Fiber reinforced plastics (FRPs) are increasingly being used to reinforce the steel or aluminum automotive structure components to reduce the weight and improve the performance. Currently, these multi-material applications are realized by a three-stage manufacturing, which require their corresponding cost. Thus, a new hybrid forming technology has been developed. It is based on the principle of hydro-mechanical sheet forming technique, and uses a heated thermoplastic FRP material (up to 280 °C for PA6) which is in a semi melting state as the pressure media to form steel or aluminum sheets. Since the sheet metals are pre-coated with adhesion promotors, the FRPs are also joined by adhesive bonding with the sheet metal during this hybrid forming process. Different adhesion promoters must be used for different thermoplastic matrix materials.

In this work, the die and especially the sealing concept for the hybrid forming will be introduced on different part geometries. The formability of sheet steels and aluminums (Nakajima test) at different temperatures, and the shear as well pull out strength of the hybrid formed sheet metal – FRP specimens will be presented and analyzed. Using the measured joining strength, FE-model parameters for static and crash simulations were calibrated, and applicable for light weight structural development. The hybrid formed parts were analyzed using optical method and section analysis. It confirms a good forming result both for sheet metal and FRPs. The joining strength for sheet metal – PA material is sufficient, and should be further improved for PP materials. A vehicle chassis component was successfully hybrid formed and joined by using DP800 steel and a PA6 GF40 material, and a body component by Al and PP GMT.