@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}}, } @article{32869, abstract = {{The further development of in-mold-assembly (IMA) technologies for structural hybrid components is of great importance for increasing the economic efficiency and thus the application potential. This paper presents an innovative IMA process concept for the manufacturing of bending loaded hybrid components consisting of two outer metal belts and an inner core structure made of glass mat reinforced thermoplastic (GMT). In this process, the core structure, which is provided with stiffening ribs and functional elements, is formed and joined to two metal belts in one single step. For experimental validation of the concept, the development of a prototypic molding tool and the manufacturing of hybrid beams including process parameters are described. Three-point bending tests and optical measurement technologies are used to characterize the failure behavior and mechanical properties of the produced hybrid beams. It was found that the innovative IMA process enables the manufacturing of hybrid components with high energy absorption and low weight in one step. The mass-specific energy absorption is increased by 693 % compared to pure GMT beams.}}, author = {{Stallmeister, Tim and Tröster, Thomas}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{1457--1467}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{In-Mold-Assembly of Hybrid Bending Structures by Compression Molding}}}, doi = {{10.4028/p-5fxp53}}, volume = {{926}}, year = {{2022}}, } @article{30213, abstract = {{Requirement changes and cascading effects of change propagation are major sources of inefficiencies in product development and increase the risk of project failure. Proactive change management of requirement changes yields the potential to handle such changes efficiently. A systematic approach is required for proactive change management to assess and reduce the risk of a requirement change with appropriate effort in industrial application. Within the paper at hand, a novel method for Proactive Management of Requirement Changes (ProMaRC) is presented. It is developed in close collaboration with industry experts and evaluated based on workshops, pilot users’ feedback, three industrial case studies from the automotive industry and five development projects from research. To limit the application effort, an automated approach for dependency analysis based on the machine learning technique BERT and semi-automated assessment of change likelihood and impact using a modified PageRank algorithm is developed. Applying the method, the risks of requirement changes are assessed systematically and reduced by means of proactive change measures. Evaluation shows high performance of dependency analysis and confirms the applicability and usefulness of the method. This contribution opens up the research space of proactive risk management for requirement changes which is currently almost unexploited. It enables more efficient product development.}}, author = {{Gräßler, Iris and Oleff, Christian and Preuß, Daniel}}, issn = {{2076-3417}}, journal = {{Applied Sciences}}, keywords = {{Fluid Flow and Transfer Processes, Computer Science Applications, Process Chemistry and Technology, General Engineering, Instrumentation, General Materials Science}}, number = {{4}}, publisher = {{MDPI AG}}, title = {{{Proactive Management of Requirement Changes in the Development of Complex Technical Systems}}}, doi = {{10.3390/app12041874}}, volume = {{12}}, year = {{2022}}, } @article{32068, abstract = {{Inspired by plant grafting, grafted vortex beams can be formed through grafting two or more helical phase profiles of optical vortex beams. Recently, grafted perfect vortex beams (GPVBs) have attracted much attention due to their unique optical properties and potential applications. However, the current method to generate and manipulate GPVBs requires a complex and bulky optical system, hindering further investigation and limiting its practical applications. Here, a compact metasurface approach for generating and manipulating GPVBs in multiple channels is proposed and demonstrated, which eliminates the need for such a complex optical setup. A single metasurface is utilized to realize various superpositions of GPVBs with different combinations of topological charges in four channels, leading to asymmetric singularity distributions. The positions of singularities in the superimposed beam can be further modulated by introducing an initial phase difference in the metasurface design. The work demonstrates a compact metasurface platform that performs a sophisticated optical task that is very challenging with conventional optics, opening opportunities for the investigation and applications of GPVBs in a wide range of emerging application areas, such as singular optics and quantum science.}}, author = {{Ahmed, Hammad and Intaravanne, Yuttana and Ming, Yang and Ansari, Muhammad Afnan and Buller, Gerald S. and Zentgraf, Thomas and Chen, Xianzhong}}, issn = {{0935-9648}}, journal = {{Advanced Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, number = {{30}}, publisher = {{Wiley}}, title = {{{Multichannel Superposition of Grafted Perfect Vortex Beams}}}, doi = {{10.1002/adma.202203044}}, volume = {{34}}, year = {{2022}}, } @article{39412, abstract = {{ The Eringen’s nonlocal elastica equation does not possess a Lagrangian formulation. In this article, we find a variational integrating factor which enables us to provide a Lagrangian and Hamiltonian structure associated to this equation. Explicit expressions of the solutions in terms of elliptic integrals of the first kind are then deduced. We then derive discrete version of the Eringen’s nonlocal elastica preserving the Lagrangian and Hamiltonian structure and compare it with Challamel’s and co-worker definition of a discrete Eringen’s nonlocal elastica. }}, author = {{Cresson, Jacky and Hariz-Belgacem, Khaled}}, issn = {{1081-2865}}, journal = {{Mathematics and Mechanics of Solids}}, keywords = {{Mechanics of Materials, General Materials Science, General Mathematics}}, publisher = {{SAGE Publications}}, title = {{{About the structure of the discrete and continuous Eringen’s nonlocal elastica}}}, doi = {{10.1177/10812865221108094}}, year = {{2022}}, } @article{39400, abstract = {{ The Eringen’s nonlocal elastica equation does not possess a Lagrangian formulation. In this article, we find a variational integrating factor which enables us to provide a Lagrangian and Hamiltonian structure associated to this equation. Explicit expressions of the solutions in terms of elliptic integrals of the first kind are then deduced. We then derive discrete version of the Eringen’s nonlocal elastica preserving the Lagrangian and Hamiltonian structure and compare it with Challamel’s and co-worker definition of a discrete Eringen’s nonlocal elastica. }}, author = {{Cresson, Jacky and Hariz Belgacem, Khaled}}, issn = {{1081-2865}}, journal = {{Mathematics and Mechanics of Solids}}, keywords = {{Mechanics of Materials, General Materials Science, General Mathematics}}, publisher = {{SAGE Publications}}, title = {{{About the structure of the discrete and continuous Eringen’s nonlocal elastica}}}, doi = {{10.1177/10812865221108094}}, year = {{2022}}, } @article{51197, abstract = {{Clinching is a cost efficient method for joining components in series production. To assure the clinch point’s quality, the force displacement curve during clinching or the bottom thickness are monitored. The most significant geometrical characteristics of the clinch point, neck thickness and undercut, are usually tested destructively by microsectioning. However, micrograph preparation goes ahead with a resetting of elastic deformations and crack-closing after unloading. To generate a comprehensive knowledge of the clinch point’s inner geometry under load, in-situ computed tomography (CT) and acoustic testing (TDA) can be combined. While the TDA is highly sensitive to the inner state of the clinch point, it could detect critical events like crack development during loading. If such events are indicated, the loading process is stopped and a stepped in-situ CT of the following crack and deformation development is performed. In this paper, the concept is applied to the process of clinching itself, providing a detailed three-dimensional insight in the development of the joining zone. A test set-up is used which allows a stepwise clinching of two aluminium sheets EN AW 6014. Furthermore, this set-up is positioned within a CT system. In order to minimize X-ray absorption, a beryllium cylinder is used within the set-up frame and clinching tools are made from Si3N4. The actuator and sensor necessary for the TDA are integrated in the set-up. In regular process steps, the clinching process is interrupted in order to perform a TDA and a CT scan. In order to enhance the visibility of the interface, a thin tin layer is positioned between the sheets prior clinching. It is shown, that the test-set up allows a monitoring of the dynamic behaviour of the specimen during clinching while the CT scans visualize the inner geometry and material flow non-destructively.}}, author = {{Köhler, Daniel and Stephan, Richard and Kupfer, Robert and Troschitz, Juliane and Brosius, Alexander and Gude, Maik}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{1489--1497}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Investigations on Combined <i>In Situ</i> CT and Acoustic Analysis during Clinching}}}, doi = {{10.4028/p-32330d}}, volume = {{926}}, year = {{2022}}, } @article{33687, author = {{Odziomek, Mateusz and Giusto, Paolo and Kossmann, Janina and Tarakina, Nadezda V. and Heske, Julian Joachim and Rivadeneira, Salvador M. and Keil, Waldemar and Schmidt, Claudia and Mazzanti, Stefano and Savateev, Oleksandr and Perdigón‐Toro, Lorena and Neher, Dieter and Kühne, Thomas and Antonietti, Markus and López‐Salas, Nieves}}, issn = {{0935-9648}}, journal = {{Advanced Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, number = {{40}}, publisher = {{Wiley}}, title = {{{“Red Carbon”: A Rediscovered Covalent Crystalline Semiconductor}}}, doi = {{10.1002/adma.202206405}}, volume = {{34}}, year = {{2022}}, } @article{37713, author = {{Murzakhanov, Fadis F. and Mamin, Georgy Vladimirovich and Orlinskii, Sergei Borisovich and Gerstmann, Uwe and Schmidt, Wolf Gero and Biktagirov, Timur and Aharonovich, Igor and Gottscholl, Andreas and Sperlich, Andreas and Dyakonov, Vladimir and Soltamov, Victor A.}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}}, number = {{7}}, pages = {{2718--2724}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Electron–Nuclear Coherent Coupling and Nuclear Spin Readout through Optically Polarized VB– Spin States in hBN}}}, doi = {{10.1021/acs.nanolett.1c04610}}, volume = {{22}}, year = {{2022}}, } @article{33080, author = {{Long, Teng and Ma, Xuekai and Ren, Jiahuan and Li, Feng and Liao, Qing and Schumacher, Stefan and Malpuech, Guillaume and Solnyshkov, Dmitry and Fu, Hongbing}}, issn = {{2198-3844}}, journal = {{Advanced Science}}, keywords = {{General Physics and Astronomy, General Engineering, Biochemistry, Genetics and Molecular Biology (miscellaneous), General Materials Science, General Chemical Engineering, Medicine (miscellaneous)}}, number = {{29}}, publisher = {{Wiley}}, title = {{{Helical Polariton Lasing from Topological Valleys in an Organic Crystalline Microcavity}}}, doi = {{10.1002/advs.202203588}}, volume = {{9}}, year = {{2022}}, } @article{36332, abstract = {{AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks during joint formation when mechanical joining technologies are used. A rise in ductility can be achieved by a considerable increase in the solidification rate which results in grain refinement. High solidification rates can be realized in twin–roll casting (TRC) by water-cooled rolls. Therefore, a hypoeutectic EN AC–AlSi9 (for European Norm - aluminum cast product) is manufactured by the TRC process and analyzed. Subsequently, joining investigations are performed on castings in as-cast and heat-treated condition using the self-piercing riveting process considering the joint formation and the load-bearing capacity. Due to the fine microstructure, the crack initiation can be avoided during joining, while maintaining the joining parameters, especially by specimens in heat treatment conditions. Furthermore, due to the extremely fine microstructure, the load-bearing capacity of the joint can be significantly increased in terms of the maximum load-bearing force and the energy absorbed.}}, author = {{Neuser, Moritz and Kappe, Fabian and Ostermeier, Jakob and Krüger, Jan Tobias and Bobbert, Mathias and Meschut, Gerson and Schaper, Mirko and Grydin, Olexandr}}, issn = {{1438-1656}}, journal = {{Advanced Engineering Materials}}, keywords = {{Condensed Matter Physics, General Materials Science}}, number = {{10}}, publisher = {{Wiley}}, title = {{{Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting}}}, doi = {{10.1002/adem.202200874}}, volume = {{24}}, year = {{2022}}, } @article{37647, abstract = {{Mechanical joining processes are an essential part of modern lightweight construction. They permit materials of different types to be joined in a way that is suitable for the loads involved. These processes reach their limits, however, as soon as the boundary conditions change. In most cases, these elements are specially adapted to the joining point and cannot be used universally. Changes require cost-intensive adaptation of both the element and the process control, thus making production more complex. This results in high costs due to the increased number of auxiliary joining element variants required and reduces the economic efficiency of mechanical joining. One approach to overcoming this issue is the use of adaptive auxiliary joining elements formed by friction spinning. This article presents the current state of research on pre-hole-free joining with adaptive joining elements. The overall process chain is illustrated, explained and analyzed. Special attention is paid to demonstrating the feasibility of pre-hole-free joining with adaptive joining elements. The chosen mechanical parameters are subsequently listed. Finally, a comprehensive outlook of the future development potential is derived.}}, author = {{Wischer, Christian and Homberg, Werner}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{1468--1478}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Further Development of an Adaptive Joining Technique Based on Friction Spinning to Produce Pre-Hole-Free Joints}}}, doi = {{10.4028/p-1n6741}}, volume = {{926}}, year = {{2022}}, } @article{34645, author = {{Tripathi, Tripurari Sharan and Wilken, Martin and Hoppe, Christian and de los Arcos, Teresa and Grundmeier, Guido and Devi, Anjana and Karppinen, Maarit}}, issn = {{1438-1656}}, journal = {{Advanced Engineering Materials}}, keywords = {{Condensed Matter Physics, General Materials Science}}, number = {{10}}, publisher = {{Wiley}}, title = {{{Atomic Layer Deposition of Copper Metal Films from Cu(acac) 2 and Hydroquinone Reductant}}}, doi = {{10.1002/adem.202100446}}, volume = {{23}}, year = {{2021}}, } @article{33587, abstract = {{Abstract We performed a virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated usingthe hybrid density functional theory including exact Hartree–Fock exchange. Our final list contains materials which have band gaps between 1.0 and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes.}}, author = {{Ranjbar, Ahmad and Mirhosseini, Hossein and Kühne, Thomas D}}, issn = {{2515-7639}}, journal = {{Journal of Physics: Materials}}, keywords = {{Condensed Matter Physics, General Materials Science, Atomic and Molecular Physics, and Optics}}, number = {{1}}, publisher = {{IOP Publishing}}, title = {{{On topological materials as photocatalysts for water splitting by visible light}}}, doi = {{10.1088/2515-7639/ac363d}}, volume = {{5}}, year = {{2021}}, } @article{33643, abstract = {{The origin of strong interactions between water molecules and porous C2N surfaces is investigated by using a combination of model materials, volumetric physisorption measurements, solid-state NMR spectroscopy, and DFT calculations.}}, author = {{Heske, Julian Joachim and Walczak, Ralf and Epping, Jan D. and Youk, Sol and Sahoo, Sudhir K. and Antonietti, Markus and Kühne, Thomas and Oschatz, Martin}}, issn = {{2050-7488}}, journal = {{Journal of Materials Chemistry A}}, keywords = {{General Materials Science, Renewable Energy, Sustainability and the Environment, General Chemistry}}, number = {{39}}, pages = {{22563--22572}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{When water becomes an integral part of carbon – combining theory and experiment to understand the zeolite-like water adsorption properties of porous C2N materials}}}, doi = {{10.1039/d1ta05122a}}, volume = {{9}}, year = {{2021}}, } @article{33657, author = {{Mirhosseini, Hossein and Tahmasbi, Hossein and Kuchana, Sai Ram and Ghasemi, Alireza and Kühne, Thomas}}, issn = {{0927-0256}}, journal = {{Computational Materials Science}}, keywords = {{Computational Mathematics, General Physics and Astronomy, Mechanics of Materials, General Materials Science, General Chemistry, General Computer Science}}, publisher = {{Elsevier BV}}, title = {{{An automated approach for developing neural network interatomic potentials with FLAME}}}, doi = {{10.1016/j.commatsci.2021.110567}}, volume = {{197}}, year = {{2021}}, } @article{33656, author = {{Wang, Mengying and Ranjbar, Ahmad and Kühne, Thomas and Belosludov, Rodion V. and Kawazoe, Yoshiyuki and Liang, Yunye}}, issn = {{0008-6223}}, journal = {{Carbon}}, keywords = {{General Chemistry, General Materials Science}}, pages = {{370--378}}, publisher = {{Elsevier BV}}, title = {{{A theoretical investigation of topological phase modulation in carbide MXenes: Role of image potential states}}}, doi = {{10.1016/j.carbon.2021.05.026}}, volume = {{181}}, year = {{2021}}, } @article{33659, abstract = {{Abstract We performed a virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated usingthe hybrid density functional theory including exact Hartree–Fock exchange. Our final list contains materials which have band gaps between 1.0 and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes.}}, author = {{Ranjbar, Ahmad and Mirhosseini, Hossein and Kühne, Thomas}}, issn = {{2515-7639}}, journal = {{Journal of Physics: Materials}}, keywords = {{Condensed Matter Physics, General Materials Science, Atomic and Molecular Physics, and Optics}}, number = {{1}}, publisher = {{IOP Publishing}}, title = {{{On topological materials as photocatalysts for water splitting by visible light}}}, doi = {{10.1088/2515-7639/ac363d}}, volume = {{5}}, year = {{2021}}, } @article{33895, abstract = {{Heat-assisted forming processes are becoming increasingly important in the manufacturing of sheet metal parts for body-in-white applications. However, the non-isothermal nature of these processes leads to challenges in evaluating the forming limits, since established methods such as Forming Limit Curves (FLCs) only allow the assessment of critical forming strains for steady temperatures. For this reason, a temperature-dependent extension of the well-established GISSMO (Generalized Incremental Stress State Dependent Damage Model) fracture indicator framework is developed by the authors to predict forming failures under non-isothermal conditions. In this paper, a general approach to combine several isothermal FLCs within the temperature-extended GISSMO model into a temperature-dependent forming limit surface is investigated. The general capabilities of the model are tested in a coupled thermo-mechanical FEA using the example of warm forming of an AA5182-O sheet metal cross-die cup. The obtained results are then compared with state of the art of evaluation methods. By taking the strain and temperature path into account, GISSMO predicts greater drawing depths by up to 20% than established methods. In this way the forming and so the lightweight potential of sheet metal parts can by fully exploited. Moreover, the risk and locus of failure can be evaluated directly on the part geometry by a contour plot. An additional advantage of the GISSMO model is the applicability for low triaxialities as well as the possibility to predict the materials behavior beyond necking up to ductile fracture.}}, author = {{Camberg, Alan Adam and Erhart, Tobias and Tröster, Thomas}}, issn = {{1996-1944}}, journal = {{Materials}}, keywords = {{General Materials Science}}, number = {{17}}, publisher = {{MDPI AG}}, title = {{{A Generalized Stress State and Temperature Dependent Damage Indicator Framework for Ductile Failure Prediction in Heat-Assisted Forming Operations}}}, doi = {{10.3390/ma14175106}}, volume = {{14}}, year = {{2021}}, } @article{34087, author = {{Knust, Steffen and Ruhm, Lukas and Kuhlmann, Andreas and Meinderink, Dennis and Bürger, Julius and Lindner, Jörg and de los Arcos de Pedro, Maria Teresa and Grundmeier, Guido}}, issn = {{0377-0486}}, journal = {{Journal of Raman Spectroscopy}}, keywords = {{Spectroscopy, General Materials Science}}, number = {{7}}, pages = {{1237--1245}}, publisher = {{Wiley}}, title = {{{In situ backside Raman spectroscopy of zinc oxide nanorods in an atmospheric‐pressure dielectric barrier discharge plasma}}}, doi = {{10.1002/jrs.6123}}, volume = {{52}}, year = {{2021}}, }