Deformation Prediction of RTM Produced Hybrid Metal-carbon Composites

A key factor for lightweight solutions is the selection of the best material for the intended application. This often results in the need for hybrid metal with fibre reinforced plastics (FRP) combinations, as for example hybrid parts made of steel and carbon fibre reinforced plastics (CFRP). Commonly, the single components may be joined after its individual manufacturing processes or alternatively as investigated in this study in a one-step solution within the Resin Transfer Moulding process (RTM). This one-step solution is more efficient in terms of production time and cost, but the geometric accuracy of the finished parts is more challenging due to the different thermal and mechanical properties of the materials in use. The different properties induce deformations during cooling after the RTM process. It is necessary to predict the evolving deformations in order to produce high quality parts with the best possible geometric accuracy. Therefore, Finite Element (FE) analyses are performed within the framework of LS-Dyna in order to run thermo-mechanical coupled simulation and to predict the deformations in an early design phase and derive corrective measures in advance. To develop the simulation model, the FE analyses were carried out on a flat hybrid plate. The plate consists of a steel and a CFRP plate, each 2 mm thick and adhesively bonded within the RTM process. For validation of the FE model, plates were manufactured and deformations measured with an ATOS 3D Scanner. The validated FE model was used to evolve measures against the residual deflection. The first possibility was to change the RTM tools for the flat plate while the second possibility was to optimise the layer structure. As the implementation of an optimised textile layup is faster and cost-efficient, experiments with optimised layup are carried out enabling further validation of the model. The paper describes the methodology for the simulation of the cooling of hybrid RTM produced components. Furthermore, the derived FE model is applied to an exemplary automotive component in order to predict the deformation and already provide recommendations for the RTM tools resulting in accurately finished parts.