TY - JOUR A1 - Fateri, Miranda A1 - Hötter, Jan-Steffen A1 - Gebhardt, Andreas T1 - Experimental and Theoretical Investigation of Buckling Deformation of Fabricated Objects by Selective Laser Melting JF - Physics Procedia N2 - Although Selective Laser Melting (SLM) process is an innovative manufacturing method, there are challenges such as inferior mechanical properties of fabricated objects. Regarding this, buckling deformation which is caused by thermal stress is one of the undesired mechanical properties which must be alleviated. As buckling deformation is more observable in hard to process materials, silver is selected to be studied theoretically and experimentally for this paper. Different scanning strategies are utilized and a Finite Element Method (FEM) is applied to calculate the temperature gradient in order to determine its effect on the buckling deformation of the objects from experiments. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.phpro.2012.10.062 SN - 1875-3892 N1 - Part of special issue "Laser Assisted Net shape Engineering 7 (LANE 2012)" VL - 39 SP - 464 EP - 470 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Gebhardt, Andreas A1 - Fateri, Miranda T1 - 3D printing and its applications JF - RTejournal - Forum für Rapid Technologie N2 - Eine zunehmende Anzahl von Artikeln in Publikumszeitschriften und Journalen rückt die direkte Herstellung von Bauteilen und Figuren immer mehr in das Bewusstsein einer breiten Öffentlichkeit. Leider ergibt sich nur selten ein einigermaßen vollständiges Bild davon, wie und in welchen Lebensbereichen diese Techniken unseren Alltag verändern werden. Das liegt auch daran, dass die meisten Artikel sehr technisch geprägt sind und sich nur punktuell auf Beispiele stützen. Dieser Beitrag geht von den Bedürfnissen der Menschen aus, wie sie z.B. in der Maslow’schen Bedürfnispyramide strukturiert dargestellt sind und unterstreicht dadurch, dass 3D Printing (oder Additive Manufacturing resp. Rapid Prototyping) bereits alle Lebensbereiche erfasst hat und im Begriff ist, viele davon zu revolutionieren. N2 - An increasing amount of popular articles focus on making models and sculptures by 3D Printing thus making more and more even private users aware of this technology. Unfortunately they mostly draw an incomplete picture of how our daily life will be influenced by this new technology. Often this is caused by a very technical point of view based on not very representative examples. This article focuses on the peoples needs as they have been structured by the so-called Maslow pyramid. Doing so, it underlines that 3D Printing (called Additive Manufacturing or Rapid Prototyping as well) already touches all aspects of life and is about to revolutionize most of them. Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0009-2-35626 SN - 1614-0923 VL - 10 IS - 1 PB - Fachhochschule Aachen CY - Aachen ER - TY - JOUR A1 - Abdel-Latif, Lotfie Ahmed A1 - Peeken, Heinz A1 - Benner, Joachim T1 - Thermohydrodynamic analysis of thrust-bearing with circular pads running on bubbly oil (BTHD-theory) JF - Journal of tribology Y1 - 1985 SN - 0742-4787 SN - 1528-8897 VL - 107 IS - 4 SP - 527 EP - 537 ER - TY - JOUR A1 - Frohberg, Martin G. A1 - Anik, Sabri T1 - The calculation of component activities of binary metallic melts from their gas solubilities JF - Zeitschrift für Metallkunde Y1 - 1985 SN - 0044-3093 VL - 76 IS - 2 SP - 135 EP - 137 ER - TY - JOUR A1 - Anik, Sabri A1 - Frohberg, Martin G. T1 - Thermodynamics and solubility of oxygen in liquid copper-lead alloys at 1200°C from E.M.F. measurements JF - Berichte der Bunsengesellschaft für physikalische Chemie Y1 - 1984 SN - 0940-483X SN - 0005-9021 VL - 88 IS - 8 SP - 707 EP - 710 ER - TY - JOUR A1 - Anik, Sabri A1 - Frohberg, Martin G. A1 - Kapoor, Madan Lal T1 - Experiments and theoretical considerations on the solution of oxygen in binary metal alloys JF - Berichte der Bunsengesellschaft für physikalische Chemie Y1 - 1983 SN - 0005-9021 SN - 0940-483X VL - 87 IS - 12 SP - 1201 EP - 1204 ER - TY - JOUR A1 - Frohberg, Martin G. A1 - Anik, Sabri T1 - Thermodynamic relations between component activities and gas solubilities in binary metallic systems JF - Berichte der Bunsengesellschaft für physikalische Chemie Y1 - 1985 SN - 0940-483X SN - 0005-9021 VL - 89 IS - 2 SP - 130 EP - 134 ER - TY - JOUR A1 - Anik, Sabri A1 - Frohberg, Martin G. T1 - Thermodynamics and solubility of oxygen in liquid bismuth-lead and bismuth-antimony alloys JF - Berichte der Bunsengesellschaft für physikalische Chemie Y1 - 1987 SN - 0940-483X SN - 0005-9021 VL - 91 IS - 7 SP - 790 EP - 794 ER - TY - JOUR A1 - Wang, Mao A1 - Anik, Sabri A1 - Frohberg, Martin G. T1 - Experiments on the electrochemical determination of the sulphur activities in the system copper-silver at 1200°C JF - Zeitschrift für Metallkunde Y1 - 1988 SN - 0044-3093 VL - 79 IS - 5 SP - 336 EP - 339 ER - TY - JOUR A1 - Anik, Sabri A1 - Frohberg, Martin G. T1 - Investigations of the thermodynamics of oxygen and the determination of the miscibility gap in the system copper-oxygen-lead at 12000C JF - Zeitschrift für Metallkunde Y1 - 1984 SN - 0044-3093 VL - 75 IS - 8 SP - 586 EP - 589 ER - TY - JOUR A1 - Frohberg, Martin G. A1 - Anik, Sabri T1 - The application of a quadi-chemical lattice model to binary metallic solvents containing oxygen in higher concentrations JF - Zeitschrift für Metallkunde Y1 - 1983 SN - 0044-3093 VL - 74 IS - 10 SP - 665 EP - 666 ER - TY - JOUR A1 - Anik, Sabri A1 - Frohberg, Martin G. T1 - Investigation of the thermodynamics of oxygen and the determination of phase boundaries in the system copper-oxygen-bismuth at 12000C JF - Zeitschrift für Metallkunde Y1 - 1983 SN - 0044-3093 VL - 74 IS - 8 SP - 530 EP - 534 ER - TY - JOUR A1 - Anik, Sabri A1 - Kapoor, Madan Lal A1 - Frohberg, Martin G. T1 - Thermodynamic behaviour of oxygen in molten substitutional alloy solvents JF - Zeitschrift für Metallkunde Y1 - 1983 SN - 0044-3093 VL - 74 IS - 1 SP - 53 EP - 58 ER - TY - JOUR A1 - Anik, Sabri A1 - Frohberg, Martin G. A1 - Kapoor, Madan Lal T1 - Prediction of thermodynamic properties of oxygen in binary metallic solvents JF - Zeitschrift für Metallkunde Y1 - 1983 SN - 0044-3093 VL - 74 IS - 6 SP - 372 EP - 375 ER - TY - JOUR A1 - Anik, Sabri A1 - Frohberg, Martin G. T1 - Thermodynamics of oxygen in the copper-antimony system at 1473K JF - Erzmetall : Rohstoffgewinnung, Verarbeitung, Recycling, Umwelttechnik Y1 - 1988 SN - 0044-2658 VL - 41 IS - 10 SP - 498 EP - 501 ER - TY - JOUR A1 - Wang, Mao A1 - Anik, Sabri A1 - Frohberg, Martin G. T1 - Thermodynamics of oxygen in the lead-antimony system at 1173 K JF - Erzmetall : Rohstoffgewinnung, Verarbeitung, Recycling, Umwelttechnik Y1 - 1987 SN - 0044-2658 VL - 40 IS - 6 SP - 316 EP - 319 ER - TY - JOUR A1 - Dilthey, Ulrich A1 - Brandenburg, Annette A1 - Schleser, Markus T1 - Dispensing and application of unfilled adhesives in the micro range JF - Welding and cutting. 3 (2004), H. 4 Y1 - 2004 SN - 1612-3433 SP - 250 EP - 254 ER - TY - JOUR A1 - Reisgen, Uwe A1 - Schleser, Markus A1 - Mokrov, Oleg A1 - Ahmed, Essam T1 - Statistical modeling of laser welding of DP/TRIP steel sheets JF - Optics and laser technology N2 - In this research work, a statistical analysis of the CO2 laser beam welding of dual phase (DP600)/transformation induced plasticity (TRIP700) steel sheets was done using response surface methodology. The analysis considered the effect of laser power (2–2.2 kW), welding speed (40–50 mm/s) and focus position (−1 to 0 mm) on the heat input, the weld bead geometry, uniaxial tensile strength, formability limited dome height and welding operation cost. The experimental design was based on Box–Behnken design using linear and quadratic polynomial equations for predicting the mathematical models. The results indicate that the proposed models predict the responses adequately within the limits of welding parameters being used and the welding speed is the most significant parameter during the welding process. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.optlastec.2011.05.025 SN - 1879-2545 (E-Journal); 0030-3992 (Print); 0308-4280 (Print) VL - 44 IS - 1 SP - 92 EP - 101 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reisgen, Uwe A1 - Schleser, Markus A1 - Mokrov, Oleg A1 - Ahmed, Essam T1 - Optimization of laser welding of DP/TRIP steel sheets using statistical approach JF - Optics and laser technology N2 - Generally, the quality of a weld joint is directly influenced by the welding input parameter settings. Selection of proper process parameters is important to obtain the desired weld bead profile and quality. In this research work, numerical and graphical optimization techniques of the CO2 laser beam welding of dual phase (DP600)/transformation induced plasticity (TRIP700) steel sheets were carried out using response surface methodology (RSM) based on Box–Behnken design. The procedure was established to improve the weld quality, increase the productivity and minimize the total operation cost by considering the welding parameters range of laser power (2–2.2 kW), welding speed (40–50 mm/s) and focus position (−1 to 0 mm). It was found that, RSM can be considered as a powerful tool in experimental welding optimization, even when the experimenter does not have a model for the process. Strong, efficient and low cost weld joints could be achieved using the optimum welding conditions. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.optlastec.2011.06.028 SN - 1879-2545 (E-Journal); 0030-3992 (Print); 0308-4280 (Print) VL - 44 IS - 1 SP - 255 EP - 262 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reisgen, Uwe A1 - Olschok, Simon A1 - Jakobs, Stefan A1 - Schleser, Markus A1 - Mokrov, Oleg A1 - Rossiter, Eduardo T1 - Laser beam submerged arc hybrid welding JF - Physics procedia N2 - The laser beam-submerged arc hybrid welding method originates from the knowledge that, with increasing penetration depth, the laser beam process has a tendency to pore formation in the lower weld regions. The coupling with the energy-efficient submerged-arc process improves degassing and reduces the tendency to pore formation. The high deposition rate of the SA process in combination with the laser beam process offers, providing the appropriate choice of weld preparation, the possibility of welding plates with a thickness larger than 20° mm in a single pass, and also of welding thicker plates with the double-sided single pass technique. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.phpro.2012.10.016 SN - 1875-3892 N1 - Part of special issue "Laser assisted net shape engineering 7 (LANE 2012)" VL - 39 SP - 75 EP - 83 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reisgen, Uwe A1 - Schleser, Markus A1 - Abdurakhmanov, Aydemir A1 - Gumenyuk, Andrey T1 - Measuring of plasma properties induced by non-vacuum electron beam welding JF - Physics of plasma N2 - Electron beam plasma measurement was realised by means of DIABEAM system invented by ISF RWTH Aachen. The Langmuir probe method is used for measurement. The relative simplicity of the method and the possibility of dispersion of high power on the probe allow its application for the investigation of high-power electron beams. The key element of the method is a rotating thin tungsten wire, which intersects the beam transversely on its axis and collects part of the current by itself. The signals, which are registered in the DIABEAM as a voltage, were taken in the form of amplitude. The conversion of the probe current into the distribution along the beam radius was realised using the Abel’s method. A voltage-current characteristic was built for the beam current. The local electron density as well as the electron temperature, the floating potential and the plasma potential were measured and calculated by means of this characteristic. Y1 - 2012 U6 - http://dx.doi.org/10.1063/1.3675874 SN - 1089-7674 (E-Journal); 1070-664X (Print) VL - 19 IS - 1 SP - 1 EP - 7 PB - AIP Publishing CY - Melville, NY ER - TY - JOUR A1 - Mukherjee, Krishnendu A1 - Ramazani, Ali A1 - Yang, Li A1 - Prahl, Ulrich A1 - Bleck, Wolfgang A1 - Reisgen, Uwe A1 - Schleser, Markus A1 - Abdurakhmanov, Aydemir T1 - Characterization of gas metal arc welded hot rolled DP600 steel JF - Steel research international Y1 - 2011 SN - 1869-344X (E-Book); 1611-3683 (Print) VL - Vol. 82 IS - Iss. 12 SP - 1408 EP - 1416 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Glowania, Michael A1 - Gries, Thomas A1 - Schoene, Jens A1 - Schleser, Markus A1 - Reisgen, Uwe T1 - Innovative coating technology for textile reinforcements of concrete applications JF - 13th International Congress on Polymers in Concrete : 10 - 12 February 2010, Funchal, Madeira, Portugal.(Key engineering materials. Vol. 466) Y1 - 2011 SN - 978-3-03785-008-4 SN - 1013-9826 (E-Journal) ; 0252-1059 (Print) SP - 167 EP - 173 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Reisgen, Uwe A1 - Schleser, Markus A1 - Mokrov, Oleg A1 - Ahmed, Essam T1 - Numerical and experimental investigation of tensile behavior of laser beam welded TRIP700 steel JF - ISIJ international Y1 - 2011 SN - 1347-5460 (E-Journal); 0915-1559 (Print) VL - Vol. 51 IS - No. 3 SP - 429 EP - 434 PB - ISIJ CY - Tōkyō ER - TY - JOUR A1 - Roesner, Andreas A1 - Scheik, Sven A1 - Olowinsky, Alexander A1 - Gillner, Arnold A1 - Propawe, Reinhart A1 - Schleser, Markus A1 - Reisgen, Uwe T1 - Innovative approach of joining hybrid components JF - Journal of laser applications Y1 - 2011 SN - 1042-346X VL - Vol. 23 IS - Iss. 3 SP - 32007 PB - Laser Institute of America CY - Orlando, Fla. ER - TY - JOUR A1 - Roesner, Andreas A1 - Scheik, Sven A1 - Olowinsky, Alexander A1 - Gillner, Arnold A1 - Reisgen, Uwe A1 - Schleser, Markus T1 - Laser assisted joining of plastic metal hybrids JF - Lasers in manufacturing 2011 : proceedings of the sixth International WLT Conference on Lasers in Manufacturing, Munich, May 23 - 26 2011. (Physics procedia ; Vol. 12 (2011), Part B) Y1 - 2011 SN - 1875-3892 (E-Journal); 1875-3884 (Print) SP - 370 EP - 377 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reisgen, Uwe A1 - Schleser, Markus A1 - Mokrov, Oleg A1 - Zabirov, Alexander T1 - Virtual welding equipment for simulation of GMAW processes with integration of power source regulation JF - Frontiers of materials science Y1 - 2011 SN - 2095-0268 (E-Journal); 2095-025X (Print) VL - Vol. 5 IS - Iss. 2 SP - 79 EP - 89 PB - Springer CY - Berlin ER - TY - JOUR A1 - Schleser, Markus A1 - Walk-Lauffer, Bernd A1 - Raupach, Michael A1 - Dilthey, Ulrich T1 - Application of polymers for textile-reinforced concrete JF - Journal of materials in civil engineering : properties, applications, durability Y1 - 2006 SN - 0899-1561 VL - 18 IS - 5 SP - 670 EP - 676 ER - TY - JOUR A1 - Feldmann, Markus A1 - Pak, Daniel A1 - Geßler, Achim A1 - Dilthey, Ulrich A1 - Schleser, Markus T1 - Bonded connections for textile reinforced concrete structures JF - Cailiao-gongcheng = Journal of materials engineering Y1 - 2006 SN - 1001-4381 IS - Special iss. SP - 123 EP - 127 ER - TY - JOUR A1 - Dilthey, Ulrich A1 - Schleser, Markus A1 - Feldmann, Martin A1 - Pak, Daniel A1 - Geßler, Achim T1 - Investigation of punctiform, plane and hybrid joints of textile-reinforced concrete parts JF - Cement and concrete composites Y1 - 2008 SN - 0958-9465 VL - Vol. 30 IS - iss. 2 SP - 82 EP - 87 ER - TY - JOUR A1 - Reisgen, Uwe A1 - Schleser, Markus A1 - Mokrov, Oleg A1 - Zabirov, Alexander A1 - Füssel, Uwe A1 - Schnick, Michael A1 - Hertel, Martin A1 - Jaeckel, Sebastian T1 - Modelling and visualisation of the GMA process JF - Welding and Cutting Y1 - 2012 SN - 1612-3433 VL - 11 IS - 4 SP - 242 EP - 249 PB - DVS Verlag CY - Düsseldorf ER - TY - JOUR A1 - Ramazani, Ali A1 - Li, Yang A1 - Mukherjee, Krishnendu A1 - Prahl, Ulrich A1 - Bleck, Wolfgang A1 - Abdurakhmanov, Aydemir A1 - Schleser, Markus A1 - Reisgen, Uwe T1 - Microstructure evolution simulation in hot rolled DP600 steel during gas metal arc welding JF - Computational materials science Y1 - 2013 SN - 1879-0801 (E-Book); 0927-0256 (Print) VL - Vol. 68 SP - 107 EP - 116 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hötter, Jan-Steffen A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Selective laser melting of metals: desktop machines open up new chances even for small companies JF - Advanced materials research N2 - Additive manufacturing (AM) of metal parts by using Selective Laser Melting (SLM) has become a powerful tool mostly in the area of automotive, aerospace engineering and others. Especially in the field of dentistry, jewelry and related branches that require individualized or even one-of-a-kind products, the direct digital manufacturing process opens up new ways of design and manufacturing. In these fields, mostly small and medium sized businesses (SME) are operating which do not have sufficient human and economic resources to invest in this technology. But to stay competitive, the application of AM can be regarded as a necessity. In this situation a new desktop machine (Realizer SLM 50) was introduced that cost about 1/3 of a shop floor SLM machine and promises small quality parts. To find out whether the machine really is an alternative for SMEs the University of Applied Science, Aachen, Germany, designed, build and optimized typical parts from the dentistry and the jewelry branches using CoCr and silver material, the latter being new with this application. The paper describes the SLM procedure and how to find and optimize the most important parameters. The test is accompanied by digital simulation in order to verify the build parameters and to plan future builds. The procedure is shown as well as the resulting parts made from CoCr and silver material. Y1 - 2012 U6 - http://dx.doi.org/10.4028/www.scientific.net/AMR.622-623.461 SN - 1662-8985 (E-Journal); 1022-6680 (Print) VL - 622-623 SP - 461 EP - 465 PB - Trans Tech Publ. CY - Baech ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas A1 - Thümmler, Stefan A1 - Thurn, Laura T1 - Experimental investigation on selective laser melting of glass JF - Physics procedia : 8th International Conference on Laser Assisted Net Shape Engineering LANE 2014 Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.phpro.2014.08.118 SN - 1875-3892 (E-Journal); 1875-3884 (Print) VL - 56 (2014) SP - 357 EP - 364 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pfaff, Raphael A1 - Burnham, Keith J. T1 - On abstraction and interpretability: a behavioural perspective JF - Systems Science Y1 - 2009 SN - 0137-1223 VL - Vol. 35 IS - Iss. 2 SP - 19 EP - 26 ER - TY - JOUR A1 - Seiler, Friedrich A1 - Pichler, Alexander A1 - Pfaff, Raphael A1 - Srulijes, Julio T1 - Novel processing tools for automated doppler picture velocimetry (DPV) evaluation JF - Journal of visualization Y1 - 2009 SN - 1343-8875 VL - Vol. 12 IS - Iss. 4 SP - 323 EP - 337 ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Selective Laser Melting of Soda-Lime Glass Powder JF - International Journal of Applied Ceramic Technology Y1 - 2015 U6 - http://dx.doi.org/10.1111/ijac.12338 SN - 1744-7402 VL - 12 IS - 1 SP - 53 EP - 61 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Process Parameters Development of Selective Laser Melting of Lunar Regolith for On-Site Manufacturing Applications JF - International Journal of Applied Ceramic Technology Y1 - 2015 SN - 1744-7402 U6 - http://dx.doi.org/10.1111/ijac.12326 VL - 12 IS - 1 SP - 46 EP - 52 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Kämper, Klaus-Peter A1 - Picard, Antoni A1 - Brill, Manfred A1 - Cassel, Detlev A1 - Jentsch, Andreas A1 - Merten, Sabine A1 - Rollwa, Markus T1 - The Virtual Clean Room - a new tool in teaching MST process technologies N2 - The Virtual Clean Room - a new tool in teaching MST process technologies University education in high-technology fields like MST is not complete without intensive laboratory sessions. Students cannot fully grasp the complexity and the special problems related to the manufacturing of microsystems without a thorough hands-on experience in a MST clean room. KW - Virtuelle Maschine KW - VM KW - Mikrosystemtechnik KW - MST KW - virtual clean room Y1 - 2003 ER - TY - JOUR A1 - Gebhardt, Andreas T1 - Generative Manufacturing of Ceramic Parts "Vision Rapid Prototyping" N2 - Table of Contents Introduction 1. Generative Manufacturing Processes 2. Classification of Generative Manufacturing Processes 3. Application of Generative Processes on the Fabrication of Ceramic Parts 3.1 Extrusion 3.2 3D-Printing 3.3 Sintering – Laser Sintering 3.4 Layer-Laminate Processes 3.5 Stereolithography (sometimes written: Stereo Lithography) 4. Layer Milling 5. Conclusion - Vision KW - Rapid prototyping KW - Rapid Technologie KW - Rapid Prototyping Y1 - 2006 ER - TY - JOUR A1 - Leidinger, Rafael A1 - Noisten, Thomas A1 - Wollert, Jörg T1 - Realtime automation networks in moVing industrial environments JF - Journal of systemics, cybernetics and informatics N2 - The radio-based wireless data communication has made the realization of new technical solutions possible in many fields of the automation technology (AT). For about ten years, a constant disproportionate growth of wireless technologies can be observed in the automation technology. However, it shows that especially for the AT, conventional technologies of office automation are unsuitable and/or not manageable. The employment of mobile services in the industrial automation technology has the potential of significant cost and time savings. This leads to an increased productivity in various fields of the AT, for example in the factory and process automation or in production logistics. In this paper technologies and solutions for an automation-suited supply of mobile wireless services will be introduced under the criteria of real time suitability, IT-security and service orientation. Emphasis will be put on the investigation and development of wireless convergence layers for different radio technologies, on the central provision of support services for an easy-to-use, central, backup enabled management of combined wired / wireless networks and on the study on integrability in a Profinet real-time Ethernet network. KW - PROFINET KW - Distributed Control Systems, KW - Industrial Automation Technology, KW - 802.15.4 KW - Bluetooth KW - Wireless Networks Y1 - 2012 SN - 1690-4532 VL - Vol. 10 IS - Iss. 2 SP - 52 EP - 56 PB - IIIC CY - Orlando ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Additive manufactured mechanical disentanglement lock JF - RTejournal - Forum für Rapid Technologie Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0009-2-42147 SN - 1614-0923 VL - 12 PB - Fachhochschule Aachen CY - Aachen ER - TY - JOUR A1 - Kessler, Julia A1 - Balc, Nicolae A1 - Gebhardt, Andreas A1 - Abbas, Karim T1 - Basic Research on Lattice Structures Focused on the Tensile Strength JF - Applied Mechanics and Materials Y1 - 2015 U6 - http://dx.doi.org/10.4028/www.scientific.net/AMM.808.193 SN - 1662-7482 N1 - MTeM ; October 14-16, 2015, Cluj-Napoca, Romania VL - Vol. 808 SP - 193 EP - 198 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Koster, Arie A1 - Scheidweiler, Robert A1 - Tieves, Martin T1 - A flow based pruning scheme for enumerative equitable coloring algorithms JF - A flow based pruning scheme for enumerative equitable coloring algorithms N2 - An equitable graph coloring is a proper vertex coloring of a graph G where the sizes of the color classes differ by at most one. The equitable chromatic number is the smallest number k such that G admits such equitable k-coloring. We focus on enumerative algorithms for the computation of the equitable coloring number and propose a general scheme to derive pruning rules for them: We show how the extendability of a partial coloring into an equitable coloring can be modeled via network flows. Thus, we obtain pruning rules which can be checked via flow algorithms. Computational experiments show that the search tree of enumerative algorithms can be significantly reduced in size by these rules and, in most instances, such naive approach even yields a faster algorithm. Moreover, the stability, i.e., the number of solved instances within a given time limit, is greatly improved. Since the execution of flow algorithms at each node of a search tree is time consuming, we derive arithmetic pruning rules (generalized Hall-conditions) from the network model. Adding these rules to an enumerative algorithm yields an even larger runtime improvement. Y1 - 2016 U6 - http://dx.doi.org/10.48550/arXiv.1607.08754 N1 - Lehrstuhl II für Mathematik, RWTH Aachen University SP - 1 EP - 30 ER - TY - JOUR A1 - Beckenbach, Isabel A1 - Scheidweiler, Robert T1 - Perfect ƒ-Matchings and ƒ-Factors in Hypergraphs - A Combinatorial Approach JF - Discrete Mathematics N2 - We prove characterizations of the existence of perfect ƒ-matchings in uniform mengerian and perfect hypergraphs. Moreover, we investigate the ƒ-factor problem in balanced hypergraphs. For uniform balanced hypergraphs we prove two existence theorems with purely combinatorial arguments, whereas for non-uniform balanced hypergraphs we show that the ƒ-factor problem is NP-hard. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.disc.2017.05.005 SN - 2192-7782 N1 - Als Volltext auch bei ZIB (Zuse Institute Berlin) VL - 240 IS - 10 SP - 2499 EP - 2506 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Scheidweiler, Robert A1 - Triesch, Eberhard T1 - A note on the duality between matchings and vertex covers in balanced hypergraphs JF - Journal of Combinatorial Optimization N2 - We present a new Min-Max theorem for an optimization problem closely connected to matchings and vertex covers in balanced hypergraphs. The result generalizes Kőnig’s Theorem (Berge and Las Vergnas in Ann N Y Acad Sci 175:32–40, 1970; Fulkerson et al. in Math Progr Study 1:120–132, 1974) and Hall’s Theorem (Conforti et al. in Combinatorica 16:325–329, 1996) for balanced hypergraphs. KW - Hall’s Theorem KW - Koenig’s Theorem KW - Duality KW - Balanced hypergraph KW - Hypergraph KW - Vertex cover KW - Matching Y1 - 2016 U6 - http://dx.doi.org/10.1007/s10878-015-9887-5 SN - 1573-2886 N1 - Lehrstuhl II für Mathematik RWTH Aachen VL - 32 IS - 2 SP - 639 EP - 644 PB - Springer CY - Berlin ER - TY - JOUR A1 - Kilic, S. A. A1 - Raatschen, Hans-Jürgen A1 - Körfgen, B. A1 - Apaydin, N. M. A1 - Astaneh-Asl, A. T1 - FE Model of the Fatih Sultan Mehmet Suspension Bridge Using Thin Shell Finite Elements JF - Arabian Journal for Science and Engineering N2 - This paper presents the results of an eigenvalue analysis of the Fatih Sultan Mehmet Bridge. A high-resolution finite element model was created directly from the available design documents. All physical properties of the structural components were included in detail, so no calibration to the measured data was necessary. The deck and towers were modeled with shell elements. A nonlinear static analysis was performed before the eigenvalue calculation. The calculated natural frequencies and corresponding mode shapes showed good agreement with the available measured ambient vibration data. The calculation of the effective modal mass showed that nine modes had single contributions higher than 5 % of the total mass. They were in a frequency range up to 1.2 Hz. The comparison of the results for the torsional modes especially demonstrated the advantage of using thin shell finite elements over the beam modeling approach. KW - Suspension bridge KW - 3D nonlinear finite element model KW - Thin shell finite elements KW - Natural frequency KW - Effective modal mass Y1 - 2017 U6 - http://dx.doi.org/10.1007/s13369-016-2316-y SN - 2191-4281 VL - 42 IS - 3 SP - 1103 EP - 1116 PB - Springer Nature ER - TY - JOUR A1 - Rieper, Harald A1 - Gebhardt, Andreas A1 - Stucker, Brent T1 - Selective Laser Melting of the Eutectic Silver-Copper Alloy Ag 28 wt % Cu JF - RTejournal - Forum für Rapid Technologie N2 - The aim of this work was to perform a detailed investigation of the use of Selective Laser Melting (SLM) technology to process eutectic silver-copper alloy Ag 28 wt. % Cu (also called AgCu28). The processing occurred with a Realizer SLM 50 desktop machine. The powder analysis (SEM-topography, EDX, particle distribution) was reported as well as the absorption rates for the near-infrared (NIR) spectrum. Microscope imaging showed the surface topography of the manufactured parts. Furthermore, microsections were conducted for the analysis of porosity. The Design of Experiments approach used the response surface method in order to model the statistical relationship between laser power, spot distance and pulse time. KW - SLM KW - Response Surface Method KW - Porositat KW - Eutectic Silver Copper alloy KW - Additive Manufacturing Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?nbn:de:0009-2-44141 SN - 1614-0923 VL - 13 ER - TY - JOUR A1 - Haag, S. A1 - Zontar, D. A1 - Schleupen, Josef A1 - Müller, T. A1 - Brecher, C. T1 - Chain of refined perception in self-optimizing assembly of micro-optical systems JF - Journal of sensors and sensor systems N2 - Today, the assembly of laser systems requires a large share of manual operations due to its complexity regarding the optimal alignment of optics. Although the feasibility of automated alignment of laser optics has been shown in research labs, the development effort for the automation of assembly does not meet economic requirements – especially for low-volume laser production. This paper presents a model-based and sensor-integrated assembly execution approach for flexible assembly cells consisting of a macro-positioner covering a large workspace and a compact micromanipulator with camera attached to the positioner. In order to make full use of available models from computer-aided design (CAD) and optical simulation, sensor systems at different levels of accuracy are used for matching perceived information with model data. This approach is named "chain of refined perception", and it allows for automated planning of complex assembly tasks along all major phases of assembly such as collision-free path planning, part feeding, and active and passive alignment. The focus of the paper is put on the in-process image-based metrology and information extraction used for identifying and calibrating local coordinate systems as well as the exploitation of that information for a part feeding process for micro-optics. Results will be presented regarding the processes of automated calibration of the robot camera as well as the local coordinate systems of part feeding area and robot base. Y1 - 2014 U6 - http://dx.doi.org/10.5194/jsss-3-87-2014 SN - 2194-878X VL - 3 IS - 1 SP - 87 EP - 95 PB - Copernicus Publ. CY - Göttingen ER - TY - JOUR A1 - Michaux, F. A1 - Mattern, P. A1 - Kallweit, Stephan T1 - RoboPIV: how robotics enable PIV on a large industrial scale JF - Measurement Science and Technology N2 - This work demonstrates how the interaction between particle image velocimetry (PIV) and robotics can massively increase measurement efficiency. The interdisciplinary approach is shown using the complex example of an automated, large scale, industrial environment: a typical automotive wind tunnel application. Both the high degree of flexibility in choosing the measurement region and the complete automation of stereo PIV measurements are presented. The setup consists of a combination of three robots, individually used as a 6D traversing unit for the laser illumination system as well as for each of the two cameras. Synchronised movements in the same reference frame are realised through a master-slave setup with a single interface to the user. By integrating the interface into the standard wind tunnel management system, a single measurement plane or a predefined sequence of several planes can be requested through a single trigger event, providing the resulting vector fields within minutes. In this paper, a brief overview on the demands of large scale industrial PIV and the existing solutions is given. Afterwards, the concept of RoboPIV is introduced as a new approach. In a first step, the usability of a selection of commercially available robot arms is analysed. The challenges of pose uncertainty and importance of absolute accuracy are demonstrated through comparative measurements, explaining the individual pros and cons of the analysed systems. Subsequently, the advantage of integrating RoboPIV directly into the existing wind tunnel management system is shown on basis of a typical measurement sequence. In a final step, a practical measurement procedure, including post-processing, is given by using real data and results. Ultimately, the benefits of high automation are demonstrated, leading to a drastic reduction in necessary measurement time compared to non-automated systems, thus massively increasing the efficiency of PIV measurements. Y1 - 2018 U6 - http://dx.doi.org/10.1088/1361-6501/aab5c1 SN - 1361-6501 N1 - Special Section on the 12th International Symposium on Particle Image Velocimetry (PIV 2017) VL - 29 IS - 7 SP - 074009 PB - IOP CY - Bristol ER -