Integrated Design for Production to Ensure Sustainability in Marine Transportation Matthew J. Streeter- Faculty of Engineering and the Environment Supervisors – Dr J.I.R. Blake, Dr S. Quinn and Mr J. Spooner Sponsors: Princess Yachts International Fluid Structure Interactions Research Group FSI Away Day 2012 Acknowledgement: This project is supported by funds from the Engineering and Physical Sciences Research Council and Princess Yachts International Background Princess Yachts International (PYI) are one of the UKs leading leisure boat builders, producing 14-40m composite luxury powerboats. In 2006 a closed mould infusion process was introduced, improving health and safety, weight, quality, repeatability and emissions. Optimization of the infusion process is now required to continue PYIs development and growth as the boundaries of the resin infusion process are pushed with the production of 40m plus hull forms. Voids are a common defect in fibre reinforced resin matrix composites, forming and growing during the fabrication process, leading to a higher level of parameter control to avoid these occurrences 1. Residual stress development during the curing phase is critical to the resulting composite quality. Residual stresses tend to develop at 2 key stages of the curing process, firstly during polymerisation which causes a chemical and physical transformation, and secondly curing cooling, where the shrinkage of the laminate creates a complex stress field 2. Understanding and control of these residual stresses is critical in the further improvement in efficiency and sustainability of composite marine vehicles. Objectives 1. Identify key locations for void and imperfections in large scale infusions. 2. Identify the key sources of residual stress in a typical large scale composite infusion. 3. Model, both computationally and experimentally, the infusion process used at PYI. 4. Design residual stress alleviation mechanisms that are not detrimental to the desired material properties or dimensional constraints by PYI. 5. Create a user friendly methodology for identifying and reducing residual stresses in composite components to be incorporated in to the design process. Figure 2: PYI Infusion Research Methodology Conclusion A field survey has been carried out to assess the quantity, location and severity of voids at PYI. An acceptable and unacceptable level has been chosen based on ALARP principle, established on PYIs desire to remain leaders in the luxury powerboat production sector. The resulting histogram can be seen in figure 1. Subsequent to identification of the void and imperfection locations shown in figure 1, a chine mould section has been taken from the A2 stern mould. Flow and cure cycle experiments will be carried out at PYI and at the University of Southampton, figure 4. Computational flow front analysis using PAM-RTM will be used to assess the injection strategy, moulding temperatures, injection pressures and key injection gate, vents and vacuum ports. The result will be validated against full scale measurements and the chine section experiments, an example infusion model can be seen in figure 3. Thermal analysis of the cure cycle will be carried out computationally and validated against the through thickness cure temperature profiles attained at PYI and from the chine moulding. All composites exhibit some form of imperfections and voiding due to residual stresses. A large level of research has been carried out on small scale infusions, however little information is available for large scale infusions such as those undertaken at PYI. This research will generate the required tools to identify the sources and control measures required to reduce voids and imperfection in large scale composite components. The implementation of such tools will lead to an increased understanding of the resulting laminate properties allowing for tighter tolerances at the design stage and further optimization of the structure. AcceptableUnacceptable Figure 1: Histogram Presenting Voiding Distribution Figure 4: Chine Section Flow Front Experiment References 1-Gu, Y., Li,M., Zhang, Z., &Sun,Z. (2009). Measuring method and process analysis of void formation conditions for resin matrix composites. ICCM 17, Edinburgh 2- D. Perreux, D. Lazuardi. (2001). The effects of residual stress on the non-linear behaviour of composite laminates. Composites Science and Technology. 61 (1), ESI Group. (2006). PAM-RTM, simulation software for resin injection and infusion on fibrous reinforcements is enabling Poncin Yachts to optimize its manufacturing processes. Available: Last accessed 27th November 2011 Figure 3: PAM-RTM Injection simulation For Harmony Yachts 3