TY - CONF A1 - Fabry, Çağtay A1 - Pittner, Andreas T1 - Data-based process monitoring and control in narrow-gap GMAW N2 - An experimental setup to integrate laser sensor into conventional GMAW setups via a unified control architecture is described. The setup is used to automate and monitor narrow-gap GMAW. A way to develop GMAW arc-sensors using artificial neural networks using the setup is shown. The control system is connected to a relational database to store various process measurements. The database can be accessed to filter previous weldments by numerous criteria which allows modelling of process parameter correlation among vast datasets. Such models can be used for process monitoring and control in future applications. T2 - IIW Commission I, IV, XII / SG 212 Intermediate Meeting CY - Genova, Italy DA - 07.03.2016 KW - Narrow gap GMAW KW - MSG-Engspaltschweißen KW - Artificial neural networks KW - Profile measurement KW - GMAW control KW - Arc-sensing KW - Künstliche neuronale Netze KW - Profilvermessung KW - MAG Prozesssteuerung KW - Lichtbogensensorik PY - 2016 AN - OPUS4-35535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Michael, Thomas A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Microcrack formation during gas metal arc welding of high-strength fine-grained structural steel N2 - The recent development of high-performance-modified spray arc processes in gas metal arc welding due to modern digital control technology and inverter power sources enables a focused spray arc, which results in higher penetration depths and welding speed. However, microcracks occurred in the weld metal while approaching the process limits of the modified spray arc, represented by a 20-mm double layer DV-groove butt-weld. These cracks were detected in structural steel exhibiting a yield strength level of up to 960 MPa and are neither dependent on the used weld power source nor a consequence of the modified spray arc process itself. The metallographic and fractographic investigations of the rather exceptional fracture surface lead to the classification of the microcracks as hot cracks. The effects of certain welding parameters on the crack probability are clarified using a statistical design of experiment. However, these microcracks do not impact the design specification for toughness in the Charpy V-notch test (absorbed energy at -40 °C for the present material is 30 J). KW - High-strength low-alloy steel KW - Welding KW - Fracture KW - Design of experiments KW - Microcracking PY - 2014 DO - https://doi.org/10.1007/s40195-013-0011-5 SN - 1006-7191 SN - 1000-9442 VL - 27 IS - 1 SP - 140 EP - 148 PB - Springer CY - Shenyang AN - OPUS4-30123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neubert, Sebastian A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Numerical sensitivity analysis of TRIP-parameter K on weld residual stresses for steel S355J2+ N N2 - A combined experimental numerical approach is applied for sensitivity analysis of the transformation induced plasticity (TRIP)-parameter K on weld residual stresses for welding of structural steel of grade S355J2+N. K was determined experimentally using the Gleeble 3500 facility. A thermomechanical FE model of the real welding process was experimentally validated against temperature field and X-ray stress measurements. Within sensitivity analyses K was varied by several orders of magnitude and the influence on the calculated residual stresses is evaluated by performing corresponding FEA. The correct order of magnitude is sufficient to reproduce the residual stresses qualitatively and quantitatively. KW - TRIP - transformation induced plasticity KW - welding residual stresses KW - sensitivity analysis KW - FEA PY - 2016 DO - https://doi.org/10.1080/01495739.2015.1124641 SN - 0149-5739 VL - 2016 IS - 39/2 SP - 201 EP - 219 PB - Journal of Thermal Stresses AN - OPUS4-35880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sproesser, Gunther A1 - Chang, Ya-Ju A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Finkbeiner, Matthias T1 - Laser-MSG-Hybridschweißen und die Ökobilanz: Sieg nach Punkten N2 - Es ist ein Naturgesetz: Mit der verarbeiteten Blechdicke steigt der Zeit-, Material- und Energiebedarf beim Fügen überproportional. Aber ist das noch umweltverträglich ? Dieser Frage stellte sich Gunther Sproesser mit seinen Kollegen an der Technischen Universität Berlin. KW - MSG-Schweißen KW - Hochleistungsschweißen KW - Ökobilanz KW - Laser-MSG-Hybridschweißen PY - 2015 UR - http://www.laser-community.com/de/schweiss-verfahren-im-oeko-check/ N1 - In Deutsch und Englisch erschienen. Titel in English: "A win on points: LAHW/GMAW welding tops life-cycle analysis study" IS - 21/November 2015 SP - 6 EP - 6 AN - OPUS4-35438 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Ökologische Bilanzierung von Schmelzschweißverfahren unter Berücksichtigung vor- und nachgelagerter Prozessschritte N2 - Kleinere und mittlere Unternehmen agieren heutzutage in einem globalen Umfeld, wodurch diese zu Elementen einer komplexen Wertschöpfungskette werden. Der zunehmende Anstieg der Preise für industriell essenzielle Ressour-cen, wie Primärenergie und Rohstoffe, sowie sich ausweitende klimapolitische Restriktion führen zur Notwendigkeit, die Wettbewerbsfähigkeit durch innovative und ökoeffiziente Fertigungsprozesse langfristig zu sichern. Rahmenbe-dingungen zu schaffen, welche die Positionierung nachhaltiger Produkte und Prozesse innerhalb globaler Wert-schöpfungsketten ermöglicht, ist daher ein wesentliches Ziel der deutschen Industriepolitik [1, 2]. Im Rahmen dieses Beitrages werden aktuelle Forschungsarbeiten zur Bewertung der Umweltwirkungen der schweiß-technischen Fertigungskette anhand ausgewählter Schmelzschweißverfahren unter Berücksichtigung vor- sowie nachgelagerter Fertigungsschritte dargestellt. Das hierzu notwendige Element zur Analyse der Fertigungsprozesse ist die Ökobilanzierung - eine weit verbreitete und standardisierte Methode zur Abschätzung der Umweltwirkungen eines Produktes oder Prozesses. Hierbei stellt die Sachbilanzierung, d.h. die Ermittlung sämtlicher relevanter Ener-gie- und Ressourcenverbräuche während der schweißtechnischen Fertigung, aufgrund des hohen Dokumentations-aufwandes sowie Ableitung assoziierter Wirkkategorien das größte Hindernis für eine Etablierung und Akzeptanz der Ökobilanzierung in der Praxis dar. Gleichwohl wird seitens Unternehmen, welche als Zulieferer von OEM’s agieren, die Dokumentation des fertigungsspezifischen CO2-Verbrauches gefordert. Ein weiterer Aspekt der Arbeiten beinhaltet folglich Methoden zur automatisierten Erfassung von schweißtechnischen Produktionsdaten sowie deren Nachverfolgbarkeit aufzuzeigen. Anhand unterschiedlicher Schweißverfahren werden die aus den Produktionsdaten abgeleiteten Energie- und Ressourcenverbräuche automatisiert in den relevanten Umweltwirkungen überführt. Die analysierten Schweißprozesse umfassen dabei ein breites für kmU relevantes Spektrum. Durch die softwareseitige Bereitstellung der aufgestellten Umweltprofile ist der Anwender in der Lage, Schweißprozesse unter ökologischen Aspekten zu bewerten und die effizienteste Variante zu identifizieren. T2 - DVS Congress 2020 CY - Online meeting DA - 14.09.2020 KW - Ökobilanzierung KW - Schweißverfahren PY - 2020 AN - OPUS4-51854 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winterkorn, R. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Wire Arc Additive Manufacturing von einer neuartigen, höherfesten Al-Mg-Si Legierungen N2 - Der Einsatz von Aluminiumlegierungen als Konstruktionswerkstoff hat in den letzten Jahrzehnten aufgrund seines überlegenen Festigkeits-/ Gewichtsverhältnisses zugenommen. Dabei spielen höherfeste aushärtbare Al-Mg-Si-Legierungen eine wichtige Rolle. Dieser Beitrag konzentriert sich auf die additive Fertigung von Prinzipbauteilen aus einer Al-Mg-Si-Aluminiumlegierung mittels Wire + Arc Additive Manufacturing. Werkstoffe dieses Legierungssystems weisen eine ausgeprägte Heißrissanfälligkeit auf, weshalb das artgleiche Fügen dieser Materialien, mittels Metallschutzgasschweißen, heutzutage immer noch eine Herausforderung darstellt. Kommerzielle Al-Mg-Si-Schweißdrähte sind am Markt nicht verfügbar. In dieser Arbeit wird die Anwendbarkeit eines neuartigen Al-Mg-Si-Schweißdrahtes mit zusätzlichen kornfeinenden Elementen für die additive Fertigung mittels MSG-Verfahren gezeigt. Dazu wird der Zusammenhang von verwendeten Prozessparametern und der resultierenden Bauteilqualität untersucht, wobei die Größe und Verteilung von Poren sowie die Kornmorphologie analysiert werden. Darüber hinaus wird der Einfluss einer T6 Wärmenachbehandlung auf die mechanischen Eigenschaften des Werkstoffes untersucht und ein Vergleich zum entsprechenden Referenzmaterial (Knetlegierung) gezogen. T2 - 40. Assistentenseminar Fügetechnik CY - Braulage, Germany DA - 25.09.2019 KW - WAAM KW - Al-Mg-Si PY - 2020 SN - 978-3-96144-071-9 VL - 357 SP - 68 EP - 77 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-52901 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Pittner, Andreas A1 - Schürmann, Karsten ED - Böhmer, Heike ED - Brinkmann-Wicke, Tanja ED - Sell, Sabine ED - Simon, Janet ED - Tebben, Cornelia T1 - Automatisierte Rohrknotenfertigung in der Offshore-Windenergie – Potenzial zum Leichtbau im schweren Stahlbau N2 - Um den Klimawandel wirksam zu bekämpfen, ist es entscheidend, fossile Brennstoffe durch erneuerbare Energiequellen wie Wind-, Solar- und Wasserkraft sowie alternative Energieträger, beispielsweise grünen Wasserstoff, zu ersetzen. Offshore-Windenergie spielt hierbei eine zentrale Rolle, da sie dank der Kombination aus globaler Verfügbarkeit, relativ geringen Betriebskosten und fortgeschrittenem technischen Entwicklungsstand besonders geeignet ist, zur regenerativen Stromerzeugung beizutragen. Sie ist zudem ein Schlüsselelement für die Umsetzung des Europäischen Green Deals, der das Ziel verfolgt, bis 2050 Klimaneutralität in der EU zu erreichen. Expertenschätzungen zufolge ist eine Steigerung der aktuellen Kapazität von 25 GW im Jahr 2020 auf etwa 450 GW notwendig, um diese ambitionierten Ziele zu erfüllen. Bei der Entwicklung zukünftiger Offshore-Windparks, insbesondere in tieferen Gewässern, gewinnen Jacket-Gründungsstrukturen an Bedeutung. Diese Strukturen, die eine höhere Steifigkeit bei geringerem Materialeinsatz im Vergleich zu den bisher vorherrschenden Monopile-Gründungen bieten, basieren auf komplexen, räumlich aufgelösten Konstruktionen, die ähnlich den Öl- und Gasplattformen entwickelt werden. Die Herstellung der Jacketknoten, die bislang überwiegend manuell geschweißt wurden, birgt erhebliches Optimierungspotential. Durch Automatisierung und Digitalisierung der Fertigungsprozesse könnten nicht nur die Effizienz gesteigert, sondern auch die Qualität der Endprodukte durch präzise Überwachung und Kontrolle der Produktionsparameter verbessert werden. Diese technologischen Fortschritte sind für die Skalierung der Offshore-Windenergie und die Erreichung der Klimaziele von entscheidender Bedeutung. KW - Automatisierte Fertigung KW - Offshore Windenergie KW - Jacket-Gründungsstrukturen KW - Aufgelöste Tragstrukturen KW - Leichtbau PY - 2022 SN - 978-3-7388-0719-6 SP - 260 EP - 266 PB - Fraunhofer IRB Verlag CY - Stuttgart AN - OPUS4-59502 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Pittner, Andreas A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Einlagiges MSG-Hochleistungsschweißen von dickwandigen Baustählen mit kontaktloser elektromagnetischer Schmelzbadsicherung N2 - Diese Arbeit zeigt erstmals die Anwendung einer elektromagnetischen Schmelzbadsicherung beim einlagigen MSG-Schweißen von dickwandigen Stählen. Die innovativen Entwicklungen im Bereich des Lichtbogenschweißverfahrens ermöglichen eine Erhöhung der Abschmelzleistung, um die Einschweißtiefe zu steigern. Somit kann die Lagenanzahl reduziert und die Produktivität gesteigert werden. Allerdings besteht insbesondere beim einlagigen Schweißen von dickwandigen Bauteilen in PA-Position ein erhöhtes Risiko für das gravitationsbedingte Austropfen der Schmelze an der Wurzel. Zur Verhinderung werden Badsicherungen eingesetzt, die mechanisch angebracht und nach dem Schweißen entfernt werden müssen, was zeit- und kostenintensiv ist. Die im Rahmen dieser Studie eingesetzte elektromagnetische Schmelzbadsicherung wirkt dem gravitationsbedingten Austropfen der Schmelze entgegen und kompensiert den hydrostatischen Druck. Sie wirkt kontaktlos, was im Gegensatz zu herkömmlichen Badsicherungen vorteilhaft ist, so dass auf eine zeit- und kostenintensive Nachbearbeitung der Schweißnahtwurzel verzichtet werden kann. Das auf extern angelegten oszillierenden Magnetfeldern beruhende Verfahren wird dabei unterhalb des zu schweißenden Bauteils positioniert. Die Magnetfeldlinien sind quer zur Schweißrichtung ausgerichtet, sodass längs zur Schweißrichtung Wirbelströme im Werkstück und eine stets nach oben gerichtete Lorentzkraft generiert werden. Mit Hilfe der elektromagnetischen Badsicherung konnten beim einlagigen MSG-Schweißen von bis zu 10 mm dicken Blechen die Tropfenbildung vermieden werden. Die innovative Technologie ermöglicht es, dickwandige Bauteile einlagig zu schweißen und reduziert die Nachbearbeitungszeiten und -kosten deutlich. T2 - DVS Congress 2022 - Große Schweißtechnische Tagung CY - Koblenz, Germany DA - 19.09.2022 KW - Elektromagnetische Schmelzbadsicherung KW - Hochleistungsschweißen KW - MSG-Schweißen PY - 2022 SN - 978-3-96144-189-1 VL - 382 SP - 640 EP - 645 PB - DVS Media GmbH AN - OPUS4-56371 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fabry, Çağtay A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Automatisierungs- und Regelkonzepte für das MSG-Engspaltschweißen - Pendel- und Füllgradregelung N2 - Das MSG-Engspaltschweißen eignet sich auf Grund der I-Nahtvorbereitung besonders für das wirtschaftliche Fügen bei hohen Blechdicken über 100 mm und bietet darüber hinaus zusätzliche technologische Vorteile. Für die automatisierte Anwendung des Verfahrens unter Produktionsbedingungen muss dabei die Prozesssicherheit auch für mitunter große Variationen der Spaltbreite entlang der Schweißnaht gesichert bleiben. In erster Linie betrifft dies bei mechanischer Auslenkung der Drahtelektrode die Adaption der Pendelbewegung auf die jeweilige Spaltbreite um eine ausreichende Flankenanbindung zu garantieren. Für die Online-Regelung der Pendelbewegung mittels Lichtbogensensorik wurde eine Methode implementiert die die notwendigen Pendelwinkel an jeder Nahtflanke unabhängig ermittelt und darüber hinaus Fehlstellungen des Brenners sowie Veränderungen des Kontaktrohrabstandes und der Prozessparameter eigenständig kompensiert. Eine Füllgradregelung auf Grundlage optischer Erfassung und Auswertung der Schweißnahtgeometrie wurde zusätzlich eingesetzt um bei veränderlichen Nahtquerschnittsflächen einen vorgegebenen, gleichbleibenden Lagenaufbau zu erzielen. T2 - WGF Assistentenseminar 2016 CY - Paewesin, Germany DA - 06.09.2016 KW - MSG-Engspaltschweißen KW - MAG Prozesssteuerung KW - Sensorik KW - Lichtbogensensorik KW - Profilvermessung PY - 2018 SN - 978-3-96144-025-2 VL - 339 SP - 1 EP - 7 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-44284 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neubert, S. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Strain-rate controlled Gleeble experiments to determine the stress-strain behavior of HSLA steel S960QL N2 - In order to generate a material data base for computational welding mechanics, temperature and strain-rate dependent stress-strain experiments were performed by using a Gleeble®3500 testing system. The object of the investigation was HSLA transformable steel S960QL and related solid phases as bainite, martensite and austenite. For the production of these solid phases, the base material was heat treated according to an average weld temperature cycle which was extracted within the heat affected zone of a thermal numerical weld simulation of a GMA weld. The hot tensile tests were carried out via cost-saving flat specimen geometries. Two experimental series with different strain-rates were conducted, where the longitudinal strain-rate was controlled by specification of the transversal strain-rate applying Poisson’s-ratio. Subsequently, the resulting stress-strain curves were approximated in accordance with the Ramberg-Osgood-materials law. Consequently, it is shown that the temperature and strain-rate dependent stress-strain behavior of metals can be successfully characterized by means of a Gleeble®-system. However, this requires a control of the longitudinal strain-rate by specification of the transversal strain-rate. The related experimental procedure and the method of evaluation are explained in detail. With regard to all tested solid phases, a significant strain-rate dependency can only be observed upwards from temperatures of 400 °C. Based on experimental results, Ramberg-Osgood-parameters will be presented to describe the stress-strain behavior of steel S960QL and related solid phases for temperatures between 25 °C and 1200 °C. Furthermore, the use of costsaving flat specimen-geometry appears reasonable. N2 - Für die Generierung einer Materialdatenbank zur Schweißstruktursimulation wurden temperatur- und dehnratenabhängige Spannungs-Dehnungsexperimente unter Einsatz einer Gleeble® 3500-Anlage durchgeführt. Als Untersuchungsgegenstand diente der hochfeste niedriglegierte Feinkornbaustahl S960QL und seine zugehörigen Festphasen Bainit, Martensit und Austenit. Zur Herstellung dieser Festphasen wurde der Grundwerkstoff Wärmebehandlungen ausgesetzt, welche die charakteristischen Merkmale eines durchschnittlichen Schweißzeittemperaturzyklus aufweisen. Dieser Temperaturzyklus wurde aus der Wärmeeinflusszone eines numerisch nachgebildeten Temperaturfeldes einer MAG-Schweißverbindung extrahiert. Die Zugversuche wurden an einer kostengünstig herzustellenden Flachprobengeometrie durchgeführt, wobei zwei Experimentalreihen mit jeweils unterschiedlichen Dehnraten realisiert wurden. Die resultierenden Spannungs-Dehnungskurven wurden durch die Ramberg-Osgood-Beziehung approximiert. Es konnte gezeigt werden, dass das temperatur- und dehnratenabhängige Spannungs-Dehnungsverhalten von Metallen durch die Anwendung eines Gleeble®-Systems erfolgreich charakterisiert werden kann. Die Einstellung der Längsdehnrate muss dabei durch die Kontrolle der Querdehnrate unter Berücksichtigung des Poisson-Verhältnisses erfolgen. Die experimentellen Prozeduren und die zugehörigen Auswertemethodiken wurden detailliert erläutert. Für alle getesteten Festphasen wurde ein signifikanter Dehnrateneinfluss erst für Temperaturen ab 400 °C aufwärts beobachtet. Die anhand der Messergebnisse abgeleiteten Ramberg-Osgood-Parameter zur Beschreibung des Verfestigungsverhaltens für den Temperaturbereich zwischen 25 °C und 1200 °C werden vollständig präsentiert. KW - Stress-strain behavior KW - Gleeble testing KW - HSLA KW - Strain-rate KW - Numerical welding simulation KW - Transformable steels PY - 2018 DO - https://doi.org/10.3139/120.111208 SN - 0025-5300 VL - 60 IS - 7-8 SP - 733 EP - 748 PB - Carl Hanser CY - München AN - OPUS4-45791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Chaudhuri, Somsubhro A1 - Pittner, Andreas A1 - Winterkorn, Rene A1 - de Finis, Rosa A1 - Palumbo, Davide A1 - Galietti, Umbero T1 - Thermographic investigation of the anisotropic behaviour of additively manufactured AISI316 steel using DED-Arc N2 - Additive manufacturing is one of the most promising techniques for industrial production and maintenance, but the specifics of the layered structure must be considered. The Direct Energy Deposition-Arc process enables relatively high deposition rates, which is favourable for larger components. For this study, specimens with different orientations were prepared from one AISI316 steel block – parallel and orthogonal to the deposition plane. Quasistatic tensile loading tests were carried out, monitored by an infrared camera. The obtained surface temperature maps revealed structural differences between both orientations. The consideration of surface temperature transients yields more details about the behaviour of the material under tensile loading than the conventional stress-strain-curve. These preliminary investigations were supplemented by thermographic fatigue trials. Although the anisotropy was also observed during fatigue loading the fatigue behaviour in general was the same, at least for both inspected specimens. The presented results demonstrate the abilities and the potential of thermographic techniques for tensile tests. T2 - 17th Quantitative Infrared Thermography Conference CY - Zagreb, Croatia DA - 01.07.2024 KW - WAAM PY - 2024 SP - 1 EP - 8 AN - OPUS4-62548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Ökobilanzierung schweißtechnischer Fertigungsverfahren - Methodik, Einflussgrößen und Implementierung N2 - Ein wesentliches Ziel der deutschen Industriepolitik besteht darin, Rahmenbedingungen zu schaffen, welche die Positionierung nachhaltiger Produkte und Prozesse innerhalb globaler Wertschöpfungsketten ermöglichen und ökoeffiziente Fertigungsprozesse langfristig sichern. In diesem Beitrag werden aktuelle Forschungsarbeiten zur Bewertung der Umweltwirkungen der schweißtechnischen Fertigungskette anhand ausgewählter Schmelzschweißverfahren unter Berücksichtigung vor- sowie nachgelagerter Fertigungsschritte dargestellt. Eine weit verbreitete und standardisierte Methode zur Abschätzung der Umweltwirkungen eines Produkts oder Prozesses ist die Ökobilanzierung. Hierbei stellen die Sachbilanzierung, das heißt die Ermittlung sämtlicher relevanter Energie- und Ressourcenverbräuche während der schweißtechnischen Fertigung, aufgrund des hohen Dokumentationsaufwands, sowie die Ableitung assoziierter Wirkkategorien das größte Hindernis für eine Etablierung und Akzeptanz der Ökobilanzierung in der Praxis dar. Gleichwohl wird seitens Unternehmen, welche als Zulieferer von OEM’s (engl.: original equipment manufacturer) agieren, die Dokumentation des fertigungsspezifischen CO2-Verbrauches gefordert. Ein weiterer Aspekt der Arbeiten beinhaltet Methoden zur automatisierten Erfassung von schweißtechnischen Produktionsdaten sowie deren Nachverfolgbarkeit. Anhand unterschiedlicher Schweißverfahren werden die aus den Produktionsdaten abgeleiteten Energie- und Ressourcenverbräuche automatisiert in die relevanten Umweltwirkungen überführt. Die analysierten Schweißprozesse umfassen dabei ein breites für kleine und mittlere Unternehmen (KMU) relevantes Spektrum. Durch die softwareseitige Bereitstellung der aufgestellten Umweltprofile ist der Anwender in der Lage, Schweißprozesse unter ökologischen Aspekten zu bewerten und die effizienteste Variante zu identifizieren. T2 - Woche der Fügetechnik 2022, HWK Münster CY - Online meeting DA - 30.11.2022 KW - Ökobilanzierung KW - Verfahrensvergleich KW - Schweißprozesse KW - Umweltwirkungen KW - Implementierung PY - 2022 AN - OPUS4-56650 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - SmartWeld - Innovatives Design und Fertigungskonzept zur Steigerung der Leichtbaupotenziale im Stahlbau N2 - Die Anwendung von Leichtbauprinzipien im Stahlbau, wie z.B. die Verwendung von aufgelösten Tragstrukturen, sog. Jackets-Fundamenten, bietet ein großes Potential zur Reduzierung des Ressourcenverbrauchs, insbesondere im Hinblick auf die benötigte Stahlmenge. In diesem Vortrag zeigen wir die Potenziale einer vollständigen Digitalisierung der schweißtechnischen Fertigungs- und Prüfkette auf, um eine vollautomatische Fertigung sowie Qualitätsprüfung von Rohrknoten als Schlüsselelement von Jackets-Fundamenten zu ermöglichen. Darüber hinaus wird der Zusammenhang zwischen der Geometrie der Nahtform und der resultierenden Ermüdungsfestigkeit durch numerische Methoden unter Einbeziehung bionischer Prinzipien bewertet. Es wird gezeigt, dass Hohlprofilknoten vollautomatisch unter Berücksichtigung von Geometrietoleranzen geschweißt werden können. Darüber hinaus konnte die Nahtform gemäß den numerischen Modellen hergestellt werden, was ein großes Potenzial für eine verlängerte Lebensdauer bietet. Anschließend werden die Verbesserungen bei der Ressourceneffizienz und die Reduzierung der Kohlendioxidemissionen durch eine Lebenszyklusanalyse bewertet. T2 - Bundesverband der Windparkbetreiber Offshore: Tagung der Arbeitsgruppe Engineering CY - Online meeting DA - 26.11.2021 KW - Offshore Windenergieanlagen KW - Gründungsstrukturen KW - Automatisierte Fertigung KW - Aufgelöste Tragstrukturen PY - 2021 AN - OPUS4-56652 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sproesser, G. A1 - Chang, Y.-J. A1 - Pittner, Andreas A1 - Finkbeiner, M. A1 - Rethmeier, Michael T1 - Environmental energy efficiency of single wire and tandem gas metal arc welding N2 - This paper investigates gas metal arc welding (GMAW) with respect to energy consumption and its associated environmental impacts. Different material transfer modes and power levels for single wire GMAW (SGMAW) and tandem GMAW (TGMAW) are evaluated by means of the indicator electrical deposition efficiency. Furthermore, the wall-plug efficiency of the equipment is measured in order to describe the total energy consumption from the electricity grid. The results show that the energy efficiency is highly affected by the respective process and can be significantly enhanced by a TGMAW process. The wall-plug efficiency of the equipment shows no significant dependency on the power range or the material transfer mode. Moreover, the method of life cycle assessment (LCA) is adopted in order to investigate the influences of energy efficient welding on the environmental impacts. In the comparative LCA study, the demand of electrical energy is reduced up to 24%. In consequence, the indicator values for global warming potential (100), acidification potential, eutrophication potential, and photochemical ozone creation potential are reduced up to 11%. KW - Energy input KW - Tandem welding KW - MAG welding KW - Environment KW - Lifetime PY - 2017 DO - https://doi.org/10.1007/s40194-017-0460-y SN - 0043-2288 SN - 1878-6669 VL - 61 IS - 4 SP - 733 EP - 743 PB - Springer CY - Heidelberg AN - OPUS4-39877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sproesser, Gunther A1 - Chang, Y.-J. A1 - Pittner, Andreas A1 - Finkbeiner, M. A1 - Rethmeier, Michael T1 - Life cycle assessment of welding technologies for thick metal plate welds N2 - Life Cycle Assessment (LCA) is applied in evaluating environmental impacts of state-of-the-art welding technologies. Manual Metal Arc Welding (MMAW), Laser Arc-Hybrid Welding (LAHW) and two Gas Metal Arc Welding (GMAW) variants are used to join a plate of 20 mm thick structural steel. The LCA results indicate that for 1 m weld seam, MMAW causes the highest environmental impacts in global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), and photochemical ozone creation potential (POCP) among the selected processes, and the LAHW variant performances the least. Filler material and electricity consumptions generally dominate the impacts and reach shares of up to 80% and 61% in the respective impact categories. However, electrode coating consumption in MMAW remarkably contributes impacts on AP and EP, for instance 52% of AP and 76% of EP. Strategies for improvement of the applied welding technologies are discussed. KW - Life Cycle Assessment (LCA) KW - Arc welding KW - Laser arc-hybrid welding KW - Resource efficiency PY - 2015 DO - https://doi.org/10.1016/j.jclepro.2015.06.121 SN - 0959-6526 VL - 108 IS - Part: A SP - 46 EP - 53 PB - Elsevier Science CY - Amsterdam AN - OPUS4-34969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Pittner, Andreas A1 - Weiss, D. A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Fast temperature field generation for welding simulation and reduction of experimental effort N2 - The quality of welding processes is governed by the occurring induced distortions yielding an increase in production costs due to necessary reworking. Especially for more complex specimens it is difficult to evaluate the optimal configuration of welding sequences in order to minimise the distortion. Even experienced welding operators can solve this task only by trial and error which is time and cost consuming. In modern engineering the application of welding simulation is already known to be able to analyse the heat effects of welding virtually. However, the welding process is governed by complex physical interactions. Thus, recent weld thermal models are based on many simplifications. The state of the art is to apply numerical methods in order to solve the transient heat conduction equation. Therefore, it is not possible to use the real process parameters as input for the mathematical model. The model parameters which allow calculating a temperature field that is in best agreement with the experiments cannot be defined directly but inversely by multiple simulations runs. In case of numerical simulation software based on finite discretisation schemes this approach is very time consuming and requires expert users. The weld thermal model contains an initial weakness which has to be adapted by finding an optimal set of model parameters. This process of calibration is often done against few experiments. The range of model validity is limited. An extension can be obtained by performing a calibration against multiple experiments. The focus of the paper is to show a combined modelling technique which provides an efficient solution of the inverse heat conduction problem mentioned above. On the one hand the inverse problem is solved by application of fast weld thermal models which are closed form solutions of the heat conduction equation. In addition, a global optimisation algorithm allows an automated calibration of the weld thermal model. This technique is able to provide a temperature field automatically that fits the experimental one with high accuracy within minutes on ordinary office computers. This fast paradigm permits confirming the application of welding simulation in an industrial environment as automotive industry. On the other hand, the initial model weakness is compensated by calibrating the model against multiple experiments. The unknown relationship between model and process parameters is approximated by a neural network. The validity of the model is increased successively and enables to decrease experimental effort. For a test case it is shown, that this approach yields accurate temperature fields within very short amount of time for unknown process parameters as input data to the model contributing to the requirement to construct a substitute system of the real welding process. KW - Welding simulation KW - Temperature field generation KW - Short calculation time KW - Multiple experiments KW - Inverse heat conduction problem KW - Neural networks PY - 2009 IS - SC-Auto-32-09 SP - 1 EP - 11 PB - International Institute of Welding CY - Paris AN - OPUS4-19744 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 - 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 - 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 - GEN A1 - Karkhin, V.A. A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Rethmeier, Michael ED - Makhnenko, V.I. T1 - Heat source models in simulation of heat flow in fusion welding T2 - 5th International Conference - Mathematical modelling and information technologies in welding and related processes CY - vil. Katsiveli, Crimea, Ukraine DA - 2010-05-25 PY - 2010 SN - 978-966-8872-15-0 SP - 56 EP - 60 CY - Kiev, Ukraine AN - OPUS4-23382 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittner, Andreas A1 - Weiß, D. A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Methodology to improve applicability of welding simulation N2 - 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. 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 DO - https://doi.org/10.1179/136217108X329322 SN - 1362-1718 SN - 1743-2936 VL - 13 IS - 6 SP - 496 EP - 508 PB - Maney CY - London AN - OPUS4-18300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Methodology for the fast temperature field generation for welding simulation T2 - 17th International Conference, "Computer Technology in Welding and Manufacturing" CY - Cranfield, England DA - 2008-06-18 PY - 2008 AN - OPUS4-20848 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Application of a combined modelling technique to reduce experimental effort-a case study for Laser-GMA-Hybrid Welding T2 - Beam Technologies & Laser Application, VI International Conference CY - Saint Petersburg, Russia DA - 2009-09-23 PY - 2009 AN - OPUS4-20851 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karkhin, Victor A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Simulation of inverse heat conduction problems in fusion welding with extended analytical heat source models N2 - 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. KW - Laser beam welding KW - Volume heat source KW - Functional-analytical solution KW - Inverse modelling PY - 2011 DO - https://doi.org/10.1007/s11706-011-0137-1 SN - 2095-025X SN - 2095-0268 VL - 5 IS - 2 SP - 119 EP - 125 PB - Springer CY - Secaucus, N.J. AN - OPUS4-24164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittner, Andreas A1 - Weiß, D. A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Fast temperature field generation for welding simulation and reduction of experimental effort N2 - The quality of welding processes is governed by the occurring induced distortions yielding an increase in production costs due to necessary reworking. Especially for more complex specimens, it is difficult to evaluate the optimal configuration of welding sequences in order to minimize the distortion. Even experienced welding operators can solve this task only by trial and error which is time and cost consuming. In modern engineering the application of welding simulation is already known to be able to analyse the heat effects of welding virtually. However, the welding process is governed by complex physical interactions. Thus, recent weld thermal models are based on many simplifications. The state of the art is to apply numerical methods in order to solve the transient heat conduction equation. Therefore, it is not possible to use the real process parameters as input for the mathematical model. The model parameters which allow calculating a temperature field that is in best agreement with the experiments cannot be defined directly but inversely by multiple simulations runs. In case of numerical simulation software based on finite discretization schemes this approach is very time consuming and requires expert users. The weld thermal model contains an initial weakness which has to be adapted by finding an optimal set of model parameters. This process of calibration is often done against few experiments. The range of model validity is limited. An extension can be obtained by performing a calibration against multiple experiments. The focus of the paper is to show a combined modelling technique which provides an efficient solution of the inverse heat conduction problem mentioned above. On the one hand the inverse problem is solved by application of fast weld thermal models which are closed form solutions of the heat conduction equation. In addition, a global optimization algorithm allows an automated calibration of the weld thermal model. This technique is able to provide a temperature field automatically that fits the experimental one with high accuracy within minutes on ordinary office computers. This fast paradigm permits confirming the application of welding simulation in an industrial environment as automotive industry. On the other hand, the initial model weakness is compensated by calibrating the model against multiple experiments. The unknown relationship between model and process parameters is approximated by a neural network. The validity of the model is increased successively and enables to decrease experimental effort, For a test case, it is shown that this approach yields accurate temperature fields within very short amount of time for unknown process parameters as input data to the model contributing to the requirement to construct a substitute system of the real welding process. KW - Heat flow KW - Neural networks KW - Simulating KW - Temperature KW - Welding PY - 2011 SN - 0043-2288 SN - 1878-6669 VL - 55 IS - 09-10 SP - 83 EP - 90 PB - Springer CY - Oxford AN - OPUS4-24603 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Michael, Thomas A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Schwierigkeiten bei der Anwendung der aktuellen Normung in Bezug auf Mikrorisse in Schweißverbindungen hochfester vergüteter Feinkornbaustähle N2 - Die aktuelle Normung bezüglich mikroskopischer Untersuchungen von Schweißverbindungen und die Zulässigkeit von Mikrorissen sowie deren Definition ist nicht eindeutig. Nach der Darstellung derzeit gültiger Normen im Bereich der Bewertung von Schweißnähten, Qualifizierung von Schweißverfahren und Ausführung von Schweißverbindungen, wird auf Grundlage aktueller Schweißversuche an hochfesten vergüteten Feinkornbaustählen die Problematik von Mikrorissen diskutiert. Offene Punkte und Fragen bzw. Verbesserungsmöglichkeiten werden aufgezeigt und zur Diskussion gestellt. Schließlich wird auf die Klärung des Einflusses von Mikrorissen auf die mechanisch- technologischen Werkstoffkennwerte der Schweißverbindung unter statischer sowie zyklischer Beanspruchung hingewiesen. --------------------------------------------------------------------------------------------------------------------------------------------------------------- Neither the latest standardisation with regard to microscopic investigations on welded joints nor the permissibility of microcracks and their definition are unambiguous. According to the representation of currently applicable standards in the fields of the assessment of welds, the qualification of welding processes and the execution of welded joints, the problems associated with microcracks are discussed on the basis of the latest welding tests on high-strength quenched-and-tempered fine-grained structural steels. Not only outstanding points and questions but also improvement possibilities are indicated and opened for discussion. Finally, attention is drawn to the clarification of the influence of microcracks on the mechanical- technological material parameters of the welded joint subjected to both static and cyclic stresses. KW - Festigkeit KW - Hochfester Stahl KW - Normen KW - Rissbildung KW - Schweißnahtfehler KW - Werkstofffragen KW - Strength KW - High-strength steel KW - Standards KW - Crack formation KW - Weld defects KW - Material questions PY - 2012 SN - 0036-7184 VL - 64 IS - 7 SP - 412 EP - 416 PB - Verl. für Schweißen u. Verwandte Verfahren, DVS-Verl. CY - Düsseldorf AN - OPUS4-26338 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Babu, S. S. T1 - Dependency of martensite start temperature on prior austenite grain size and its influence on welding-induced residual stresses N2 - Austenite grain growth during welding is a critical factor for controlling weld microstructure in addition to nominal composition and thermal cycles. Recently, experimental data suggesting a decrease in martensite start temperature with a decrease in prior austenite grain size has been published. However, the actual sensitivity of this phenomenon on residual stresses evolution in the heat-affected zone has not been investigated, yet. Therefore, a numerical model was modified to consider this phenomenon. Numerical simulations were performed for welding of a low-alloy structural steel with minimum yield strength of 355 MPa (S355J2+N) and a heat-resistant steel P91 or 9Cr–1Mo, respectively. The results clarify the influence of prior austenite grain size on the residual stress development and show the importance martensite transformation temperatures and final martensite fraction. Consequently, the residual stress evolution of P91, which completely transforms to martensite while cooling, based on the enhanced model leads to maximum stress differences of 200 MPa in the heat-affected zone. KW - Prior austenite grain size KW - Martensite start temperature KW - Welding-induced residual stress KW - Numerical simulation KW - Gas metal arc welding PY - 2013 DO - https://doi.org/10.1016/j.commatsci.2012.11.058 SN - 0927-0256 VL - 69 SP - 251 EP - 260 PB - Elsevier CY - Amsterdam AN - OPUS4-27633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Winterkorn, René T1 - Wire arc additive manufacturing of high strength al-mg-si alloys N2 - Direct energy deposition additive manufacturing technologies utilizing an electric arc offer a great potential in generating large volume metal components. However, the selection of process parameters that yield the desired near net shape design as well as the requested mechanical component behavior is not a trivial task due to the complex relationship. Exemplarily for additive manufacturing of high-strength precipitation hardening AlMgSi-aluminum alloy this paper shows the application of a newly developed matching solid welding wire doped with TiB as grain refiner. The correlation between process parameters and component quality is examined analyzing the size and distribution of pores as well as the grain morphology. Furthermore, the influences of different post-weld heat treatments are evaluated to meet the reference mechanical properties of the corresponding wrought material. Finally, the digital integration of the entire additive manufacturing chain enables an overall traceability of the relevant process steps which is the basis for a reliable subsequent quality assessment. T2 - THERMEC'2023 International Conference on PROCESSING & MANUFACTURING OF ADVANCED MATERIALS: Processing, Fabrication, Properties, Applications CY - Vienna, Austria DA - 02.07.2023 KW - Additive Manufacturing KW - DED-Arc KW - Grain refinement KW - High strength AlMgSi aluminium alloys KW - Mechanical properties PY - 2023 AN - OPUS4-59500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sproesser, G. A1 - Chang, Y.-J. A1 - Pittner, Andreas A1 - Finkbeiner, M. A1 - Rethmeier, Michael T1 - Energy efficiency and environmental impacts of high power gas metal arc welding N2 - Single-wire gas metal arc welding (SGMAW) and high power tandem GMAW (TGMAW) are evaluated with respect to energy efficiency. The key performance indicator electrical deposition efficiency is applied to reflect the energy efficiency of GMAW in different material transfer modes. Additionally, the wall-plug efficiency of the equipment is determined in order to identify the overall energy consumption. The results show that energy efficiency can be increased by 24% and welding time is reduced over 50% by application of the tandem processes. A comparative life cycle assessment of a 30-mm-thick weld is conducted to investigate the influences of the energy efficiency on the environmental impacts. The environmental impacts on the categories global warming potential, acidification potential, eutrophication potential, and photochemical ozone creation potential can be reduced up to 11% using an energy-efficient TGMAW process. KW - Tandem gas metal arc welding KW - Life cycle assessment (LCA) KW - Energy efficiency KW - High power welding PY - 2017 DO - https://doi.org/10.1007/s00170-017-9996-7 SN - 0268-3768 SN - 1433-3015 VL - 91 IS - 9-12 SP - 3503 EP - 3513 PB - Springer CY - London AN - OPUS4-39564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 UR - https://nbn-resolving.org/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 - JOUR A1 - Schempp, Philipp A1 - Häcker, Ralf A1 - Pittner, Andreas A1 - Cross, C.E. A1 - Rethmeier, Michael T1 - Influence of grain size on mechanical properties of aluminium GTA weld metal N2 - Surface modification of mild steel was undertaken using two covered electrodes and two tubular electrodes. The two covered electrodes are DIN 8555: E6-UM-60 and E10-UM-60GR; however, the two tubular electrodes are E10-GF-60GR1 and E10-GF-60GR2. Chemical analysis for the weld metal and XRD of the flux covering for covered electrodes and flux core for tubular electrodes were conducted. The most important factor in determining the wear resistance is the microstructure of the deposit layers. In similar carbon equivalent electrodes E10-UM-60GR and E10-GF-60GR1, electrode E10-GF-60GR1 (tubular) shows larger carbides area fraction and better wear resistance than electrode E10-UM-60GR (covered). This could be attributed to a lower dilution associated with tubular electrode compared with covered electrode. The two tubular electrodes showed higher wear resistance than the covered electrodes which is mainly due to the larger Fe-Cr carbide precipitation area fraction. KW - GTA welding KW - Aluminium KW - Grain refinement KW - Tensile tests KW - Tear tests PY - 2014 DO - https://doi.org/10.1007/s40194-014-0132-0 SN - 0354-7965 VL - 58 IS - 4 SP - 491 EP - 497 PB - Drustvo za Unapredjivanje Zavarivanja u Srbiji CY - Beograd AN - OPUS4-35103 LA - srp AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schaumann, P. A1 - Schürmann, K. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Experimental investigations on the fatigue resistance of automatically welded tubular X-joints for jacket support structures N2 - The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to current standards due to the lack of suitable S-N curves. Therefore, 32 axial fatigue tests on single and double-sided automatically welded tubular X-joints have been performed to determine a new hot spot stress related S-N curve. Based on these constant amplitude fatigue tests a new S-N curve equal to a FAT 126 curve was computed which implicitly includes the benefits of the automatically welding procedure. T2 - EERA Deep Wind 2020 CY - Trondheim, Norway DA - 15.01.2020 KW - Notch stress approach KW - Fatigue tests KW - Automated manufacturing KW - Tubular X-joints KW - Structural stress approach PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518509 DO - https://doi.org/10.1088/1742-6596/1669/1/012022 VL - 1669 SP - 012022 PB - IOP Publishing Ltd AN - OPUS4-51850 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fabry, Çağtay A1 - Pittner, Andreas A1 - Hirthammer, Volker A1 - Rethmeier, Michael T1 - Recommendations for an Open Science approach to welding process research data N2 - The increasing adoption of Open Science principles has been a prevalent topic in the welding science community over the last years. Providing access to welding knowledge in the form of complex and complete datasets in addition to peer-reviewed publications can be identified as an important step to promote knowledge exchange and cooperation. There exist previous efforts on building data models specifically for fusion welding applications; however, a common agreed upon implementation that is used by the community is still lacking. One proven approach in other domains has been the use of an openly accessible and agreed upon file and data format used for archiving and sharing domain knowledge in the form of experimental data. Going into a similar direction, the welding community faces particular practical, technical, and also ideological challenges that are discussed in this paper. Collaboratively building upon previous work with modern tools and platforms, the authors motivate, propose, and outline the use of a common file format specifically tailored to the needs of the welding research community as a complement to other already established Open Science practices. Successfully establishing a culture of openly accessible research data has the potential to significantly stimulate progress in welding research. KW - Welding KW - Research data management KW - Open science KW - Digitalization KW - Weldx KW - Open source PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-529332 DO - https://doi.org/10.1007/s40194-021-01151-x SN - 1878-6669 SN - 0043-2288 SP - 1 EP - 9 PB - Springer CY - Heidelberg AN - OPUS4-52933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winterkorn, René A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Wire arc additive manufacturing with novel Al-Mg-Si filler wire - Assessment of weld quality and mechanical properties N2 - Wire arc additive manufacturing enables the production of near-net shape large-volume metallic components leveraging an established industrial base of welding and cladding technology and adapting it for layer-wise material deposition. However, the complex relationship between the process parameters and resulting mechanical properties of the components still remains challenging. In case of high-strength Al-Mg-Si aluminum alloys, no commercial filler wires are yet available due the high susceptibility of solidification cracking as well as the necessary efforts to obtain acceptable mechanical properties. To address this need, we evaluated a novel filler wire based on AlMg0.7Si doped with a Ti5B1 master alloy to foster fine equiaxed grains within the deposited metal. The correlation between the process parameters and component quality was examined by analyzing the size and distribution of pores as well as the grain morphology. Furthermore, we evaluated the influence of different post-weld heat treatment strategies to achieve mechanical properties corresponding to the reference wrought material. We demonstrated that fine equiaxed grains in the weld metal reduced the susceptibility of solidification cracking significantly. The novel AlMg0.7Si-TiB (S Al 6063-TiB) filler wire facilitated wire arc additive manufacturing of high-strength aluminum components with mechanical properties that were almost as superior as the corresponding wrought base material. KW - Wire arc additive manufacturing KW - Precipitation hardening aluminum alloys KW - AlMg0.7SiTiB filler wire KW - Grain refinement KW - Mechanical properties PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538327 DO - https://doi.org/10.3390/met11081243 SN - 2075-4701 VL - 11 IS - 8 SP - 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-53832 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strobl, Dominic A1 - Unger, Jörg F. A1 - Ghnatios, C. A1 - Klawoon, Alexander A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Robens-Radermacher, Annika T1 - Efficient bead-on-plate weld model for parameter estimation towards effective wire arc additive manufacturing simulation N2 - Despite the advances in hardware and software techniques, standard numerical methods fail in providing real-time simulations, especially for complex processes such as additive manufacturing applications. A real-time simulation enables process control through the combination of process monitoring and automated feedback, which increases the flexibility and quality of a process. Typically, before producing a whole additive manufacturing structure, a simplified experiment in the form of a beadon-plate experiment is performed to get a first insight into the process and to set parameters suitably. In this work, a reduced order model for the transient thermal problem of the bead-on-plate weld simulation is developed, allowing an efficient model calibration and control of the process. The proposed approach applies the proper generalized decomposition (PGD) method, a popular model order reduction technique, to decrease the computational effort of each model evaluation required multiple times in parameter estimation, control, and optimization. The welding torch is modeled by a moving heat source, which leads to difficulties separating space and time, a key ingredient in PGD simulations. A novel approach for separating space and time is applied and extended to 3D problems allowing the derivation of an efficient separated representation of the temperature. The results are verified against a standard finite element model showing excellent agreement. The reduced order model is also leveraged in a Bayesian model parameter estimation setup, speeding up calibrations and ultimately leading to an optimized real-time simulation approach for welding experiment using synthetic as well as real measurement data. KW - Proper generalized decomposition KW - Model order reduction KW - Hardly separable problem KW - Additive manufacturing KW - Model calibration KW - Wire arc additive manufacturing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596502 DO - https://doi.org/10.1007/s40194-024-01700-0 SN - 0043-2288 SP - 1 EP - 18 PB - Springer AN - OPUS4-59650 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Life Cycle Assessment of Fusion Welding Processes - A Case Study of Resistance Spot Welding Versus Laser Beam Welding N2 - 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. KW - Resistance spot welding KW - Carbon dioxide footprint KW - Environmental impact categories KW - Laser beam welding KW - Life cycle assessment PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-566458 DO - https://doi.org/10.1002/adem.202101343 SN - 1438-1656 VL - 24 IS - 6 SP - 1 EP - 14 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56645 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 - JOUR A1 - Zhang, Lei A1 - Pittner, Andreas A1 - Michael, Thomas A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Effect of cooling rate on microstructure and properties of microalloyed HSLA steel weld metals N2 - Two high strength Nb/Ti microalloyed S690QL steels were welded with identical filler material, varying welding parameters to obtain three cooling rates: slow, medium and fast cooling. As cooling rate increased, the predominantly acicular ferrite in Nb weld metal (WM) is substituted by bainite, with a consequence of obvious hardness increase, but in Ti WM, no great variation of acicular ferrite at all cooling rates contributed to little increment of hardness. The transition between bainite and acicular ferrite has been analysed from the point view of inclusions characteristics, chemical composition and cooling rate. Excellent Charpy toughness at 233 K was obtained with acicular ferrite as predominantly microstructure. Even with bainite weld of high hardness, the toughness was nearly enough to fulfill the minimal requirements. WM for Ti steel showed to be markedly less sensitive to the variations of cooling rate than that for Nb steel. KW - High strength steel KW - Weld metal KW - Cooling rate KW - Charpy toughness KW - Acicular ferrite PY - 2015 DO - https://doi.org/10.1179/1362171815Y.0000000026 SN - 1362-1718 VL - 20 IS - 5 SP - 371 EP - 377 PB - Taylor and Francis CY - London, UK AN - OPUS4-36518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schempp, Philipp A1 - Cross, C.E. A1 - Häcker, Ralf A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Influence of grain size on mechanical properties of aluminium GTA weld metal N2 - Grain refinement is an important possibility to enhance the mechanical properties such as strength, ductility and toughness of aluminium weld metal. In this study, grain refinement was achieved through the addition of commercial grain refiner Al Ti5B1 to gas tungsten arc weld metal of the aluminium alloys 1050A (Al 99.5) and 5083 (Al Mg4.5Mn0.7). The grain refiner additions led to a significant reduction of the weld metal mean grain size (Alloy 1050A, 86 %; Alloy 5083, 44 %) with a change in grain shape from columnar to equiaxed. Tensile tests showed for Alloy 5083 that the weld metal's ductility can be increased through grain refinement. No improvement in weld metal strength (i.e. yield strength and ultimate tensile strength) was observed. Furthermore, tear tests with notched specimens revealed that the resistance against initiation and propagation of cracks in the weld metal can be enhanced through grain refinement. The toughness was observed to increase clearly by grain refinement in weld metal of commercial pure Al (Alloy 1050A). In Alloy 5083 weld metal, the toughness was not improved through grain refinement, likely because of a semi-continuous network of brittle intermetallic phases that facilitate crack propagation. KW - GTA welding KW - Aluminium KW - Grain size KW - Tensile tests KW - Dynamic fracture tests PY - 2013 DO - https://doi.org/10.1007/s40194-013-0026-6 SN - 0043-2288 SN - 1878-6669 VL - 57 IS - 3 SP - 293 EP - 304 PB - Springer CY - Oxford AN - OPUS4-28065 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schempp, Philipp A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Tang, Z. A1 - Seefeld, T. A1 - Cross, C.E. ED - Babu, S. S. ED - Bhadeshia, H.K. ED - Cross, C.E. ED - David, S.A. ED - DebRoy, T. ED - DuPont, J.N. ED - Koseki, T. ED - Liu, S. T1 - Influence of alloy and solidification parameters on grain refinement in aluminium weld metal due to inoculation N2 - Refinement of the weld metal grain structure can improve the mechanical properties of the weld and decrease the susceptibility to solidification cracking of the weld metal. In this study, commercial Al Ti5B1 grain refiner was used to refine the microstructure of LB (laser beam) and GTA (gas tungsten arc) aluminum welds by inoculation. The grain refiner additions led to a significant decrease in the weld metal mean grain size whereby a transition from columnar to equiaxed grain structure (Columnar to Equiaxed Transition, CET) was observed. The development of both grain size and shape depended upon the base metal (Al alloys 1050A, 5083 and 6082) and upon the welding process. The GTA welding process allowed a more pronounced and a more efficient refinement than in LB welds. Furthermore, the influence of the solidification conditions on the CET was investigated through temperature measurements in the weld metal. The temperature profiles revealed a faster solidification of LB welds than in GTA welds. The results from the temperature measurements were also used to estimate (according to an existing model) the critical thermal gradient at which the CET occurs. T2 - 9th International conference on trends in welding research CY - Chicago, Illinois, USA DA - 04.06.2012 KW - Aluminium KW - LBW KW - GTAW KW - Grain refinement KW - Alloy 1050A KW - Alloy 5083 KW - Alloy 6082 KW - Al Ti5B1 PY - 2013 SN - 978-1-62708-998-2 SP - 98 EP - 107 PB - ASM international AN - OPUS4-27907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Structural welding simulation - Perspective and needs for industrial implementation N2 - The digitalization of industrial processes is the most discussed topic in society these days. New business models have been developed to benefit from the opportunities offered by a digitally connected world. However, the focus in on the smart factory consisting of autonomous acting cyber physical systems (CPS). The efficient implementation of such CPS within an industrial environment requires the digitalization of the corresponding production processes. The digital twin of the process under investigation enables to develop sophisticated monitoring and control strategies which are necessary to fulfil the requirements of individual product design. The need for a digitalization of the welding process is a logical consequence especially with regards to its industrial importance. The theoretical investigations and derived mathematical models of the welding process are well known since many decades. Anyhow, there is still a lack of industrial applicability of such models for an efficient and safe design of welded components. With respect to structural welding simulation that targets the heat effects of welding in terms of global quantities like temperature, solid phase distribution and residual stresses as well as distortions, the limited predictability of these quantities for arbitrary process parameters hinders its usability. This presentation aims to give an overview of the current state of the art in structural welding simulation to predict the evolution of welding induced temperatures, stresses and distortions. Emphasis is given to industrial applicability of such models by reduction of the calculation times for large real-world structures and improved prediction of optimal process parameters. Furthermore, the role of such models within a weld data management system is demonstrated. The accumulation and relational storage of simulation and measuring data improves the overall process knowledge. This enables virtual cause and effect analyses of new process parameters as basis for a control system design. T2 - 70th IIW Annual Assembly & International Conference CY - Shanghai, China DA - 25.06.2017 KW - Structural welding simulation KW - Digitalization KW - Residual stress and distortion KW - Reduction of calculation time KW - Control system design PY - 2017 AN - OPUS4-46635 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Fast Generation and Prediction of Welding Temperature Fields for Multiple Experiments T2 - The Fourth International Conference "Mathematical Modelling and Information, Technologies in Welding and Related Processes", vil. Katsively CY - Crimea, Ukraine DA - 2008-05-27 PY - 2008 AN - OPUS4-20849 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Fast Temperature Field Generation for Welding Simulation and Reduction of Experimental Effort T2 - IIW SC Auto, 62nd IIW Annual Assembly CY - Singapore DA - 2009-07-12 PY - 2009 AN - OPUS4-22362 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Heat source models in simulation of heat flow in fusion welding T2 - 1st Sino-German Workshop "Simulation of Welding" CY - Berlin, Germany DA - 2010-10-26 PY - 2010 AN - OPUS4-22496 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chang, Y.-J. A1 - Sproesser, G. A1 - Neugebauer, S. A1 - Wolf, K. A1 - Scheumann, R. A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Finkbeiner, M. T1 - Environmental and social life cycle assessment of welding technologies N2 - Life Cycle Assessment (LCA) and Social Life Cycle Assessment (SLCA) are applied in evaluating possible social and environmental impacts of the state-of-art welding technologies, such as Manual Metal Arc Welding (MMAW), Manual Gas Metal Arc Welding (GMAW), Automatic GMAW and Automatic Laser-Arc Hybrid Welding (LAHW). The LCA results indicate that for 1 meter weld seam, MMAW consumes the largest amount of resources (like filler material and coating on electrodes) and energy, which contributes to comparatively higher environmental impacts in global warming potential, acidification, photochemical ozone creation potential and eutrophication than other chosen processes. With regard to social aspects, the health issues and fair salary are under survey to compare the relative potential risk on human health caused by fumes in different welding technologies, and to indicate the sufficiency of current salary of welders in Germany. The results reflect that the wage status of welders is still fair and sufficient. The manual processes bring much higher potential risk of welders’ health than the automatic processes, especially MMAW. KW - Fair salary KW - Human health KW - Life Cycle Assessment (LCA) KW - Social Life Cycle Assessment (SLCA) KW - Welding PY - 2015 DO - https://doi.org/10.1016/j.procir.2014.07.084 SN - 2212-8271 VL - 26 SP - 293 EP - 298 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-33036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schempp, Philipp A1 - Cross, C.E. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Influence of solute content and solidification parameters on grain refinement of aluminum weld metal N2 - Grain refinement provides an important possibility to enhance the mechanical properties (e.g., strength and ductility) and the weldability (susceptibility to solidification cracking) of aluminum weld metal. In the current study, a filler metal consisting of aluminum base metal and different amounts of commercial grain refiner Al Ti5B1 was produced. The filler metal was then deposited in the base metal and fused in a GTA welding process. Additions of titanium and boron reduced the weld metal mean grain size considerably and resulted in a transition from columnar to equiaxed grain shape (CET). In commercial pure aluminum (Alloy 1050A), the grain-refining efficiency was higher than that in the Al alloys 6082 and 5083. Different welding and solidification parameters influenced the grain size response only slightly. Furthermore, the observed grain-size reduction was analyzed by means of the undercooling parameter P and the growth restriction parameter Q, which revealed the influence of solute elements and nucleant particles on grain size. KW - Aluminium KW - GTA welding KW - Grain refinement KW - Alloy 1050A KW - Alloy 5083 KW - Alloy 6082 KW - Al Ti5B1 PY - 2013 DO - https://doi.org/10.1007/s11661-013-1649-3 SN - 1073-5623 SN - 1543-1940 VL - 44A IS - 7 SP - 3198 EP - 3210 PB - The Minerals, Metals and Materials Society CY - Warrendale AN - OPUS4-28656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Welding Simulation by Means of Phenomenological and Empirical Modelling T2 - AnSim Workshop 2011 CY - Berlin, Germany DA - 2011-03-23 PY - 2011 AN - OPUS4-23429 LA - deu 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 - CONF A1 - Pittner, Andreas T1 - Simulation of Welding Temperature Field in Laser Beam Welding by Inverse Techniques T2 - 13th NOLAMP, Conference on Laser Materials Processing in the Nordic Countries CY - Trondheim, Norway DA - 2011-06-27 PY - 2011 AN - OPUS4-24162 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas T1 - Potenzial der Schweißsimulation bei fügetechnischen Fragestellungen T2 - Treffen des DVS Beziksverband Berlin, BAM CY - Berlin, Germany DA - 2012-10-31 PY - 2012 AN - OPUS4-28678 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -