Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Effect of heat source configuration on the result quality of numerical calculation of welding-induced distortion
    ( 2012)
    Heinze, C.
    ;
    Schwenk, C.
    ;
    Rethmeier, M.
    The results of numerical welding simulations strongly depend on its temperature field. In the present paper, the temperature field of a pulsed gas metal arc weld of structural steel S355J2+N (ASTM A572 Gr. 50) with a thickness of 5 mm is experimentally and numerically investigated. In the case of temperature field validation, volumetric Gauss and double-ellipsoid Goldak heat sources are applied. Additionally, different heat source configurations, including adaptations of thermal conductivity, are analyzed regarding their influence on the calculation of welding-induced distortion. The investigations clarify the influence of heat source configurations on the calculated results, thus, contribute to an improved prediction of welding-induced distortion.
  • Publication
    Case study for welding simulation in the automotive industry
    ( 2011)
    Perret, W.
    ;
    Thater, R.
    ;
    Alber, U.
    ;
    Schwenk, C.
    ;
    Rethmeier, M.
    Welding is one of the most widely used joining processes in structural applications, like in car body production in the automotive industry. It is well-known that distortions and residual stresses occur during and after the welding process. Many procedures exist to decrease these negative heat effects of welding, but are often coupled with highly cost intensive experiments. For several decades, simulation models have been developed to understand and predict the heat effects of welding and to reduce experimental effort. In the production planning of various Original Equipment Manufacturers (OEM), some simulation tools are already well established, e.g. for crash test, forming or casting simulations. For welding, the demand is high but the implementation of welding simulation software is sti ll not established yet. Welding is a complex process and the development of a flexible simulation tool, which produces good simulation results without expert knowledge in simulation, is not an easy task. In this paper, a welded assembly from the automotive industry has been simulated and compared to experimental data. Temperature fields and transient distortion distributions have been measured with thermocouples and with an optical 3D deformations analysis tool, respectively. The simulation has been run with a commercially available welding simulation software. The simulated temperature fields match the numerical ones perfectly. The simulated distortions are also qualitatively in best agreement with the experimental ones. Quantitatively, a difference of approximately 20 % between the simul ated and the measured distortions is visible; this is acceptable considering the simplifications and assumptions of the simulation model. The global time to solution to get these results without expert knowledge in welding simulation was between 4 and 6 weeks, which is a reasonable time frame for an industrial application of welding simulation.
  • Publication
    Approach to assess a fast welding simulation in an industrial environment - application for an automotive welded part
    ( 2011)
    Perret, W.
    ;
    Thater, R.
    ;
    Alber, U.
    ;
    Schwenk, C.
    ;
    Rethmeier, M.
    Fusion welding processes are widely used for joining metal structures, such as pipes, ships, and cars. In general, these joining processes offer a very good compromise between reliability, safety, cost and maintenance which are important issues in the current economical context. The negative heat effects of welding, i.e. distortions and residual stresses of the welded parts, are well known and many researches in this field have already been done in the last decades in order to minimize them. On the experimental side, many sophisticated procedures have become state of the art to deal with this problem. On the computational side, the improvement of the simulation algorithms and the computing power enables the simulations of many physical phenomena occurring during the welding process. The implementation of welding simulation techniques is nevertheless not an easy task and often associated with expert knowledge which hinders their global application in an industrial environment. This paper is focused on the industrial requirements of a welding simulation software with special respect to the needs of the automotive industry. The necessary information to run a welding simulation and the expectations of a weld specialist without deep knowledge in numerical methods are investigated. These expectations are tested on an automotive welded assembly with a commercially available welding simulation software designed especially for the needs of the automotive industry. A welding experiment is done and the measured temperature distributions and distortions serve as reference to validate the simulation results. The result quality of the simulations of temperature fields and distortions is in best agreement with experimental data. The workflow is well adapted for the considered industrial requirements and the time-tosolution as well as the computational costs are acceptable, whereas the efficient calibration of the heat input model is still a point which will be further investigated in current and future research works.
  • Publication
    Industrial application of welding temperature field and distortion visualization using FEA
    ( 2010)
    Thater, R.
    ;
    Perret, W.
    ;
    Schwenk, C.
    ;
    Alber, U.
    ;
    Rethmeier, M.
    Welding simulation offers with its holistic visualization of physical phenomena occurring during and after the welding process, like temperature and distortions, the opportunity to clearly identify the mechanisms responsible for the global deformations of welded parts. With this information, a target-oriented adaption of the welding parameters like welding sequence and clamping conditions is possible in order to minimize the welding distortions, whereby the required number of experimental iterations can be significantly reduced. Nevertheless, the industrial application of welding simulation is not yet established widely because of reservations regarding the computation costs and the result accuracy. The aim of this study is to show the applicability of the welding simulation within an ind ustrial environment and to com-pare its visualization capabilities and implementation to experimental procedures. For this purpose a welded assembly from the automotive industry has been simulated and compared with experimental data. The calculation is in a reasonable time frame and the characteristics of welding distortions are reproduced by the simulation in detail. Finally, it is shown that the numerical visualization with its high flexibility compared to experimental visualization has a great potential as part of a target-oriented distortion optimization to reduce experimental iteration steps.