Die Concepts and formability for simultaneous forming of sheet metals and FRPs

Abstract

Fiber-reinforced plastics (FRPs) are increasingly being used to reinforce steel or aluminum (Al) automotive structure components. Currently, these multi-material applications are realized via three-stage manufacturing, which require the corresponding costs. Thus, a new hybrid forming technology has been developed and will be presented here. It is based on the principle of the hydro-mechanical sheet metal-forming technique and uses a heated thermoplastic FRP material (up to 280°C) in a half melting state as the pressure media to form steel or aluminum sheets. Since the sheet metals are pre-coated with an adhesion promoter, the FRPs are also joined with the sheet metal during this hybrid forming process. In this work, the die and especially the sealing concepts for hybrid forming will be introduced based on different part geometries. The formability of the sheet metals (Nakajima test) at different temperatures up to 280°C, for each two steel and Al alloys, will be presented. The hybrid formed parts were analyzed using optical method and section analysis. Good forming results were confirmed for both sheet metal and FRPs. A vehicle chassis component was successfully hybrid formed using CP-W800 steel and FRP, and a body component was produced using an Al5182 alloy and an FRP.