TY - THES A1 - Pittner, Andreas T1 - A Contribution to the Solution of the Inverse Heat Conduction Problem in Welding Simulation N2 - The present thesis provides a contribution to the solution of the inverse heat conduction problem in welding simulation. The solution strategy is governed by the need that the phenomenological simulation model utilised for the direct solution has to provide calculation results within short computational time. This is a fundamental criterion in order to apply optimisation algorithms for the detection of optimal model parameter sets. The direct simulation model focuses on the application of functional-analytical methods for solving the corresponding partial differential equation of heat conduction. In particular, volume heat sources with a bounding of the domain of action are applied. Besides the known normal and exponential distribution, the models are extended by the introduction of parabolically distributed heat sources. Furthermore, the movement on finite specimens under consideration of curved trajectories has been introduced and solved analytically. The calibration of heat source models against experimental reference data involves the simultaneous adaptation of model parameters. Here, the global parameter space is searched in a randomised manner. However, an optimisation pre-processing is needed to get information about the sensitivity of the weld characteristics like weld pool dimension or objective function due to a change of the model parameters. Because of their low computational cost functional-analytical models are well suited to allow extensive sensitivity studies which is demonstrated in this thesis. For real welding experiments the applicability of the simulation framework to reconstruct the temperature field is shown. In addition, computational experiments are performed that allow to evaluate which experimental reference data is needed to represent the temperature field uniquely. Moreover, the influence of the reference data like fusion line in the cross section or temperature measurements are examined concerning the response behaviour of the objective function and the uniqueness of the optimisation problem. The efficient solution of the inverse problem requires two aspects, namely fast solutions of the direct problem but also a reasonable number of degrees of freedom of the optimization problem. Hence, a method was developed that allows the direct derivation of the energy distribution by means of the fusion line in the cross section, which allows reducing the dimension of the optimisation problem significantly. All conclusions regarding the sensitivity studies and optimisation behaviour are also valid for numerical models for which reason the investigations can be treated as generic. T3 - BAM Dissertationsreihe - 85 KW - Analytical Solution KW - Global Optimisation KW - Neural Networks KW - Welding KW - Temperature Field PY - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-733 SN - 978-3-9815134-9-1 SN - 1613-4249 VL - 85 SP - 1 EP - 213 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-73 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pittner, Andreas A1 - Weiss, D. A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - A methodology for the fast temperature field generation for welding simulation T2 - 17th International Conference "Computer Technology in Welding and Manufacturing" CY - Cranfield, UK DA - 2008-06-18 KW - Welding simulation KW - Temperature field generation KW - Short calculation time KW - Multiple experiments KW - Inverse heat conduction problem KW - Neural networks PY - 2008 SN - 978-1-903761-07-6 SP - 1 EP - 12 PB - TWI CY - Cambridge AN - OPUS4-18290 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Weiß, D. A1 - Rethmeier, Michael ED - Cerjak, H. ED - Enzinger, N. T1 - An efficient solution of the inverse heat conduction problem for welding simulation PY - 2010 SN - 978-3-85125-127-2 SP - 761 EP - 791 PB - Verlag der Technischen Universität Graz AN - OPUS4-23154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Weiß, D. A1 - Rethmeier, Michael T1 - Application of a combined modelling technique to reduce experimental effort - a case study for laser-GMA-hybrid welding T2 - VI. International conference "Beam technologies & laser application" CY - Saint Petersburg, Russia DA - 2009-09-23 PY - 2009 SP - 97 EP - 102 CY - Saint Petersburg, Russia AN - OPUS4-20882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Häberle, Nicolas A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Falkenberg, Rainer A1 - Kahlcke, Ole T1 - Application of multi-phase viscoplastic material modelling to computational welding mechanics of grade-s960ql steel N2 - The sound numerical prediction of welding-induced thermal stresses, residual stresses, and distortions strongly depends on the accurate description of a welded material’s thermomechanical deformation behaviour. In this work, we provide experimental data on the viscoplastic deformation behaviour of a grade-s960ql steel up to a temperature of 1000 ◦C. In addition, a multi-phase viscoplastic material model is proposed, which accounts for the experimentally observed isothermal deformation behaviour of grade-s960ql steel base and austenitised material, as well as for athermal contributions that originate from solid-state phase transformations. The multi-phase viscoplastic and a classic rateindependent isotropic hardening material model were applied in the numerical simulations of both-ends-fixed bar Satoh tests and a single-pass gas metal arc weld. The influence of material modelling choices on the agreement between numerical simulation and experimental results is discussed, and recommendations for further work are given. KW - Residual stress KW - Viscoplasticity KW - Material modeling KW - Grade S960QL steel PY - 2018 U6 - https://doi.org/10.1016/j.crme.2018.08.001 VL - 346 IS - 11 SP - 1018 EP - 1032 PB - Elsevier Masson SAS AN - OPUS4-46512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ward, H. A1 - Burger, M. A1 - Chang, Y.-J. A1 - Fürstmann, P. A1 - Neugebauer, S. A1 - Radebach, A. A1 - Sproesser, G. A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Uhlmann, E. A1 - Steckel, J. Ch. T1 - Assessing carbon dioxide emission reduction potentials of improved manufacturing processes using multiregional input output frameworks N2 - Evaluating innovative process technologies has become highly important within the last decades. As standard tools different Life Cycle Assessment methods have been established, which are continuously improved. While those are designed for evaluating single processes they run into difficulties when it comes to assessing environmental impacts of process innovations at macroeconomic level. In this paper we develop a multi-step evaluation framework building on multi regional inputeoutput data that allows estimating macroeconomic impacts of new process technologies, considering the network characteristics of the global economy. Our procedure is as follows: i) we measure differences in material usage of process alternatives, ii) we identify where the standard processes are located within economic networks and virtually replace those by innovative process technologies, iii) we account for changes within economic systems and evaluate impacts on emissions. Within this paper we exemplarily apply the methodology to two recently developed innovative technologies: longitudinal large diameter steel pipe welding and turning of high-temperature resistant materials. While we find the macroeconomic impacts of very specific process innovations to be small, its conclusions can significantly differ from traditional process based approaches. Furthermore, information gained from the methodology provides relevant additional insights for decision makers extending the picture gained from traditional process life cycle assessment. KW - Economic wide technology replacement KW - Sustainability assessment KW - Multi-regional inputeoutput data KW - Life-cycle assessment KW - Greenhouse gas mitigation KW - Process innovations PY - 2017 U6 - https://doi.org/10.1016/j.jclepro.2016.02.062 SN - 0959-6526 SN - 1879-1786 VL - 163 SP - 154 EP - 165 PB - Elsevier Ltd. AN - OPUS4-41356 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Winterkorn, René A1 - Fabry, Cagtay T1 - Automated arc welding of support structures for offshore wind turbines N2 - Offshore wind energy plays an important role for the desired transition towards a carbon dioxide free industry within the next decades. However, the grounding of the offshore wind plants governs the overall installation process besides bureaucratic bottlenecks. The application of lightweight principles in steel construction, e.g. the usage dissolved load-bearing structures, so called Jackets foundations, offer great potential in reducing the resource consumption, especially with respect to the needed amount of steel. In this context this paper focuses on a fully digitalization of the welding manufacturing and as well as testing chain to enable a fully automated manufacturing as well as quality assessment of tubular nodes as key element of Jackets foundation structures. Furthermore, the relationship between the seam shape geometry and resulting fatigue strength is evaluated by numerical methods incorporating bionic principles. It is shown that tubular nodes can be welded fully automatically taking geometry tolerances into account. Moreover, the seam shape could be manufactured as requested by the numerical models which offers great potential for an extended lifetime. Subsequently, the improvements in resource efficiency and reduction of carbon dioxide emissions are evaluated by a life-cycle-assessment. T2 - IIW Annual Assembly 2022 Tokyo, Japan CY - Tokyo, Japan DA - 21.07.2022 KW - Offshore wind turbines KW - Support structures KW - Automated welding KW - Lightweight principles PY - 2022 AN - OPUS4-56653 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Weiß, D. T1 - Automated generation of temperature fields for numerical welding simulation KW - Welding simulation KW - Temperature field generation KW - Optimization KW - Neural networks PY - 2009 SN - 0288-4771 VL - 27 IS - 2 SP - 219 EP - 224 CY - Tokyo, Japan AN - OPUS4-19826 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Weiß, D. ED - Hirata, Yoshinori ED - Manabu Tanaka, T1 - Automated generation of temperature fields for numerical welding simulation T2 - 8th International Welding Symposium - Innovations in Welding and Joining for a New Era in Manufacturing CY - Kyoto, Japan DA - 2008-11-16 KW - Welding simulation KW - Temperature Field Generation KW - Optimization KW - Neural Networks PY - 2008 SP - 158 PB - Japan Welding Society CY - Kyoto AN - OPUS4-18614 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Fabry, Cagtay A1 - Rethmeier, Michael T1 - Automated welding of support structures for offshore wind turbines N2 - Offshore wind energy plays an important role for the desired transition towards a carbon dioxide free industry within the next decades. However, the grounding of the offshore wind plants governs the overall installation process besides bureaucratic bottlenecks. The application of lightweight principles in steel construction, e.g. the usage dissolved load-bearing structures, so called Jackets foundations, offer great potential in reducing the resource consumption, especially with respect to the needed amount of steel. In this context this paper focuses on a fully digitalization of the welding manufacturing and as well as testing chain to enable a fully automated manufacturing as well as quality assessment of tubular nodes as key element of Jackets foundation structures. Furthermore, the relationship between the seam shape geometry and resulting fatigue strength is evaluated by numerical methods incorporating bionic principles. It is shown that tubular nodes can be welded fully automatically taking geometry tolerances into account. Moreover, the seam shape could be manufactured as requested by the numerical models which offers great potential for an extended lifetime. Subsequently, the improvements in resource efficiency and reduction of carbon dioxide emissions are evaluated by a life-cycle-assessment. T2 - THERMEC'2023 International Conference on PROCESSING & MANUFACTURING OF ADVANCED MATERIALS: Processing, Fabrication, Properties, Applications CY - Vienna, Austria DA - 02.07.2023 KW - Offshore Wind energy KW - Automated welding KW - Life cycle assessment KW - Jacket foundations KW - Fatigue life PY - 2023 AN - OPUS4-59501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -