Structural components fabricated by use of fibre reinforced plastics (FRP) exhibit a high lightweight potential due to the high strength and low density. For serial applications such as automotive sector, thermoplastic matrices are highly demanded, because already existing forming technologies enable economical processing and short clock cycles. Many concept cars of OEMs show the strategy to substitute single metallic components or subassemblies by FRPs in areas with the highest lightweight- and cost potential. The advantage of this multi material design (MMD) is to use the locally optimized materials with the required properties and low costs. A vital challenge of the MMD is the demand for suitable technologies for joining different types of materials like metal and FRP concerning the performance and large-scale production.
Novel lightweight-optimized hybrid metal-FRP structures contain locally reinforced joining areas. A suitable process for high volume production is the thermoforming process for FRP. The base material is a planar FRP organic sheet. If both – metal structures and FRP reinforcements – have to be integrated locally into the FRP part, this requires a modified thermoforming process which ensures the forming from planar base material to final 3D part and a proper joining between the FRP/FRP and FRP/metal interface in the area of reinforcements during consolidation. The metal reinforcement in the joining area is a structural optimized part which can be customized for different loads.
In this project different production approaches have been developed and evaluated: a multi-step process with separated forming of metal and FRP plus final downstream consolidation of both, and a novel customized process with integral forming and consolidation of all parts in a single step. Large-scale parts have been produced with a wide range of process parameters. The two main aspects of this presentation are to give an overview of different structural optimized metal reinforcements and to highlight the pros and cons of the mentioned processes regarding technological and economical aspects.