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Title: Mechanisms of defect formation in carbon fibre composites
Author: Lightfoot , James S.
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Defects in composite materials lead to reductions in the mechanical performance of components. The presence of fibre waviness and through-thickness ply wrinkles has been shown to reduce the Compressive strength of laminates, and are therefore subject to significant scrutiny in the aerospace industry. Whilst a large volume of industrial effort and published research has addressed the reduction of the compressive strength Due to defects, the source of such defects is currently not well understood. The work presented in this thesis aims to elucidate the source of fibre waviness and ply wrinkles. Its ultimate goal is to understand the link between material and manufacturing process variations with the formation of such defects. Once mechanisms for defect generation are understood, measures can be taken by industrial manufacturers to mitigate their formation. As a result, part acceptance rates will increase; the composites industry depends on the reliability of component manufacture. A number of themes have been investigated by proposing specific mechanisms for the formation of fibre waviness and Ply wrinkles. Such themes include fibre-matrix interaction, tool part interaction and consideration. The most significant mechanism Has been shown to be consolidation. In both prepreg and woven preform materials, poor layup has been shown to lead to severe Ply bridging at tooling radii.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available