Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-18300 Zeitschriftenartikel Pittner, Andreas; Weiß, D.; Schwenk, Christopher; Rethmeier, Michael Methodology to improve applicability of welding simulation The objective of this paper is to demonstrate a new simulation technique which allows fast and automatic generation of temperature fields as input for subsequent thermomechanical welding simulation. The basic idea is to decompose the process model into an empirical part based on neural networks and a phenomenological part that describes the physical phenomena. The strength of this composite modelling approach is the automatic calibration of mathematical models against experimental data without the need for manual interference by an experienced user. As an example for typical applications in laser beam and GMA-laser hybrid welding, it is shown that even 3D heat conduction models of a low complexity can approximate measured temperature fields with a sufficient accuracy. In general, any derivation of model fitting parameters from the real process adds uncertainties to the simulation independent of the complexity of the underlying phenomenological model. The modelling technique presented hybridises empirical and phenomenological models. It reduces the model uncertainties by exploiting additional information which keeps normally hidden in the data measured when the model calibration is performed against few experimental data sets. In contrast, here the optimal model parameter set corresponding to a given process parameter is computed by means of an empirical submodel based on relatively large set of experimental data. The approach allows making a contribution to an efficient compensation of modelling inaccuracies and lack of knowledge about thermophysical material properties or boundary conditions. Two illustrating examples are provided. London Maney Institute of Materials, Minerals and Mining 2008 Science and technology of welding and joining 13 6 496 508 10.1179/136217108X329322 2016-02-19 OPUS4-19639 Beitrag zu einem Tagungsband Pittner, Andreas; Weiss, D.; Schwenk, Christopher; Rethmeier, Michael V.I. Makhnenko, Fast generation and prediction of welding temperature fields for multiple experiments The objective of this paper is to demonstrate a new simulation technique which allows the fast and automatic generation to temperature fields based on a combination of empirical and phenomenological modelling techniques. The automatic calibration of the phenomenological model is performed by a multi-variable global optimisation routine which yields the optimal fit between simulated and experimental weld charcteristics without the need for initial model parameters. For exemplary welding processes it is shown that linear 3D heat conduction models can approximate measured temperature fields with a high accuracy. The modelling approach presented comprises the automatic calibration against multiple experiments which permits simulating the temperature field for unknown process parameters. The validation of this composite simulation model is performed for exemplary welding processes and includes the prediction of the fusion line in the cross section and the corresponding thermal cycles. Kiev, Ukraine E.O. Paton Electric Welding Institute of the NAS of Ukraine 2008 Mathematical modelling and information technologies in welding and related processes - 4th International Conference (Proceedings) 4th International Conference - Mathematical modelling and information technologies in welding and related processes Katsiveli, Crimea, Ukraine 2008-05-27 2008-05-30 134 140 2016-02-19 OPUS4-56645 Zeitschriftenartikel Pittner, Andreas; Rethmeier, Michael Life Cycle Assessment of Fusion Welding Processes - A Case Study of Resistance Spot Welding Versus Laser Beam Welding The high amount of resource consumption of fusion welding processes offers the potential to reduce their environmental impact. While the driving forces are known froma qualitative perspective, the quantitative assessment of the crucial parameters is not a trivial task. Therefore, herein, a welding-specific methodology to utilize life cycle assessment as a tool for evaluating the environmental impact of fusion welding processes is presented. In this context, two welding processes, resistance spot welding and laser beam welding, are analyzed for two different use cases. These comprise the welding of shear test specimens and a cap profile made of electrogalvanized sheets of DC 05þ ZE (1.0312) as representative of an automotive application. For both welding processes, the main influences on the resulting environmental impact categories are evaluated and compared. The requirements for ecological efficient welding processes are discussed and implemented. Weinheim Wiley-VCH 2022 Advanced Engineering Materials 24 6 1 14 urn:nbn:de:kobv:b43-566458 10.1002/adem.202101343 https://creativecommons.org/licenses/by/4.0/deed.de 2022-12-21 OPUS4-24164 Zeitschriftenartikel Karkhin, Victor; Pittner, Andreas; Schwenk, Christopher; Rethmeier, Michael Simulation of inverse heat conduction problems in fusion welding with extended analytical heat source models The paper presents bounded volume heat sources and the corresponding functional-analytical expressions for the temperature field. The power density distributions considered here are normal, exponential and parabolic. The sources model real heat sources like the welding arc, laser beam, electron beam, etc., the convection in the weld pool as well as the latent heat due to fusion and solidification. The parameters of the heat source models are unknown a priori and have to be evaluated by solving an inverse heat conduction problem. The functional-analytical technique for calculating 3D temperature fields in butt welding is developed. The proposed technique makes it possible to reduce considerably the total time for data input and solution. It is demonstrated with an example of laser beam welding of steel plates. Secaucus, N.J. Springer 2011 Frontiers of materials science 5 2 119 125 10.1007/s11706-011-0137-1 2016-02-19 OPUS4-24165 Beitrag zu einem Tagungsband Karkhin, Victor; Pittner, Andreas; Schwenk, Christopher; Rethmeier, Michael Halmoy, E. Simulation of the temperature field in laser beam welding by inverse technique This paper presents volume heat sources and the corresponding functional analytical Solutions for the transient temperature field. The considered energy distributions are normal, exponential and parabolic. The method follows the common approach in Computational Welding Mechanics (CWM) to account for the physics of the welding process and the resulting temperature field by phenomenological models for heat conduction. Therefore, the used heat source models are apparent heat sources that incorporate the real heat input as well as the fluid flow in the weld pool and the latent heat connected with phase transformations. The heat source models provide welding characteristics like thermal cycle and Fusion line in the cross section within short computational time. Consequently, inverse techniques on basis of optimisation algorithms enable the adaptation of the models to the experimental data efficiently. Furthermore, the direct evaluation of the energy distribution for the experimental fusion line in the cross section is demonstrated which enhances the numerical optimisation by reducing the number of unknown model Parameters and providing a reasonable initial guess within the model parameter space. The proposed temperature field models are validated with real laser beam welding experiments. Norwegian university of science and technology 2011 13th Conference on laser materials processing in the nordic countries 13th Conference on laser materials processing in the nordic countries Trondheim, Norway 27.06.2011 29.06.2011 223 234 2016-02-19