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Session: Session 4: Manufacturing Simulation
Session starts: Tuesday 14 April, 15:50
Presentation starts: 15:50
Room: Main

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Dominic Stratton (NCC)

Abstract:
Large aerospace composite structures rely on accurate, reliable and rate capable cutting processes to ensure the components are manufactured on time to the near net-edge design tolerances. Classically composite preforms are cut mechanically with various types of blades or knifes . These mechanical cutting systems start having issues when the preform thickness increases. This manifests as increased blade breakages, reduced cutting speed, and reduced cutting accuracy. The cutting process needs to develop to achieve the rate and quality requirements of the composites industry including a reduction in post-cure machining operations. This has motivated an exploration of alternative methods. This study investigated laser cutting as a potential solution. Initial trials found two suitable laser cutting systems to focus our development efforts. Development trials then focused on understanding the how the lasers settings influenced cut quality. Data was gathered on focal position, cutting speed, laser power, multi-pass cutting strategy, multi-pass with changing focal positions, tooling, and cooling solutions. Using this data, three possible pathing strategies were designed and used to manufacture test coupons. When infusing the laser cut preforms it is evident that there is little difference to the infusion-rate and the preforms accepted resin during infusion when compared to virgin material. Mechanical tests of the infused preforms highlighted a trend that the higher the energy density of the laser cut, the worse the coupon would perform in mechanical testing via ASTM D3039. This project has demonstrated laser cutting as a technology capable of achieving cutting rate requirements (100mm/s) at preform thicknesses of ≈5mm and have successfully cut a carbon fibre preform at 18mm thickness. Work is ongoing to understand the effect of laser cut edges and the heat affected zone. The estimated Technology Readiness Level (TRL) for this process is TRL III. To conclude this study has developed an increased understanding on the potential for laser cutting carbon fibre preforms at rate for large structure aerospace applications, and whilst the are results are promising, further study, particularly on the mechanisms of mechanical performance degradation is required.