As part of the IGF projecttitled "High-Strength Aluminium Profile Components – Roll-Formed, ClosedProfiles Made of High-Strength Aluminium Alloys for Semifinishe and ComplexComponent Geometries," an efficient process strategy is being developedfor producing complex component geometries from high-strength, closed aluminiumprofiles using hydroforming. The profiles are manufactured through roll formingand high-frequency induction welding, offering the advantage of a continuousproduction process and improved cost efficiency compared to traditionalextrusion methods. The project's objective is to implement this process chainfor high-strength aluminium alloys in the 6000 and 7000 series and to assessthe formability of the profiles—including the weld seam and the heat-affectedzone, which undergo microstructural changes—using IHU.
Key scientific questionsconcern the formability and weldability of the alloys, the quality andmanufacturability of the weld seams, and the assessment of process-relatedmaterial properties through tube expansion testing. In addition toexperimentally investigating and optimizing individual process steps, theresults will be used to validate the simulation models of the entire processchain. An innovative aspect of the project involves managing input and outputparameters of the simulations via a centralized data platform. This platformenables statistical correlation and targeted optimization of processparameters, semi-finished product characteristics, and component quality. It isreferred to as a digital shadow, based on a simplified digital twin. Finally,the new process routes will be compared and evaluated against establishedmanufacturing methods from both economic and environmental perspectives,including the use of alloys with high recycled content. The goal is to supportresource-efficient and cost-effective production of high-strength,dimensionally stable lightweight profile components at scale.
Research projects
Expansion of the joinability and improvement of the joint properties in mechanical joning processes by tailor heat treated aluminum semi-finished parts
(Third Party Funds Single)
Term: 1. October 2025 - 30. September 2027
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The increasing demands on the automotive industry to reduce the vehicle weight and to increase crash safety at the same time require the extensive use of modern high-performance materials as well as the production of car bodies with a multi-material design. This results in new challenges for joining technologies. This applies in particular to the joining of dissimilar, high-strength materials. Against this background, within the first phase of the project, the focus was to extend the process limits for shear-clinching high-strength aluminum alloys of the 7000 series by means of a tailored short-term heat treatment. The localization of the heat treatment enables the targeted setting of strength gradients in the sheet and thus the influencing of the material flow in the joining process with the aim of improving the properties of the joints. Within the second phase, the findings are to be transferred to joining with auxiliary joining parts. For this purpose, the investigations will be carried out using semi-tubular self-piercing riveting as an example. Furthermore, the control of the cooling rate during the retrogression of precipitation-hardenable aluminum makes it possible to influence the aging behavior and thus the resulting mechanical properties of the alloys. This circumstance is to be used to achieve not only an improvement of the joint geometry by the local heat treatment, but also to influence the resulting application properties by the complete control of the local temperature-time curves. With the aid of numerical simulation, the interaction between the heat treatment layout and the resulting material flow in the semi-tubular punch riveting process is investigated. After cold and artificial aging of the specimens, the resulting application properties are determined by varying the heat treatment layout and the realized cooling rate. In particular, the focus is on the strength under cyclic loading and the susceptibility of the alloy to stress corrosion cracking. It is known from the literature that retrogression followed by re-aging has a beneficial effect on corrosion behavior. The influence of such a heat treatment on the application properties of mechanical joining points is therefore to be analyzed as part of the research project.
Roll-formed profiles of high-strength aluminum alloys for semifinished products and complex component geometries (High-strength Al profile components)
(Third Party Funds Single)
Term: 1. August 2025 - 31. July 2027
Acronym: 01|F23805N
Funding source: andere Förderorganisation
URL: https://www.lft.fau.de/rollgeformte-geschlossene-profile-aus-hochfesten-aluminiumlegierungen-fuer-halbzeuge-und-komplexe-bauteilgeometrien-hochfeste-al-profilbauteile/
As part of the IGF projecttitled "High-Strength Aluminium Profile Components – Roll-Formed, ClosedProfiles Made of High-Strength Aluminium Alloys for Semifinishe and ComplexComponent Geometries," an efficient process strategy is being developedfor producing complex component geometries from high-strength, closed aluminiumprofiles using hydroforming. The profiles are manufactured through roll formingand high-frequency induction welding, offering the advantage of a continuousproduction process and improved cost efficiency compared to traditionalextrusion methods. The project's objective is to implement this process chainfor high-strength aluminium alloys in the 6000 and 7000 series and to assessthe formability of the profiles—including the weld seam and the heat-affectedzone, which undergo microstructural changes—using IHU.
Key scientific questionsconcern the formability and weldability of the alloys, the quality andmanufacturability of the weld seams, and the assessment of process-relatedmaterial properties through tube expansion testing. In addition toexperimentally investigating and optimizing individual process steps, theresults will be used to validate the simulation models of the entire processchain. An innovative aspect of the project involves managing input and outputparameters of the simulations via a centralized data platform. This platformenables statistical correlation and targeted optimization of processparameters, semi-finished product characteristics, and component quality. It isreferred to as a digital shadow, based on a simplified digital twin. Finally,the new process routes will be compared and evaluated against establishedmanufacturing methods from both economic and environmental perspectives,including the use of alloys with high recycled content. The goal is to supportresource-efficient and cost-effective production of high-strength,dimensionally stable lightweight profile components at scale.
Prediction of tool fatigue in cold forging processes
(Third Party Funds Group – Sub project)
Project leader: Marion Merklein
Term: 1. April 2025 - 30. September 2027
Funding source: Bayerische Forschungsstiftung
Cold forging has been pioneering for more than 2000 years. In order toaddress current ecological and economic challenges and reduce CO2 emissions, technical components areprimarily produced using cold forging. This combines advantages such as theelimination of energy-intensive heat treatment and surface scaling. In order tomeet diverse requirements such as high load-bearing capacity and eco-friendlyproduction, the use of tools with complex internal geometries is necessary toenable the production of near-net-shape components. High contact pressures andtensile stresses due to high yield stresses lead to high loads on tools. Thiscan lead to fatigue failure, resulting in economic disadvantages that areassociated with an inhibition threshold for the use of efficient cold forgingprocesses.
The goal of the project partners is to develop concepts forextending tool life of cold forging tools. Using numerical simulation models,it is possible to analyse tool loads in detail. To achieve this objective,geometric and mechanical component properties are analysed and used as adatabase for tool stress. Integrated into a simulation model, this data is usedto determine the tool life. In order to validate the accuracy of thepredictions, the methods are transferred to industrial processes.
The calculation and subsequent extension of tool lifecontribute to more economical production of cold forged components and promotethe spread of eco-friendly manufacturing technologies in Bavaria as a businesslocation.
Forming tailored hybrid semi-finished products - Tailored Additive Blanks
(Third Party Funds Group – Sub project)
Project leader: Marion Merklein
Term: 1. October 2024 - 30. September 2027
Acronym: FORAnGen
Funding source: Bayerische Forschungsstiftung
The load-specific design of functional components is a promising way of responding to the increasing demands in terms of sustainability and resource efficiency. Tailored blanks have therefore become increasingly important in the field of sheet metal forming in recent years. The semi-finished product properties are customised to meet the final requirements. From an industrial perspective, it is of great interest to additionally increase the geometric flexibility and customisability of these tailored blanks by specifically combining forming technology methods with additive manufacturing. The technological advantages of the two processes complement each other perfectly and enable the efficient production of components with locally customised geometric and mechanical properties that clearly stand out from the state of the art. However, the interaction of the two processes under industry-related boundary conditions is still largely unknown.
The aim of TP 3 is therefore to develop a holistic understanding of the material-efficient production and forming of customised, hybrid semi-finished sheet metal products. The integration of the hybrid manufacturing approach into generative design enables a continuous, economical product development process, which also allows the reduced CO2 footprint of the technology to be quantified by recording the process data in advance.
Basic research and determination of process limitations in bulk forming processes of microgears from sheet metal - phase 2
(Third Party Funds Single)
Term: 1. July 2024 - 30. June 2026
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
There is a trend towards miniaturization of technical systems in numerous industries. This trend is characterized by minimizing geometric dimensions while increasing functionality and quality. These products include miniaturized drive systems with geared micro components, which have been used in a wide variety of industries for many years. Given the increasing demand for microgears, research into efficient manufacturing processes that enable economical and precise production of metal microgears is necessary. Cold solid forming processes offer technological, economic and ecological advantages compared to other manufacturing processes. However, at the current state of the art, the production of micro gears using cold solid forming processes for modules smaller than 0.2 mm is not possible due to high tool stress, size effects and handling problems.
Theobjective of the second project phase is the fundamental analysis of anextended process chain for the manufacturing of microgears with a module of0.1 mm. This includes the investigation of functional interactions ofsingle process steps as well as the forming-related properties on theapplication behavior of the microgears. Based on the findings of the firstproject phase with regard to the three-stage process chain, the process chainwill be extended in the second phase by an additional VFP stage and by theextrusion of a cup as a gear holder. The aim of the process extension by amulti-stage VFP is to identify effects and interactions between the influencingvariables punch diameter and penetration depth in order to analyze the effectson the material flow and the homogeneity of the deformation on the basis of theeffect mechanism determined in the first phase. The process understandinggained will subsequently be used to adjust required pin properties throughtargeted material flow control for subsequent forming of the gear holder, aswell as to reduce the process forces identified as critical in the first phase.Another sub-objective is to develop a substantial process understanding formulti-stage microforming process chains through the integration of cup formingas well as through the final separation from the sheet metal strip. For thispurpose, a suitable forming strategy for the integration of a cup extrusion isdeveloped and interactions between the forming stages are identified, resultingin a fundamental process knowledge. In addition, the forming possibilities ofthe process chain and the component spectrum will be significantly expanded. Afurther sub-objective is to evaluate the application behavior of the impactextruded microgears on the basis of the analysis of runnability in a practical laboratorytest on a gear test rig. Finally, functional relationships are determined andthe findings from both phases are evaluated to derive a process window anddevelop a detailed understanding of the process.
Analysis of the elastic-plastic material behavior of higher-strength steel materials under cyclic and swelling loading depending on the relaxation behavior
(Third Party Funds Single)
Term: 1. March 2024 - 28. February 2026
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The objective of the research project isto analyze the elastic-plastic material behavior under cyclic and discontinuousloading of high-strength steel materials. In addition to a pronouncedBauschinger effect, these materials exhibit nonlinear elastic material behaviorunder swelling loading. By modeling these properties and investigating theunderlying cause-effect relationships, the numerical prediction of sheet metalforming processes with high-strength steels will be improved. Both effects havea significant influence on the springback occurring after a forming process,but have so far only been taken into account independently of each other in asimulative design of components in basic scientific investigations.Metal-physical approaches exist to explain both effects, although research intothe interrelationship of the two characteristics is necessary for clearassignment. The analysis of a possible correlation of both mechanisms as wellas the influence of relaxation effects, i.e. a time-dependent stress behaviorunder constant load application, represent key aspects for improving theunderstanding of materials and thus the numerical description. The hypothesisof the project is that there is a systematic relationship between materialproperties, such as nonlinear elasticity, the Bauschinger effect and relaxationprocesses. In the first phase of the project, the mechanical behavior of thematerial is analyzed under cyclic and pulsating loads, with continuous anddiscontinuous load application, in order to investigate the functionalrelationships between the aforementioned effects in the subsequent workpackages. Here, the material-specific influence of the stress state, theanisotropy, the pre-strain as well as the load and unload phases will beinvestigated. In order to be able to determine the causes of identifiedinteractions, microstructural characterizations will also be carried out withthe aid of scanning electron microscopy and X-ray diffraction investigations.The evaluation of the results in work phase 2 with regard to the occurringmechanisms of action will improve the understanding of the material. Furthermore,mechanical parameters for the description of the Bauschinger effect and therelaxation behavior will be derived, which will provide new approaches forplastomechanical modeling. The subsequent significance evaluation of theeffects as well as the adaptation of existing material models should improvethe numerical prediction of the springback. Finally, the validity of thederived conclusions and modeling approaches will be verified in a near-processlaboratory test.
Data-based identification and prediction of the die surface condition and interactions in sheet bulk metal forming processes from coil
(Third Party Funds Group – Sub project)
Project leader: Marion Merklein
Term: 1. November 2023 - 31. October 2026
Funding source: DFG / Schwerpunktprogramm (SPP)
Notch Rolling and Cyclic Bending - Basic Investigations for the Production of Bulk Materials with a Low Aspect Ratio out of Strip Material
(Third Party Funds Single)
Term: 1. April 2020 - 31. March 2026
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Inorder to increase the productivity of the production process of steel wires,the process chain of notch rolling and cyclic bending is fundamentallyanalyzed. During notch rolling, notches are formed on both sides of a sheetmetal strip, in whose areas the material fatigues and forms cracks during thesubsequent fulling process. The numerical and experimental implementation ofboth process steps enables the identification of relevant influencingparameters and their interactions. Parameters taken into account are, amongothers, the notch radius, notch angle and web thickness in notch rolling, andthe bending angle and number of cycles to breakage or to the desired residualweb thickness in cyclic bending. Numerical and experimental studies of ductiledamage are required to evaluate material separation.
Mechanical joining without auxiliary elements
(Third Party Funds Group – Sub project)
Project leader: Dietmar Drummer, Marion Merklein
Term: 1. July 2019 - 30. June 2027
Acronym: TRR 285 C01
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: https://trr285.uni-paderborn.de/
The aim of this project is to conduct fundamental scientific research into joining without auxiliary element using metallic pin structures produced by forming technology, which are pressed into the joining partner or caulked after insertion into a perforated joining partner, and the joint properties that can be achieved with this. This includes the development of a fundamental understanding of the acting mechanisms with a focus on feasibility in phase 1, the optimisation of the pin structure with regard to geometry and arrangement as well as the joining process for the targeted adjustment of joining properties in phase 2 and the transferability of the technology to an extended range of applications in phase 3. The aim in phase 1 is therefore to develop a fundamental understanding of the extrusion of defined metallic pin geometries from the sheet plane using local material accumulation in order to be able to determine local changes in the material properties, such as strength. Simultaneously, different process control strategies for joining metal and FRP as well as different metals will be fundamentally researched and process windows will be derived.In the case of FRP, various process routes will be investigated with a focus on fibre-friendly injection of the pin structures or hole forming for caulking of the pin structures without delamination of the FRP. Ultrasound, vibration, infrared radiation or combinations of these methods are used to melt the matrix with the goal of identifying suitable process routes and generating an understanding of the mechanisms at work. Based on the findings of the pin manufacturing and the results regarding the joining processes, a fundamental understanding of the process will be developed, which will allow the further development of the pin geometry and the definition of suitable simple, regular pin arrangements and dimensions in the next step. In order to meet the different requirements of the pin manufacturing process and the joining method, the adaptability of the tool and joining technology is essential. Accordingly, the adaptation on the tool side and the specific process control during pin production will be investigated in order to demonstrate the possible variations. In addition, the adaptability of the joining operation will be achieved by adapting the process control, especially in the case of metal-FRP joints, in order to react to different conditions, such as the fibre layer and layer structure of the FRP. Finally, the direction-dependent joint properties and the application behaviour of the multi-material joints joined with the developed pin geometries will be characterised and evaluated depending on the pin dimensioning and arrangement in order to identify the decisive influencing factors on the joint properties.
Center for Nanoanalysis and Electron Microscopy
(FAU Funds)
Term: 1. January 2010 - 3. March 2038
Acronym: CENEM
The support of the core facility CENEM by the German Science Foundation (DFG) and the Cluster of Excellence EXC 315 “Engineering of Advanced Materials” is gratefully acknowledged.
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