No abstract

No abstract

Fiber reinforced plastics (FRPs) are increasingly being used to reinforce the steel or aluminum automotive structure components. Currently, these multi-material applications are realized in general by a multi-stage manufacturing with considerable cost increase. To avoid this, a new hybrid forming method has been proposed and developed. It uses the half liquid FRP as a pressure media to hydro-form the sheet metals, form the reinforcement ribs of FRPs, and create the bonding between metal sheet and FRP in the same time and process step. In this work, the die sealing concepts for two test geometries could be successfully developed. The hybrid forming parameters (Temperature, pressure, speed etc.) are in a reasonable range and can be accepted by the industry. It could be approved that high strength steels with up to 800 MPa tensile strength could be hybrid formed successfully together with a LFT PA6 GF40 for a real car component. 20% weight reduction could be achieved.

<div class="section abstract"><div class="htmlview paragraph">Hybrid structural parts combining aluminum or steel sheets with long glass fiber reinforced thermoplastics (LFT) offer a great opportunity to reduce component weight for automotive applications. But due to high manufacturing cost, metal-LFT hybrid components are still scarcely used in automotive large-scale production. Thus in this work a novel cost- and time efficient manufacturing process for simultaneous metal sheet forming and compression molding of long fiber reinforced thermoplastics to manufacture automotive lightweight components is presented. In this manufacturing process, which is referred to as “Hybrid forming”, a fiber reinforced thermoplastic melt is used as a forming medium in the manner of well-known hydroforming processes. After forming the metal sheet by polymer melt in combination with the rigid die, the melt solidifies and forms a local reinforcement structure in the hybrid component. Since the metal sheet is pre-coated with a bonding agent prior to the forming process, a firmly bonded connection between metal and LFT can be achieved.</div><div class="htmlview paragraph">For proof of concept a longitudinal control arm in a multi-link rear axle is chosen. By utilizing Hybrid forming a hybrid steel-LFT control arm is manufactured with weight savings of 20 % with regard to the metal reference component. Weight savings are derived by reducing the metal thickness and compensate stiffness and strength with local load-conforming LFT ribs. The metal part of the hybrid control arm guaranties the same positive fail-safe behavior of a metal component in contrast to the brittle failure mechanics of pure CFRP/GFRP components.</div><div class="htmlview paragraph">To verify the resilience of the hybrid component and especially the bonding surface between steel and LFT quasi-static tests and fatigue tests were conducted. The results are compared with the FE-simulations to validate the simulation technique, which can be used to design metal-LFT structural parts manufactured by hybrid forming for future applications.</div></div>

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.