Macroscopic transition structures for a graded transition of properties in hybrid metal/polymer compounds - MÜGRA

• Applicants: Professorin Dr.-Ing. Birgit Awiszus; Professor Dr.-Ing. Guntram Wagner
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434351205

The aim of the project "Macroscopic transition structures for a graded transition of properties in hybrid metal/polymer compounds" is the load-capable design of the metal/polymer interface in injection moulding of fibre-reinforced thermoplastics by means of variable metal structures. Due to the novel design of the transition zone in the range of the macroscopic scale, significantly higher mechanical loads of the material compound are possible. The main goal is to achieve a graded transition between the sheet metal and the polymer component by the use of transition structures. The graded geometric design of a permeable structure of wire spirals or machined cell structures should result in a graded transition of properties. A further focus is on the variable design of the transition structures in order to transmit forces for different load types. The material-physical modelling of the regularly arranged structures should form the basis for the simulation of the material compound behaviour in the transition area. The new findings of the material compound behaviour are elaborated on the material system made of galvanized steel sheet and short fibre reinforced polyamide. In order to join the transition structures to the metal component, joining processes are further developed, which allow an efficient application and high load capacity. In particular, the zinc layer on the steel sheet is used for joining the transition structures. The hybrid material compounds are produced by insert moulding the permeable transition structures. The aim is to examine the behaviour of highly viscous short-fibre-reinforced thermoplastic melts when passing through complex geometrical obstacles. The investigations are carried out experimentally and numerically, by fluid-structure interaction of CFD and FEM simulation. New knowledge is created about the shrinkage behaviour of (fibre-reinforced) thermoplastics in permeable structures as well as the alignment behaviour of the short fibre reinforcement as a result of flow through the structures depending on permeability and process technology parameters. The processes are examined systematically and improved iteratively. A significant improvement of the adhesion behaviour is expected in comparison with the form fit elements known from the state of the art.The actual occurring stresses in a metal/polymer hybrid component are characterised by complex superimposed stress states of the individual components. The resulting mechanical properties of the material system metal/transition structure/polymer are determined by suitable test specimen.

• DFG Programme: Research Grants