Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Application of Hybrid Laser Arc Welding for Construction of LNG Tanks Made of Thick Cryogenic 9% Ni Steel Plates

2023-10-18 , Gook, Sergej , El-Batahgy, Abdel-Monem , Gumenyuk, Andrey , Biegler, Max , Rethmeier, Michael

Hybrid laser-arc welding (HLAW) was applied for butt welding of 14.5 mm thick plates of ferritic cryogenic steel X8Ni9 containing 9% Ni, which is used for manufacturing storage and transport facilities of liquefied natural gas (LNG). The weld seam formation and the achievable metallurgical and mechanical properties of the hybrid welds were investigated experimentally for two types of filler wire, an austenitic wire dissimilar to the base metal (BM) and an experimentally produced matching ferritic wire. Safe penetration and uniform distribution of the austenitic filler metal in the narrow hybrid weld could only be achieved in the upper, arc-dominated part of the weld. The pronounced heterogeneous distribution of the austenitic filler metal in the middle part and in the root area of the weld could not ensure sufficient notched impact toughness of the weld metal (WM). As a result, a decrease in the impact energy down to 17 ± 3 J was observed, which is below the acceptance level of ≥ 34 J for cryogenic applications. In contrast, the use of a matching ferritic filler wire resulted in satisfactory impact energy of the hybrid welds of up to 134 ± 52 J at the concerned cryogenic temperature of-196 °C. The obtained results contribute to an important and remarkable conversion in automated manufacturing of LNG facilities. In other words, the results will help to develop a new laser-based welding technology, where both quality and productivity are considered. The efficiency of the developed welding process has been demonstrated by manufacturing a prototype where a segment of the inner wall of large size LNG storage tank was constructed. In this concern, hybrid laser arc welding was conducted in both horizontal (2G) and vertical (3G) positions as a simulation to the actual onsite manufacturing. The prototype was fabricated twice where its quality was confirmed based on non-destructive and destructive examinations.

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Optimization of Segmented Thermal Barrier Coatings (s-TBCs) for High-Temperature Applications

2023-08-29 , Yalcinyüz, Behiye Aybike , Kamutzki, Franz , Gurlo, Aleksander , Rupprecht, Christian

Hot section components of stationary gas turbines, such as turbine blades and vanes, are coated with thermal barrier coatings (TBCs) to increase the component life. TBCs provide thermal insulation to the metallic components from hot gas in the gas turbines. The TBCs represent high-performance ceramics and are mainly composed of yttria-stabilized zirconia (YSZ) to fulfill the thermal insulation function. The microstructure of the TBCs should be porous to decrease heat conduction. Besides the porous TBCs, the subsequently developed vertically segmented thermal barrier coatings (s-TBCs) feature outstanding thermal durability. For the formation of this segmented coating microstructure, the YSZ should be deposited under high thermal tensile stress during the coating process. Therefore, substrates are heated just before the coating by plasma or in an oven in recent research. In this work, the development of process parameters for s-TBCs produced by atmospheric plasma spray (APS) without pre-heating is presented. Within the experiments, the relevant process parameters, such as plasma gases, powder feed rate, surface speed, and pathway strategy, have been optimized to achieve the segmented coating microstructure with high deposition efficiency by a conventional plasma torch. Furthermore, YSZ powders used in this study are characterized, and the effect of powder characteristics on the coating microstructure is investigated. The coating microstructure in this work aims to achieve the formation of a high number of vertical cracks with a combination of low internal residual stress and high adhesive tensile strength for the s-TBCs.

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Entwicklung eines Prozess- und Informationsmodells für das Produktlebenszyklusmanagement in der digitalen Transformation

2023 , Schindlbeck, Roman , Rethmeier, Michael , Stark, Rainer , Dust, Robert

Die Digitalisierung erfordert von industriellen Unternehmen, reaktionsfähig neue Kundenbedürfnisse zu bedienen. Der tägliche Umgang mit digitalen Technologien verändert die Erwartungen der Nutzer an Produkte und Services. Um im Wettbewerb zu bestehen, sind Geschäftsmodelle konsequent kundenorientiert auszurichten und permanent anzupassen. Innovationen ressourceneffizient und schnell in Form von Produkten und Services zu operationalisieren, setzt voraus, dass die Prozesse und Systeme von Unternehmen ein durchgängiges, anpassbares und transparentes Wissens-, Informations- und Datenmanagement gewährleisten. In dieser Arbeit wird ein Modell für ein strukturiertes Vorgehen entwickelt, um neue Geschäftsmodelle zu gestalten und die dafür notwendigen Adaptionen des Produktlebenszyklusmanagements vorzunehmen. Die Anforderungen an das Modell werden anhand der praxisbezogenen Aktionsforschung und qualitativer Untersuchungsmethoden abgeleitet. Darauf aufbauend erfolgt die Modellbildung, in die konkrete Techniken und Handlungsanleitungen einfließen. Anschließend wird das Modell durch den Use Case „Automatisiertes Laden“ evaluiert.

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A Data-Driven Concept and Realization for Engineering Change Management Decision Support

2023 , Pan, Yuwei , Krüger, Jörg

In today's automotive industry, quickly reacting to engineering changes and providing market-driven products within a short period remains a competence for all Original Equipment Manufacturers (OEMs). Due to the complexity of products, changes to one component can lead to unexpected chain reactions in others. Besides, from creation to the approval of a change request can take weeks or even months without apparent reasons for the delays. To coordinate and control changes, companies established Engineering Change Management (ECM) processes. ECM processes can impact all determinants of competition of products: cost, quality, and time-to-market. Without proper management of Engineering Changes (ECs), negative impacts will happen. In the scope of this dissertation, a machine-learning based ECM decision support solution is developed which includes two main functions: change impacts prediction and lead time prediction. These functions support engineers to have an overview of change consequences in the early phase of the ECM process. The solution was evaluated based on the data from an automotive company and reached good performance. Therefore it was rated as beneficial to increase the efficiency, effectiveness, and quality of the existing ECM processes.

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The Identification of a New Liquid Metal Embrittlement (LME) Type in Resistance Spot Welding of Advanced High-Strength Steels on Reduced Flange Widths

2023-10-16 , Yang, Keke , Meschut, Gerson , Seitz, Georg , Biegler, Max , Rethmeier, Michael

Liquid metal embrittlement (LME) cracking is a phenomenon observed during resistance spot welding (RSW) of zinc-coated advanced high-strength steels (AHSS) in automotive manufacturing. In this study, severe cracks are observed at the edge of the sheet under reduced flange widths. These cracks, traversing the AHSS sheet, culminate at the edge with a width of approximately 1.2 mm. Through combined numerical and experimental investigations, and material testing, these cracks are identified and validated as a new type of LME crack. The mechanism behind this crack formation is attributed to unique geometric conditions that, when compared to center welding, amplify radial material flow by ninefold to 0.87 mm. The resultant tangential tensile stresses approximate 760 MPa, which exceed the yield strength of the examined advanced high-strength steel (AHSS) under heightened temperature conditions, and when combined with liquid zinc, promote the formation of this new type of LME crack.

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Process Setup and Boundaries of Wire Electron Beam Additive Manufacturing of High-Strength Aluminum Bronze

2023-08-08 , Raute, Maximilian Julius , Biegler, Max , Rethmeier, Michael

In recent years, in addition to the commonly known wire-based processes of Directed Energy Deposition using lasers, a process variant using the electron beam has also developed to industrial market maturity. The process variant offers particular potential for processing highly conductive, reflective or oxidation-prone materials. However, for industrial usage, there is a lack of comprehensive data on performance, limitations and possible applications. The present study bridges the gap using the example of the high-strength aluminum bronze CuAl8Ni6. Multi-stage test welds are used to determine the limitations of the process and to draw conclusions about the suitability of the parameters for additive manufacturing. For this purpose, optimal ranges for energy input, possible welding speeds and the scalability of the process were investigated. Finally, additive test specimens in the form of cylinders and walls are produced, and the hardness profile, microstructure and mechanical properties are investigated. It is found that the material CuAl8Ni6 can be well processed using wire electron beam additive manufacturing. The microstructure is similar to a cast structure, the hardness profile over the height of the specimens is constant, and the tensile strength and elongation at fracture values achieved the specification of the raw material.

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A life cycle assessment of joining processes in the automotive industry, illustrated by the example of an EV battery case

2023 , Brunner-Schwer, Christian , Lemke, Josefine , Biegler, Max , Schmolke, Tobias , Spohr, Sebastian , Meschut, Gerson , Eckstein, Lutz , Rethmeier, Michael

Current ecological, economic and social changes are leading to a change in development, design and production of future vehicles. In this context, it is the stated goal of many manufacturers to advance the development of an environmentally friendly vehicle and climate-neutral production throughout the entire supply chain. This study presents a comparative life cycle assessment of the joining processes laser beam welding, laser brazing and resistance spot welding. For this purpose, an approach tailored to welding processes is presented and applied to the example of a battery case for electric vehicles. For the welding process under consideration, the main influences on the resulting environmental impact categories are evaluated and compared. The requirements for ecologically efficient welding processes are discussed and outlined. The results show that particularly the materials involved, such as the consumption of the filler material, have the greatest environmental impact and thus offer the greatest potential for savings.

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Künstliche Neuronale Netze zur Qualitätsprognose von Funktional Gradierten Materialien im laserbasierten Directed Energy Deposition

2023-09-25 , Marquardt, Raphael , Bähring, Stefan , Biegler, Max , Rethmeier, Michael

Durch pulverbasiertes Directed-Energy Deposition lassen sich Gradierungen fertigen, um diskrete Materialübergänge zu vermeiden und die Lebensdauer von Hartschichten zu erhöhen. Die Kombination aus Stahl als Basiswerkstoff und einer verschleiß- und korrosionsbeständigen Co-Cr Legierung verspricht durch Vermeiden von Spannungskonzentrationen das Verhindern von Abplatzungen und Rissen in der Schutzschicht. Um die Qualität des gefertigten Bauteils zu beurteilen, liegen für solche Funktional Gradierten Materialien (FGM) wenig Erkenntnisse vor. Daher wird im Rahmen dieser Studie eine Methodik erarbeitet, um die relative Dichte eines Funktional Gradierten Materials auf Stahl und Co-Cr Basis mittels Maschinendaten zu bestimmen. Anschließend wird unter Einsatz eines künstlichen neuronalen Netzes anhand von Sensordaten die relative Dichte vorhergesagt. Das trainierte Netz erreicht eine Vorhersagegenauigkeiten von 99,83%. Abschließend wird eine Anwendung anhand von einem Demonstrator gezeigt.

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Feasibility study of joining of carbon fibre-reinforced polymer composites and aluminium alloys by electron beam welding for use in lightweight construction

2023-05-12 , Yalcinyüz, Behiye Aybike , Brunner-Schwer, Christian , Biegler, Max , Rethmeier, Michael

In recent years, new solutions to reduce the weight of components used in the automotive, railway, and aircraft industries have been researched. Carbon Fibre Composites (CFC) have been used to replace metals in products requiring lightweight construction, such as aircraft or high-performance vehicles due to their exceptional mechanical strength. However, the use of CFCs is limited by the reason of their poor thermal conductivity, particularly on components requiring effective dissipation of power losses. To respond to the requirements, the idea of the material combination of metals and polymer-based composites is proposed. In this study, electron beam welding is used for the joining of aluminium alloys and polymer-based composites. Within the experiments, the relevant process parameters such as beam current, welding speed, and heat input have been optimized to achieve the welding of the aluminium alloys. Then, the joining of aluminium alloys and carbon fibre-reinforced polymer composites has been investigated through the optimized welding process parameters for aluminium alloys. Conclusions are drawn regarding the carbon-fibre reinforced polymer composites (PA6-CF) and aluminium alloys (AlMg3) being joinable through electron beams.

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Methode zur Quantifizierung von Einsatzgrenzen einer zentralen und dezentralen Struktur für die Fertigungssteuerung

2023 , Willeke, Nils , Krüger, Jörg

In der Massenfertigung werden flexible Organisationsformen und dezentrale Steuerungsstrukturen als Lösungsansätze für volatile Märkte seit mehr als einem Jahrzehnt diskutiert. Über die Einsatzgrenzen in einem Fertigungssystem kann jedoch ohne einen Leistungsvergleich keine Aussage getroffen werden. Die Untersuchung einer Vielzahl von Algorithmen ist zeit- und ressourcenaufwändig. Um eine praxistaugliche Schätzung der Einsatzgrenzen zu ermöglichen, wird eine Angleichung der Auswahllogik bei der Entscheidungsfindung vorgenommen, sodass diese anhand der Eigenschaften proaktives Rüsten und Aktualität der Entscheidungsgrundlage bestimmt werden können. Ein Simulationsmodell wurde entwickelt und Simulationsstudien durchgeführt. Für die Berechnung einer Kennzahl und den Vergleich von Simulationsalternativen wurde ein existierendes Verfahren automatisiert. Die Sieger aus den Vergleichen werden in Entscheidungshilfen operationalisiert. Das entwickelte Verfahren ermöglicht eine performantere Simulation und die Bestimmung minimal möglicher Einsatzgrenzen der Werkstattfertigung.

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