Jean Pierre Bergmann

Jean Pierre Bergmann
Technische Universität Ilmenau | TUI · Production technology Group

Prof. Dr.-Ing.
Full Professor

About

308
Publications
40,903
Reads
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1,598
Citations
Citations since 2017
171 Research Items
1268 Citations
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20172018201920202021202220230100200300
20172018201920202021202220230100200300
20172018201920202021202220230100200300

Publications

Publications (308)
Article
Full-text available
This review sheds novel insights on the residual oxide behaviour of solid-state weld joints of aluminium alloys. Understanding the influence of oxides on the aluminium surface before and during welding, its impact on the weld structure and possible solutions for reducing its impact were addressed. The solid-state techniques most relevant to the tra...
Article
Multi material pairings like metal-plastic hybrid compounds are becoming increasingly important across all industrial sectors. However, the substitution of metals by plastics leads to a multitude of challenges based on the combination of dissimilar materials. The variations in the chemical and physical properties of the used materials require innov...
Article
Full-text available
Friction stir welding (FSW) is a solid-state joining process with a wide range of applications in the E-mobility, automotive, aerospace and energy industries. However, FSW is subjected to specific challenges including comparatively high process forces and high requirements on the clamping technique as well as tool wear resulting from the tool-workp...
Article
Mischverbindungen aus normalfesten und hochfesten Stählen ermöglichen einen optimierten Materialeinsatz durch die Anpassung an die einwirkenden Kräfte. Das führt ökologisch und wirtschaftlich zu Vorteilen durch einen reduzierten Materialverbrauch und kleinere Schweißnahtgeometrien. Da normativ derzeit keine Regelungen für stumpfgeschweißte Mischver...
Article
Full-text available
Laser beam welding with solid-state lasers leads to the formation of spatters at relevant processing speeds (≥ 8 m/min). The use of local gas flows proved to be adequate to avoid these phenomena. This publication examines the mechanical effect of a local supply of argon, nitrogen and helium to provide a deeper understanding of the local pressure di...
Article
Full-text available
Increasing beam power of solid-state lasers enables high welding speeds for laser welding processes. However, increasing welding speeds lead to imperfections, especially spatter formation while processing high-alloy steels. A recent and novel approach to reduce the spatter formation is the utilization of a local gas flow to manipulate the keyhole p...
Article
Full-text available
Joining of thin aluminum sheets (<1mm) is widely used in the industry for electronic housings or EMC shielding. Aluminum alloys of the 6xxx series are particularly relevant for such applications. However, their use is very challenging in welding processing due to the hot cracking phenomenon. Hot cracks are known to form during the solidification ph...
Article
Full-text available
Laser welding of copper is of great importance for industrial applications, e.g., for manufacturing of electrical components such as hairpins. Solid state lasers are widely used due to the high power and beam brilliance, but the implementation can be challenging in terms of process instabilities and resulting weld defects, i.e., spatter and pore fo...
Article
Full-text available
Laser beam butt welding of thin sheets of high-alloy steel can be really challenging due to the formation of joint gaps, affecting weld seam quality. Industrial approaches rely on massive clamping systems to limit joint gap formation. However, those systems have to be adapted for each individually component geometry, making them very cost-intensive...
Article
Ultrasonic metal welding (USMW) is an industrially applied joining technology that is highly complex since the weld quality is influenced by numerous factors. The relationships between these factors and the quality remain partly unavailable resulting in a need for improvement in process monitoring and quality management. This work focuses on explor...
Poster
Full-text available
The development of today's glass constructions are driven by the desire for an increased building transparency and the reduction of unattractive attachment points, whereby the load-bearing capacity of glass as a construction material and its resistance to occurring forces is becoming increasingly important. To confirm the durability of a glass cons...
Chapter
In this paper, the possibility of additively producing individual 3D-structures with borosilicate and soda-lime glass based on a laser process with glass rods is demonstrated. In a previous study, process parameters, which show the geometrically defined deposition of individual layers were determined (Fröhlich et al. in Herstellung individueller St...
Chapter
Currently, destructive or non-destructive testing methods are used to verify the weld seam quality subsequent to the manufacturing process. Therefore, pre-processes such as visible or mechanical testing require additional efforts, which can lead to expensive reworking or rejection of the components. The acoustic process characterization for Frictio...
Article
Full-text available
An efficient and productive joining technique to weld aluminium has become a priority challenge for promoting the use of aluminium in the electrical industry. One of the challenges is to obtain welds with superior mechanical properties with the consistent quality of weld surface as well as low electrical resistance. In this paper, the influence of...
Article
Electric mobility has become increasingly important in recent years. For this purpose, the use of copper is essential due to its electrical properties. In order to save weight and costs, copper is replaced by aluminum in many electrical conductors.In this paper, the required joining time for pulsed laser beam welding of aluminum-copper joints is in...
Article
Full-text available
Friction stir welding is a solid-state joining process with a wide range of industrial applications in the e-mobility, automotive, aerospace and energy industries. However, friction stir welding is subjected to process-specific challenges, including comparatively high process forces and friction stir welding tool wear resulting from tribological in...
Conference Paper
By estimating manufacturing costs and times at an early design stage, design of a part and production planning can be improved to significantly reduce product costs. Therefore, a concept for automated estimation of costs and times based on similarity analysis is introduced. This concept is based on a semantic and machine-interpretable representatio...
Article
Full-text available
The use of shielding gases in laser beam welding is of particular interest for materials interacting with ambient oxygen, e.g., copper, titanium or high-alloy steels. These materials are often processed by remote laser beam welding where short welds (e.g., up to 40 mm seam length) are commonly used. Such setups prevent gas nozzles from being carrie...
Article
Full-text available
Today, the quality of welded seams is often examined off-line with either destructive or non-destructive testing. These test procedures are time-consuming and therefore costly. This is especially true if the welds are not welded accurately due to process anomalies. In manual welding, experienced welders are able to detect process anomalies by liste...
Article
Full-text available
According to the technical breakthrough towards E-Mobility, current-carrying dissimilar joints between aluminum and copper are gaining an increasing relevance for the automotive industry and thus, coming into focus of many research activities. The joining of dissimilar material in general is well known to be a challenging task. Furthermore, the cur...
Article
Challenges in civil engineering and construction industries increase, and simultaneously it is necessary to provide a sustainable utilization of resources. Optimising material applications and manufacturing processes is therefore essential for modern constructions. Highly optimised structural components are already in use in lightweight constructio...
Article
Full-text available
For fulfilling the demand of durable yet lightweight electrical connections in transportation industries, ultrasonic metal welding (USMW) sees widespread use in these branches. As the ultrasound oscillations utilized in the welding procedure occur at a range of only a few micrometers at frequencies of 20–100 kHz for an overall duration of only 50–1...
Article
Höherfeste Stähle erlauben hohe Beanspruchungen, insbesondere im Zugbereich, in Konstruktionen aufzunehmen und führen zur Reduzierung tragender Querschnitte, zur Verringerung des Materialverbrauchs und der Herstellungskosten. Da die Bemessungsregeln für Verbindungen ausschließlich auf Konzepten beruhen, die für normalfeste Stähle bis fy,k = 360 N/m...
Article
Full-text available
The demand for efficient and digital systems for supporting the decision making during the design of a product is a key issue in manufacturing companies. Decisions made during the development and design of a product have a strong impact on the costs and delivery times of a product. Hence, a digital system which supports the engineer during and afte...
Article
The application of fused tungsten carbides (FTCs) in nickel-based alloys is important for improving the wear resistance of tooling equipment in the mining industry. However, FTCs are thermally unstable and will dilute under excessive energy input during welding. The parameters affecting dilution in this context are diverse and not yet completely un...
Article
Zur Verkürzung der Zeitspanne zwischen der Entwicklung bis zur Auslieferung von neuen Produkten wird am Fachgebiet Fertigungstechnik der TU Ilmenau eine Methode entwickelt, mit der bereits in der Entwicklungsphase Kapazitäten für die Produktion reserviert und die Kostenkalkulation angegangen werden können, damit Unternehmen ihre Liefertermine einha...
Chapter
Companies that manufacture their own products and also provide after-market service are common and usually involve in-house manufacturing and assembly. The limited capacity of in-house resources and the requirement to meet delivery deadlines forces companies to deviate from the cost-optimal production strategy and to produce quantities according to...
Article
Wire-assisted pulsed laser beam welding is one option for processing high-strength γ‘-precipitation hardening nickel-base superalloys. It facilitates crack-reduced repair of similar material pairings through material-adapted pulse shapes. The limited average power output of pulsed laser beam sources confines the deposition rate and thus the product...
Article
Full-text available
This research presents a hybrid approach to generate sample data for future machine learning applications for the prediction of mechanical properties in directed energy deposition-arc (DED-Arc) using the GMAW process. DED-Arc is an additive manufacturing process which offers a cost-effective way to generate 3D metal parts, due to its high depositio...
Conference Paper
Full-text available
In the presented paper, the influence of the lateral distance between the deposited lines on the geometric dimensions and the degree of mixing of additively manufactured glass structure is investigated. Initial experimental investigations have shown that additive manufacturing of quartz, soda-lime and borosilicate glass is possible when material- a...
Article
Das gepulste Laserstrahlauftragschweißen mit drahtförmigem Zusatzwerkstoff ist eine Möglichkeit zur Verarbeitung von hochfesten γ‘-ausscheidungshärtenden Nickelbasis-Superlegierungen. Es ermöglicht eine heißrissarme Reparatur von artgleichen Werkstoffpaarungen durch werkstoffangepasste Pulsformen. Die begrenzte mittlere Leistung gepulster Laserstra...
Article
Full-text available
Friction stir welding (FSW) has developed into a reliable and increasing used industrial joining technology. Various tool configurations can be used for FSW, each of which has advantages and challenges. State-of-the-art FSW employs various tool configurations, including the conventional, the stationary shoulder, and the dual-rotational configuratio...
Article
Die vorliegende Studie zeigt Grundzüge eines Verfahrens, welches Potentiale zum Ausgleich der Defizite bisheriger additiver Verfahren bezüglich Maßhaltigkeit, Homogenität und Transparenz der Struktur aufweist. Silikatische Gläser werden durch eine CO2-Laserquelle aufgeschmolzen. Ein Dreiachssystem defokussiert den Laserstrahl, um die Intensitäten z...
Conference Paper
Full-text available
Spatter formation is a major issue in deep penetration welding with solid-state lasers at high welding speeds. The use of local gas supplied near to the keyhole proved to be very effective to avoid spatter formation. This publication examines the flow conditions and pressure field of a local supply of argon/helium by welding stainless steel (X5CrNi...
Conference Paper
Full-text available
Laser-assisted joining enables a direct connection between polymers and metals without using additional elements (e.g. screws, rivets) or adhesives. The process is well known in terms of surface pretreatment, achievable mechanical properties and materials. However, the quality of the joint is affected by varying manufacturing conditions, e.g. heat...
Conference Paper
Full-text available
Pulsed laser beam welding is of high importance in micro-welding applications and used for materials susceptible to hot cracking, e.g. 6xxx aluminum alloys. Pulse shapes are adjusted to prevent hot cracks by reducing solidification rates which is accompanied by decreased welding speeds. Numerical simulations are now used for optimizing the tradeoff...
Conference Paper
Full-text available
The combination of high processing speeds and improved beam qualities enlarges the possible fields of laser applications enormously. Gas-free sheet cutting and precise mass corrections represent examples where spatter formation is applied as the primarily removal mechanism under the use of cw-mode laser radiation. For a deeper insight into spatter...
Article
The desire to generate a stress optimised structural node with maximum stability is often coupled with the goal of low manufacturing costs and an adapted and minimal use of material. The complex, three-dimensional free-form structures, which are created by means of topology-optimisation, are only partially suitable for conventional manufacturing. T...
Article
Full-text available
High processing speeds enormously enlarge the number of possible fields of application for laser processes. For example, material removal for sheet cutting using multiple passes or precise mass corrections can be achieved by means of spatter formation. For a better understanding of spatter formation at processing speeds of several hundred meters pe...
Conference Paper
Ultrasonic metal welding as a contacting technology has attracted new interest within the last years due to the fact that it enables cost-efficient joining of dissimilar materials. In the course of continuing electrification and lightweight-construction, for example in the automotive sector, the ability to weld aluminium and copper, also in presenc...
Article
Full-text available
The transition of the powertrain from combustion to electric systems increases the demand for reliable copper connections. For such applications, laser welding has become a key technology. Due to the complexity of laser welding, especially at micro welding with small weld seam dimensions and short process times, reliable in-line process monitoring...
Article
Full-text available
Friction stir spot welding (FSSW) is a solid-state welding process, wherein the properties of a weld joint are influenced by the state of friction and localised thermodynamic conditions at the tool-workpiece interface. An issue well-known about FSSW joints is their lack of reliability since they abruptly delaminate at the weld-faying interface (WFI...
Article
Full-text available
Friction stir spot welding is an emerging spot-welding technology that offers opportunities for joining a wide range of materials with minimum energy consumption. To increase productivity, the present work addresses production challenges and aims to find solutions for the lap-welding of multiple ultrathin sheets with maximum productivity. Two conve...
Chapter
This study systematically analyzes effective wear mechanismsWear mechanisms at the shoulder and probe, separately for plungingPlungingand weldingWelding. The investigations were carried out with a robotic welding setup in which AA-6060 T66AA- 6060 T66 sheets with a thickness of 8 mm were joined by weld seam lengths of up to 80 m. To compare and dif...
Conference Paper
Das Laserstrahlschweißen bedingt aufgrund des lokalen Aufschmelz- und Erstarrungsprozesses die Entstehung ei-nes dehnungsfeldbasierten Fügespaltes. Industrielle Lösungsansätze setzen zur Begrenzung dieses Phänomens massive Spannsysteme ein, welche sehr kostenintensiv sind und zugleich bei Änderungen der Bauteilgeometrie individuell angepasst werden...
Article
Full-text available
Stainless steels are indispensable materials in many industrial fields. They can be easily shaped and joined by traditional welding methods. Some problematics such as possible decrease in corrosion resistance at the welding bead and in the heat-effected zone, residual stress, crack formation and distortions may take place after welding. Friction St...
Chapter
This chapter gives an overview of ultrasonic welding, especially ultrasonic metal welding. The principles of ultrasonics are briefly described following by the assembly of an ultrasonic metal device with functions of the individual components as well as a survey about typical joint configurations and materials. Further, current challenges and appli...
Conference Paper
Full-text available
The demand for efficient and digital systems for supporting the decision making during the design of a product is a key issue in manufacturing companies. Decisions made during the development and design of a product have a strong impact on the costs and delivery times of a product. Hence, a digital system which supports the engineer during and afte...
Article
Full-text available
This paper examined the joining zone between semi-crystalline polyamide 6 and aluminum EN AW 6082 in laser-based joining and evaluated the mechanical properties of the joint. The joint tests were carried out in overlap configuration and a characterized in terms of energy per unit length. The mechanical properties were examined to the point of cohes...
Article
Es wird ein Einblick in die Vorgehensweise zur Fertigung von Knotenstrukturen im Stahlbau mittels Wire and Arc Additive Manufacturing (WAAM) und der numerischen und experimentellen Untersuchung der Knotenstrukturen gegeben. Ausgehend von der geometrischen Komplexität sich schneidender Profilstäbe aus Stahl werden wesentliche Punkte bei der simulati...
Article
A customized code using the free and fully open-source CFD software package OpenFOAM was developed to simulate a two-dimensional axisymmetric model of an inductively coupled plasma torch. To efficiently calculate the high-frequency magnetic fields generated by the inductive coil, a technique based on the vector potential formulation of Maxwell’s eq...
Article
Full-text available
The increasing demand for energy-efficient vehicles requires suitable methods for cost and weight reduction. This can be achieved by the replacement of copper by aluminum, in particular for the on-board power systems. However, the complete substitution is restricted by the mechanical and physical material properties of aluminum as well as challenge...
Article
Full-text available
The load increase method, which is highly efficient in rapidly identifying the fatigue performance and strength of materials, is used in this study to investigate friction stir welded (FSW) EN AW-5754 aluminum alloys. Previous investigations have demonstrated the accuracy and efficiency of this method compared to Woehler tests. In this study, it is...
Article
Full-text available
Heat conduction joining is mainly used in laser-based joining of metals with polymers but results in a large amount of dissipated heat. The consideration of thermal efficiency allows the determination of power actually used for creating the joint, which is highly relevant for technical and economic reasons, e.g., for calculating the carbon footprin...
Article
Full-text available
Glass ceramics are highly specialized composite materials, which have a partly polycrystalline and a partly glassy state. Due to their special properties such as good mechanical strength, low thermal expansion, and excellent thermal shock resistance, they are especially well known for their use in consumer goods industry. But also in the high-tech...
Article
Full-text available
Vanadium carbide (VC) reinforced FeCrVC hardfacings have become important to improve the lifetime of tools suffering abrasive and impact loads. This is because the microstructural properties of such hardfacings enable the primary VCs to act as obstacles against the penetrating abrasive. Because dilution is supposed to be the key issue influencing t...
Poster
The application of self-heating exothermal reactions based on free-standing reactive nano-multilayer foils allows it to join components under short heating durations as a result of extremely fast reaction times and therefore joining velocities. Within the DFG project “tailored heat release characteristics for reactive joining processes” – subprojec...
Conference Paper
Full-text available
Die Reparatur von Turbinenschaufeln erfolgt heutzutage vorzugsweise durch den Einsatz von manuellen Schweißverfahren. Dabei werden duktile Zusatzwerkstoffe eingesetzt, um die schweißtechnischen Herausforderungen der Heißrissbildung zu begrenzen, allerdings reichen diese nicht an die mechanisch-technologischen Eigenschaften der zu reparierenden Werk...
Article
Full-text available
In today's business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production systems as well as to choose the optimal product matches, product analys...
Conference Paper
Full-text available
Structure-borne acoustic emission (AE) measurement shows major advantages regarding quality assurance and process control in industrial applications. In this paper, laser beam welding of steel and aluminum was carried out under varying process parameters (welding speed, focal position) in order to provide data by means of structure-borne AE and sim...
Conference Paper
Full-text available
Laser-assisted metal-polymer joining gains importance in several applications due to the possibility of a direct connection between both materials. Aside from lightweight construction, a direct metal-polymer connection shows a high economic potential especially in large series production, e.g. domestic appliances. Based on this motivation, laser-as...
Conference Paper
Full-text available
Balancing processes require highly precise mass corrections especially in case of high-speed turning rotors. Material removal by means of cw-mode laser radiation represents a novel approach for industrial balancing applications in order to achieve sufficient removal rates. Thereby, spatter formation was identified as primary removal mechanism. In t...
Conference Paper
Full-text available
Joining of metallic material combinations with limited solubility is a challenging task. Because of low solubility, such material combinations lead to the formation of intermetallic compounds (IMC) during common weld bath. IMC then lead to increased hardness and brittleness. Generally, these properties are undesirable and the aim is to reduce inter...
Chapter
The paper concentrates on the external elimination of bottlenecks by using congruent shared capacities within a non-hierarchical organized network. The study assumes that the capacity of assembly can be adapted by increasing the resources of the company. Conversely, the capacity of production is restricted by technological requirements and regulate...