Bentley Motors and Sigmatex (Runcom, Cheshire, U.K.) have announced that they have recently completed a research and development program partially funded by the Technology Strategy Board under the Advanced Composite Truss Structures (ACTS).
The project included a study of fabrication costs between composites versus the baseline aluminum construction in an automotive structural element. In the study, a sample “A” pillar node was fabricated using the Bentley automated fiber deposition process, finished by pressing, and by the Sigmatex One Piece 3D weaving process with subsequent resin infusion. In this study, the technically superior composite solution was produced using the 3-D woven preform and the resin infusion process. In reaching this conclusion, the study put a value of weight saving at €5/kg for this automotive application.
The study, the companies say, demonstrates that 3-D woven preforms can be cost competitive in low-volume, complex-shape automotive applications. Due to the higher mechanical properties and reduced variability through automated process control, the component fabricated from 3-D fabric would have a lower weight than the automated fiber placement component and a very significant improvement compared to the aluminum part.
The 3-D weaving process that Sigmatex has developed differs from conventional 3-D in that the throughput rates are substantially higher, resulting in lower costs. This lower cost basis enabled the 3-D/infusion approach to compete with traditional fabrication processes such as automated fiber placement (AFP) and hand layup. In production, this type of preform can be nested to reduce scrap and supplied on 100m/328-ft rolls, with approximately 200 preforms per roll.
“The Sigmatex 3-D weaving process enables complex components to be manufactured with fibers and weave architectures designed to form integral strength and stiffness. Although a little way off manufacturing a One Piece Woven Body in White, we can demonstrate that 3-D woven structures can meet the technical and cost requirements for the Automotive sector.” said Chris McHugh, technical manager for Sigmatex.
Lee Bateup, advanced vehicle technologies specialist for Bentley, comments, “The program successfully demonstrated that a 3-D woven composite preform was very well suited to the very complex and highly loaded nodal structure within an automotive spaceframe. Sigmatex has made a step change in quality and cost through improved automation compared to a conventional 2-D composite. The solution offers very significant weight, functionality and performance benefits compared to the incumbent aluminum component. Combined with reduced investment costs, this is a very attractive proposition for future vehicle platforms.”