Solid State Phenomena Vol. 390

Abstract: Metal-polymer-metal (mpm) sandwich sheets are considered a lightweight alternative to conventional steel sheets in the automotive industry. First studies have experimentally and numerically demonstrated the use of mpm-sandwiches in automotive crash structures. However, the sandwich forming process can compromise the crash performance through pre-damage. Finite element simulations could help predict the forming process and its limits. Current simulation approaches, however, consider neither strain rate effects and failure of the polymer and the adhesive, respectively, nor do they study the influence of inevitable material variabilities on the forming and failure behavior. In this work, a detailed finite element model of the core materials is developed. An approach for the determination of the stress strain rate dependency is proposed by evaluating the local strains on the surface, which allows to capture the main material behavior with little effort. Additional specialized tensile tests and lap-shear tests provide information about the failure of the polymer and the adhesive, respectively. Validation of the core materials model is achieved by comparing the cover layer displacements of swivel bending specimens in experiment and simulation. The influence of material variabilities on the forming and failure behavior is studied in a full factorial material parameter sweep of simulated lap-shear tests and the applicability of the model to the simulation of bending processes is demonstrated. The results prove the applicability of the proposed material characterization methods, while the parameter study and the bending simulations show how the model can be used to predict a sandwich’s formability and failure modes.