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Title: Optimisation of high-speed automated layup of thermoset carbon-fibre preimpregnates
Author: Lukaszewicz, Dirk Hans-Joachim Adrian
ISNI:       0000 0004 2706 0679
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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Automated lay-up of prepreg is slowly replacing manual layup during the production of composite parts for aerospace, automotive and renewable energy applications. This is driven by a need for higher manufacturing rates from aerospace manufacturers and a need for high quality manufacture for wind and tidal power blades. The main methods for automated layup are Automated Tape Laying (ATL) and Automated Fibre Placement (AFP). However, despite its industrial importance the amount of research into both processes is limited, in particular with respect to productivity and process reliability. The study outlined in this presentation aims to investigate feasible processing conditions for automated layup that may improve laminate quality and productivity both analytically and experimentally whilst curing out-of-autoclave. Prepreg properties relevant to automated processing are identified. Lastly, requirements for an optimised layup system are proposed. A detailed study of the resin content of automation grade prepreg shows a significant variability of resin content that may affect tack and lead to unsuccessful layup. High product quality is governed by the amount of voidage entrapped in the uncured plies. A study of the surface roughness of uncured prepreg shows the potential for significant entrapment of air during layup. Since debulking is commonly omitted for continuous processing a large amount of voidage is entrapped in the uncured laminate and may have detrimental impact on mechanical performance. A model was developed that takes into account the prepreg interface and forming behaviour during automated processing to predict the amount of entrapped air and allow optimisation of processing conditions. A two-stage layup model was implemented in Abaqus/Implicit to study the process in detail. First, the interaction between ply and layup system was studied in detail, the results were then used to predict the forming behaviour of uncured prepreg on a microscopic scale. To understand the effect of processing conditions in more detail a laboratory Iayup system was built that enables layup at conditions currently not achievable with industrial equipment. The interaction between layup temperature and pressure was studied experimentally to validate previously developed models
Supervisor: Weaver, Paul ; Potter, Kevin Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available