TY - GEN A1 - Heinze, Christoph A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Experimentelle und numerische Analyse des Geometrieeinflusses auf den Schweißeigenspannungszustand N2 - Die vorliegende Arbeit stellt Untersuchungen im Rahmen eines Forschungsprojektes mit Schwerpunkt in der experimentellen und numerischen Analyse schweißbedingter Eigenspannungen und Verzüge beim Mehrlagenschweißen dar. Das Auftreten von kritischen Eigenspannungszuständen und untolerierbaren Verzügen während des Fertigungsprozesses verursacht durch erforderliche Nacharbeiten, wie z.B. Richten oder Wärmenachbehandlungen, zusätzliche Kosten. Diese Nacharbeiten können vermieden werden, wenn die numerische Schweißsimulation auf der Grundlage von zuverlässigen Berechnungsergebnissen zur Optimierung angewandt wird. Die Analyse des Eigenspannungszustandes erfolgt an 5 mm dicken Blechen des unlegierten Baustahls S355J2, wobei Stumpfnaht-Verbindungen mittels Metall-Aktiv-Gas-(MAG)-Schweißen ausgeführt worden sind. Im Zusammenhang mit den Experimenten werden sowohl Temperaturzyklen und Eigenspannungen gemessen als auch Schmelzbadgeometrie und Mikrostruktur ermittelt. Auf der Basis eines experimentell validierten Temperaturfeldes und umfangreichen röntgenografischen Eigenspannungsuntersuchungen erfolgen numerische Strukturberechnungen. Die auftretenden Phasenumwandlungen werden in der Simulation berücksichtigt. Die Betrachtung verschiedener Blechkonfigurationen gibt den Einfluss der Blechlänge auf das Niveau der entstehenden Eigenspannungen wieder. Es stellt sich heraus, dass sich die Quereigenspannungen in den nahtnahen Bereich mit zunehmender Blechlänge in den Druckbereich verschieben. Dieses Verhalten kann durch die experimentell validierte Struktursimulation des vorliegenden Prozesses numerisch abgebildet werden und schafft somit den Ausgangspunkt für die spätere Berechnung von mehrlagigen Schweißnähten. T2 - SYSWELD Forum 2009 CY - Weimar, Deutschland DA - 2009-10-22 KW - Schweißsimulation KW - Eigenspannungen KW - Geometrie KW - Validierung KW - Sysweld PY - 2009 SN - 978-3-86068-401-6 SP - 62 EP - 74 PB - Universitätsverlag Weimar AN - OPUS4-20674 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwenk, Christopher T1 - Simulation Based Approach for Distortion Analysis and Optimisation of Beam Welded Automotive Parts T2 - Beam Technologies & Laser Application, Abstracts of papers, VI International Conference CY - Saint Petersburg, Russia DA - 2009-09-23 PY - 2009 AN - OPUS4-20814 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Perret, William A1 - Thater, R. A1 - Alber, U. A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Case study for welding simulation in the automotive industry T2 - INPRO - Intermediate meeting - IIW-Select committee "automotive and road transport" DA - 2010-04-21 KW - Welding simulation KW - Temperature field KW - Distortion KW - Automotive industry KW - Experimental validation PY - 2010 IS - IIW-Doc. No. SC-Auto-37-10 SP - 1 EP - 13 AN - OPUS4-22541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thater, Raphael A1 - Perret, William A1 - Schwenk, Christopher A1 - Alber, U. A1 - Rethmeier, Michael T1 - Industrial application of welding temperature field and distortion visualization using FEA N2 - The non-uniform heat input during the welding process leads to problematic permanent deformations of welded parts. The control of these welding distortions is, with the absence of the knowledge of the fundamental mechanisms responsible for these deformations, an extremely time and cost consuming iterative “trial-and-error” optimization process. The visualization of the involved physical phenomena, like temperature and distortions, .is an indispensable tool to clearly identify these mechanisms in order to adapt the welding parameters and clamping conditions target-oriented. Both experimental and virtual methods exist to obtain these physical data, however the possibilities to visualize them with experimental methods are laborious, expensive and limited in their application. Welding Simulation using finite element analysis (FEA) offers many benefits and has a great potential to reduce the experimental effort. Nevertheless, the industrial application of welding Simulation is not yet established widely because of reservations regarding the computation costs and the resulting accuracy for instance. In this paper, the results of a case study for a welding Simulation with an industrial background are presented. A welded assembly from the automotive industry has been investigated with numerical and experimental methods. A comparison between both methods demonstrates the Potentials of welding Simulation in terms of visualization. Furthermore, the numerical results reveal the possibilities of current resources. regarding calculation time and result accuracy of an industrial applied welding Simulation. T2 - VISUAL-JW 2010 - The international symposium on visualization in joining & welding science through advanced measurements and simulation CY - Osaka, Japan DA - 11.11.2010 KW - Numerical welding simulation KW - Temperature field KW - Distortion KW - Industrial application KW - Automotive assembly PY - 2010 VL - 1 IS - PT-31 SP - 245 EP - 246 AN - OPUS4-22721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Influences of mesh density and transformation behavior on the result quality of numerical calculation of welding induced distortion N2 - Welding simulation is a powerful, cost-efficient tool to predict welding induced distortion. Nevertheless, effects on calculation result quality are often unknown, thus, sensitivity analyses should be performed to evaluate the influences of certain parameters on distortion development. In the present paper, a single-layer gas metal arc (GMA) weld of 5 mm thick structural steel S355J2+N is experimentally and numerically investigated. Subsequent to welding, the numerical modeling begins with a mesh analysis based on modal analyses. Hereby, the influence of different coarsening methods and element edge length (EEL) in welding direction on the deformation behavior or the stiffness of the discrete geometry is the focus of the analysis. Secondly, phase transformations in structural steels such as S355J2+N are decisive for final product properties. The sensitivity of welding-induced distortion is examined regarding different continuous cooling transformation (CCT) diagrams for S355J2+N. The present investigations deal with different relevant influences on numerical calculation of welding-induced distortion. The quality and quantity of these effects are clarified based on the experimental and numerical set-up employed. Consequently, prediction of welding-induced distortion is possible and potential for pre-production optimization is present. KW - Welding simulation KW - Gas metal arc welding KW - Welding-induced distortion KW - Mesh analysis KW - CCT sensitivity PY - 2011 DO - https://doi.org/10.1016/j.simpat.2011.05.001 SN - 1569-190X VL - 19 IS - 9 SP - 1847 EP - 1859 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-23874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brauser, Stephan A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Noack, T. A1 - Jüttner, S. T1 - Einfluss von schweißbedingten Rissen auf die Schwingfestigkeit von Widerstandspunktschweißverbindungen aus hochfestem austenitischen Stahl N2 - Unter den rauen Bedingungen in der Automobilkarosseriefertigung lassen sich schweißbedingte Imperfektionen wie Risse beim Widerstandspunktschweißen von hochfesten Stählen nicht immer vermeiden. Dabei ist der Einfluss solcher Risse auf die Schwingfestigkeit insbesondere von modernen hochfesten austenitischen Stählen derzeit nicht hinreichend bekannt. Im Rahmen dieser Arbeit wurde daher der Einfluss von Schweißrissen verschiedener Lage und Ausbildung untersucht. Dabei konnte durch die Analyse der normierten Steifigkeitsverläufe von Proben sowie durch die Gegenüberstellung der Versagensschwingspielzahlen nachgewiesen werden, dass die spritzerfrei erzeugten Oberflächenrisse im Zentrum, im Übergangsbereich sowie im Randbereich der Schweißlinse keinen negativen Einfluss auf die Schwingfestigkeit des hier untersuchten hochfesten austenitischen Werkstoffs haben. Proben, die mit Schweißspritzern hergestellt wurden und Risse im Randbereich aufweisen, zeigen deutliche höhere Versagensschwingspielzahlen als rissfreie Referenzproben. ---------------------------------------------------------------------------------------------------------------------------------------------- In the rough conditions in the fabrication of automobile bodies, it is not always possible to avoid welding-induced imperfections such as cracks during the resistance spot welding of highstrength steels. In this respect, the influence of such cracks on the fatigue strength particularly of modern high-strength austenitic steels is not sufficiently well-known at present. The influence of welding cracks with various positions and formations was therefore investigated within the framework of this paper. In this case, the analysis of the standardised stiffness courses of specimens and the comparison of the numbers of failure stress cycles served to prove that the surface cracks produced without any spatter in the centre, interfacial region and peripheral region of the weld nugget do not have any negative influence on the fatigue strength of the high-strength austenitic material investigated here. Specimens which were manufactured with welding spatter and exhibit cracks in the peripheral region show considerably higher numbers of failure stress cycles than crack-free reference specimens. KW - Festigkeit KW - Hochfester Stahl KW - Rissbildung KW - Widerstandspressschweißen KW - Werkstofffragen KW - Fahrzeugbau PY - 2012 SN - 0036-7184 VL - 64 IS - 1-2 SP - 28 EP - 31 PB - Verl. für Schweißen u. Verwandte Verfahren, DVS-Verl. CY - Düsseldorf AN - OPUS4-25623 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwenk, Christopher T1 - Optimierung von Verzug und Eigenspannungen beim Schweißen dickwandiger Bauteile T2 - Kolloquium "Schweißbedingter Verzug - Möglichkeiten der Vorausberechnung" Präsentation zu AiF Vorhaben IG 15746 N CY - Braunschweig, Germany DA - 2010-04-22 PY - 2010 AN - OPUS4-21213 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thater, R. A1 - Perret, William A1 - Schwenk, Christopher A1 - Alber, U. A1 - Rethmeier, Michael ED - Vollertsen, F. T1 - Different modeling approaches for efficient distortion calculation of an automotive assembly N2 - In contrast to other simulation fields like forming simulation, welding simulation is still not widely used in industrial environments. A high user expertise, a high time-to-solution and the result accuracy are the most important problems that hinder its extensively application. Different modeling approaches influence these aspects and an analysis of their implementation is of interest especially for the automotive industry as a key user for production Simulation. T2 - International workshop on thermal forming and welding distortion - IWOTE´ 11 CY - Bremen, Germany DA - 06.04.2011 KW - Welding distortions KW - Automotive assembly KW - Modeling approach KW - Time-to-solution PY - 2011 SN - 978-3-933762-35-1 SP - 279 EP - 291 CY - Bremen AN - OPUS4-23627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chen, Ji A1 - Schwenk, Christopher A1 - Wu, Chuan Song A1 - Rethmeier, Michael T1 - Prediction of weld pool shape and influence of joint preparation angle for new gas metal arc welding processes N2 - This article studies the three dimensional transient weld pool dynamics and the influence of joint preparation angle on welding of low carbon structural steel plates using the ForceArc® process. ForceArc is a new gas metal arc welding technology which allows adequate fusion and penetration with a smaller V groove angle. This enhances welding efficiency significantly because of reduction of layers and low material consumption. The deformation of the weld bead is calculated with an accurate coupling of the heat transfer with fluid flow through continuity, momentum and the energy equations combined with the effect of droplet impingement, gravity, electromagnetic force, buoyancy, drag forces and surface tension force (Marangoni effect). Four different angles of V groove are employed with the same welding parameters and their influence on the weld pool behavior and weld bead geometry is calculated and analyzed, to allow subsequent calculations of residual stress and distortion of the workpiece. Such a simulation is an effective way to study welding processes because the influence of all the welding parameters can be analyzed separately with respect to thermal cycle, weld bead formation, and the microstructure of the weld. Good agreement is shown between the predicted and experimentally determined weld bead dimensions. It was found that with a larger groove angle, the penetration depth increases. Furthermore, a higher wire feeding rate is needed to fill the larger groove. The model presented can be used for further analyses of GMAW processes as well as input data for the numerical calculation of welding induced residual stresses and distortions using Computational Weld Mechanics CWM. T2 - JOM-16 - 16th International Conference on the Joining of Materials CY - Tisvildeleje, Denmark DA - 10.05.2011 KW - Numerical simulation KW - Gas metal arc welding KW - Weld pool shape KW - Fluid flow KW - V groove PY - 2011 SN - 87-89582-19-5 IS - JOM 7 / J15 SP - 1 EP - 13 AN - OPUS4-23984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karkhin, Victor A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Rethmeier, Michael ED - Halmoy, E. T1 - Simulation of the temperature field in laser beam welding by inverse technique N2 - 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. T2 - 13th Conference on laser materials processing in the nordic countries CY - Trondheim, Norway DA - 27.06.2011 KW - Volume heat source KW - Inverse modelling KW - Functional analysis KW - Laser beam welding PY - 2011 SP - 223 EP - 234 AN - OPUS4-24165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Effect of heat source configuration on the result quality of numerical calculation of welding-induced distortion N2 - 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. KW - Welding simulation KW - Heat source calibration KW - Gas metal arc welding KW - Sensitivity analysis KW - Distortion KW - Schweißsimulation KW - Verzug KW - Wärmequellenkonfiguration KW - Sysweld KW - Heat source configuration PY - 2011 DO - https://doi.org/10.1016/j.simpat.2011.09.004 SN - 1569-190X VL - 20 IS - 1 SP - 112 EP - 123 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-24684 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Standards and guidelines for numerical welding simulation PY - 2011 SN - 1001-1382 VL - 459 IS - 9 SP - 5 EP - 8 PB - Jixie Dianzi Gongye Bu * Harbin Hanjie Yanjiusuo AN - OPUS4-24644 LA - zho AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Perret, William A1 - Thater, R. A1 - Alber, U. A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Approach to assess a fast welding simulation in an industrial envrionment - application for an automotive welded part N2 - 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. KW - Welding simulation KW - Distortion KW - Automotive industry KW - Work-flow KW - Time-to-solution KW - Simufact.welding PY - 2011 DO - https://doi.org/10.1007/s12239-011-0102-0 SN - 1229-9138 VL - 12 IS - 6 SP - 895 EP - 901 PB - KSAE / Springer CY - Seoul / Berlin ; Heidelberg AN - OPUS4-25139 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Perret, William A1 - Thater, Raphael A1 - Alber, U. A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Case study for welding simulation in the automotive industry N2 - 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 still 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 simulated 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. KW - Automobiles KW - Distortion KW - Simulating KW - Temperature KW - Welding KW - Aluminium alloys KW - Al Mg Si alloys KW - Automobile engineering KW - Finite elements analysis KW - Mathematical models KW - MIG welding KW - Residual stresses KW - Vehicle bodies PY - 2011 DO - https://doi.org/10.1007/BF03321546 SN - 0043-2288 SN - 1878-6669 VL - 55 IS - 11/12 SP - 89 EP - 98 PB - Springer CY - Oxford AN - OPUS4-25029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Numerical calculation of residual stress development of multi-pass gas metal arc welding under high restraint conditions N2 - During welding, residual stresses build-up created by the steep thermal gradient that occurs in the weld zone from localized heating and cooling, and phase transformations appearing in low-alloyed structural steel is inevitable. Welding of rather simple test plates do not cover the actual structural effects, which have to be considered during real component welding. However, the resulting welding-induced residual stress state is highly influenced by the structural characteristics, i.e. restraint conditions, of the welded construction. Therefore, a unique large-scale testing facility providing a specific shrinkage restraint while welding and subsequent cooling was used for the present investigations. Hereby, a six bead multi-pass gas metal arc weld of 20 mm thick structural steel S355J2 + N was welded under shrinkage restraint. The residual stresses were experimentally and numerically investigated, and compared to an analysis of plates welded under force-free support and free shrinkage conditions. The experimentally determined and calculated residual stresses using both 2D and 3D numerical models are in a good agreement. Furthermore, the influence of a shrinkage restraint on the residual stress distribution is both experimentally and numerically shown for the present test set-up. KW - Welding KW - Shrinkage KW - Ferrous metals and alloys PY - 2011 DO - https://doi.org/10.1016/j.matdes.2011.09.021 SN - 0261-3069 SN - 0264-1275 VL - 35 SP - 201 EP - 209 PB - Elsevier Science CY - Oxford AN - OPUS4-25036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chen, Ji A1 - Schwenk, Christopher A1 - Wu, Chuan Song A1 - Rethmeier, Michael T1 - Predicting the influence of groove angle on heat transfer and fluid flow for new gas metal arc welding processes N2 - This article studies the three dimensional transient weld pool dynamics and the influence of groove angle on welding of low carbon structural steel plates using the ForceArc® process. The deformation of the weld bead is also calculated with an accurate coupling of the heat transfer with fluid flow through continuity, momentum and the energy equations combined with the effect of droplet impingement, gravity, electromagnetic force, buoyancy, drag forces and surface tension force (Marangoni effect). Different angles of V groove are employed under the same welding parameters and their influence on the weld pool behavior and weld bead geometry is calculated and analyzed, which is needed for subsequent calculations of residual stress and distortion of the workpiece. Such a simulation is an effective way to study welding processes because the influence of all welding parameters can be analyzed separately with respect to heat transfer, weld pool dynamic, and microstructure of the weld. Good agreement is found between the predicted and experimentally determined weld bead cross-section and temperature cycles. It is found that the main flow pattern is more or less the same although the groove angle increases, but it will evoke larger amount of fluid to flow downward to get deeper penetration. KW - Numerical simulation KW - Gas metal arc welding KW - Weld pool dynamics KW - Fluid flow KW - V groove PY - 2012 DO - https://doi.org/10.1016/j.ijheatmasstransfer.2011.08.046 SN - 0017-9310 VL - 55 IS - 1-3 SP - 102 EP - 111 PB - Elsevier CY - Amsterdam AN - OPUS4-26001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brauser, Stephan A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Noack, T. A1 - Jüttner, S. T1 - Influence of welding-induced cracks on the fatigue strength of resistance-spot-welded joints made of high-strength austenitic steel N2 - In the rough conditions in the fabrication of automobile bodies, it is not always possible to avoid welding-induced imperfections such as cracks during the resistance spot welding of high-strength steels. In this respect, the influence of such cracks on the fatigue strength particularly of modern high-strength austenitic steels is not sufficiently well-known at present. The influence of welding cracks with various positions and formations was therefore investigated within the framework of this paper. In this case, the analysis of the standardised stiffness courses of specimens and the comparison of the numbers of failure stress cycles served to prove that the surface cracks produced without any spatter in the centre, interfacial region and peripheral region of the weld nugget do not have any negative influence on the fatigue strength of the high-strength austenitic material investigated here. Specimens which were manufactured with welding spatter and exhibit cracks in the peripheral region show considerably higher numbers of failure stress cycles than crack-free reference specimens. PY - 2012 SN - 1612-3433 VL - 11 IS - 4 SP - 232 EP - 235 PB - DVS - German Welding Society CY - Düsseldorf AN - OPUS4-26346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Weiss, D. A1 - Schwenk, Christopher A1 - Rethmeier, Michael ED - V.I. Makhnenko, T1 - Fast generation and prediction of welding temperature fields for multiple experiments N2 - 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. T2 - 4th International Conference - Mathematical modelling and information technologies in welding and related processes CY - Katsiveli, Crimea, Ukraine DA - 2008-05-27 KW - Welding simulation KW - GMA-laser hybrid welding KW - Laser beam welding KW - Neural networks KW - Global optimisation KW - Stochastic search method KW - Inverse heat conduction problem KW - Model prediction PY - 2008 SP - 134 EP - 140 CY - Kiev, Ukraine AN - OPUS4-19639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwenk, Christopher T1 - Anwendungsmöglichkeiten der Schweißsimulation zur Analyse und Verbesserung der Sicherheit gefügter Bauteile T2 - SYSWELD Forum 2007, Bauhaus-Universität Weimar, Professur Stahlbau CY - Weimar, Germany DA - 2007-11-15 PY - 2007 AN - OPUS4-16103 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Dilger, K. A1 - Michailov, V. ED - H.K.D.H. Bhadeshia, ED - H. Cerjak, ED - E. Kozeschnik, T1 - Sensitivity Analysis of Welding Simulation Depending on Material Properties Value Variation PY - 2007 SN - 978-3-902465-69-6 SP - 1107 EP - 1128 CY - Graz, Austria AN - OPUS4-16488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Dilger, K. ED - H.K.D.H. Bhadeshia, ED - H. Cerjak, ED - E. Kozeschnik, T1 - Analysis of the transient deformation behaviour and numerical optimisation of an electron beam welded gearwheel PY - 2007 SN - 978-3-902465-69-6 SP - 1155 EP - 1166 CY - Graz, Austria AN - OPUS4-16490 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -