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Foto: Universität Paderborn

Dr.-Ing. Mathias Bobbert

Dr.-Ing. Mathias Bobbert

Werkstoff- und Fügetechnik

Geschäftsführer - Wissenschaftlicher Mitarbeiter - TRR285

+49 5251 60-3035
+49 5251 60-3229
Pohlweg 47-49
33098 Paderborn

Sonderforschungsbereich Transregio 285

Geschäftsführer - Mitarbeiter - Teilprojekt Z

+49 5251 60 3035

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Joining suitability of cast aluminium for self-piercing riveting

M. Neuser, F. Kappe, M. Busch, O. Grydin, M. Bobbert, M. Schaper, G. Meschut, T. Hausotte, 2021

Influence of various procedures for the determination of flow curves on the predictive accuracy of numerical simulations for mechanical joining processes

M. Böhnke, F. Kappe, M. Bobbert, G. Meschut, Materials Testing (2021), 63(6), pp. 493-500

The predictive quality of numerical simulations for mechanical joining processes depends on the implemented material model, especially regarding the plasticity of the joining parts. Therefore, experimental material characterization processes are conducted to determine the material properties of sheet metal and generate flow curves. In this regard, there are a number of procedures which are accompanied by varying experimental efforts. This paper presents various methods of determining flow curves for HCT590X as well as EN AW-6014, including varying specimen geometries and diverse hardening laws for extrapolation procedures. The flow curves thus generated are compared considering the variety of plastic strains occurring in mechanical joining processes. The material data generated are implemented in simulation models for the joining technologies, clinching and self-piercing riveting. The influence of the varied methods on the predictive accuracy of the simulation model is analysed. The evaluation of the differing flow curves is achieved by comparing the geometric formation of the joints and the required joining forces of the processes with experimentally investigated joints.

    Development of a Method for the Identification of Friction Coefficients in Sheet Metal Materials for the Numerical Simulation of Clinching Processes

    M.S. Rossel, M. Böhnke, C.R. Bielak, M. Bobbert, G. Meschut, in: Sheet Metal 2021, Trans Tech Publications Ltd, 2021, pp. 81-88

    In order to reduce the fuel consumption and consequently the greenhouse emissions, the automotive industry is implementing lightweight constructions in the body in white production. As a result, the use of aluminum alloys is continuously increasing. Due to poor weldability of aluminum in combination with other materials, mechanical joining technologies like clinching are increasingly used. In order to predict relevant characteristics of clinched joints and to ensure the reliability of the process, it is simulated numerically during product development processes. In this regard the predictive accuracy of the simulated process highly depends on the implemented friction model. In particular, the frictional behavior between the sheet metals affects the geometrical formation of the clinched joint significantly. This paper presents a testing method, which enables to determine the frictional coefficients between sheet metal materials for the simulation of clinching processes. For this purpose, the correlation of interface pressure and the relative velocity between aluminum sheets in clinching processes is investigated using numerical simulation. Furthermore, the developed testing method focuses on the specimen geometry as well as the reproduction of the occurring friction conditions between two sheet metal materials in clinching processes. Based on a methodical approach the test setup is explained and the functionality of the method is proven by experimental tests using sheet metal material EN AW6014.

      Intrinsische Hybridverbunde für Leichtbautragstrukturen

      S. Sander, M. Bobbert, G. Meschut, Springer Vieweg, 2021, pp. 332


      Numerical analysis of the robustness of clinching process considering the pre-forming of the parts

      C.R. Bielak, M. Böhnke, R. Beck, M. Bobbert, G. Meschut, Journal of Advanced Joining Processes. (2020)

      Investigation of influencing parameters on the joint formation of the self-piercing riveting process

      F. Kappe, S. Wituschek, M. Lechner, M. Bobbert, G. Meschut, M. Merklein, 2020



      Tolerance Analysis of Adhesive Bonds in Crash Simulation

      G. Schwarzkopf, M. Bobbert, D. Teutenberg, G. Meschut, A. Matzenmiller, Procedia CIRP (2016), pp. 321-326


      Simulation und Bewertung von Fertigungstoleranzen

      G. Kruschinski, A. Matzenmiller, M. Bobbert, D. Teutenberg, G. Meschut, adhäsion KLEBEN & DICHTEN (2013), pp. 38-43

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