Sustainable manufacturing of composite materials

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Since their introduction in the 1960's, advanced carbon fibre composites have been used to develop application-specific structures featuring as much as a 30% reduction in weight compared to their metallic predecessors. The potential benefit to the aerospace industry is clear, as a reduction of 20% of an aircraft mass yields significant fuel cost savings and reduces CO2 emissions on a scale equivalent to removing a thousand cars from circulation. Composites have also changed how aircrafts are built. Large structural elements are assembled layer by layer with automated fibre placement machines and then cured in large pressurized autoclaves. Final nondestructive inspection of the parts ensure that they are free of defects and ready for the next step of the assembly process. While many progresses have been made in the last twenty years, the manufacturing process of composite structures is far from perfect. Today, about 66% of the raw material is wasted during the material deposition phase from prepreg cutting or prepreg rolls that have exceeded their shelf life. More cured composite waste is generated during the final trimming of the part. Furthermore, if excessive manufacturing defects are detected in the final component, rejection of the part can significantly increase the overall manufacturing scrap rate. Composite manufacturing waste and products at the end of their useful life are mostly landfilled, which is detrimental for the environment. The objective of this work is to develop new processes, material systems and design tools in order to reduce manufacturing costs and improve the environmental impact of composite materials manufacturing. We propose the use of process modelling tools to reduce risks during the design phase and the amount of trial-and-error that often generates very high volumes of scraps. We will develop an automated material inspection method in order to reduce material process variability that can cause defects in the final part. We will implement new heated tooling concepts in which the heat from the tool is transferred directly to the part to realize additional energy savings. Finally, we will transform prepreg wastes from ply-cutter offcuts or expired rolls into a value added product. The results of this work will provide Canadian SMEs with cost-effective modifications to their production lines in order to cope with new environmental regulations and to augment their market share.