The University of Sheffield Advanced Manufacturing Research Centre with Boeing (AMRC) have invested £150,000 ($231,540) in an FT Dornier Rapier Loom for its Composite Centre to weave their own materials and improve on resin transfer molding (RTM) processes.
The rapier loom is specially designed to weave composites without the risk of the highly electrically conductive carbon fibers causing the loom to short circuit. Previously, team members have been limited to using commercially available woven reinforcing materials; now, the AMRC will be able to design and weave its own material. The AMRC says the new capability means the center will be able to push the boundaries of processes like RTM, where components are made by injecting resin into a mold into which dry fiber has been laid down.
“RTM is supposed to be a very rapid and highly production-orientated process, but getting it right can involve trial and error,” says the AMRC Composite Centre’s Jody Turner. “Sometimes the resin doesn’t penetrate all of the material and parts of the component are left completely dry, which makes it useless. We plan to carry out research that will help us to understand more about what happens during RTM injection and why results can be so erratic.”
Composite Centre researchers have already been studying how resin flows through fabrics made from carbon fiber and have found the resin flow through the fabric isn’t symmetrical, despite the weave pattern being perfectly symmetrical. They believe this may be a result of slightly differing yarn tensions within the fabric. Now they hope to expand their knowledge by experimenting with different tensions for the warp (the long continuous threads) and the weft (the thread that is fed across the loom) between the warp threads to create the woven material.
“If we can control warp and weft tension we might be able to influence resin flow,” says Turner. If the researchers are successful, they could be able to weave materials that could be opened up to form a series of boxes or a honeycomb structure that would give the completed composite component additional strength.