Numerical and experimental investigations of thermal riveting of polymeric materials

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Due to the comparison between experiment and simulation, the geometrical-constructive, material and process-technical factors influencing thermal plastic riveting can be realistically recorded and modeled. The usage of numerical models should increase the process transparency and should lead to manageable design criteria for plastic riveted joints. The classification of thermal riveting methods are based on the type of energy input like the hot air riveting (convection) and the hot forming (heat conduction). Based on the experimentally determined material behavior, numerical models have to be developed which simulate the thermal riveting processes close to reality. The aim is to characterize the process-specific interactions between the heating and forming behavior and to link them with the resulting material structure. Furthermore, the mechanical joining properties have to be correlated with the non-measurable or difficult-to-measure physical parameters (e.g. stress, strain) using the FEM. These physical parameters are depending on the used riveting pin geometry, the stamp design and the process parameters. In addition, the quasi-static strength characteristics determined in the simulation and in laboratory tests are to be transferred to the operating behavior under dynamic load. It should be scientifically explained, under which restrictions the short-term properties, determined by simulation and experiment, can be used to evaluate the long-term properties. For this purpose, vibration tests (shakers), dynamic head tensile tests and long-term investigations under the influence of media and temperature are carried out. Fracture-mechanical, light microscopic and thermal analyzes are done to characterize the failure modes, the failure process and the material condition.