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Optical strain rate control in material characterization
(Third Party Funds Group – Overall project)
By improving the accuracy with which material behavior is represented in simulations, components and manufacturing processes can be designed more resourceefficiently. Thus, material characterization plays a central role in the implementation of new lightweight design strategies and the achievement of better vehicle crash behavior.
A fundamental knowledge of material behavior is necessary for the targeted forming of metallic materials. Characterization tests, such as the tensile test, are used to determine specific material parameters such as yield stress, tensile strength, uniform elongation and elongation at break. In addition, the elastic-plastic material behavior can be analyzed. Through the appropriate choice of a material model, this material behavior is mapped in a simulation. Formingsimulations represent the manufacturing process and are used for the design of tools and sheets and contribute to the safe and resource-saving design of parts.
Most metallic materials exhibit strain rate sensitivity. This means that the material behavior changes depending on the forming speed. In particular, quasi-static characterization tests carried out at low strain rates, which hardly ever occur in real forming processes, lead to deviations from the real material behavior. Thus, the consideration of the actual strain rate sensitivity leads to an improved material modeling and thus simulative representation of the material behavior.
The aim of the research project is therefore to develop, in cooperation with the project partners, a robust method for carrying out optically strain-rate-controlled tests and to analyze the influence on the prediction quality of simulations. This will reduce the difference between the nominally selected strain rate and the actual strain rate. By this method, more accurate material parameters are measured, which in turn enables an improved component and process design.
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Improvement of the application characteristics of multi-layered sheet material for forming technology produced via Accumulative Roll Bonding (continued)
(Third Party Funds Single)
Term: 1. February 2023 - 31. January 2025
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Accumulative roll bonding enablesstrenghtening of sheet materials accompanied by a reduction in ductilitythrough the formation of an ultrafine-grained microstructure. However, theformability and in particular the failure behavior of the multilayeredsemi-finished products is also dependent on the bond strength between theindividual layers. In the project, the cause-effect relationships between theprocess input parameters and the resulting interface properties areinvestigated. Based on a reproducible pretreatment, correlations betweensurface, bonding and forming properties are analyzed with the aim of improvingthe formability of accumulatively rolled aluminum products by suitable processmeasures.
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FE-based springback prediction of sheet metal forming processes from lightweight materials considering anisotropic hardening (continued)
(Third Party Funds Single)
Term: 1. February 2023 - 31. January 2025
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The overall objective in the second project phase is to improve thenumerical design of deep drawing processes at elevated temperatures as afunction of the strain rate. According to previous investigations, aluminiumalloys of the 7000 series show both a tensile-compression asymmetric andstrain-rate sensitive material behaviour. These aspects influence not only thetemperature but also the hardening and springback behaviour. For this reason, aphenomenological material model is being developed, taking into account theanisotropic hardening as a function of the temperature and the strain rate, inorder to be able to numerically represent the specific material behaviour ofhigh-strength aluminium alloys. Based on the results from the first projectphase, it is only possible to a limited extent to investigate the stress-statedependent forming behaviour of AA7020-T6 and AA7075-T6 at temperatures above100 °C with the given test setups. It is therefore necessary to modify the testsetups in order to investigate the material behaviour in a temperature rangerelevant for 7000 aluminium alloys. Using this analysis, the material model tobe developed in the first phase will be extended by one term as a function ofstrain rate and temperature. By modelling the anisotropic hardening behaviourin correlation to the forming rate and forming temperature an improvedrepresentation of the material behaviour is given. In order to validate thematerial model, deep-drawing tests with a circular cup at elevated temperaturesand different forming speeds are performed. The validation is based on thesheet thinning and the force-displacement curve during the deep drawingprocess. In addition, the springback behaviour with open cross profiles andopen T-profiles are to be determined. Since the friction between tool andworkpiece influences the deep drawing process, the corresponding frictioncoefficients are determined in the strip drawing test. Thus, after successfulvalidation of the material model as a function of the forming speed andtemperature, the numerical mapping accuracy and prediction quality of warm andhot forming processes can be improved with regard to the springback behaviour.As a result, process design time is saved, because expensive experimentaliteration loops are avoided.
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Experimental investigation and modeling of heat transfer during hot stamping
(Third Party Funds Single)
Term: 1. January 2023 - 31. December 2024
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The hotstamping process has been established as a manufacturing process for theproduction of ultra-high-strength components. The process is based on amartensite transformation when quenching rates exceed a theoretical value of 27K/s. Investigations have already shown that the process-side parameters cansignificantly influence the critical cooling rate and thus the resultingmicrostructure formation. The goal of the research project is to develop afundamental understanding of the heat transfer mechanisms involved in hotstamping and the dominant influencing variables in order to derive a physicallybased model. This is the basic prerequisite for the precise representation ofall relevant sub-processes in hot stamping and will enable the transfer andapplication of simulation models and results to thermally assisted material processingmethods in the future.
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Manufacturing of helical-toothed functional components from sheet metal by developing and analyzing a forming process of sheet bulk metal forming
(Third Party Funds Single)
Term: 1. January 2023 - 31. December 2024
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The overarching objective is to determine the basiccausal relationships between component and process parameters and to derivecausalities in the manufacture of helical components using sheet metal forming.The process-specific challenges, a robust process window and the process limitsare to be worked out for a process chain consisting of deep drawing, extrusionand upsetting. In order to enable the industrial use of sheet metal forming forthe production of helical components in the medium term, the process must befundamentally researched and a continuous understanding of the process must begenerated from process design to the production of ready-to-use components. Inthe present project, a parameter-dependent process window with the achievablecomponent properties is to be derived on the basis of an extensive processanalysis. Furthermore, the extension of the component functionality that can berealized by forming helical gears with different modules and helix angles onsemi-finished sheet metal products by sheet metal forming is fundamentallyinvestigated. A two-stage process chain consisting of deep-drawing/extrusionand upsetting is used as part of the investigations. With the help of anumerical process model, a comprehensive process analysis is carried out andbasic causal relationships between the influencing parameters are determined.Based on these findings, the design of the reference process and theexperimental implementation are carried out. The simulation model is validatedusing process and component-specific parameters such as process force, geometryand hardness distribution. Parameter-dependent process limits are identifiedthrough the detailed investigation of the influence of the gear geometry andthe materials used on the resulting component properties and the tool stress.At the end of the first funding period, a number of sub-goals are being aimedfor. Process-specific challenges with regard to the flow paths that can beachieved and the resulting mold filling are identified. In addition, ananalysis of the influence of the material flow specific to helical gears on thecomponent properties relevant to use, such as strain hardening and gearquality, is to be carried out. Finally, an adapted process control to avoidsubsequent machining is developed
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Metamodel-based consideration of the process chain in the mechanical joining of sheet metal components
(Third Party Funds Single)
Term: 1. June 2022 - 31. May 2024
Funding source: AIF Arbeitsgemeinschaft industrieller Forschungsvereinigungen
Chargen-und Prozessschwankungen führen bei der Herstellung von Blechbauteilen zuAbweichungen der resultierenden Bauteileigenschaften, was nachfolgendeProzessschritte beeinflusst. Die Nutzung von mittels einer Prozessüberwachungakquirierten Daten bietet die Möglichkeit, Fertigungsprozesse in Abhängigkeitvariierender Randbedingungen anzupassen und dadurch eine konstanteBauteilqualität sicherzustellen. Voraussetzung hierfür ist die Kenntnis überprozesskettenübergreifende Zusammenhänge.
Indiesem Projekt wird die datenbasierte Prozessadaption anhand einer Prozesskettebestehend aus den Schritten Umformen, Spannen und Fügen untersucht. Ziel desForschungsvorhabens ist es, die gesamte Prozesskette mit Metamodellenabzubilden, welche mithilfe von automatisiertem maschinellem Lernen abgeleitetwerden. Dies soll die Prognose der Bauteilqualität sowie die inverse Anpassungder Teilprozessparameter zum Ausgleich von Chargen- und Prozessschwankungenermöglichen. Der Fokus am LFT liegt auf der umformtechnischenBauteilherstellung mittels Tiefziehen. Die nachfolgenden ProzessschritteSpannen und Fügen werden am Fraunhofer-Institut für Großstrukturen in derProduktionstechnik (Fh-IGP) in Rostock respektive am Laboratorium fürWerkstoff- und Fügetechnik (LWF) der Universität Paderborn untersucht.
Ausgehendvon der Definition der Modellanforderungen folgt die Datengenerierung für dieMetamodellierung durch die Korrelation der Prozessdaten undHalbzeugeigenschaften mit den resultierenden Bauteileigenschaften. Die Prognoseder Bauteileigenschaften nach dem Tiefziehen sowie die Modellierung derprozesskettenübergreifenden Zusammenhänge gestattet die Adaption derProzessparameter beim nachfolgenden Spannen und Fügen. Die Abbildung der Prozesskettedurch Metamodelle ermöglicht zudem die inverse Auslegung der Prozesskette durchdie Definition der Anforderungen an den Fügepunkt. Grundlage für die Vernetzungder Teilprozesse ist die Definition geeigneter Schnittstellen zur Realisierungdes prozessübergreifenden Datenaustauschs.
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Failure analysis under plane strain
(Third Party Funds Single)
Term: 1. April 2022 - 31. March 2024
Funding source: Bundesministerium für Wirtschaft und Klimaschutz (BMWK)
The challenge of this research project is the exact design of products made of sheet metal materials. In common practice, components manufactured in this way are nowadays designed by means of numerical simulations. This type of design is significantly influenced by the quality of the input parameters, such as the characteristic values from the material characterization. The assumption of wrong input parameters can predict a component failure too late or a component failure too early. For this very reason, large safety factors are often included in practical applications, leading to a conservative design with only moderate utilization of the material's limits. However, an improvement in the utilization of the material's potential is significantly influenced by an exact material characterization. In particular, the area of plane strain, which is often the cause of failure in deep-drawing or stretch-forming components, must be investigated and improved. Conventional characterization tests under plane strain can show nonlinearities in the strain path or are friction-induced or strongly affected by assumptions due to their test setup. Thus, the objective of this research project is to improve the characterization under plane strain for an improved failure prediction in order to shift the process limits to higher forming ratios and higher achievable drawing depths. The conventional characterization of forming limit change is to be improved to better predict failure under plane strain in order to increase the quality of input parameters for component design.
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Improvement of the geometrical accuracy of parts by material flow-optimized coil layouts when extruding functional components
(Third Party Funds Single)
Term: 1. April 2022 - 31. March 2024
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
For the production of functionally integratedcomponents made of sheet metal materials, the processes of Sheet-Bulk MetalForming are suitable, which enable the production of planar components withlocal functional elements. Limitations in the diefilling of the functional elements and high die loads are a result of thedemanding forming and process conditions that occur within these processes. When transferring this process class to efficientproduction from coil, previous investigations also identified anisotropicmaterial flow and anisotropic die loads as relevant process influences whencarrying out extrusion processes from sheet coils.
Based on this, theinfluence of the component design on a multi-stage extrusion process from coilwill be analyzed numerically and experimentally within the scope of thisresearch project. In the first step,cause-effect relationships are to be investigated with regard to the local diefilling of the functional elements and the local die load when the blank andcoil geometry is varied. Furthermore, usingthese findings, the potential for controlling the material flow and thusimproving die filling by adapting the possible stage sequences is to bederived.
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Close-to-series design of modified tool surfaces for low-lubrication deep drawing
(Third Party Funds Group – Sub project)
Overall project: Seriennahe Auslegung modifizierter Werkzeugoberflächen für das schmierstoffreduzierte Tiefziehen
Term: 1. March 2022 - 29. February 2024
Funding source: Bundesministerium für Wirtschaft und Klimaschutz (BMWK)
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Qualification of a fatigue test for the investigation of the behavior of high-strength tool materials under realistic conditions by elastomer compression
(Third Party Funds Single)
Term: 1. January 2022 - 31. December 2023
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Tools and tool failure have major influence on the economic efficiencyof cold forging processes. In order to minimize losses due to machinedowntimes, it is necessary to accurately predict the service life. A challengein the prediction of tool life is that there is little data on the fatiguebehaviour of the used high strength steel materials. In addition, the qualityof the available data is limited, as it does not reflect the multi-axial stressconditions of cold forging. The objective of the research project is thereforeto investigate a new fatigue test, which can realistically model the stressstate occurring in cold forming tools considering both the multi-axiality andthe application of compressive prestresses. For this purpose, an elastomer madeof polyurethane is used as a pressure medium in a tool for fatigue testing. Acyclic hydrostatic pressure is applied by the repeated compression of theelastomer. The comparability of the tool stresses to the forming of steel isensured by analyzing the stresses both numerically and experimentally. Achallenge in the experimental concept is wear on the elastomer specimen, whichis to be minimized by adapting the test parameters. In order to illustraterealistic load cases, the transferability of the test results to systems underpreload is demonstrated. In a combined numerical-experimental approach, bothconventional reinforcements and new concepts for local prestressing will beinvestigated. This enables the identification of cause effect relationshipsbetween the stresses and strains caused by the reinforcement and the servicelife of the tools under realistic loads. Finally, the obtained results will beused to evaluate the potential of the test and the benefit compared toconventional fatigue tests.
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Use of versatile joining processes for the production of hybrid component structures in an industrial environment
(Third Party Funds Group – Sub project)
Overall project: Method development for mechanical joinability in versatile process chains
Term: 1. January 2022 - 31. December 2024
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
The subject of the transfer project is the analysis and transferability of the methodology of the transformability of a wobbling semi-hollow punch riveting process from sub-project C02 "Adaptable joining with auxiliary joining part" under industrial boundary conditions and an extension in the Transregio 285 collaborative research center (SFB/TRR285) "Method development for mechanical joinability in versatile process chains". through targeted adjustment of relevant process parameters. The central goal of the research project is the transfer of basic scientific findings for the targeted production of geometric characteristics of joints such as undercuts in wobbling semi-tubular punch riveting to the new approach of joining by tumbling.
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Manufacturing of tailored aluminum parts by controlling the local cooling rates in a combined forming, quenching and hardening process (Tailor Quenched Forming)
(Third Party Funds Single)
Term: 1. January 2022 - 30. September 2023
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
A common method for increasing passenger safety invehicles is the use of high strength materials for structural safety-relevantparts. Due to the targeted adjustment of the mechanical properties, tailoredcomponents can be manufactured with locally adapted component strengths. Incase of a crash, they have the ability to absorb or transfer the occurringenergy to other regions of the vehicle. It is relevant that these componentscombine high-strength as well as ductile regions. Until now these componentsare only produced by modified press hardening operations of steel components.In association with the light-weight concept, a new opportunity to realizetailored components is the use of adapted, high-strength, hardenable aluminumcomponents. During the forming process, the properties of previously solution-annealedcomponents can be adjusted by simultaneous quenching and forming operations.The key influencing factor in quenching and forming operations is the coolingrate. In future, it will be possible to produce property-adapted structuralcomponents using high-strength aluminum alloys with the help of different localtool temperatures. Thermally coupled material models are necessary for thesimulation of this forming process.
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Fundamental investigations on the production of functional components from coil
(Third Party Funds Single)
Term: 1. January 2022 - 31. December 2023
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The applicationof bulk forming processes to sheet metal, also known as sheet-bulk metalforming, extends the existing forming limits of established sheet and bulkforming processes. This enables the resource-efficient production offunctionally integrated lightweight components. In previous research, sheet-bulkmetal forming of pre-cut blanks was investigated. By using coil assemi-finished products, the advantages of manufacturing from coil in terms ofsimplified component handling and as a result higher output quantity arecombined with the advantages of sheet-bulk metal forming in terms of extendedforming limits.
The usage ofcoils, however, results in an anisotropic material flow and consequently an unequalshape of the formed components. This worsens the component application behaviorand is especially a challenge for cyclically symmetrical parts. In additionasymmetrical tool loads, critical for fatigue, occur. Considering this, theobjective is to elaborate a process understanding for extrusion of gears fromcoil. It should be investigated how the anisotropic material flow affects the formingof the individual functional elements of cyclically symmetrical components andthe tool loads.
In order to increasethe application potential of extrusion of gears from coil, another objective isto provide measures to reduce the anisotropic material flow and to improve thegeometrical accuracy of formed parts. For this purpose, different approaches formaterial flow control, such as adjusting the coil width, feed width, toolgeometry and local adaptation of friction should be analyzed for cyclicallysymmetrical parts. In addition to the effectiveness, the wear-behavior of the measureshas to be investigated in tool life tests.
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In-situ characterization of a locally carburized complex phase steel for manufacturing of tailored semi-finished products
(Third Party Funds Single)
Term: 1. October 2021 - 30. September 2024
Funding source: Deutsche Forschungsgemeinschaft (DFG)
Local carburization of semi-finished sheet material is a process variant to manufacture hot stamped parts with tailored properties. In this research project, the process combination of local carburization and hot stamping shall be qualified for carburization temperatures above 950 °C to reduce the required process time. The dependence of the mechanical properties and resulting microstructure on the process-relevant influencing factors will be determined by means of in-situ characterizations. Furthermore, the accuracy of the numerical simulation will be improved by extending existing material models. The material models will then be validated by additional experiments and the findings will be verified by application to a demonstrator geometry.
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Reduction of local tool stresses in cold forging tools
(Third Party Funds Single)
Term: 1. July 2021 - 31. December 2023
Funding source: Bayerische Forschungsstiftung
Part geometry is a major influence on the formation of local stress in cold forging tools. Non-constant asymmetrical cross-sections result in axial and tangential stress concentrations. This challenge can be seen in the processes of the industrial partners, where fatigue failure occurs in local elements. In order to counteract fatigue and improve process economics, the formation of local tool stresses is to be analysed using a model process. Using the process the influence of functional elements and changes in cross-section on the stress state of the die is researched. With an understanding of the mechanisms of the stress formation, adapted tool concepts will be developed, which enable a suitable improvement of the stress state depending on the part and tool geometry. To evaluate the effectiveness of the new tool designs, they will be implemented in the processes of the industrial partners. That way, the effect on tool life can be analysed for different die materials. These are usually cold working steels or cemented carbides, which react very sensibly to tensile stresses. Finally, the new tool concepts will be evaluated using the developed process understanding and the experimental results regarding the tool life.
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Development of a forming process to manufacture near-net-shape functional components with a gradient in sheet thickness
(Third Party Funds Group – Sub project)
Overall project: Manufacturing of complex functional components with variants by using a new sheet metal forming process - Sheet-Bulk Metal Forming
Term: 1. January 2021 - 30. September 2023
Funding source: Deutsche Forschungsgemeinschaft (DFG)
Within the TCRC, the process of orbital forming was investigated fundamentally and the technolog-ical potential was shown. The process understanding referring to the possibility of controlled material flow forms the basis for the present transfer project. A high complexity as well as a long process dura-tion are unsolved challenges today. The system specific dependency of a tumbling plate results in an additional restriction of a maximum tumbling angle of Θmax = 1°, which severely limits the forming ca-pacity.The aim of the submitted transfer project is the substitution of the conventional orbital forming process by an iterative combination of tilting and turning. The overall objective is to extend the process limits known from fundamental research by using an adapted process. On the one hand, the essential find-ings of fundamental research regarding the control of the material flow should be applied. On the other hand, the formability and efficiency of the process should be improved. A basic advantage of the new process is the ability to use a conventional press, thus significantly reducing the process time and removing the restriction of a maximum tumbling angle of Θmax = 1°. An increase of the tumbling angle offers the potential of a reduced contact area, realizing an increased forming capacity.Challenges of the innovative manufacturing process can be derived from the modified process charac-teristics and forming kinematics. Besides the analysis of the tilting process, the number of forming steps required to achieve the desired form filling should be evaluated. In addition, the maximum tilt angle and the resulting influence on the functional components must be evaluated. In order to in-crease the load capacity, the hardening behaviour of strongly hardened high performance steels dur-ing the forming process should be analysed to verify the omission of a subsequent hardening process. The target parameters should be optimized by an investigation and application of comprehensive pro-cess strategies.The process characteristics to be investigated can be reproduced by using the current orbital forming process setup, allowing the characteristic tilting kinematic. Thus, the new process can be investigated fundamentally and at the same time, the effort for the production of the new tool concept can be pre-vented. Therefore, the development of a suitable method to ensure the applicability is required. Due to the expected change of the material flow components caused by the modified process kinematics, a material flow control is essential. A numerical simulation is used for the analysis of the material flow. The influence of the process parameters on the actual process should be investigated by evaluating reference parts produced with the adapted process. Due to the mentioned disadvantages of the cur-rent orbital forming process setup, the results of the adapted process transferred to a flexible tool con-cept for the use on a conventional press.
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Resource-minimized production through hybrid and highly networked processes
(Third Party Funds Single)
Term: 1. November 2020 - 31. October 2023
Funding source: Bundesministerium für Wirtschaft und Technologie (BMWi)
Consistent lightweight construction realized through high-performance and resource-efficient manufacturing processes represents a key technology for securing long-term competitiveness of the German industry while simultaneously reducing CO2 emissions. By combining individual production technologies new opportunities are created, allowing the overcoming of limits that are currently set by conventional processes. HyConnect aims to combine forming technology with additive manufacturing in order to enhance the advantages of both process classes and to replace previous energy-intensive manufacturing methods (see Figure). In addition, digital solutions for a cross-company exchange and analysis of production data are being implemented, researched and evaluated. These are necessary to realize both the before described technical as well as environmentally added values and ensure that the safety requirements of the participating companies are met.
Within this project, the aim is to expand the existing fundamental knowledge of hybrid component manufacturing by combining laser metal deposition (LMD) and deep drawing. Interactions between the individual processes as well as influences resulting from the production sequence stand in the foreground of upcoming investigations. With the support of the below listed project partners, an exemplary bearing sleeve is planned to be manufactured with reduced material resources and CO2 emissions.
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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 - 30. September 2024
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.
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Investigation of residual stress related elementary processes in cold forged components in the manufacturing and operating phase
(Third Party Funds Single)
Term: 1. January 2018 - 31. March 2024
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The operational behavior of steel components is significantly influenced by their residual stress state. On the basis of forward rod extrusion of stainless steel, methods for the controlled generation of residual stresses are being investigated, their stability under typical operating conditions is being analyzed and their effects on the operating behavior are being identified in this research project. In the first phase, basic mechanisms of the generation of residual stresses were identified. In the current second phase, parameters for a robust adjustment of the residual stress state during forming were developed, whereby lubrication in particular was identified as relevant. Furthermore, the influence of thermal and mechanical loads on the stability of the residual stresses in the components is being investigated.
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Forming and joining of semitubular self-piercing rivets made of high-strength steel with adapted mechanical properties and numerical analysis of the process chain
(Third Party Funds Single)
Term: 1. January 2018 - 30. November 2024
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Joining is an important method of productionengineering, for which reason the efficiency of such manufacturing processes ishighly relevant. Self-piercing riveting is a mechanical joining process, usinga rivet as fastener to join two or more sheets. This makes it possible to joindissimilar materials and to realize multi-material design. However, the rivetproduction is a time-consuming process, including the steps hardening andcoating in order to achieve an adequate strength and a high ductility as wellas corrosion resistance. The use of high strain hardening materials as rivetmaterials, such as high nitrogen steels, shows a huge potential concerning thereduction of production steps and thus a shortening of the rivet manufactureprocess chain since the conventional hardening, tempering and coating steps afterforming are not necessary anymore. However, the challenging high tool loadsduring cold bulk forming of high nitrogen steels represent a major challengefor the manufacturing process.
The objective is to investigate fundamentalinfluencing factors on the forming process for manufacturing rivets using highstrain hardening materials, the resulting rivet properties, the joining processand the achievable joint properties. The LFT is working on this project incollaboration with the Laboratory for material and joining technology (LWF) at Paderborn University. At the LFT, the projectfocus is on the development of the forming tools and appropriate formingstrategies in order to realise the forming process despite the high tool loads.In this context, fundamental correlations between the forming temperature, theachievable die filling during forming and the mechanical properties of theformed rivets are investigated. By choosing a suitable forming strategy and rivetgeometry, the mechanical properties of the rivets are to be adapted accordingto the requirements of the joining process.
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Center for Nanoanalysis and Electron Microscopy
(FAU Funds)
Term: 1. January 2010 - 3. March 2038
The Center for Nanoanalysis and Electron Microscopy (CENEM) is a facility featuring cutting-edge instrumentation, techniques and expertise required for microscopic and analytical characterization of materials and devices down to the atomic scale. CENEM focuses on several complementary analysis techniques, which closely work together: Electron Microscopy, X-ray Microscopy, Cryo-TEM, Scattering Methods, Scanning Probes and Atom Probe Microscopy. With the combination of these methods new materials, particles, structures and devices are characterized not only microscopically and analytically on all length scales even down to the atomic scale but also by various in situ investigations and 3D methods. The knowledge gained through the versatile characterization methods is then used to further develop and improve materials and devices.
CENEM was established in 2010 to provide a forefront research center for the versatile characterization of materials and devices with state-of-the-art instrumentation and expertise and to intensify the interdisciplinary research. The big CENEM network represents the strong collaborations within the University of Erlangen-Nürnberg as well as the collaboration with other universities, dedicated research institutes and industry.
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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TRR 73: Manufacturing of complex functional components with variants by using a new sheet metal forming process - Sheet-Bulk Metal Forming
(Third Party Funds Group – Overall project)
Term: 1. January 2009 - 28. February 2024
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: http://www.tr-73.de
Research projects
Current projects
Optical strain rate control in material characterization
(Third Party Funds Group – Overall project)
Term: 1. February 2023 - 31. January 2025
Funding source: Bayerische Forschungsstiftung
URL: https://forschungsstiftung.de/Projekte/Details/Optische-Dehnratenregelung-in-der-Werkstoffcharakterisierung.html
A fundamental knowledge of material behavior is necessary for the targeted forming of metallic materials. Characterization tests, such as the tensile test, are used to determine specific material parameters such as yield stress, tensile strength, uniform elongation and elongation at break. In addition, the elastic-plastic material behavior can be analyzed. Through the appropriate choice of a material model, this material behavior is mapped in a simulation. Formingsimulations represent the manufacturing process and are used for the design of tools and sheets and contribute to the safe and resource-saving design of parts.
Most metallic materials exhibit strain rate sensitivity. This means that the material behavior changes depending on the forming speed. In particular, quasi-static characterization tests carried out at low strain rates, which hardly ever occur in real forming processes, lead to deviations from the real material behavior. Thus, the consideration of the actual strain rate sensitivity leads to an improved material modeling and thus simulative representation of the material behavior.
The aim of the research project is therefore to develop, in cooperation with the project partners, a robust method for carrying out optically strain-rate-controlled tests and to analyze the influence on the prediction quality of simulations. This will reduce the difference between the nominally selected strain rate and the actual strain rate. By this method, more accurate material parameters are measured, which in turn enables an improved component and process design.
Improvement of the application characteristics of multi-layered sheet material for forming technology produced via Accumulative Roll Bonding (continued)
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Accumulative roll bonding enablesstrenghtening of sheet materials accompanied by a reduction in ductilitythrough the formation of an ultrafine-grained microstructure. However, theformability and in particular the failure behavior of the multilayeredsemi-finished products is also dependent on the bond strength between theindividual layers. In the project, the cause-effect relationships between theprocess input parameters and the resulting interface properties areinvestigated. Based on a reproducible pretreatment, correlations betweensurface, bonding and forming properties are analyzed with the aim of improvingthe formability of accumulatively rolled aluminum products by suitable processmeasures.
FE-based springback prediction of sheet metal forming processes from lightweight materials considering anisotropic hardening (continued)
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The overall objective in the second project phase is to improve thenumerical design of deep drawing processes at elevated temperatures as afunction of the strain rate. According to previous investigations, aluminiumalloys of the 7000 series show both a tensile-compression asymmetric andstrain-rate sensitive material behaviour. These aspects influence not only thetemperature but also the hardening and springback behaviour. For this reason, aphenomenological material model is being developed, taking into account theanisotropic hardening as a function of the temperature and the strain rate, inorder to be able to numerically represent the specific material behaviour ofhigh-strength aluminium alloys. Based on the results from the first projectphase, it is only possible to a limited extent to investigate the stress-statedependent forming behaviour of AA7020-T6 and AA7075-T6 at temperatures above100 °C with the given test setups. It is therefore necessary to modify the testsetups in order to investigate the material behaviour in a temperature rangerelevant for 7000 aluminium alloys. Using this analysis, the material model tobe developed in the first phase will be extended by one term as a function ofstrain rate and temperature. By modelling the anisotropic hardening behaviourin correlation to the forming rate and forming temperature an improvedrepresentation of the material behaviour is given. In order to validate thematerial model, deep-drawing tests with a circular cup at elevated temperaturesand different forming speeds are performed. The validation is based on thesheet thinning and the force-displacement curve during the deep drawingprocess. In addition, the springback behaviour with open cross profiles andopen T-profiles are to be determined. Since the friction between tool andworkpiece influences the deep drawing process, the corresponding frictioncoefficients are determined in the strip drawing test. Thus, after successfulvalidation of the material model as a function of the forming speed andtemperature, the numerical mapping accuracy and prediction quality of warm andhot forming processes can be improved with regard to the springback behaviour.As a result, process design time is saved, because expensive experimentaliteration loops are avoided.
Experimental investigation and modeling of heat transfer during hot stamping
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The hotstamping process has been established as a manufacturing process for theproduction of ultra-high-strength components. The process is based on amartensite transformation when quenching rates exceed a theoretical value of 27K/s. Investigations have already shown that the process-side parameters cansignificantly influence the critical cooling rate and thus the resultingmicrostructure formation. The goal of the research project is to develop afundamental understanding of the heat transfer mechanisms involved in hotstamping and the dominant influencing variables in order to derive a physicallybased model. This is the basic prerequisite for the precise representation ofall relevant sub-processes in hot stamping and will enable the transfer andapplication of simulation models and results to thermally assisted material processingmethods in the future.
Manufacturing of helical-toothed functional components from sheet metal by developing and analyzing a forming process of sheet bulk metal forming
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The overarching objective is to determine the basiccausal relationships between component and process parameters and to derivecausalities in the manufacture of helical components using sheet metal forming.The process-specific challenges, a robust process window and the process limitsare to be worked out for a process chain consisting of deep drawing, extrusionand upsetting. In order to enable the industrial use of sheet metal forming forthe production of helical components in the medium term, the process must befundamentally researched and a continuous understanding of the process must begenerated from process design to the production of ready-to-use components. Inthe present project, a parameter-dependent process window with the achievablecomponent properties is to be derived on the basis of an extensive processanalysis. Furthermore, the extension of the component functionality that can berealized by forming helical gears with different modules and helix angles onsemi-finished sheet metal products by sheet metal forming is fundamentallyinvestigated. A two-stage process chain consisting of deep-drawing/extrusionand upsetting is used as part of the investigations. With the help of anumerical process model, a comprehensive process analysis is carried out andbasic causal relationships between the influencing parameters are determined.Based on these findings, the design of the reference process and theexperimental implementation are carried out. The simulation model is validatedusing process and component-specific parameters such as process force, geometryand hardness distribution. Parameter-dependent process limits are identifiedthrough the detailed investigation of the influence of the gear geometry andthe materials used on the resulting component properties and the tool stress.At the end of the first funding period, a number of sub-goals are being aimedfor. Process-specific challenges with regard to the flow paths that can beachieved and the resulting mold filling are identified. In addition, ananalysis of the influence of the material flow specific to helical gears on thecomponent properties relevant to use, such as strain hardening and gearquality, is to be carried out. Finally, an adapted process control to avoidsubsequent machining is developed
Metamodel-based consideration of the process chain in the mechanical joining of sheet metal components
(Third Party Funds Single)
Funding source: AIF Arbeitsgemeinschaft industrieller Forschungsvereinigungen
Chargen-und Prozessschwankungen führen bei der Herstellung von Blechbauteilen zuAbweichungen der resultierenden Bauteileigenschaften, was nachfolgendeProzessschritte beeinflusst. Die Nutzung von mittels einer Prozessüberwachungakquirierten Daten bietet die Möglichkeit, Fertigungsprozesse in Abhängigkeitvariierender Randbedingungen anzupassen und dadurch eine konstanteBauteilqualität sicherzustellen. Voraussetzung hierfür ist die Kenntnis überprozesskettenübergreifende Zusammenhänge.
Indiesem Projekt wird die datenbasierte Prozessadaption anhand einer Prozesskettebestehend aus den Schritten Umformen, Spannen und Fügen untersucht. Ziel desForschungsvorhabens ist es, die gesamte Prozesskette mit Metamodellenabzubilden, welche mithilfe von automatisiertem maschinellem Lernen abgeleitetwerden. Dies soll die Prognose der Bauteilqualität sowie die inverse Anpassungder Teilprozessparameter zum Ausgleich von Chargen- und Prozessschwankungenermöglichen. Der Fokus am LFT liegt auf der umformtechnischenBauteilherstellung mittels Tiefziehen. Die nachfolgenden ProzessschritteSpannen und Fügen werden am Fraunhofer-Institut für Großstrukturen in derProduktionstechnik (Fh-IGP) in Rostock respektive am Laboratorium fürWerkstoff- und Fügetechnik (LWF) der Universität Paderborn untersucht.
Ausgehendvon der Definition der Modellanforderungen folgt die Datengenerierung für dieMetamodellierung durch die Korrelation der Prozessdaten undHalbzeugeigenschaften mit den resultierenden Bauteileigenschaften. Die Prognoseder Bauteileigenschaften nach dem Tiefziehen sowie die Modellierung derprozesskettenübergreifenden Zusammenhänge gestattet die Adaption derProzessparameter beim nachfolgenden Spannen und Fügen. Die Abbildung der Prozesskettedurch Metamodelle ermöglicht zudem die inverse Auslegung der Prozesskette durchdie Definition der Anforderungen an den Fügepunkt. Grundlage für die Vernetzungder Teilprozesse ist die Definition geeigneter Schnittstellen zur Realisierungdes prozessübergreifenden Datenaustauschs.
Failure analysis under plane strain
(Third Party Funds Single)
Funding source: Bundesministerium für Wirtschaft und Klimaschutz (BMWK)
The challenge of this research project is the exact design of products made of sheet metal materials. In common practice, components manufactured in this way are nowadays designed by means of numerical simulations. This type of design is significantly influenced by the quality of the input parameters, such as the characteristic values from the material characterization. The assumption of wrong input parameters can predict a component failure too late or a component failure too early. For this very reason, large safety factors are often included in practical applications, leading to a conservative design with only moderate utilization of the material's limits. However, an improvement in the utilization of the material's potential is significantly influenced by an exact material characterization. In particular, the area of plane strain, which is often the cause of failure in deep-drawing or stretch-forming components, must be investigated and improved. Conventional characterization tests under plane strain can show nonlinearities in the strain path or are friction-induced or strongly affected by assumptions due to their test setup. Thus, the objective of this research project is to improve the characterization under plane strain for an improved failure prediction in order to shift the process limits to higher forming ratios and higher achievable drawing depths. The conventional characterization of forming limit change is to be improved to better predict failure under plane strain in order to increase the quality of input parameters for component design.
Improvement of the geometrical accuracy of parts by material flow-optimized coil layouts when extruding functional components
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
For the production of functionally integratedcomponents made of sheet metal materials, the processes of Sheet-Bulk MetalForming are suitable, which enable the production of planar components withlocal functional elements. Limitations in the diefilling of the functional elements and high die loads are a result of thedemanding forming and process conditions that occur within these processes. When transferring this process class to efficientproduction from coil, previous investigations also identified anisotropicmaterial flow and anisotropic die loads as relevant process influences whencarrying out extrusion processes from sheet coils.
Based on this, theinfluence of the component design on a multi-stage extrusion process from coilwill be analyzed numerically and experimentally within the scope of thisresearch project. In the first step,cause-effect relationships are to be investigated with regard to the local diefilling of the functional elements and the local die load when the blank andcoil geometry is varied. Furthermore, usingthese findings, the potential for controlling the material flow and thusimproving die filling by adapting the possible stage sequences is to bederived.
Close-to-series design of modified tool surfaces for low-lubrication deep drawing
(Third Party Funds Group – Sub project)
Term: 1. March 2022 - 29. February 2024
Funding source: Bundesministerium für Wirtschaft und Klimaschutz (BMWK)
Qualification of a fatigue test for the investigation of the behavior of high-strength tool materials under realistic conditions by elastomer compression
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Tools and tool failure have major influence on the economic efficiencyof cold forging processes. In order to minimize losses due to machinedowntimes, it is necessary to accurately predict the service life. A challengein the prediction of tool life is that there is little data on the fatiguebehaviour of the used high strength steel materials. In addition, the qualityof the available data is limited, as it does not reflect the multi-axial stressconditions of cold forging. The objective of the research project is thereforeto investigate a new fatigue test, which can realistically model the stressstate occurring in cold forming tools considering both the multi-axiality andthe application of compressive prestresses. For this purpose, an elastomer madeof polyurethane is used as a pressure medium in a tool for fatigue testing. Acyclic hydrostatic pressure is applied by the repeated compression of theelastomer. The comparability of the tool stresses to the forming of steel isensured by analyzing the stresses both numerically and experimentally. Achallenge in the experimental concept is wear on the elastomer specimen, whichis to be minimized by adapting the test parameters. In order to illustraterealistic load cases, the transferability of the test results to systems underpreload is demonstrated. In a combined numerical-experimental approach, bothconventional reinforcements and new concepts for local prestressing will beinvestigated. This enables the identification of cause effect relationshipsbetween the stresses and strains caused by the reinforcement and the servicelife of the tools under realistic loads. Finally, the obtained results will beused to evaluate the potential of the test and the benefit compared toconventional fatigue tests.
Use of versatile joining processes for the production of hybrid component structures in an industrial environment
(Third Party Funds Group – Sub project)
Term: 1. January 2022 - 31. December 2024
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
The subject of the transfer project is the analysis and transferability of the methodology of the transformability of a wobbling semi-hollow punch riveting process from sub-project C02 "Adaptable joining with auxiliary joining part" under industrial boundary conditions and an extension in the Transregio 285 collaborative research center (SFB/TRR285) "Method development for mechanical joinability in versatile process chains". through targeted adjustment of relevant process parameters. The central goal of the research project is the transfer of basic scientific findings for the targeted production of geometric characteristics of joints such as undercuts in wobbling semi-tubular punch riveting to the new approach of joining by tumbling.
Manufacturing of tailored aluminum parts by controlling the local cooling rates in a combined forming, quenching and hardening process (Tailor Quenched Forming)
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
A common method for increasing passenger safety invehicles is the use of high strength materials for structural safety-relevantparts. Due to the targeted adjustment of the mechanical properties, tailoredcomponents can be manufactured with locally adapted component strengths. Incase of a crash, they have the ability to absorb or transfer the occurringenergy to other regions of the vehicle. It is relevant that these componentscombine high-strength as well as ductile regions. Until now these componentsare only produced by modified press hardening operations of steel components.In association with the light-weight concept, a new opportunity to realizetailored components is the use of adapted, high-strength, hardenable aluminumcomponents. During the forming process, the properties of previously solution-annealedcomponents can be adjusted by simultaneous quenching and forming operations.The key influencing factor in quenching and forming operations is the coolingrate. In future, it will be possible to produce property-adapted structuralcomponents using high-strength aluminum alloys with the help of different localtool temperatures. Thermally coupled material models are necessary for thesimulation of this forming process.
Fundamental investigations on the production of functional components from coil
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The applicationof bulk forming processes to sheet metal, also known as sheet-bulk metalforming, extends the existing forming limits of established sheet and bulkforming processes. This enables the resource-efficient production offunctionally integrated lightweight components. In previous research, sheet-bulkmetal forming of pre-cut blanks was investigated. By using coil assemi-finished products, the advantages of manufacturing from coil in terms ofsimplified component handling and as a result higher output quantity arecombined with the advantages of sheet-bulk metal forming in terms of extendedforming limits.
The usage ofcoils, however, results in an anisotropic material flow and consequently an unequalshape of the formed components. This worsens the component application behaviorand is especially a challenge for cyclically symmetrical parts. In additionasymmetrical tool loads, critical for fatigue, occur. Considering this, theobjective is to elaborate a process understanding for extrusion of gears fromcoil. It should be investigated how the anisotropic material flow affects the formingof the individual functional elements of cyclically symmetrical components andthe tool loads.
In order to increasethe application potential of extrusion of gears from coil, another objective isto provide measures to reduce the anisotropic material flow and to improve thegeometrical accuracy of formed parts. For this purpose, different approaches formaterial flow control, such as adjusting the coil width, feed width, toolgeometry and local adaptation of friction should be analyzed for cyclicallysymmetrical parts. In addition to the effectiveness, the wear-behavior of the measureshas to be investigated in tool life tests.
In-situ characterization of a locally carburized complex phase steel for manufacturing of tailored semi-finished products
(Third Party Funds Single)
Funding source: Deutsche Forschungsgemeinschaft (DFG)
Local carburization of semi-finished sheet material is a process variant to manufacture hot stamped parts with tailored properties. In this research project, the process combination of local carburization and hot stamping shall be qualified for carburization temperatures above 950 °C to reduce the required process time. The dependence of the mechanical properties and resulting microstructure on the process-relevant influencing factors will be determined by means of in-situ characterizations. Furthermore, the accuracy of the numerical simulation will be improved by extending existing material models. The material models will then be validated by additional experiments and the findings will be verified by application to a demonstrator geometry.
Reduction of local tool stresses in cold forging tools
(Third Party Funds Single)
Funding source: Bayerische Forschungsstiftung
Part geometry is a major influence on the formation of local stress in cold forging tools. Non-constant asymmetrical cross-sections result in axial and tangential stress concentrations. This challenge can be seen in the processes of the industrial partners, where fatigue failure occurs in local elements. In order to counteract fatigue and improve process economics, the formation of local tool stresses is to be analysed using a model process. Using the process the influence of functional elements and changes in cross-section on the stress state of the die is researched. With an understanding of the mechanisms of the stress formation, adapted tool concepts will be developed, which enable a suitable improvement of the stress state depending on the part and tool geometry. To evaluate the effectiveness of the new tool designs, they will be implemented in the processes of the industrial partners. That way, the effect on tool life can be analysed for different die materials. These are usually cold working steels or cemented carbides, which react very sensibly to tensile stresses. Finally, the new tool concepts will be evaluated using the developed process understanding and the experimental results regarding the tool life.
Development of a forming process to manufacture near-net-shape functional components with a gradient in sheet thickness
(Third Party Funds Group – Sub project)
Term: 1. January 2021 - 30. September 2023
Funding source: Deutsche Forschungsgemeinschaft (DFG)
Resource-minimized production through hybrid and highly networked processes
(Third Party Funds Single)
Funding source: Bundesministerium für Wirtschaft und Technologie (BMWi)
Consistent lightweight construction realized through high-performance and resource-efficient manufacturing processes represents a key technology for securing long-term competitiveness of the German industry while simultaneously reducing CO2 emissions. By combining individual production technologies new opportunities are created, allowing the overcoming of limits that are currently set by conventional processes. HyConnect aims to combine forming technology with additive manufacturing in order to enhance the advantages of both process classes and to replace previous energy-intensive manufacturing methods (see Figure). In addition, digital solutions for a cross-company exchange and analysis of production data are being implemented, researched and evaluated. These are necessary to realize both the before described technical as well as environmentally added values and ensure that the safety requirements of the participating companies are met.
Within this project, the aim is to expand the existing fundamental knowledge of hybrid component manufacturing by combining laser metal deposition (LMD) and deep drawing. Interactions between the individual processes as well as influences resulting from the production sequence stand in the foreground of upcoming investigations. With the support of the below listed project partners, an exemplary bearing sleeve is planned to be manufactured with reduced material resources and CO2 emissions.
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)
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.
Investigation of residual stress related elementary processes in cold forged components in the manufacturing and operating phase
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
The operational behavior of steel components is significantly influenced by their residual stress state. On the basis of forward rod extrusion of stainless steel, methods for the controlled generation of residual stresses are being investigated, their stability under typical operating conditions is being analyzed and their effects on the operating behavior are being identified in this research project. In the first phase, basic mechanisms of the generation of residual stresses were identified. In the current second phase, parameters for a robust adjustment of the residual stress state during forming were developed, whereby lubrication in particular was identified as relevant. Furthermore, the influence of thermal and mechanical loads on the stability of the residual stresses in the components is being investigated.
Forming and joining of semitubular self-piercing rivets made of high-strength steel with adapted mechanical properties and numerical analysis of the process chain
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Joining is an important method of productionengineering, for which reason the efficiency of such manufacturing processes ishighly relevant. Self-piercing riveting is a mechanical joining process, usinga rivet as fastener to join two or more sheets. This makes it possible to joindissimilar materials and to realize multi-material design. However, the rivetproduction is a time-consuming process, including the steps hardening andcoating in order to achieve an adequate strength and a high ductility as wellas corrosion resistance. The use of high strain hardening materials as rivetmaterials, such as high nitrogen steels, shows a huge potential concerning thereduction of production steps and thus a shortening of the rivet manufactureprocess chain since the conventional hardening, tempering and coating steps afterforming are not necessary anymore. However, the challenging high tool loadsduring cold bulk forming of high nitrogen steels represent a major challengefor the manufacturing process.
The objective is to investigate fundamentalinfluencing factors on the forming process for manufacturing rivets using highstrain hardening materials, the resulting rivet properties, the joining processand the achievable joint properties. The LFT is working on this project incollaboration with the Laboratory for material and joining technology (LWF) at Paderborn University. At the LFT, the projectfocus is on the development of the forming tools and appropriate formingstrategies in order to realise the forming process despite the high tool loads.In this context, fundamental correlations between the forming temperature, theachievable die filling during forming and the mechanical properties of theformed rivets are investigated. By choosing a suitable forming strategy and rivetgeometry, the mechanical properties of the rivets are to be adapted accordingto the requirements of the joining process.
Center for Nanoanalysis and Electron Microscopy
(FAU Funds)
CENEM was established in 2010 to provide a forefront research center for the versatile characterization of materials and devices with state-of-the-art instrumentation and expertise and to intensify the interdisciplinary research. The big CENEM network represents the strong collaborations within the University of Erlangen-Nürnberg as well as the collaboration with other universities, dedicated research institutes and industry.
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.
TRR 73: Manufacturing of complex functional components with variants by using a new sheet metal forming process - Sheet-Bulk Metal Forming
(Third Party Funds Group – Overall project)
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: http://www.tr-73.de
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