@inproceedings{34208,
  abstract     = {{Computational homogenization is a powerful tool which allows to obtain homogenized properties of materials on the macroscale from the simulation of the underlying microstructure. The response of the microstructure is, however, strongly affected by variations in the microstructure geometry. The effect of geometry variations is even stronger in cases when the material exhibits plastic deformations. In this work we study a model of a steel alloy with arbitrary distributed elliptic voids. We model one single unit cell of the material containing one single void. The geometry of the void is not precisely known and is modeled as a variable orientation of an ellipse. Large deformations applied to the unit cell necessitate a finite elasto-plastic material model. Since the geometry variation is parameterized, we can utilize the method recently developed for stochastic problems but also applicable to all types of parametric problems — the isoparametric stochastic local FEM (SL-FEM). It is an ideal tool for problems with only a few parameters but strongly nonlinear dependency of the displacement fields on parameters. Simulations demonstrate a strong effect of parameter variation on the plastic strains and, thus, substantiate the use of the parametric computational homogenization approach.}},
  author       = {{Pivovarov, Dmytro and Mergheim, Julia and Willner, Kai and Steinmann, Paul}},
  booktitle    = {{PAMM}},
  issn         = {{1617-7061}},
  number       = {{1}},
  publisher    = {{Wiley}},
  title        = {{{Parametric FEM for computational homogenization of heterogeneous materials with random voids}}},
  doi          = {{10.1002/pamm.202000071}},
  volume       = {{20}},
  year         = {{2021}},
}

@article{23843,
  author       = {{Meier, F. and Protte, M. and Baron, E. and Feneberg, M. and Goldhahn, R. and Reuter, Dirk and As, Donat Josef}},
  issn         = {{2158-3226}},
  journal      = {{AIP Advances}},
  title        = {{{Selective area growth of cubic gallium nitride on silicon (001) and 3C-silicon carbide (001)}}},
  doi          = {{10.1063/5.0053865}},
  year         = {{2021}},
}

@article{23469,
  abstract     = {{The implementation of control systems in metal forming processes improves product quality and productivity. By controlling workpiece properties during the process, beneficial effects caused by forming can be exploited and integrated in the product design. The overall goal of this investigation is to produce tailored tubular parts with a defined locally graded microstructure by means of reverse flow forming. For this purpose, the proposed system aims to control both the desired geometry of the workpiece and additionally the formation of strain-induced α′-martensite content in the metastable austenitic stainless steel AISI 304 L. The paper introduces an overall control scheme, a geometry model for describing the process and changes in the dimensions of the workpiece, as well as a material model for the process-induced formation of martensite, providing equations based on empirical data. Moreover, measurement systems providing a closed feedback loop are presented, including a novel softsensor for in-situ measurements of the martensite content.}},
  author       = {{Riepold, Markus and Arian, Bahman and Vasquez, Julian Rozo and Homberg, Werner and Walther, Frank and Trächtler, Ansgar}},
  issn         = {{2666-9129}},
  journal      = {{Advances in Industrial and Manufacturing Engineering}},
  title        = {{{Model approaches for closed-loop property control for flow forming}}},
  doi          = {{10.1016/j.aime.2021.100057}},
  year         = {{2021}},
}

@inproceedings{24101,
  abstract     = {{Arburg Plastic Freeforming (APF) is an additive manufacturing process with which three-dimensional, thermoplastic components can be produced layer by layer. Visual and geometrical properties are a major criterion for characterizing the resulting component quality. The aim of this study was to investigate the influences on visual and geometrical properties of APF components depending on process parameters. Initially the focus was on the analysis of the shrinkage behavior of ABS-M30 (Stratasys). On the basis of the results and an existing procedure by the machine manufacturer, an optimized procedure for determining the scaling factors was developed to counteract the shrinkage. With this procedure a higher dimensional accuracy of the components can be achieved. In addition, it was investigated whether an adaption of the form factor based on a mathematical model depending on the component geometry makes sense. The results were transferred into manufacturing guidelines, which allow the user of the APF-technology to optimize process parameters more efficiently.}},
  author       = {{Moritzer, Elmar and Hecker, Felix and Elsner, Christian Lennart and Hirsch, André}},
  booktitle    = {{Proceedings: 2021 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2021)}},
  editor       = {{Bourell, David}},
  location     = {{Austin, Texas, USA}},
  pages        = {{467--474}},
  title        = {{{Investigations for the Optimization of Visual and Geometrical Properties of Arburg Plastic Freeforming Components}}},
  doi          = {{10.26153/tsw/17567}},
  year         = {{2021}},
}

@inproceedings{24099,
  abstract     = {{The additive manufacturing process Fused Deposition Modeling (FDM) is established in the industry for many years. A new, similar process to FDM is the Arburg Plastic Freeforming (APF). The main differences between both processes are the form of the starting material (FDM: Filaments, APF: Conventional granulate) and the material deposition during the layer formation (FDM: Melt strand, APF: fine molten droplets).
Since the two processes can be used in similar applications, the aim of this study is to compare both processes in a holistic way. Furthermore, the advantages and disadvantages of the processes are to be highlighted. The systematic comparison between a Stratasys 400mc and the Freeformer 200-3X is divided into the areas of component properties, design limitations and economic efficiency. The material ABS-M30 (Stratasys) is used in both processes. The results show comparable component properties regarding mechanical and optical properties but also differences in design limitations and cost efficiency.
}},
  author       = {{Moritzer, Elmar and Hecker, Felix and Driediger, Christine and Hirsch, André}},
  booktitle    = {{Proceedings: 2021 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2021)}},
  editor       = {{Bourell, David}},
  location     = {{Austin, Texas, USA}},
  pages        = {{575--584}},
  title        = {{{Comparison of Component Properties and Economic Efficiency of the Arburg Plastic Freeforming and Fused Deposition Modeling}}},
  doi          = {{10.26153/tsw/17577}},
  year         = {{2021}},
}

@inproceedings{24096,
  abstract     = {{The Arburg Plastic Freeforming (APF) is an additive manufacturing process with which three-dimensional, thermoplastic components can be produced layer by layer. One disadvantage of the APF is the long residence time of the molten material in the plasticizing unit compared to conventional injection moulding. The dosing volume is emptied very slowly due to only discharging fine plastic droplets. As a result, long residence times can be expected, which can lead to thermal degradation of the material.
The aim of this study was to develop a model for calculating the residence time of the material in the APF. The residence time of the material in the thermally critical dosing volume is predicted using software developed in-house. The accuracy of the model could be verified by experimental investigations. Finally, the thermal degradation of the material was investigated by analyzing the correlation to the mechanical properties of tensile strength specimens.
}},
  author       = {{Moritzer, Elmar and Hecker, Felix and Hirsch, André}},
  booktitle    = {{Proceedings: 2021 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2021)}},
  editor       = {{Bourell, David}},
  location     = {{Austin, Texas, USA}},
  pages        = {{1268--1275}},
  title        = {{{Investigation and Modeling of the Residence Time Dependent Material Degradation in the Arburg Plastic Freeforming}}},
  doi          = {{10.26153/tsw/17643}},
  year         = {{2021}},
}

@inproceedings{24160,
  abstract     = {{In automotive and other fields of application media-carrying components often have complex, flow-optimized geometries and are made of plastics for reasons of weight and cost. Therefore, the laser sintering technology is predestinated to manufacture these components as it offers a very high degree of design freedom and good mechanical properties.
For industrial applications the long-term properties of the SLS material in contact with liquid media are important and were therefore investigated for PA12, PP and PA613. Hereby, different media such as motor oil or Glysantin based coolant were tested with different temperatures and immersion times of up to 26 weeks. The mechanical properties were tested after immersion and compared to injection molded samples. Furthermore, laser sintering design guidelines for media-carrying components were developed. These guidelines for instance include the minimum wall thickness to ensure media tightness and the removal of powder from channels with a high length to diameter ratio.}},
  author       = {{Kletetzka, Ivo and Kummert, Christina and Schmid, Hans-Joachim}},
  booktitle    = {{Proceedings of the 32nd Annual International Solid Freeform Fabrication Symposium}},
  location     = {{Austin}},
  publisher    = {{Laboratory for Freeform Fabrication and University of Texas}},
  title        = {{{Laser Sintering Design Guidelines for media transmitting Components}}},
  doi          = {{http://dx.doi.org/10.26153/tsw/17548}},
  volume       = {{32}},
  year         = {{2021}},
}

@article{24535,
  abstract     = {{<jats:p>Implementing the concept of mixed construction in modern automotive engineering requires the joining of sheet metal or extruded profiles with cast components made from different materials. As weight reduction is desired, these cast components are usually made from high-strength aluminium alloys of the Al-Si (Mn, Mg) system, which have limited weldability. The mechanical joinability of the cast components depends on their ductility, which is influenced by the microstructure. High-strength cast aluminium alloys have relatively low ductility, which leads to cracking of the joints. This limits the range of applications for cast aluminium alloys. In this study, an aluminium alloy of the Al-Si system AlSi9 is used to investigate relationships between solidification conditions during the sand casting process, microstructure, mechanical properties, and joinability. The demonstrator is a stepped plate with a minimum thickness of 2.0 mm and a maximum thickness of 4.0 mm, whereas the thickness difference between neighbour steps amounts to 0.5 mm. During casting trials, the solidification rates for different plate steps were measured. The microscopic investigations reveal a correlation between solidification rates and microstructure parameters such as secondary dendrite arm spacing. Furthermore, mechanical properties and the mechanical joinability are investigated.</jats:p>}},
  author       = {{Neuser, Moritz and Grydin, Olexandr and Andreiev, Anatolii and Schaper, Mirko}},
  issn         = {{2075-4701}},
  journal      = {{Metals}},
  title        = {{{Effect of Solidification Rates at Sand Casting on the Mechanical Joinability of a Cast Aluminium Alloy}}},
  doi          = {{10.3390/met11081304}},
  year         = {{2021}},
}

@article{24537,
  author       = {{Neuser, Moritz and Kappe, Fabian and Busch, M and Grydin, Olexandr and Bobbert, Mathias and Schaper, Mirko and Meschut, Gerson and Hausotte, T}},
  issn         = {{1757-8981}},
  journal      = {{IOP Conference Series: Materials Science and Engineering}},
  title        = {{{Joining suitability of cast aluminium for self-piercing riveting}}},
  doi          = {{10.1088/1757-899x/1157/1/012005}},
  year         = {{2021}},
}

@inproceedings{22285,
  author       = {{Biermeier, Kai and Yigitbas, Enes and Weidmann, Nils and Engels, Gregor}},
  booktitle    = {{Proceedings of the International Workshop on Human-Centered Software Engineering for Changing Contexts of Use }},
  title        = {{{Ensuring User Interface Adaptation Consistency through Triple Graph Grammers}}},
  year         = {{2021}},
}

@misc{54402,
  abstract     = {{Dataset of the publication “Nondegenerate two-photon absorption in ZnSe: Experiment and theory“, L. Krauss-Kodytek, W.-R. Hannes, T. Meier, C. Ruppert, and M. Betz, Phys. Rev. B 104, 085201 (2021). ( https://doi.org/10.1103/PhysRevB.104.085201 ). The zip file includes the data on which the plots shown in figures 3, 4, and 5 are based.}},
  author       = {{Krauss-Kodytek, Laura and Hannes, Wolf-Rüdiger and Meier, Torsten and Ruppert, Claudia and Betz, Markus}},
  publisher    = {{LibreCat University}},
  title        = {{{Nondegenerate two-photon absorption in ZnSe: Experiment and theory}}},
  doi          = {{10.5281/ZENODO.5195116}},
  year         = {{2021}},
}

@misc{54401,
  abstract     = {{Dataset of the publication “Controlling the emission time of photon echoes by optical freezing of exciton dephasing and rephasing in quantum-dot ensembles“, Proc. SPIE 11684,116840X (2021) ( https://doi.org/10.1117/12.2576887 ). The zip file includes the data on which the figures are based, the gnuplot files for the figures, and an explaining readme.txt.}},
  author       = {{Reichelt, Matthias and Rose, Hendrik and Kosarev, Alexander N. and Poltavtsev, Sergey V. and Bayer, Manfred and Akimov, Ilya A. and Schneider, Christian and Kamp, Martin and Höfling, Sven and Meier, Torsten}},
  publisher    = {{LibreCat University}},
  title        = {{{Controlling the emission time of photon echoes by optical freezing of exciton dephasing and rephasing in quantum-dot ensembles}}},
  doi          = {{10.5281/ZENODO.5226911}},
  year         = {{2021}},
}

@article{21821,
  abstract     = {{We present a combined experimental and numerical study of the far-field emission properties of optical travelling wave antennas made from low-loss dielectric materials. The antennas considered here are composed of two simple building blocks, a director and a reflector, deposited on a glass substrate. Colloidal quantum dots placed in the feed gap between the two elements serve as internal light source. The emission profile of the antenna is mainly formed by the director while the reflector suppresses backward emission. Systematic studies of the director dimensions as well as variation of antenna material show that the effective refractive index of the director primarily governs the far-field emission pattern. Below cut off, i.e., if the director’s effective refractive index is smaller than the refractive index of the substrate, the main lobe results from leaky wave emission along the director. In contrast, if the director supports a guided mode, the emission predominately originates from the end facet of the director.}},
  author       = {{Leuteritz, T. and Farheen, Henna and Qiao, S. and Spreyer, F. and Schlickriede, Christian and Zentgraf, Thomas and Myroshnychenko, Viktor and Förstner, Jens and Linden, S.}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{tet_topic_opticalantenna}},
  number       = {{10}},
  title        = {{{Dielectric travelling wave antennas for directional light emission}}},
  doi          = {{10.1364/oe.422984}},
  volume       = {{29}},
  year         = {{2021}},
}

@inproceedings{36845,
  author       = {{Kruse, Anne and Ott, Manuel and Risse, Lena and Koch, Rainer}},
  location     = {{Berlin}},
  publisher    = {{Deutscher Verband für Materialforschung und -prüfung e.V.}},
  title        = {{{3D-Druck - Eine Technologie als Schlüssel zur Steigerung der Teilhabe}}},
  doi          = {{10.48447/Add-2021-016}},
  year         = {{2021}},
}

@article{25556,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>In order to reduce fuel consumption and thus pollutant emissions, the automotive industry is increasingly developing lightweight construction concepts that are accompanied by an increasing usage of aluminum materials. Due to poor weldability of aluminum in combination with other materials, mechanical joining methods such as clinching were developed and established in series production. In order to predict the relevant characteristics of clinched joints and to ensure the reliability of the process, it is simulated numerically during product development processes. In this regard, the predictive accuracy of the simulated process highly depends on the implemented friction model. In particular, the frictional behavior between the sheet metals as well as between the sheet metal and clinching tools has a significant impact on the geometrical formation of the clinched joint. No testing methods exist that can sufficiently investigate the frictional behavior in sheet materials, especially under high interface pressures, different relative velocities, and long friction paths, while allowing a decoupled consideration of the test parameters. This paper describes the development of further testing concepts based on a proven tribo-torsion test method for determining friction coefficients between sheet metal materials for the simulation of clinching processes. For this purpose, the correlation of interface pressure and the relative velocity between aluminum and steel sheet material in clinching processes is investigated using numerical simulation. Based on these findings, the developed concepts focus on determining friction coefficients at interface pressures of the above materials, yield stress, as well as the reproduction of the occurring friction conditions between sheet metal materials and tool surfaces in clinching processes using tool substitutes. Furthermore, wear investigations between sheet metal material and tool surface were carried out in the friction tests with subsequent EDX analyses of the frictioned tool surfaces. The developed method also allows an optical deformation measurement of the sheet metal material specimen by means of digital image correlation (DIC). Based on a methodological approach, the test setups and the test systems used are explained, and the functionality of the concepts is proven by experimental tests using different sheet metal materials.</jats:p>}},
  author       = {{Böhnke, Max and Rossel, Moritz Sebastian and Bielak, Christian Roman and Bobbert, Mathias and Meschut, Gerson}},
  issn         = {{0268-3768}},
  journal      = {{The International Journal of Advanced Manufacturing Technology}},
  title        = {{{Concept development of a method for identifying friction coefficients for the numerical simulation of clinching processes}}},
  doi          = {{10.1007/s00170-021-07986-4}},
  year         = {{2021}},
}

@article{38517,
  author       = {{Popp, Julian and Kleffel, Tobias and Drummer, Dietmar}},
  journal      = {{Joining Plastics}},
  number       = {{3-4}},
  title        = {{{Influence of pin geometry on the joint strength of CFRT-metal hybrid parts with metallic pins}}},
  volume       = {{15}},
  year         = {{2021}},
}

@inproceedings{34472,
  author       = {{Kullmer, Gunter and Weiß, Deborah and Schramm, Britta}},
  location     = {{Bremen}},
  pages        = {{107--116}},
  title        = {{{Entwicklung einer Methode zur differenzierten Messung des Wachstums der Rissenden von Innenrissen mit der Elektropotentialmethode}}},
  doi          = {{10.48447/BR-2021-013}},
  volume       = {{DVM-Bericht 253}},
  year         = {{2021}},
}

@inproceedings{24006,
  author       = {{Weiß, Deborah and Schramm, Britta and Neuser, Moritz and Grydin, Olexandr and Kullmer, Gunter}},
  location     = {{Bremen}},
  pages        = {{231--240}},
  title        = {{{Experimentelle bruchmechanische Untersuchung eines clinchgeeigneten Bleches aus HCT590X mithilfe einer neuen Probengeometrie}}},
  doi          = {{10.48447/BR-2021-025}},
  volume       = {{DVM-Bericht 253}},
  year         = {{2021}},
}

@article{34227,
  abstract     = {{In order to reduce the fuel consumption and consequently the greenhouse emissions, the automotive industry is implementing lightweight constructions in the body in white production. As a result, the use of aluminum alloys is continuously increasing. Due to poor weldability of aluminum in combination with other materials, mechanical joining technologies like clinching are increasingly used. In order to predict relevant characteristics of clinched joints and to ensure the reliability of the process, it is simulated numerically during product development processes. In this regard the predictive accuracy of the simulated process highly depends on the implemented friction model. In particular, the frictional behavior between the sheet metals affects the geometrical formation of the clinched joint significantly. This paper presents a testing method, which enables to determine the frictional coefficients between sheet metal materials for the simulation of clinching processes. For this purpose, the correlation of interface pressure and the relative velocity between aluminum sheets in clinching processes is investigated using numerical simulation. Furthermore, the developed testing method focuses on the specimen geometry as well as the reproduction of the occurring friction conditions between two sheet metal materials in clinching processes. Based on a methodical approach the test setup is explained and the functionality of the method is proven by experimental tests using sheet metal material EN AW6014.}},
  author       = {{Rossel, Moritz Sebastian and Böhnke, Max and Bielak, Christian Roman and Bobbert, Mathias and Meschut, Gerson}},
  issn         = {{1662-9795}},
  journal      = {{Key Engineering Materials}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}},
  pages        = {{81--88}},
  publisher    = {{Trans Tech Publications, Ltd.}},
  title        = {{{Development of a Method for the Identification of Friction Coefficients in Sheet Metal Materials for the Numerical Simulation of Clinching Processes}}},
  doi          = {{10.4028/www.scientific.net/kem.883.81}},
  volume       = {{883}},
  year         = {{2021}},
}

@article{26889,
  author       = {{Luo, Kai Hong and Santandrea, Matteo and Stefszky, Michael and Sperling, Jan and Massaro, Marcello and Ferreri, Alessandro and Sharapova, Polina and Herrmann, Harald and Silberhorn, Christine}},
  issn         = {{2469-9926}},
  journal      = {{Physical Review A}},
  title        = {{{Quantum optical coherence: From linear to nonlinear interferometers}}},
  doi          = {{10.1103/physreva.104.043707}},
  year         = {{2021}},
}