@article{47535, abstract = {{Consistent lightweight construction in the area of vehicle manufacturing requires the increased use of multi-material combinations. This, in turn, requires an adaptation of standard joining techniques. In multi-material combinations, the importance of integral cast components, in particular, is increasing and poses additional technical challenges for the industry. One approach to solve these challenges is adaptable joining elements manufactured by a thermomechanical forming process. By applying an incremental and thermomechanical joining process, it is possible to react immediately and adapt the joining process inline to reduce the number of different joining elements. In the investigation described in this publication, cast plates made of the cast aluminium alloy EN AC-AlSi9 serve as joining partners, which are processed by sand casting. The joining process of hypoeutectic AlSi alloys is challenging as their brittle character leads to cracks in the joint during conventional mechanical joining. To solve this, the frictional heat of the novel joining process applied can provide a finer microstructure in the hypoeutectic AlSi9 cast alloy. In detail, its Si is finer-grained, resulting in higher ductility of the joint. This study reveals the thermomechanical joining suitability of a hypoeutectic cast aluminium alloy in combination with adaptively manufactured auxiliary joining elements.}}, author = {{Borgert, Thomas and Neuser, Moritz and Hoyer, Kay-Peter and Homberg, Werner and Schaper, Mirko}}, issn = {{2504-4494}}, journal = {{Journal of Manufacturing and Materials Processing}}, keywords = {{Industrial and Manufacturing Engineering, Mechanical Engineering, Mechanics of Materials}}, number = {{5}}, publisher = {{MDPI AG}}, title = {{{Thermomechanical Joining of Hypoeutectic Aluminium Cast Plates}}}, doi = {{10.3390/jmmp7050169}}, volume = {{7}}, year = {{2023}}, } @inproceedings{43031, abstract = {{Requirements of multi-material construction involve adjustments to standard joining techniques. Especially the growing importance of integral cast components poses additional engineering challenges for the industry. One approach to achieve these goals are adaptable joining elements formed by friction spinning. This approach uses friction-induced heat to form customisable joining elements to join sheets for different boundary conditions, even for brittle cast materials. It is possible to react immediately to adapt to the joining process inline and reduce the amount of different joining elements. As the joining partner serve casting plates of the aluminium casting alloy EN AC–AlSi9, which is processed in the sand casting. Joining hypoeutectic AlSi alloys constitutes a challenge because the brittle character of these cause cracks in the joint during conventional mechanical joining. Furthermore, the friction-induced heat of the novel joining process causes a finer microstructure in the hypoeutectic AlSi9 casting alloy. In particular, the eutectic Si is more fine-grained, resulting in higher joint ductility. This study indicates the joining suitability of a hypoeutectic aluminium casting alloy in combination with adaptive manufactured additional joining elements. Here, various mechanical and microstructural investigations validate the influence of the thermomechanical joining technique. In conclusion, the potential of this joining process is presented regarding the joinability of cast aluminium components.}}, author = {{Borgert, Thomas and Neuser, Moritz and Wiens, Eugen and Grydin, Olexandr and Homberg, Werner and Schaper, Mirko}}, booktitle = {{Materials Research Proceedings}}, issn = {{2474-395X}}, location = {{Nürnberg}}, pages = {{187--194}}, publisher = {{Materials Research Forum LLC}}, title = {{{Influence of thermo-mechanical joining process on the microstructure of a hypoeutectic aluminium cast alloy}}}, doi = {{10.21741/9781644902417-24}}, volume = {{25}}, year = {{2023}}, } @inproceedings{34001, author = {{Arian, Bahman and Homberg, Werner and Kersting, Lukas and Trächtler, Ansgar and Rozo Vasquez, Julian}}, booktitle = {{36. Aachener Stahlkolloquium – Umformtechnik “Ideen Form geben“}}, isbn = {{978-3-95886-460-3}}, pages = {{333--347}}, title = {{{Produktkennzeichnung durch lokal definierte Einstellung von ferromagnetischen Eigenschaften beim Drückwalzen von metastabilen Stahlwerkstoffen}}}, year = {{2022}}, } @inproceedings{34003, author = {{Arian, Bahman and Oesterwinter, Annika and Homberg, Werner and Rozo Vasquez, Julian and Walther, Frank and Kersting, Lukas and Trächtler, Ansgar}}, booktitle = {{19th Int. Conference on Metal Forming 2022}}, title = {{{A flow forming process model to predict workpiece properties in AISI 304L}}}, year = {{2022}}, } @article{34216, abstract = {{Mechanical joining technologies are increasingly used in multi-material lightweight constructions and offer opportunities to create versatile joining processes due to their low heat input, robustness to metallurgical incompatibilities and various process variants. They can be categorised into technologies which require an auxiliary joining element, or do not require an auxiliary joining element. A typical example for a mechanical joining process with auxiliary joining element is self-piercing riveting. A wide range of processes exist which are not requiring an auxiliary joining element. This allows both point-shaped (e.g., by clinching) and line-shaped (e.g., friction stir welding) joints to be produced. In order to achieve versatile processes, challenges exist in particular in the creation of intervention possibilities in the process and the understanding and handling of materials that are difficult to join, such as fiber reinforced plastics (FRP) or high-strength metals. In addition, predictive capability is required, which in particular requires accurate process simulation. Finally, the processes must be measured non-destructively in order to generate control variables in the process or to investigate the cause-effect relationship. This paper covers the state of the art in scientific research concerning mechanical joining and discusses future challenges on the way to versatile mechanical joining processes.}}, author = {{Meschut, Gerson and Merklein, M. and Brosius, A. and Drummer, D. and Fratini, L. and Füssel, U. and Gude, M. and Homberg, Werner and Martins, P.A.F. and Bobbert, Mathias and Lechner, M. and Kupfer, R. and Gröger, B. and Han, Daxin and Kalich, J. and Kappe, Fabian and Kleffel, T. and Köhler, D. and Kuball, C.-M. and Popp, J. and Römisch, D. and Troschitz, J. and Wischer, Christian and Wituschek, S. and Wolf, M.}}, issn = {{2666-3309}}, journal = {{Journal of Advanced Joining Processes}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}}, publisher = {{Elsevier BV}}, title = {{{Review on mechanical joining by plastic deformation}}}, doi = {{10.1016/j.jajp.2022.100113}}, volume = {{5}}, year = {{2022}}, } @article{32412, abstract = {{Friction-spinning as an innovative incremental forming process enables large degrees of deformation in the field of tube and sheet metal forming due to a self-induced heat generation in the forming zone. This paper presents a new tool and process design with a driven tool for the targeted adjustment of residual stress distributions in the friction-spinning process. Locally adapted residual stress depth distributions are intended to improve the functionality of the friction-spinning workpieces, e.g. by delaying failure or triggering it in a defined way. The new process designs with the driven tool and a subsequent flow-forming operation are investigated regarding the influence on the residual stress depth distributions compared to those of standard friction-spinning process. Residual stress depth distributions are measured with the incremental hole-drilling method. The workpieces (tubular part with a flange) are manufactured using heat-treatable 3.3206 (EN-AW 6060 T6) tubular profiles. It is shown that the residual stress depth distributions change significantly due to the new process designs, which offers new potentials for the targeted adjustment of residual stresses that serve to improve the workpiece properties.}}, author = {{Dahms, Frederik and Homberg, Werner}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, location = {{Braga, Portugal}}, pages = {{683--689}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Manufacture of Defined Residual Stress Distributions in the Friction-Spinning Process: Driven Tool and Subsequent Flow-Forming}}}, doi = {{10.4028/p-3rk19y}}, volume = {{926}}, year = {{2022}}, } @article{29357, abstract = {{Friction-spinning as an innovative incremental forming process enables high degrees of deformation in the field of tube and sheet metal forming due to self-induced heat generation in the forming area. The complex thermomechanical conditions generate non-uniform residual stress distributions. In order to specifically adjust these residual stress distributions, the influence of different process parameters on residual stress distributions in flanges formed by the friction-spinning of tubes is investigated using the design of experiments (DoE) method. The feed rate with an effect of −156 MPa/mm is the dominating control parameter for residual stress depth distribution in steel flange forming, whereas the rotation speed of the workpiece with an effect of 18 MPa/mm dominates the gradient of residual stress generation in the aluminium flange-forming process. A run-to-run predictive control system for the specific adjustment of residual stress distributions is proposed and validated. The predictive model provides an initial solution in the form of a parameter set, and the controlled feedback iteratively approaches the target value with new parameter sets recalculated on the basis of the deviation of the previous run. Residual stress measurements are carried out using the hole-drilling method and X-ray diffraction by the cosα-method.}}, author = {{Dahms, Frederik and Homberg, Werner}}, issn = {{2075-4701}}, journal = {{Metals}}, keywords = {{General Materials Science, Metals and Alloys}}, number = {{1}}, publisher = {{MDPI AG}}, title = {{{Manufacture of Defined Residual Stress Distributions in the Friction-Spinning Process: Investigations and Run-to-Run Predictive Control}}}, doi = {{10.3390/met12010158}}, volume = {{12}}, year = {{2022}}, } @article{34000, abstract = {{Abstract This paper presents the characterization of the microstructure evolution during flow forming of austenitic stainless steel AISI 304L. Due to plastic deformation of metastable austenitic steel, phase transformation from γ-austenite into α’-martensite occurs. This is initiated by the formation of shear bands as product of the external stresses. By means of coupled microscopic and micromagnetic investigations, a characterization of the microstructure was carried out. In particular, this study shows the distribution of the strain-induced α’-martensite and its influence on material properties like hardness at different depths. The microstructural analyses by means of electron backscattered diffraction (EBSD) technique, evidence a higher amount of α’-martensite (ca. 23 %) close to the outer specimen surface, where the plastic deformation and the direct contact with the forming tool take place. In the middle area (ca. 1.5 mm depth from the outer surface), the portion of transformed α’-martensite drops to 7 % and in the inner surface to 2 %. These results are well correlated with microhardness and micromagnetic measurements at different depths. EBSD and atomic force microscopy (AFM) were used to make a detailed characterization of the topography and degree of deformation of the shear bands. Likewise, the mechanisms of nucleation of α’-martensite were discussed. This research contributes to the development of micromagnetic sensors to monitor the evolution of properties during flow forming. This makes them more suitable for closed-loop property control, which offers possibilities for an application-oriented and more efficient production.}}, author = {{Rozo Vasquez, Julian and Kanagarajah, Hanigah and Arian, Bahman and Kersting, Lukas and Homberg, Werner and Trächtler, Ansgar and Walther, Frank}}, issn = {{2195-8599}}, journal = {{Practical Metallography}}, keywords = {{Metals and Alloys, Mechanics of Materials, Condensed Matter Physics, Electronic, Optical and Magnetic Materials}}, number = {{11}}, pages = {{660--675}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Coupled microscopic and micromagnetic depth-specific analysis of plastic deformation and phase transformation of metastable austenitic steel AISI 304L by flow forming}}}, doi = {{10.1515/pm-2022-0064}}, volume = {{59}}, year = {{2022}}, } @article{33999, abstract = {{The production of complex multi-functional, high-strength parts is becoming increasingly important in the industry. Especially with small batch size, the incremental flow forming processes can be advantageous. The production of parts with complex geometry and locally graded material properties currently depicts a great challenge in the flow forming process. At this point, the usage of closed-loop control for the shape and properties could be a feasible new solution. The overall aim in this project is to establish an intelligent closed-loop control system for the wall thickness as well as the α’-martensite content of AISI 304L-workpieces in a flow forming process. To reach this goal, a novel sensor concept for online measurements of the wall thickness reduction and the martensite content during forming process is proposed. It includes the setup of a modified flow forming machine and the integration of the sensor system in the machine control. Additionally, a simulation model for the flow forming process is presented which describes the forming process with regard to the plastic workpiece deformation, the induced α’-martensite fraction, and the sensor behavior. This model was used for designing a closed-loop process control of the wall thickness reduction that was subsequently realized at the real plant including online measured feedback from the sensor system.}}, author = {{Kersting, Lukas and Arian, Bahman and Vasquez, Julian Rozo and Trächtler, Ansgar and Homberg, Werner and Walther, Frank}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{862--874}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Innovative Online Measurement and Modelling Approach for Property-Controlled Flow Forming Processes}}}, doi = {{10.4028/p-yp2hj3}}, volume = {{926}}, year = {{2022}}, } @inproceedings{36563, author = {{Rozo Vasquez, Julian and Walther, Frank and Arian, Bahman and Homberg, Werner and Kersting, Lukas and Trächtler, Ansgar}}, booktitle = {{Proceedings of the 14th International Conference on Barkhausen Noise and Micromagnetic Testing}}, location = {{Stockholm}}, title = {{{Soft sensor concept for micromagnetic depth-specific analysis of phase transformation during flow forming of AISI 304L steel.}}}, year = {{2022}}, } @book{36412, author = {{Kersting, Lukas and Trächtler, Ansgar and Arian, Bahman and Homberg, Werner and Rozo Vasquez, Julian and Walther, Frank}}, isbn = {{978-3-948749-23-1 }}, publisher = {{Diedrich}}, title = {{{Echtzeitfähige Modellierung eines innovativen Drückwalzprozesses für die eigenschaftsgeregelte Herstellung gradierter Bauteile.}}}, year = {{2022}}, } @article{23469, abstract = {{The implementation of control systems in metal forming processes improves product quality and productivity. By controlling workpiece properties during the process, beneficial effects caused by forming can be exploited and integrated in the product design. The overall goal of this investigation is to produce tailored tubular parts with a defined locally graded microstructure by means of reverse flow forming. For this purpose, the proposed system aims to control both the desired geometry of the workpiece and additionally the formation of strain-induced α′-martensite content in the metastable austenitic stainless steel AISI 304 L. The paper introduces an overall control scheme, a geometry model for describing the process and changes in the dimensions of the workpiece, as well as a material model for the process-induced formation of martensite, providing equations based on empirical data. Moreover, measurement systems providing a closed feedback loop are presented, including a novel softsensor for in-situ measurements of the martensite content.}}, author = {{Riepold, Markus and Arian, Bahman and Vasquez, Julian Rozo and Homberg, Werner and Walther, Frank and Trächtler, Ansgar}}, issn = {{2666-9129}}, journal = {{Advances in Industrial and Manufacturing Engineering}}, title = {{{Model approaches for closed-loop property control for flow forming}}}, doi = {{10.1016/j.aime.2021.100057}}, year = {{2021}}, } @inproceedings{21477, author = {{Rostek, Tim and Makeieva, Hanna and Homberg, Werner}}, booktitle = {{Proceedings of the 13th International Conference on the Technology of Plasticity}}, editor = {{Daehn, G. and Cao, J. and Kinsey, B. and Tekkaya, A. E. and Vivek, A. and Yoshida, Y}}, isbn = {{978-3-030-75380-1}}, location = {{Columbus}}, pages = {{2115--2125}}, publisher = {{Springer, Cham}}, title = {{{Cutting Blades for Food Processing Applications Manufactured Using Innovative Spin Forming}}}, doi = {{10.1007/978-3-030-75381-8_178}}, year = {{2021}}, } @inbook{22766, author = {{Dahms, Frederik and Homberg, Werner}}, booktitle = {{Forming the Future}}, issn = {{2367-1181}}, location = {{Ohio, USA, VIRTUAL EVENT}}, pages = {{2249--2259}}, publisher = {{Springer, Cham}}, title = {{{Investigations and Improvements in 3D-DIC Optical Residual Stress Analysis—A New Temperature Compensation Method}}}, doi = {{10.1007/978-3-030-75381-8_189}}, year = {{2021}}, } @inproceedings{30297, author = {{Rozo Vasquez, Julian and Arian, Bahman and Riepold, Markus and Walther, Frank and Homberg, Werner and Trächtler, Ansgar}}, booktitle = {{Proceedings of the 11th International Work­shop NDT in Progress}}, location = {{Prague}}, title = {{{Magnetic Barkhausen noise analysis for microstructural effects separation during flow forming of metastable austenite 304L.}}}, year = {{2021}}, } @inproceedings{23465, abstract = {{One of the main objectives of production engineering is to reproducibly manufacture (complex) defect-free parts. To achieve this, it is necessary to employ an appropriate process or tool design. While this will generally prove successful, it cannot, however, offset stochastic defects with local variations in material properties. Closed-loop process control represents a promising approach for a solution in this context. The state of the art involves using this approach to control geometric parameters such as a length. So far, no research or applications have been conducted with closed-loop control for microstructure and product properties. In the project on which this paper is based, the local martensite content of parts is to be adjusted in a highly precise and reproducible manner. The forming process employed is a special, property-controlled flow-forming process. A model-based controller is thus to generate corresponding correction values for the tool-path geometry and tool-path velocity on the basis of online martensite content measurements. For the controller model, it is planned to use a special process or microstructure (correlation) model. The planned paper not only describes the experimental setup but also presents results of initial experimental investigations for subsequent use in the closed-loop control of α’-martensite content during flow-forming.}}, author = {{Arian, Bahman and Homberg, Werner and Riepold, Markus and Trächtler, Ansgar and Rozo Vasquez, Julian and Walther, Frank}}, isbn = {{978-2-87019-302-0}}, keywords = {{Flow-forming, Spinning, Process Strategy, Martensite Content, Property Control, Micromagnetic Measurement, Metastable Austenitic Stainless Steel}}, location = {{Liège, Belgium}}, publisher = {{ULiège Library}}, title = {{{Forming of metastable austenitic stainless steel tubes with axially graded martensite content by flow-forming}}}, year = {{2021}}, } @inbook{30296, author = {{Wiens, Eugen and Homberg, Werner and Arian, Bahman and Möhring, Kerstin and Walther, Frank}}, booktitle = {{Forming the Future}}, isbn = {{9783030753801}}, issn = {{2367-1181}}, location = {{Virtual Event}}, publisher = {{Springer International Publishing}}, title = {{{Forming of Parts with Locally Defined Mechanical and Ferromagnetic Properties by Flow-Forming}}}, doi = {{10.1007/978-3-030-75381-8_160}}, year = {{2021}}, } @article{26082, author = {{Wischer, Christian and Wiens, Eugen and Homberg, Werner}}, issn = {{2666-3309}}, journal = {{Journal of Advanced Joining Processes}}, publisher = {{Elsevier}}, title = {{{Joining with versatile joining elements formed by friction spinning}}}, doi = {{10.1016/j.jajp.2021.100060}}, volume = {{3}}, year = {{2021}}, } @proceedings{22453, editor = {{Wiens, Eugen and Wischer, Christian and Homberg, Werner}}, title = {{{Development of a novel adaptive joining technology employing Friction-Spun Joint Connectors (FSJC)}}}, doi = {{10.25518/esaform21.4682}}, year = {{2021}}, } @inproceedings{22965, author = {{Rozo Vasquez, Julian and Arian, Bahman and Riepold, Markus and Homberg, Werner and Trächtler, Ansgar and Walther, Frank}}, booktitle = {{ 54. Metallographie-Tagung}}, pages = {{75--81}}, title = {{{Microstructural investigation on phase transformation during flow forming of the metastable austenite AISI 304 }}}, year = {{2020}}, }