Finite element analyses and simulation of the failure of short-fiber reinforced thermoplastics and aluminium blanks by clinching

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Recently, in different engineering applications, especially in the automotive and aeronautical industries, the advent of new composites is promoting the replacement of the traditionally employed metals with the aim of producing highly optimized structural components, principally in terms of structural weight, stiffness and strength. This is the case for instance for the use of short fiber reinforced plastics (SFRPs) for the realization of intricate design concepts in the automotive sector, where very high production rates are required. At comparable ultimate strength, SFRPs are lighter than metallic materials, allowing a significant weight reduction in the new generation of automobiles which leads to higher performances and lower fuel consumption. Simultaneously, SFRPs shows highly complex nonlinear material behavior under multiaxial loading condition due to their corresponding production process using injection molding procedures.The current trend in automotive industry is the conception of a new generation of automobile construction where multi-material or hybrid specimen definitions are being gradually employed. Accordingly, aluminum metal sheet can be used in combination with short fiber reinforced plastics (SFRPs) for the production of a hybrid component. Tempered clinching is a promising mechanical joining process that is investigated numerically and experimentally in this project. Considering the strength and stiffness behavior, the key challenge in the tempered clinching process is to take into account the temperature-dependent deformations as well as the highly anisotropic material behavior of both materials. In the third phase of the SPP 1640 program, in addition to the consideration of plasticity, the progressive damage and failure of short fiber reinforced plastics and aluminum is characterized, modeled and integrated into an overall finite element model for different material sheet thicknesses. The progressive damage and failure of aluminum and short fiber reinforced plastics by the clinching process are numerically simulated and experimentally investigated. Accordingly, the numerical results are correlated with the experimental investigations results. Subsequently, the clinching process is parameterized and FE analyses of the progressive damage and failure of the resulting clinching joints are carried out. As a result, the relevant geometrical parameters of the tools are clearly identified and the optimum tools geometry are determined and validated. These developments will allow the simulation-based assessment and improvement of the resistance of the resulting clinching joints to be carried out, which leads to a reliable and robust manufacturing of hybrid clinching joints.