Papers by Author: S. Bickerton

Abstract: This research addresses the influence of various processing parameters on the post cure quality of carbon fibre composites. Four processing parameters were investigated in the study, in terms of their impact on void content and overall compressive strength. The first parameter distinguishes between laminates cured in a vacuum oven and those cured in an autoclave under high positive pressure. The second parameter describes the impact on voids of differing fibre architectures, comparing a unidirectional fibre structure to that of woven cloth. Thirdly, the influence of compaction during manufacture is analysed and lastly, variation in cure temperature was tested to determine its effect on final laminate quality. The quality of the cured laminate samples was assessed from visual inspection, and in terms of compressive strength and void fraction calculated by Micro-CT X-ray Tomography. The results show that autoclave-cured samples feature significant quality improvements in terms of void fraction and compressive strength when compared to oven-cured samples. Unidirectional laminates incur higher sensitivity to void inclusion than cloth laminates due to the influence of fibre wrinkling. Compaction has no effect on laminate strength; it does however reduce variability in certain cases. Temperature affects different fibre structures in different ways, these being highly dependent on curing method. Finally, it was discerned that curing by autoclave was the dominant processing parameter. Thus, regardless of other manufacturing techniques, the autoclave samples featured almost zero voids and were consequently of the highest quality.

Abstract: Liquid Composite Moulding (LCM) processes are commonly used techniques for the manufacture of advanced composite structures. This study explores the potential of wood fibres as reinforcement for LCM preforms, considering mats produced using dry and wet methods. The compaction response of these mats has been investigated with and without the presence of a test fluid. Permeability of these mats was also measured as a function of fibre volume fraction. Reinforcement permeability and compaction response data were used to model two different LCM processes. The simulation results have been compared with experiments.

Abstract: The term Liquid Composite Moulding (LCM) encompasses a growing list of composite manufacturing processes. The focus of this paper is prediction of tooling forces for Resin Transfer Moulding (RTM). Previous experimental work has demonstrated the influence of reinforcement compaction behaviour, which is strongly non-elastic. A viscoelastic compaction model has been developed which addresses both dry and wet response, and is implemented in RTM simulations of simple flat parts. Non-planar geometries introduce a tangential stress acting on mould surfaces, due to shear of the reinforcement. The tooling force analysis is extended to complex parts using an existing RTM filling simulation, LIMS, which has been developed at the University of Delaware.