TY - GEN A1 - Schlier, Lorenz M. A1 - Zhang, Wei A1 - Travitzky, Nahum A1 - Greil, Peter A1 - Cypris, Jochen A1 - Weclas, Miroslaw T1 - Macro-Cellular Silicon carbide Reactors for Nonstationary Combustion Under Piston Engine-Like Conditions T2 - International Journal of Applied Ceramic Technology KW - Three-dimensional printing KW - Macro-cellular SISIC KW - Complex shaped ceramic composites Y1 - 2011 U6 - https://doi.org/10.1111/j.1744-7402.2010.02591.x SN - 1744-7402 VL - 8 IS - 5 SP - 1237 EP - 1245 ER - TY - GEN A1 - Zhang, Wei A1 - Travitzky, Nahum A1 - Hu, Chunfeng A1 - Zhou, Yanchun A1 - Greil, Peter T1 - Reactive Hot Pressing and Properties of Nb2AlC T2 - Journal of the American Ceramic Society KW - MAX phases KW - Ceramic KW - Reactive Hot Pressing Y1 - 2009 U6 - https://doi.org/10.1111/j.1551-2916.2009.03187.x SN - 1551-2916 SN - 0002-7820 VL - 92 IS - 10 SP - 2396 EP - 2399 ER - TY - GEN A1 - Zhang, Wei A1 - Travitzky, Nahum A1 - Greil, Peter T1 - Formation of NbAl3/Al2O3 Composites by pressureless reactive Infiltration T2 - Journal of the American Ceramic Society KW - NbAl3/Al2O3 Composites KW - Pressing and three-dimensional printing KW - Reactive Infiltration Y1 - 2008 U6 - https://doi.org/10.1111/j.1551-2916.2008.02583.x SN - 1551-2916 SN - 0002-7820 VL - 91 IS - 9 SP - 3117 EP - 3120 ER - TY - GEN A1 - Melcher, Reinhold A1 - Zhang, Wei A1 - Travitzky, Nahum A1 - Greil, Peter T1 - 3D-Printing of Al2O3/Cu-O Composites T2 - Ceramic Forum international KW - Al2O3/Cu-O Composites KW - Pressureless Infiltration KW - 3D-Printing Y1 - 2006 SN - 0173-9913 VL - 83 IS - 13 SP - 18 EP - 22 ER - TY - GEN A1 - Jakobsen, Daniel A1 - Zhang, Wei A1 - Doynov, Nikolay A1 - Böhm, Anna A1 - Malzbender, Jürgen A1 - Michailov, Vesselin A1 - Roosen, Andreas T1 - Thermal shock behaviour of laminated multilayer refractories for steel casting applications reinforced by residual stresses T2 - Ceramics International Y1 - 2016 U6 - https://doi.org/10.1016/j.ceramint.2016.05.149 SN - 0272-8842 VL - 42 IS - 12 SP - 13562 EP - 13571 ER - TY - GEN A1 - Zhang, Wei A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Physical and FE-Simulation of Thermal Shock Behaviour of Refractory Ceramics T2 - refractories WORLDFORUM Y1 - 2016 SN - 1868-2405 VL - 8 IS - 2 SP - 110 EP - 117 ER - TY - CHAP A1 - Zhang, Wei A1 - Priefer, Marian A1 - Olenina, Mariia A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Additive manufacturing by laser beam build-up welding T2 - 6th International Conference on Additive Technologies - iCAT 2016, Nürnberg, Germany, 29. - 30. November 2016 Y1 - 2016 SN - 978-961-285-537-6 SP - 324 EP - 327 ER - TY - CHAP A1 - Zhang, Wei A1 - Schramm, Maximilian A1 - Kaneneks, Michael A1 - Michailov, Vesselin A1 - Fleischhauer, Matthias T1 - Laserstrahl-Auftragschweißen mit pulverförmigen keramischen und metallischen Zusatzwerkstoffen zur Herstellung von Gradientenwerkstoffen T2 - Große Schweißtechnische Tagung, Nürnberg, 15. - 17. September 2015 Y1 - 2015 SN - 978-3-945023-46-4 SP - 842 EP - 845 PB - DVS Media CY - Düsseldorf ER - TY - CHAP A1 - Zhang, Wei A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Scheithauer, Uwe A1 - Michaelis, Alexander T1 - Investigation of thermal shock behaviour of refractory ceramics based on the calcium-aluminate T2 - 14th Biennial Worldwide Congress Unified International Technical Conference on Refractories (UNITECR) 2015, Vienna, Austria, September 15-18, 2015 Y1 - 2015 SN - 978-3-9815813-1-7 CY - Hannover ER - TY - GEN A1 - Atanga, Valetine Kubong A1 - Zhang, Wei A1 - Dreibati, Ossama A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Scheffler, Michael T1 - Alumina-mullite Materials for Refractory Applications: Microstructure, Physical and Finite Element Simulation of Thermal Shock Behaviour T2 - refractories WORLDFORUM Y1 - 2012 SN - 1868-2405 VL - 4 IS - 1 SP - 159 EP - 164 ER - TY - GEN A1 - Hantelmann, Cord A1 - Fritzsche, Sebastian A1 - Michailov, Vesselin A1 - Boywitt, Ralf A1 - Risse, Steffen A1 - Paulinus, Dietmar T1 - Utilisation of aluminium foam sandwich components in welded structures T2 - Welding and Cutting Y1 - 2016 SN - 1612-3433 IS - 5 SP - 317 EP - 325 ER - TY - GEN A1 - Hantelmann, Cord A1 - Fritzsche, Sebastian A1 - Michailov, Vesselin A1 - Boywitt, Ralf A1 - Risse, Steffen A1 - Paulinus, Dietmar T1 - Einsatz von Aluminiumschaum-Sandwich-Bauteilen in Schweißkonstruktionen T2 - Schweissen und Scheiden Y1 - 2016 SN - 0036-7184 VL - 68 IS - 3 SP - 106 EP - 114 ER - TY - GEN A1 - Genchev, Gancho Vladimirov A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Modelling the Local Microstructure Properties due to Multi-Pass Welding T2 - Materials Science Forum Y1 - 2017 U6 - https://doi.org/10.4028/www.scientific.net/MSF.879.595 SN - 0255-5476 SN - 1662-9752 N1 - International Conference on Processing & Manufacturing of Advanced Materials Processing, Fabrication, Properties, Applications, May 29 - June 3, 2016 Graz, Austria VL - Vol. 879 SP - 595 EP - 600 ER - TY - GEN A1 - Michailov, Vesselin A1 - Doynov, Nikolay T1 - Analytical-Numerical Modeling Approach for Calculation of the Structural Distortions after Welding and Thermal Straightening T2 - Journal of Mechanics Engineering and Automation Y1 - 2016 U6 - https://doi.org/10.17265/2159-5275/2016.05.004 SN - 2159-5283 SN - 2159-5275 VL - 6 IS - 5 SP - 246 EP - 253 ER - TY - CHAP A1 - Doynov, Nikolay T1 - Anwendungsnahe Simulation des thermischen Richtens T2 - Schweißen in der Maritimen Technik und im Ingenieurbau, 16. Tagung, 20./21. April 2016 in Hamburg Y1 - 2016 SP - 78 EP - 88 PB - GSI SLV Nord CY - Hamburg ER - TY - CHAP A1 - Hantelmann, Cord A1 - Fritzsche, Sebastian A1 - Michailov, Vesselin A1 - Paulinus, Dietmar T1 - Einsatz von Aluminiumschaumsandwich in Schweißkonstruktionen T2 - DVS Congress 2014, Große Schweißtechnische Tagung, DVS-Studentenkongress, Vorträge der Veranstaltungen in Berlin am 15. und 16. September 2014 Y1 - 2014 SN - 978-3-945023-03-7 PB - DVS Media GmbH CY - Düsseldorf ER - TY - CHAP A1 - Seidlitz, Holger A1 - Fritzsche, Sebastian A1 - Schleuß, Leander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Neuartige Fügetechnologie zum Herstellen von hochbelastbaren Multi-Material-Bauweisen aus textilverstärkten Kunststoffen und Metallen bei einseitiger Zugänglichkeit der Fügestelle T2 - DVS Congress 2016, Große Schweißtechnische Tagung, Vorträge der Veranstaltungen in Leipzig am 19. und 20. September 2016 Y1 - 2016 SN - 978-3-945023-74-7 SP - 424 EP - 428 PB - DVS-Verlag CY - Düsseldorf ER - TY - GEN A1 - Koltsova, Tatiana S. A1 - Michailov, Vesselin T1 - Hybrid Composite Materials Aluminum-Carbon Nanostructures T2 - Materials science medziagotyra Y1 - 2015 SN - 1392-1320 SN - 2029–7289 VL - 21 IS - 3 SP - 372 EP - 375 ER - TY - GEN A1 - Koltsova, Tatiana S. A1 - Tolochko, Oleg V. A1 - Michailov, Vesselin T1 - Effect of hot pressing modes on the structure and properties of an aluminum-carbon nanofibers’ composite material T2 - Metal Science and Heat Treatment Y1 - 2015 U6 - https://doi.org/10.1007/s11041-015-9793-6 SN - 0026-0673 SN - 1573-897 VL - 56 IS - 9–10 SP - 525 EP - 530 ER - TY - CHAP A1 - Naumov, Anton A1 - Chenikov, Evgenii V. A1 - Golubev, Iurii A1 - Michailov, Vesselin T1 - Numerical simulation and microstructure analysis of friction stir welded Al 6082 T2 - METAL 2015, 24th International Conference on Metallurgy and Materials, conference proceedings, June 3rd-5th 2015, Brno Y1 - 2015 SN - 978-80-87294-62-8 PB - Tanger CY - Ostrava ER - TY - CHAP A1 - Genchev, Gancho Vladimirov A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Schweißtechnische Simulation der lokalen Eigenschaften in der Wärmeeinflusszone von Mehrlagenschweißungen T2 - ANSYS Conference & 33rd CADFEM Users' Meeting, 24. - 26. Juni, Bremen, conference proceedings Y1 - 2015 PB - CADFEM GmbH CY - Grafing ER - TY - CHAP A1 - Doynov, Nikolay A1 - Kuke, Felix A1 - Michailov, Vesselin T1 - Thermal straightening simulation of welded structures T2 - Proceedings, METEC & 2nd ESTAD 2015, European Steel Technology and Application Days, Düsseldorf, Germany, CCD Congress Center Düsseldorf, 15 - 19 June 2015 Y1 - 2015 SN - 978-3-00-049542-7 SP - P 709, 1 EP - 6 PB - TEMA Technologie Marketing AG CY - Aachen ER - TY - CHAP A1 - Fritzsche, Sebastian A1 - Seidlitz, Holger A1 - Winkelmann, Kai A1 - Michailov, Vesselin ED - Pająk, Anna T1 - Structural reinforced FRP sandwich constructions for lightweight floor panels T2 - Conference papers, APT '15, 11th International Conference Advances in Plastics Technology, Sosnowiec, 13 - 15 October 2015 Y1 - 2015 SN - 978-83-63555-47-4 CY - Gliwice ER - TY - CHAP A1 - Golubev, Iurii A1 - Naumov, Anton A1 - Michailov, Vesselin T1 - Developing finite element model of the friction stir welding for temperature calculation T2 - METAL 2014, International Conference on Metallurgy and Materials, May 21 st - 23rd 2014, Brno Y1 - 2014 SN - 978-80-87294-54-3 SP - 1242 EP - 1248 ER - TY - GEN A1 - Genchev, Gancho Vladimirov A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Bokuchava, Gizo A1 - Petrov, Peter A1 - Michailov, Vesselin T1 - Numerical and Experimental Study of Residual Stress Distribution in Laser Beam Welded Joint Y1 - 2016 UR - https://www.tugraz.at/fileadmin/user_upload/Events/Seggau/Dokumente/Dokumente_THERMEC/Program_Book_April_2016.pdf N1 - THERMEC 2016, 9th International Conference on Processing & Manufacturing of Advanced Materials, May 29-June 03, 2016, Graz, Austria SP - S. 20 ER - TY - GEN A1 - Michailov, Vesselin T1 - Prediction of the Properties of Heat-Affected Zone of Welded Joints of Sheets from Aluminum Alloys with Structured Surface T2 - Metal Science and Heat Treatment Y1 - 2016 SN - 0026-0673 SN - 1573-8973 VL - 58 IS - 1-2 SP - 46 EP - 50 ER - TY - GEN A1 - Karkhin, Victor A. A1 - Garkov, Sergey Vladimirovich A1 - Michailov, Vesselin T1 - Calculation of thermal processes in welding thick plates with moving axisymmetric heat sources T2 - Welding International Y1 - 2016 SN - 0950-7116 SN - 1754-2138 VL - 30 IS - 9 SP - 708 EP - 711 ER - TY - CHAP A1 - Ivanov, Sergey Y. A1 - Panchenko, Oleg V. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin A1 - Velichko, Olga V. T1 - Comparative study of mechanical inhomogeneity of laser and friction stir welded joints of Al-Mg-Si alloy T2 - METAL 2015, 24th International Conference on Metallurgy and Materials, conference proceedings, June 3rd-5th 2015, Brno Y1 - 2016 SN - 978-80-87294-62-8 PB - Tanger CY - Ostrava ER - TY - CHAP A1 - Kuke, Felix A1 - Kloshek, Alexander A1 - Michailov, Vesselin T1 - Untersuchung des Einflusses von rohrförmigen Stahlelektroden auf das Prozessverhalten und den Werkstoffübergang beim MSG-Schweißen T2 - DVS Congress, September 2015, Nürnberg Y1 - 2015 SN - 978-3-945023-46-4 SP - 615 EP - 620 PB - DVS Media GmbH CY - Düsseldorf ER - TY - CHAP A1 - Naumov, Anton A1 - Chenikov, Evgenii V. A1 - Golubev, Iurii A1 - Michailov, Vesselin T1 - Research of temperature distribution during friction stir welding of 2 mm Aw 6082 sheets T2 - METAL 2015, 24th International Conference on Metallurgy and Materials, conference proceedings, June 3rd-5th 2015, Brno Y1 - 2015 SN - 978-80-87294-62-8 SP - 651 EP - 653 PB - Tanger CY - Ostrava ER - TY - GEN A1 - Schleuß, Leander A1 - Richter, Thomas A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Plasma Cutting of Structured Sheet Metals in Comparison with Laser Beam Cutting T2 - Journal of Materials Science and Engineering Y1 - 2015 U6 - https://doi.org/10.17265/2161-6221/2015.3-4.004 SN - 2161-6221 VL - 5 IS - 3-4 SP - 135 EP - 144 ER - TY - BOOK A1 - Michailov, Vesselin A1 - Karkhin, Victor A. A1 - Petrov, Peter T1 - Principles of welding Y1 - 2016 SN - 978-5-7422-5569-7 PB - Polytechnic Univ. Publ. CY - St. Petersburg ER - TY - CHAP A1 - Petrov, Peter A1 - Bokuchava, Gizo A1 - Papushkin, Igor A1 - Genchev, Gancho Vladimirov A1 - Doynov, Nikolay A1 - Michailov, Vesselin A1 - Ormanova, Maria T1 - Neutron diffraction studies of laser welding residual stresses T2 - 19th International Conference and School on Quantum Electronics: Laser Physics and Applications, 26–30 September 2016 Sozopol, Bulgaria Y1 - 2017 UR - http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2597355 SN - 978-1-5106-0953-2 SN - 978-1-5106-0954-9 U6 - https://doi.org/10.1117/12.2261802 PB - SPIE CY - Bellingham, Wash. ER - TY - GEN A1 - Nikitin, Alexander A1 - Schleuß, Leander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Corrosion Behavior of Brazed Zinc-Coated Structured Sheet Metal T2 - International Journal of Corrosion Y1 - 2017 U6 - https://doi.org/10.1155/2017/4768505 SN - 1687-9333 SN - 1687-9325 VL - 2017 SP - 4768505 ER - TY - CHAP A1 - Tolochko, Oleg V. A1 - Michailov, Vesselin A1 - Rudskoy, Andrey I. ED - Devezas, Tessaleno ED - Leitão, João ED - Sarygulov, Askar T1 - Metal Matrix/Nanocarbons Composites Based on Copper and Aluminum T2 - Industry 4.0 : Entrepreneurship and Structural Change in the New Digital Landscape Y1 - 2017 SN - 978-3-319-49604-7 SN - 978-3-319-49603-0 SP - 205 EP - 217 PB - Springer International Publishing CY - Cham ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin A1 - Martikainen, J. A1 - Hiltunen, E. T1 - Modellierung der Entstehung von Heißrissen beim Laserschweißen von Al-Mg-Si-Legierungen T1 - Моделирование образования ликвационных трещин при лазерной сварке Al-Mg-Siсплаво T2 - Izvestija Tul'skogo Gosudarstvennogo Universiteta T2 - Nachrichten der staatlichen Universität Tula Y1 - 2015 SN - 2071-6168 VL - 6 IS - 2 SP - 66 EP - 74 ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin T1 - Modellierung thermodynamischer Prozesse beim Schweißen von ungeraden Nähten T1 - Моделирование тепловых процессов при сварке соединений с криволинейными швами T2 - Izvestija Tul'skogo Gosudarstvennogo Universiteta T2 - Nachrichten der staatlichen Universität Tula Y1 - 2015 SN - 2071-6168 VL - 6 IS - 2 SP - 62 EP - 66 ER - TY - GEN A1 - Isupov, Fedor A1 - Ganin, Sergey A1 - Tcemenko, Valeriy A1 - Michailov, Vesselin T1 - Numerical simulation of sheet profiling process from aluminum alloy T2 - METAL 2015, 24th International Conference on Metallurgy and Materials, Brno, Czech Republic, June 3rd-5th, 2015, Conference proceedings Y1 - 2015 SN - 978-80-87294-62-8 SP - 1463 EP - 1468 PB - Tanger CY - Ostrava ER - TY - CHAP A1 - Golubev, Iurii A1 - Naumov, Anton A1 - Chernikov, Evgenii V. A1 - Michailov, Vesselin ED - Mishra, Rajiv S. ED - Mahoney, Murray W. ED - Sato, Yutaka ED - Hovanski, Yuri T1 - Temperature distribution and welding distortion measurements after FSW of Al 6082-T6 sheets T2 - Friction Stir Welding and Processing VIII, 144th Annual Meeting and Exhibition, 15.03.2015, Orlando Y1 - 2015 SN - 978-3-319-48604-8 SN - 978-3-319-48173-9 U6 - https://doi.org/10.1007/978-3-319-48173-9 SP - 289 EP - 295 PB - Springer CY - Cham ER - TY - CHAP A1 - Ivanov, Sergey Y. A1 - Panchenko, Oleg V. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin T1 - Optimization technique for arc welding of structured sheet T2 - METAL 2015, 24th International Conference on Metallurgy and Materials, conference proceedings, June 3rd-5th 2015, Brno Y1 - 2015 UR - http://konsys2.tanger.cz/files/proceedings/21/papers/3950.pdf SN - 978-80-87294-62-8 PB - Tanger CY - Ostrava ER - TY - BOOK A1 - Michailov, Vesselin A1 - Stapelfeld, Christoph T1 - Erweiterung eines analytisch-numerischen Hybridmodells für die Verzugssimulation von Großstrukturen Y1 - 2014 SN - 978-3-942541-35-0 PB - Verlag und Vertriebsgesellschaft mbH CY - Düsseldorf ER - TY - GEN A1 - Koltsova, Tatiana S. A1 - Shakov, Fedor M. A1 - Voznyakovskiy, A. A. A1 - Lyashkov, A. I. A1 - Tolochko, Oleg V. A1 - Rudskoy, Andrey I. A1 - Nasibulin, Albert G. A1 - Michailov, Vesselin T1 - Fabrication of a Compacted Aluminum-Carbon Nanofiber Material by Hot Pressin T2 - Technical Physics Y1 - 2014 U6 - https://doi.org/10.1134/S1063784214110139 SN - 1063-7842 VL - 59 IS - 11 SP - 1626 EP - 1630 ER - TY - CHAP A1 - Krawczynski, Damian A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Minimization of Residual Welding Stress and Distortins in Aluminium-Steel Hybrid Structure T2 - Innowacje w procesach produkcyjnych, technologicznych i bezpieczeństwie : XXXVIII Studencka Sesja Naukowa, Częstochowa, 29 maj 2014 : praca zbiorowa Y1 - 2014 SN - 879-83-63989-02-6 SP - 59 EP - 63 PB - Wydawnictwo Wydziału Inżynierii Produkcji i Technologii Materiałów Politechniki Częstochowskie CY - Częstochowa ER - TY - GEN A1 - Bobrynina, Elizaveta A1 - Alkhalaf, Ahmad A. A1 - Shamshurin, Aleksey A1 - Tolochko, Oleg V. A1 - Michailov, Vesselin T1 - Synthesis of Fe-ZrO2 composite powders by thermochemical method T2 - Key Engineering Materials Y1 - 2017 U6 - https://doi.org/10.4028/www.scientific.net/KEM.721.285 SN - 1662-9795 VL - 721 SP - 285 EP - 289 ER - TY - GEN A1 - Hartel, Udo A1 - Ilin, Alexander A1 - Sonntag, Steffen A1 - Michailov, Vesselin T1 - Nonlinear optimization methods for the determination of heat source model parameters T2 - Materials Science Forum Y1 - 2017 U6 - https://doi.org/10.4028/www.scientific.net/MSF.879.2008 SN - 1662-9752 SN - 0255-5476 VL - 879 SP - 2008 EP - 2013 ER - TY - GEN A1 - Hartel, Udo A1 - Ilin, Alexander A1 - Michailov, Vesselin A1 - Gibmeier, Jens A1 - Bantel, Christoph T1 - Finite Element Modelling for the Structural Analysis of Al-Cu Laser Beam Welding T2 - Physics Procedia Y1 - 2016 U6 - https://doi.org/10.1016/j.phpro.2016.08.147 SN - 1875-3892 VL - 83 SP - 1404 EP - 1414 ER - TY - CHAP A1 - Zhang, Wei A1 - Priefer, Marian A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Neue Möglichkeiten für die Additive Fertigung durch Laser-Pulver-Auftragschweißen T2 - DVS Congress 2017, Große Schweißtechnische Tagung, DVS Studentenkongress, Vorträge der Veranstaltungen in Düsseldorf vom 26. bis 29. September 2017 KW - Laser Additive Fertigung Y1 - 2017 SN - 978-3-96144-008-5 SP - 278 EP - 282 PB - DVS Media CY - Düsseldorf ER - TY - GEN A1 - Genchev, Gancho Vladimirov A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Bokuchava, Gizo A1 - Petrov, Peter T1 - Residual stresses formation in multi-pass weldment: A numerical and experimental study T2 - Journal of Constructional Steel Research N2 - In this study, the residual stresses distribution induced by multi-pass arc welding of the steel S355J2+N are investigated experimentally and numerically. An extended approach is used for the simulations, which considers the change of the local microstructure properties due to multiple reheating. Experimental material data obtained from physical welding simulations with Gleeble® are used for the model calibration. The experimental stress study is performed using a neutron diffraction method on a fourier stress diffractometer. Numerical analysis of the welding stresses formation in the weldment is performed and compared to the experimental study. The results explain the influence of the welding thermal history on the resulting local thermo-mechanical properties in the heat-affected zone and, thus, on the residual stress distribution. The consideration of the local microstructure properties in the welding simulation leads to a significant increase in accuracy of the numerical results. The major influence factor on the residual stress formation is the change in the interpass microstructure yield strength. When a root pass with short cooling times is subjected to re-austenitisation in the fine-grained zone, the yield strength increases in this area and affects consequently the residual stress distribution. The influence of the reheating is detectable in the depth of the weldment, but it is less significant for the residual stress formation near the surface of the welded joint. KW - Multi-pass weldment KW - Steel S355 KW - Thermo-mechanical properties KW - Stress distribution KW - Welding simulation KW - Neutron diffraction Y1 - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0143974X17303358 U6 - https://doi.org/10.1016/j.jcsr.2017.08.017 SN - 0143-974X VL - 138 SP - 633 EP - 641 ER - TY - GEN A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Distortion analysis of heat spot straightening thin-walled welded structures: part 2: analytical-numerical approach T2 - International Journal of Advanced Manufacturing Technology N2 - An analytical model based on a theoretical model established in the previous work (part 1) is developed. The analytical model considers the particular case of an instantaneous high-density heat source acting on a thin pre-stressed plate. It calculates the plastic strain and the area of the zone of plastic deformation. A theoretical study is performed in order to quantify the major factors that influence the plastic strain formation. Furthermore, the work presents a calculation procedure for distortion analysis of lar ge and complex structures, intended to be used for solving industrial tasks. The calculation procedure consists of a combination of the analytical solution and an elastic finite element analysis with the aid of the inherent strain approach. Various aspects of its application are also discussed. The calculation procedure is finally explained using a simple example. Its reliability and practicability are demonstrated through verification and validation studies. The work is dedicated to the thermal straightening of thin-walled welded structures; however, it can also be related to other processes. KW - Thermal straightening KW - Distortion analysis KW - Computational welding mechanics KW - Finite element analysis KW - Inherent strain method KW - Virtual manufacturing Y1 - 2018 UR - https://link.springer.com/article/10.1007%2Fs00170-017-1214-0 U6 - https://doi.org/10.1007/s00170-017-1214-0 SN - 0268-3768 SN - 1433-3015 VL - 95 IS - 1-4 SP - 469 EP - 478 ER - TY - BOOK A1 - Michailov, Vesselin A1 - Doynov, Nikolay A1 - Kuke, Felix T1 - Anwendungsnahe Simulation des thermischen Richtens : Forschungsvorhaben P 1008/IGF-Nr. 17970 BR Y1 - 2016 SN - 978-3-946885-03-0 PB - Verlag und Vertriebsgesellschaft mbH CY - Düsseldorf ER - TY - GEN A1 - Kondratyev, Alex A1 - Morozova, Iuliia A1 - Golubev, Iurii A1 - Hantelmann, Cord A1 - Naumov, Alexander A1 - Michailov, Vesselin T1 - Микроструктура и механические свойства швов после различных режимов импульсной сварки Al – Mg – Si сплавов трением с перемешиванием T1 - Untersuchung von Mikrostruktur und mechanischen Eigenschaften der Al-Mg-Si Legierungen beim Impuls-Rührreibschweißen mit unterschiedlichen Schweißparametern T2 - Metallovedenie i termicheskaya obrabotka metallov N2 - Welded joints of aluminum alloy 6082-T6 formed by the method of pulse friction stir welding are studied. The effect of the power and frequency of the pulses on the microstructure and mechanical properties of the welded joints is determined. Application of an additional pulse during the welding affects the surface quality and the shape of the weld, the distribution of the oxide layer and of particles of the hardening phase, and the grain size in the zone of dynamic recrystallization. KW - pulse friction stir welding KW - power and frequency of pulses KW - microstructure KW - mechanical properties KW - Al – Mg – Si alloy Y1 - 2017 SN - 0026-0819 IS - 11 SP - 25 EP - 30 ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin T1 - Optimization of welding conditions for curvilinear T2 - Welding International KW - Arc welding KW - optimization KW - structured panel KW - curvilinear seam KW - sources method KW - fastest descent method Y1 - 2017 U6 - https://doi.org/10.1080/09507116.2017.1353276 SN - 0950-7116 VL - 31 IS - 12 SP - 929 EP - 933 ER - TY - GEN A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Distortion analysis of heat spot straightening thin-walled welded structures: part 1: analytical-numerical approach T2 - The International Journal of Advanced Manufacturing Technology N2 - The work deals with the elastic-plastic thermo-mechanical deformation process after spot heating of large thin plates. It promotes a new theoretical model of the process. The main target is to clarify the kinetics of the plastic strain formation during thermal straightening and to explore the main interactions. For this purpose, a simplified mechanical problem is formulated and applied. As a result, definite thermo-mechanical relations between temperature, initial strain, and accumulated plastic strain are obtained. Finally, a verification study is presented and discussed. The results contribute to extending the knowledge about the process and to establishing a theoretical background for development of applied analytical or analytical-numerical approaches for practical use in the designing and planning phases in welding production. An application to a particular case is described in an accompanying paper (part 2). KW - Straightening KW - Elastic-plastic analysis KW - Distortion analysis KW - Computational welding mechanics KW - Virtual manufacturing Y1 - 2018 UR - https://link.springer.com/article/10.1007%2Fs00170-017-0911-z U6 - https://doi.org/10.1007/s00170-017-0911-z SN - 0268-3768 SN - 1433-3015 VL - 94 IS - 1-4 SP - 667 EP - 676 ER - TY - CHAP A1 - Golubev, Iurii A1 - Doynov, Nikolay A1 - Hantelmann, Cord A1 - Michailov, Vesselin T1 - Wärmequellemodell und FE-Temperaturfeldsimulation für das Rührreibschweißen T2 - DVS Congress 2017 : Große Schweißtechnische Tagung : DVS-Studentenkongress : Vorträge der Veranstaltungen in Düsseldorf vom 26. bis 29. September 2017 KW - Wärmequellemodell KW - FE-Temperaturfeldsimulation KW - Rührreibschweißen Y1 - 2017 SN - 978-3-96144-008-5 SP - 112 PB - DVS Media CY - Düsseldorf ER - TY - GEN A1 - Evdokimov, Anton A1 - Springer, Katrin A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Heat source model for laser beam welding of steel-aluminum lap joints T2 - International Journal of Advanced Manufacturing Technology N2 - In this study, a three-dimensional thermal conduction model based on the finite element analysis was established to predict a heat distribution during laser welding in overlap configuration of austenitic stainless steel 1.4301 and hardenable aluminum alloy 6016. A hybrid model based on two expanded curve-rotated volumetric heat sources is suggested to capture the complex weld geometry. Since thermal flow in the overlap area is a crucial part of the model, an analytic calculation of a thermal contact conductance between the plates and its subsequent implementation in the FE model through a superposition of two contact surfaces are described in details in this paper. Full thermal cycles, weld shapes, and thus mixing grades were successfully predicted by means of the developed model for different parameter combinations. KW - Laser welding Dissimilar joint Heat source model Finite element analysis Thermal simulation Weld shape KW - Dissimilar joint KW - Heat source model KW - Finite element analysis KW - Thermal simulation KW - Weld shape Y1 - 2017 UR - https://link.springer.com/article/10.1007/s00170-017-0569-6 U6 - https://doi.org/10.1007/s00170-017-0569-6 SN - 0268-3768 SN - 1433-3015 VL - 93 IS - 1-4 SP - 709 EP - 716 ER - TY - GEN A1 - Shapovalov, Oleg A1 - Hantelmann, Cord A1 - Michailov, Vesselin A1 - Kodgaspirov, G. E. T1 - Influence of welding method on fatigue strength and destruction character of aluminum foam sandwiches T2 - Deformatsiya i Razrushenie materialov N2 - An influence of the arc welding and the laser welding on fatigue properties and destruction mechanisms of aluminum foam sandwich has been studied. It was found that specimens made by the arc welding had the best fatigue strength. Comparative results of four point bending fatigue tests of the non-welded specimens such as butt welded joints made by different welding methods are presented. KW - aluminum foam KW - metallic foam sandwich KW - fatigue strength KW - four-point bending KW - butt welded joint Y1 - 2017 UR - http://www.nait.ru/journals/number.php?p_number_id=2612 SN - 1814-4632 IS - 5 ER - TY - CHAP A1 - Panchenko, Oleg V. A1 - Ivanov, Sergey Y. A1 - Kol'Tsova, Tatyana A1 - Michailov, Vesselin T1 - Survivability of Carbon Nanotubes During Arc Welding T2 - Nanocon 2016, conference proceedings, 8th international conference, October 19th-21st, 2016, Brno, Czech Republic, EU KW - Carbon KW - Arc Welding Y1 - 2017 SN - 978-80-87294-71-0 SP - 59 EP - 63 PB - Tanger CY - Ostrava ER - TY - CHAP A1 - Golubev, Iurii A1 - Morozova, Iuliia A1 - Naumov, Anton A1 - Hantelmann, Cord A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Numerical simulation and experimental investigation on Numerical simulation of 6082-T6 aluminum alloy T2 - Materials Science and Technology 2017, (MS&T17), Pittsburgh, Pennsylvania, USA, October 8-12, 2017, volume 2 N2 - The series of impulse friction stir welding (IFSW) experiments for aluminum alloy 6082-T6 butt joints was performed to obtain micrographs, tensile and hardness test samples and to receive the validation data for a numerical model of the process. Impulse force and frequency were varied to determine the effect of individual process parameters on microstructure evolution and mechanical properties of the welded butt joints. A three-dimensional model was established to simulate temperature distribution, heat generation and contact state between the tool and the workpiece during IFSW. Based on the numerical simulation, the influence of the impulses on heat input, maximum weld temperatures and contact state was found. The combination of impulse force and frequency effected the grain refinement. The influence of impulses on the elongation and hardness of the welded joints during IFSW were determined. KW - Aluminum alloy KW - Numerical simulation Y1 - 2017 SN - 978-1-5108-5058-3 SP - 987 EP - 994 PB - Curran Associates, Inc. CY - Red Hook, NY ER - TY - CHAP A1 - Hantelmann, Cord A1 - Fritzsche, Sebastian A1 - Michailov, Vesselin A1 - Boywitt, Ralf T1 - Einsatz von Aluminiumschaumsandwich in Schweißkonstruktionen T2 - DVS Congress 2017 : Große Schweißtechnische Tagung : DVS-Studentenkongress : Vorträge der Veranstaltungen in Düsseldorf vom 26. bis 29. September 2017 N2 - In der vorgestellten Arbeit wird die Anwendbarkeit von Aluminiumschaumsandich in Schweißkonstruktionen vorgestellt. Systematische Betrachtungen zur Schweißbarkeit mittels Laserstrahlschweißen, MSG - Kurzlichtbogen und Rührreibschweißen sowohl im geschäumten als auch im ungeschäumten Zustand werden beschrieben. Dazu wurden verschiedene Knotenformen wie I-Stoß- bzw. T-Stoßverbindungen hergestellt und deren mechanischtechnologische Eigenschaften ermittelt. Neben der quasistatischen Prüfung, wurde jede Ausführungsform des Knotens auf deren Schwingfestigkeit hin geprüft und die Anwendbarkeit bestehender Regelwerke wie die FKMRichtlinie oder der Eurocode 9 für die Nachweisführung betrachtet. Die Ergebnisse sind abschließend in einem Gestaltungskatalog als Hilfsmittel für den Konstrukteur zusammengefasst. Parallel dazu wurden die experimentellen Untersuchungen mittels FEM begleitet. Es wird die FE-Modellentwicklung für die Berechnung des Sandwichverbundes an sich als auch von Fügeknoten dargestellt wie auch die Modellvalidierung mit einem Musterbauteil aus einer Hubarbeitsbühne. KW - Aluminiumschäume KW - FE-Simulation KW - Aluminiumschaumsandwich KW - Schweißkonstruktionen Y1 - 2017 SN - 978-3-96144-008-5 SP - 173 PB - DVS Media CY - Düsseldorf ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin A1 - Martikainen, J. A1 - Hiltunen, E. T1 - Оценка чувствительности сварных соединений Al - Mg - Si-сплавов к ликвационным трещинам при лазерной сварке T1 - Empfindlichkeitsbetrachtung von Heißrissen beim Laserschweißen von Al-Mg-Si-Legierungen T2 - Metallovedenie i termicheskaya obrabotka metallov Y1 - 2017 UR - http://mitom.folium.ru/contents/2017/2017-12.php SN - 0026-0819 IS - 12 ER - TY - GEN A1 - Evdokimov, Anton A1 - Obrosov, Aleksei A1 - Ossenbrink, Ralf A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Mechanical properties of dissimilar steel-aluminum weld T2 - Materials Science and Engineering: A N2 - Knowledge of the properties of dissimilar welds is of great significance for the development of multi-material lightweight structures. In this study, stainless steel (1.4301) and aluminum alloy (6082-T6) sheets were welded in overlap configuration in keyhole mode. The resulting weld metals were investigated with respect to their mechanical properties. Several samples were cut out of different locations along the welds and their cross-sections were subjected to indentation testing and energy dispersive X-ray (EDS) analysis. Young's modulus E, yield stress σy, and strain hardening exponent n, were determined by means of reverse analysis of the indentation load (P) – depth (h) curves, allowing construction of true stress – true strain relations. An essential increase in yield stress in comparison to the one of the base alloys was observed inside the weld metal. In contrary, Young's modulus and strain hardening exponent of the welds were almost identical to corresponding values of the base steel metal. Due to the sensitivity of yield stress to the aluminum content, slight variations of the welding parameters lead to significant changes in elastic-plastic behavior of the weld metal. KW - Mechanical properties KW - Indentation KW - Reverse analysis KW - EDS measurements KW - Dissimilar steel aluminum welding KW - FEM Y1 - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0921509318303563 U6 - https://doi.org/https://doi.org/10.1016/j.msea.2018.03.019 SN - 0921-5093 VL - Volume 722 SP - 242 EP - 254 ER - TY - PAT A1 - Brobeck, Andreas F. W. A1 - Michailov, Vesselin A1 - Ossenbrink, Ralf A1 - Polzin, Ralf A1 - Schleuß, Leander T1 - Rollennahtelektrode N2 - Eine Rollennahtelektrode zur Verwendung beim Rollennahtschweißen umfasst eine segmentförmige Elektrodenfläche (2) zur Anpressung der zu verbindenden Bauteile und zur Einleitung des Schweißstroms und der Schweißspannung. Die Elektrodenfläche (2) ist derart dreieckförmig oder mäanderförmig oder zueinander beabstandet ausgebildet, dass in der ebenen Abwicklung der Elektrodenfläche (2) ein Zickzack-Muster oder ein Wellen-Muster oder ein Steppnaht-Muster oder ein Rechteck-Muster vorliegt. Y1 - 2017 UR - https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=DE102015114937A1 N1 - Offenlegungsschrift ER - TY - PAT A1 - Kloshek, Alexander A1 - Michailov, Vesselin T1 - Schweißeinrichtung, Verfahren zur Herstellung eines Bauteils mittels Schweißung und Verwendung einer Elektrode aus Schweißzusatzwerkstoff N2 - Schweißeinrichtung (1) zum Schweißen von Werkstücken (100), umfassend eine Laserstrahlquelle (10) zur Emission eines Laserstrahls (11), eine Vorschubeinrichtung zur Realisierung einer Vorschubbewegung einer abzuschmelzenden Elektrode (70) aus Schweißzusatzwerkstoff (30) in einer Transportrichtung (21) in eine Abschmelzzone, und eine Stromkontakteinheit (60) zur Anlegung einer elektrischen Spannung an die abzuschmelzende Elektrode (70), wobei die Laserstrahlquelle (10), die Vorschubeinrichtung und die Stromkontakteinheit (60) derart relativ zueinander angeordnet und ausgebildet sind, dass die Längsachse des von der Laserstrahlquelle (10) aussendbaren Laserstrahls (11) im Wesentlichen parallel zur Transportrichtung (21) der Elektrode (70) verläuft, dadurch gekennzeichnet, dass sie eine Elektrodenformungseinrichtung (40) aufweist, mit der ein Querschnitt der Elektrode (70) erzeugbar ist, der den von der Laserstrahlquelle (10) aussendbaren Laserstrahl (11) zumindest in einem Winkelbereich von 180° umgibt. Y1 - 2016 UR - https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=DE102014104936B4 ER - TY - PAT A1 - Michailov, Vesselin A1 - Ossenbrink, Ralf A1 - Schleuß, Leander A1 - Springer, Katrin A1 - Zoeke, Jörg T1 - Strukturierte Tailored Blanks T1 - Structured tailored blank useful as a semi-finished product or a finished product, which is used as a component, preferably wall element, floor element, ceiling element and/or element of chassis of vehicle, comprises at least two sheets N2 - Die Erfindung betrifft ein strukturiertes Tailored Blank, umfassend mindestens zwei Fügepartner, wobei mindestens ein Fügepartner ein strukturierter Fügepartner ist und wobei der strukturierte Fügepartner regelmäßig angeordnete Versteifungselemente umfasst und wobei der strukturierte Fügepartner an mindestens einen weiteren Fügepartner gefügt ist. N2 - Structured tailored blank comprises at least two sheets. At least one sheet is at least one structured sheet. The structured sheet comprises regularly arranged stiffening elements of honeycomb shapes without planar sections. The stiffening elements are separated by bars. The structured sheet is joined to at least one additional sheet, and both the sheets are not similar. An independent claim is also included for producing the structured tailored blank, comprising the providing first structured sheet, providing at least one additional sheet, which is not similar to the first sheet, and joining the first sheet with at least one additional sheet. Y1 - 2014 UR - https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=DE102013101171A1 ER - TY - PAT A1 - Schleuß, Leander A1 - Seidlitz, Holger A1 - Michailov, Vesselin T1 - Neue Fügetechnologie für Mischverbindungen Y1 - 2017 UR - https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=DE102015118058A1 N1 - Offenlegungsschrift ER - TY - GEN A1 - Kondrat’ev, Sergey A1 - Morozova, Iuliia A1 - Golubev, Iurii A1 - Hantelmann, Cord A1 - Naumov, Alexander A1 - Michailov, Vesselin T1 - Microstructure and Mechanical Properties of Welds of Al – Mg – Si Alloys After Different Modes of Impulse Friction Stir Welding T2 - Metal Science and Heat Treatment N2 - Welded joints of aluminum alloy 6082-T6 formed by the method of impulse friction stir welding are studied. The effect of the power and frequency of the pulses on the microstructure and mechanical properties of the welded joints is determined. Application of an additional pulse during the welding affects the surface quality and the shape of the weld, the distribution of the oxide layer and of particles of the hardening phase, and the grain size in the zone of dynamic recrystallization. KW - impulse friction stir welding KW - power and frequency of pulses KW - microstructure KW - mechanical properties KW - Al – Mg – Si alloy Y1 - 2018 UR - https://link.springer.com/article/10.1007%2Fs11041-018-0213-6 U6 - https://doi.org/10.1007/s11041-018-0213-6 SN - 0026-0673 VL - 59 IS - 11-12 SP - 697 EP - 702 ER - TY - GEN A1 - Michailov, Vesselin A1 - Fritzsche, Sebastian A1 - Hantelmann, Cord A1 - Ossenbrink, Ralf T1 - Aluminium foam sandwiches for lightweight structures T2 - Metal Science and Heat Treatment N2 - The properties of sandwiches with aluminum foam and the special features of their use in lightweight welded structures are determined. The weldability of such sandwiches in foamed and non-foamed conditions is analyzed under friction stir welding, laser beam welding and short arc welding in protective gas. The process and mechanical properties of the welds are studied. The results are generalized in a catalog that may be useful for materials scientists and designers. KW - aluminum KW - aluminum foam KW - welded structures KW - composite materials KW - structure KW - mechanical properties Y1 - 2018 U6 - https://doi.org/10.1007/s11041-018-0238-x SN - 1573-8973 VL - 60 IS - 1-2 SP - 44 EP - 49 ER - TY - GEN A1 - Wasilewski, Eric A1 - Wolf, Matthias A1 - Zhang, Wei A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Cu/LaCrO₃ joining by local melt infiltration through laser cladding T2 - Journal of the American Ceramic Society N2 - Direct bonding of copper and porous LaCrO₃ without an extra filler interlayer was successfully completed using local and fast Cu‐infiltration through laser cladding. This significantly reduced the susceptibility of the ceramic to cracking. A high‐speed camera investigation into the wetting and infiltration behavior of a Cu‐melt into LaCrO₃ with a porosity of ~63 vol% was performed. By adjusting the focal distance with a constant laser power of 300 W, the Cu‐melt was rapidly infiltrated into the ceramic preform in 10 seconds. This was completed under atmospheric air conditions, without added inert gas. The joining process developed can be used to fabricate ceramic/metal joints with targeted (micro‐) structure properties by adjusting the infiltrated melt and the infiltration depth, which would be suitable for many applications, such as multifunctional devices, solid oxide fuel cells or heating elements. Y1 - 2018 U6 - https://doi.org/10.1111/jace.15767 SN - 1551-2916 SN - 0002-7820 VL - 101 IS - 10 SP - 4472 EP - 4472 ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Panchenko, Oleg V. A1 - Michailov, Vesselin T1 - Comparative analysis of non-uniformity of mechanical properties of welded joints of Al - Mg - Si alloys in friction stir welding and laser welding T2 - Metal Science and Heat Treatment N2 - The properties of the welded joints of 6082-T6 alloy produced by friction stir welding (FSW) and laser welding(LW) were studied. The maximum temperature and microhardness fields in the friction stir-welded joints were shown to be asymmetrical. The concentrated energy input during laser welding yields a narrow heat-affected zone (HAZ) with sharp changes in mechanical properties. The strength of the FSW joint constitutes 72% and that of the LWjoint—67% of the base metal strength. In case of LW, the minimum hardness of the joint corresponds to the metal of the welded joint, while in case of FSW, it corresponds to the heat-affected zone. At the same maximum heating temperature, the hardness of the heat-affected zone of the friction stir-welded joint is lower compared to laser welding due to substantially lower rates of heating and cooling. KW - friction stir welding KW - laser welding KW - Al – Mg – Si alloy KW - temperature field KW - welded joint KW - microstructure KW - mechanical properties KW - non-uniformity Y1 - 2018 UR - https://link.springer.com/article/10.1007/s11041-018-0289-z U6 - https://doi.org/10.1007/s11041-018-0289-z SN - 0026-0673 VL - 60 SP - 393 EP - 398 ER - TY - CHAP A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - The Influence of Geometrical and Welding Imperfections on the Strength of Stiffened Structures T2 - High Performance Steel Structures Research Council (HPSSRC), Delft, Netherlands, 2018 N2 - The strength calculation of stiffened plates and shells via finite element simulation has been part of the state of the art for a long time. Geometrical nonlinearities as well as the nonlinear material behavior are considered within the calculation. To simplify, both types of imperfections, geometrical and structural ones, are mostly combined in these strength calculations being considered as equivalent geometrical imperfections. Values for standard cases are included in EN 1993-1-5 in case of plated structures or 1-6 in case of shells. A second possibility is the separate definition of fabrication tolerances and residual stresses, as far as they are known. With increasing complexity of the structure, less information are however available on geometrical and particularly structural imperfections. Nevertheless, by means of a more realistic consideration of these values, the actual ultimate load can be determined significantly more exactly and the performance of high performance steel structures is increased. In the investigated cases, deformations and stresses arise mainly due to welding. Therefore, the topic of this article is the application of an analytical numerical hybrid model for predicting imperfections induced by welds. This is presented on an example of a stiffened steel structure and a subsequent ultimate load calculation. At the beginning the analytical model, its physical basis as well as the physical interrelationships are introduced and explained. This is followed by the explanation of the coupling procedure between the analytical model and the numerical calculation for the calculation of weld-induced deformations and residual stresses. The significance of the hybrid model is proven by means of a few sample applications. For a realistic determination of the weld imperfections in the investigated stiffened structure, the coupled hybrid model is used afterwards. An ultimate load analysis gives information about the load carrying behavior under axial loading. The results are compared with the results of an ultimate load analysis from a literature example assuming different eigenvalues with different scaling. The results underline the potential additional utilization of load bearing capacity by this new approach. KW - Welding KW - Stresses KW - Strains KW - Imperfections KW - Stiffened Structures KW - Distortions Y1 - 2018 UR - https://www-docs.b-tu.de/fg-stahlbau/public/Fachgebiet_Stahlbau/publikationen/Workshop_Proceedings_of_HPSSRC-updated_cs.pdf SP - 191 EP - 201 ER - TY - CHAP A1 - Ginzburg, Svetlana A1 - Morozova, Iuliia A1 - Kloshek, Alexander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Schweißen von Stahl mit Nanopartikel modifizierten Fülldrähten - Schweißnahtgefüge und -eigenschaften T2 - DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vorträge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018 N2 - Analyse des Schweißnahtgefüges und -eigenschaften beim Schweißen von Stahl mit Nanopartikel modifizierten Fülldrähten KW - Schweißen KW - Fülldraht KW - Nano KW - Nanotechnologie KW - Stahl KW - Gefüge Y1 - 2018 SN - 978-3-96144-036-8 SP - 40 EP - 46 PB - DVS Media GmbH CY - Düsseldorf ER - TY - CHAP A1 - Fritzsche, Sebastian A1 - Kloshek, Alexander A1 - Dietz, Eric A1 - Michailov, Vesselin A1 - Seidlitz, Holger A1 - Ossenbrink, Ralf T1 - SLM gefertigte Verbindungsknoten für Leichtbaurahmenelemente T2 - DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vorträge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018 N2 - SLM gefertigte Verbindungsknoten für Leichtbaurahmenelemente KW - Selective Laser Melting KW - SLM KW - Leichtbau KW - 1.4404 KW - Topologieoptimierung KW - Schubfeld Y1 - 2018 SN - 978-3-96144-036-8 IS - 264 EP - 258 PB - DVS Media GmbH CY - Düsseldorf ER - TY - CHAP A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Unterstützung beim thermischen Richten von geschweißten Großstrukturen durch praktikable Computersimulationen T2 - DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vorträge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018 N2 - Unterstützung beim thermischen Richten von geschweißten Großstrukturen durch praktikable Computersimulationen KW - Thermisches Richten KW - Großstrukturen KW - Simulation KW - Umformen KW - Schiffbau KW - Richten Y1 - 2018 SN - 978-3-96144-036-8 SP - 364 EP - 369 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Bokuchava, Gizo A1 - Petrov, Peter A1 - Genchev, Gancho Vladimirov A1 - Michailov, Vesselin A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf T1 - Residual stress analysis in welded joints by neutron difffraction and comouter modeling T2 - Romanian Journal of Physics N2 - Numerical models for thermo-mechanical simulation of the welding residual stresses in laser beam and multi-pass arc welded joints are developed. The models describe the resulting microstructure as a function of the peak temperature, austenization time, cooling time and take into account the microstructure formed after single or multiple thermal cycles. The results of simulations are validated by neutron diffraction experiments performed on FSD diffractometer at the IBR-2 pulsed reactor in FLNP JINR (Dubna, Russia). The elaborated numerical models are in good agreement with obtained neutron diffraction data, which enable to study the influence of different conditions and process parameters on the distribution of residual welding stresses. KW - residual stress KW - neutron diffraction KW - computer modeling KW - welding Y1 - 2018 SN - 1221-146X VL - Vol. 63 IS - 7-8 ER - TY - GEN A1 - Zhang, Wei A1 - Evdokimov, Anton A1 - Schleuß, Leander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Laser beam build-up welding of AlSi12-powder on AlSi1MgMn-alloy substrate T2 - Progress in Additive Manufacturing N2 - In the present work, laser beam build-up welding of AlSi12 alloy powder on AlSi1MgMn-alloy (EN AW-6082) substrate has been studied to determine the laser deposition strategy for fabrication of 3-D structure. First, the influence of laser power, scanning speed and powder feeding rate on the output parameters, such as clad geometry, dilution ratio, powder efficiency and porosity were analysed for deposition of a single track. Mathematical relationships were then established and the optimal parameters were identified by the desirability approach. Second, these optimal process parameters are furthermore adjusted to fabricate rectangular, cylindrical and complex combination volumes; different layer deposition strategies are used and evaluated. Finally, by using an adapted deposition strategy, one prototype consisted of different complexly shaped elements on one curved Al-alloy substrate without welding fusion defects was manufactured. The average tensile strength of deposited samples with four different layer deposition directions (vertical 0°/90°; horizontal 0°/90°; horizontal 0° and horizontal 90°) was measured, respectively, which are comparable strengths or higher than those of cast samples. The microstructure of the laser-deposited material is investigated using optical microscopy and scanning electron microscopy as well as microcomputed tomography. Microstructure and hardness of deposited multilayers exhibit inhomogeneous distributions, which vary with the deposit location KW - Laser beam build-up welding KW - Laser metal deposition KW - AlSi12 KW - Additive manufacturing KW - Build-up strategy Y1 - 2019 UR - https://doi.org/10.1007/s40964-018-0065-z SN - 2363-9512 VL - 4 IS - 2 SP - 117 EP - 129 ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin A1 - Martikainen, J. A1 - Hiltunen, E. T1 - Assessment of the Sensitivity of Welded Joints of Al –Mg – Si Alloys to Liquation Cracks Under Laser Welding T2 - Metal Science and Heat Treatment N2 - The microstructure and the distribution of chemical elements in laser-welded joints of Al – Mg – Si alloy 6005-T6 are studied. Segregations of chemical elements are detected over grain boundaries in the heat-affected zones of the welded joints. The joints fracture by the intergrain mechanism. A Gleeble 3800 device is used to determine the temperature dependences of the mechanical properties of the alloy with allowance for the special features of the welding cycle. Amethod for evaluating the sensitivity of welded joints of aluminum alloys to formation of liquation cracks with allowance for the local properties of the metal, the welding conditions, and the rigidity of the construction is suggested. KW - laser welding KW - Al – Mg – Si alloy KW - microstructure KW - microscopic chemical analysis KW - liquation cracks KW - stress-strain state Y1 - 2018 U6 - https://doi.org/10.1007/s11041-018-0225-2 SN - 0026-0673 VL - Vol. 59 IS - 11-12 SP - 773 EP - 778 ER - TY - GEN A1 - Bobrynina, E. V. A1 - Larionova, T. V. A1 - Koltsova, Tatiana S. A1 - Ginzburg, S. A. A1 - Michailov, Vesselin T1 - Effect of alumina addition on weld deposits microstructure at the welding of carbon steel T2 - Materials Physics and Mechanics N2 - The formation of acicular ferrite in the structure of weld deposits when welding carbon steels is often associated with the introduction of nonmetallic additives into the electrode material. Fe–alumina composite powders with alumina particles less than 1 µm were used as a filler for cored welding wire and the influence of aluminum oxide additives up to 2,5 wt.% on the structure of the welded seam was studied. It was shown that the addition of aluminum oxide to the welding wire led to the initiation of the formation of intragranular acicular ferrite in the weld deposit and to a more even distribution of hardness through the zones of weld seam. KW - acicular ferrite KW - alumina KW - welding KW - carbon steel Y1 - 2018 U6 - https://doi.org/10.18720/MPM.3812018_4 SN - 1605-8119 VL - Vol. 38 IS - 1 SP - 26 EP - 32 ER - TY - GEN A1 - Bonnel, Jean-Marie A1 - Maurer, Michael A1 - Rosert, Reinhard T1 - Submerged-arc surfacing of higt-alloy steels by flux-cored wires T2 - Avtomatičeskaja svarka = Automatic welding N2 - Cored wires are used in numerous welding processes with or without extern al gas or flux shielding. Submerged are welding (SAW) with eored wires, seamed or seamless, for joining mild and low alloyed steel grades is a technique that has demonstrated clear advantages during the three last decades. Ever since its invention, the SAW process has evolved with one main goal: to combine quality with produetivity. With low alloy wires, the benefits have already been clearly demonstrated and widely exploited. However, little has been written on SA Wand cladding with eored wires for eorrosion or he at resisting applieations. Its extension to high alloy eompositions brings eorresponding benefits and adds so me specific and unique features. This paper foeuses on consumable specificities and on the quality and productivity features of SAW with CRA (corrosion resistant alloy) cored wires. It deseribes the potential as weIl as the limitations ofthis technique. Cored wires are now used for submerged are welding of almost aIl stainless steels ranging from soft martensitic to super-duplex, and for aseries of nickel base compositions as weIl as for cladding cobalt base aIloys. Examples of industrial applications with austenitic, duplex, martensitic and heat resisting stainless steels are given to illustrate the potential ofthe eored wire solution. KW - Submerged are welding KW - surfacing KW - cored wire KW - high-alloy steels Y1 - 2019 U6 - https://doi.org/10.15407/as2019.06.01 SN - 0005-111X IS - 6 SP - 4 EP - 13 ER - TY - GEN A1 - Doynov, Nikolay A1 - Stapelfeld, Christoph A1 - Michailov, Vesselin A1 - Pasternak, Hartmut A1 - Launert, Benjamin ED - Sommitsch, Christof ED - Enzinger, Norbert ED - Mayr, Peter T1 - Distortion analysis of large scaled welded structures T2 - Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria N2 - The work presents an innovative approach for simulation of welding induced distortions, which allows taking into consideration the local effects of the welding process as well as the global interactions in the structure. The approach bases on an integration of analytical and numerical calculation’s procedures in a hybrid model, realized with the aid of the inherent strain concept. The analytical procedure calculates the shrinkage strain components and area of the plastic deformed zone, caused by welding. The calculated strains are then transferred to the global finite element model in order to predict the distortions and stresses in the structure after every welding stage, as well as their final state. The consideration of welding scenarios, weld sequence, clamping conditions and the assembling stages is done by taking into account the intermediate variation of the strain state during the manufacturing steps. The article gives the theoretical basis of the analytical model. The consideration of the essential physical relations is put into discussion. The application of the model is illustrated on complex structures. Its reliability and practicability are demonstrated by means of a validation study. Y1 - 2019 SN - 978-3-85125-615-4 U6 - https://doi.org/10.3217/978-3-85125-615-4 SP - 254 EP - 280 PB - Verlag der Technischen Universität Graz CY - Graz ER - TY - GEN A1 - Naumov, Anton A1 - Morozova, Iuliia A1 - Rylkov, Evgenii A1 - Obrosov, Aleksei A1 - Isupov, Fedor A1 - Michailov, Vesselin A1 - Rudskoy, Andrey I. T1 - Metallurgical and Mechanical Characterization of High-Speed Friction Stir Welded AA 6082-T6 Aluminum Alloy T2 - Materials N2 - The objective of this study was to investigate the effect of the high welding speed on the mechanical properties and their relations to microstructural characteristics of butt friction stir welded joints with the use of 6082-T6 aluminum alloy. The aluminum sheets of 2.0 mm thick were friction stir welded at low (conventional FSW) and high welding speeds (HSFSW) of 200 and 2500 mm/min, respectively. The grain size in the nugget zone (NZ) was decreased; the width of the softened region was narrowed down as well as the lowest microhardness value located in the heat-affected zone (HAZ) was enhanced by HSFSW. The increasing welding speed resulted in the higher ultimate tensile strength and lower elongation, but it had a slight influence on the yield strength. The differences in mechanical properties were explained by analysis of microstructural changes and tensile fracture surfaces of the welded joints, supported by the results of the numerical simulation of the temperature distribution and material flow. The fracture of the conventional FSW joint occurred in the HAZ, the weakest weld region, while all HSFSW joints raptured in the NZ. This demonstrated that both structural characteristics and microhardness distribution influenced the actual fracture locations. KW - high-speed friction stir welding (HSFSW) KW - aluminum alloy KW - remnant oxide line (ROL) KW - microstructural characteristics KW - mechanical properties KW - fracture behavior KW - FEM Y1 - 2019 UR - https://www.mdpi.com/1996-1944/12/24/4211 U6 - https://doi.org/10.3390/ma12244211 SN - 1996-1944 VL - 12 IS - 24 ER - TY - GEN A1 - Morozova, Iuliia A1 - Bonnel, Jean-Marie A1 - Rosert, Reinhard A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Einfluss der Schweißposition beim MSG-Fülldrahtschweißen auf die Kerbschlagzähigkeit von hoch- und niedriglegierten Stählen T2 - DVS Congress 2019Große Schweißtechnische Tagung : DVS-Studentenkongress : Vorträge der Veranstaltungen in Düsseldorf vom 16. bis 17. September 2019 N2 - Die Schweißposition beeinflusst erheblich die mechanischen Eigenschaften der Schweißnaht, insbesondere die Kerbschlagzähigkeit. Dies zeigt ein umfassender Vergleich der mechanischen Eigenschaften von Schweißgütern, die in der Steigposition (PF) und Wannenlage (PA) ausgeführt wurden. Schweißgüter von Kohlenstoff-Mangan-Stählen weisen in der PF-Position eine reduzierte Kerbschlagarbeit im Vergleich zur PA-Position auf. Dagegen ist bei austenitischen und Duplexstählen der Einfluss der Schweißposition auf die Kerbschlagarbeit genau entgegengesetzt. Der Vortrag fasst den Einfluss der Schweißpositionen auf die mechanischen Eigenschaften zusammen und liefert eine Erklärung für die gegensätzlichen Auswirkungen auf die Kerbschlagzähigkeit der Schweißgüter. Der Schwerpunkt liegt dabei auf hochlegierten Fülldrähten mit einer schnell erstarrenden Schlacke. Die Schlackeneigenschaften, Schweißgutmikrostruktur, Delta-Ferrit-Gehalte für Schweißgüter vom Typ Duplexstahl (2209) und von austenitischen Schweißgütern (308L) sowie die Auswirkungen der Schweißposition auf die Richtung des Schweißkornwachstums werden erläutert. Zum Vergleich werden Kohlenstoff-Mangan-Rutil-Fülldrähte mit schnell erstarrender Schlacke herangezogen. Y1 - 2019 UR - https://www.gbv.de/dms/tib-ub-hannover/1067034390.pdf SN - 978-3-96144-066-5 SP - 310 EP - 318 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Naumov, Anton A1 - Isupov, Fedor A1 - Golubev, Iurii A1 - Morozova, Iuliia T1 - Effect of the temperature of friction stir welding on the microstructure and mechanical properties of welded joints of an Al-Cu-Mg alloy T2 - Metal Science and Heat Treatment N2 - Amethod for assessing the effect of the temperature of friction stir welding on the microstructure and mechanical properties of welded joints of aluminum alloy D16AT is suggested. The temperature cycles in different zones of a welded joint are determined by mathematical simulation. The computed temperature cycles are implemented in a Gleeble-3800 system. It is shown that the welding temperature affects little the evolution of the microstructure in different zones of the welded joints of alloy D16AT. Y1 - 2019 U6 - https://doi.org/10.1007/s11041-019-00342-0 SN - 1573-8973 SN - 0026-0673 VL - 60 SP - 695 EP - 700 ER - TY - GEN A1 - Naumov, Anton A1 - Morozova, Iuliia A1 - Isupov, Fedor A1 - Golubev, Iurii A1 - Michailov, Vesselin T1 - Temperature Influence on Microstructure and Properties Evolution of Friction Stir Welded Al-Mg-Si Alloy T2 - Key Engineering Materials N2 - The temperature influence on the microstructure evolution and microhardness of the agehardenable aluminium alloy 6082 T6 during friction stir welding was defined. In order to achieve this aim, the thermocycles calculated using the developed 3D Finite Element Model were physically simulated on the Gleeble-3800 in the points which located in the different zones of the weld. The microstructure in the chosen points after Gleeble testing was investigated as well as the microhardness was measured. The results were consequently compared with the relevant results obtained after friction stir welding. It was shown that the microstructure and microhardness profile are influenced not only by temperature but by deformation. The increase in hardness in different zones after FSW compared to Gleeble testing can be explained by the grain refinement in the nugget zone as well as the hardening precipitate distribution along the weld which can occur more rapidly due to the deformation influence. Y1 - 2019 U6 - https://doi.org/10.4028/www.scientific.net/KEM.822.122 SN - 1662-9795 VL - 822 SP - 122 EP - 128 ER - TY - GEN A1 - Naumov, Anton A1 - Isupov, Fedor A1 - Golubev, Iurii A1 - Morozova, Iuliia A1 - Spree, Cornelius T1 - Development of Methodology to Determine the Temperature Influence on Microstructure Evolution during Friction Stir Welding T2 - Papers from Materials Science and Technology 2018 (MS&T18), October 14–18, 2018, Greater Columbus Convention Center, Columbus, Ohio, USA Y1 - 2018 UR - https://www.researchgate.net/publication/328772948_DEVELOPMENT_OF_METHODOLOGY_TO_DETERMINE_THE_TEMPERATURE_INFLUENCE_ON_MICROSTRUCTURE_EVOLUTION_DURING_FRICTION_STIR_WELDING U6 - https://doi.org/10.7449/2018mst/2018/mst_2018_795_802 ER - TY - GEN A1 - Golubev, Iurii A1 - Morozova, Iuliia A1 - Naumov, Anton A1 - Hantelmann, Cord A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Numerical Simulation and Experimental Investigation on Impulse Friction Stir Welding of 6082-T6 Aluminum Alloy T2 - Papers from Materials Science and Technology 2017 (MS&T17), October 8 – 12, 2017, David L. Lawrence Convention Center, Pittsburgh, Pennsylvania USA N2 - The series of impulse friction stir welding (IFSW) experiments for aluminum alloy 6082-T6 butt joints was performed to obtain micrographs, tensile and hardness test samples and to receive the validation data for a numerical model of the process. Impulse force and frequency were varied to determine the effect of individual process parameters on microstructure evolution and mechanical properties of the welded butt joints. A three-dimensional model was established to simulate temperature distribution, heat generation and contact state between the tool and the workpiece during IFSW. Based on the numerical simulation, the influence of the impulses on heat input, maximum weld temperatures and contact state was found. The combination of impulse force and frequency effected the grain refinement. The influence of impulses on the elongation and hardness of the welded joints during IFSW were determined. Y1 - 2017 UR - https://www.researchgate.net/publication/326434324_Numerical_Simulation_and_Experimental_Investigation_on_Impulse_Friction_Stir_Welding_of_6082-T6_Aluminum_Alloy U6 - https://doi.org/10.7449/2017/mst_2017_987_994 SP - 987 EP - 994 ER - TY - GEN A1 - Evdokimov, Anton A1 - Ossenbrink, Ralf A1 - Doynov, Nikolay A1 - Michailov, Vesselin ED - Sommitsch, Christof ED - Enzinger, Norbert ED - Mayr, Peter T1 - Laser beam welding of steel-aluminum joints - influence of weld metal elastic-plastic properties on the distortions T2 - Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria N2 - Great attention is focused nowadays on laser welding of dissimilar steel-aluminum joints in overlap configuration in key-hole mode. It was found that elastic-plastic properties of the weld metal exhibit strong difference to those of the base alloys and can be defined as a function of aluminum content in the weld metal. A developed Finite-Element simulation model allows prediction of the aluminum content as a function of welding parameters and subsequently the elastic-plastic properties of the weld metal as a function of the determined content. The main goal of the present study is to show the impact of the weld metal properties on welding distortions and residual stresses. For that purpose, a sensitivity analysis of the thermomechanical model was performed, where the distortions and residual stresses were computed as a function of welding parameters and therefore as a function of corresponding weld metal properties. The analysis showed that the influence of the weld metal is essential, and its properties should be taken into consideration in the models for better prediction accuracy. Y1 - 2019 SN - 978-3-85125-615-4 U6 - https://doi.org/10.3217/978-3-85125-615-4 SP - 431 EP - 440 PB - Verlag der Technischen Universität Graz CY - Graz ER - TY - GEN A1 - Kaisheva, Darina A1 - Bokuchava, Gizo A1 - Papushkin, Igor A1 - Genchev, Gancho Vladimirov A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Petrov, Peter T1 - Determination of residual stresses in fiber laser welded stainless steel joints by neutron diffraction method T2 - Proc. SPIE 11047, 20th International Conference and School on Quantum Electronics: Laser Physics and Applications N2 - This study presents an experimental results of residual stress states in stainless steel plate samples with size 100 x 50 x 10 mm welded using a high-power fiber laser. The technological parameters of the welding process were: laser power Q = 15 kW; laser spot size = 0.65 mm; welding speed V = 3 m/min; 4 m/min; 5 m/min, using 30 L/min of protective Ar gas. The neutron diffraction method was used to determine the residual stresses in the bulk of the material. The neutron experiments were performed on the FSD diffractometer at the IBR-2 pulsed reactor in the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research - Dubna, Russian Federation. The measured residual stress distributions exhibit maxima at weld seam centers. As expected, for all specimens the residual stress is falling down in regions distant from the weld zone. Maximal residual stress value of 492 MPa was observed for sample welded with speed of V = 5 m/min. KW - Diffraction KW - Laser welding KW - Metals KW - Fiber laser KW - Laser processing KW - Laser applications KW - Sensors Y1 - 2019 U6 - https://doi.org/10.1117/12.2516421 CY - Nessebar ER - TY - GEN A1 - Shapovalov, Oleg A1 - Kodzhaspirov, Georgii A1 - Hantelmann, Cord A1 - Michailov, Vesselin T1 - Effect of a Welding Method on the Fatigue Strength and Fracture of Foam–Aluminum Sandwiches T2 - Russian Metallurgy (Metally) N2 - The influence of argon-arc welding and laser welding on the fatigue properties and the fracture of a foam–aluminum sandwich is studied. Argon-arc-welded samples are found to have the highest fatigue strength. KW - aluminum sandwich KW - fatigue strength KW - four-point bending KW - butt weld Y1 - 2019 UR - https://link.springer.com/journal/11505/2019/10/page/2 U6 - https://doi.org/10.1134/S0036029519100239 SN - 0036-0295 VL - Vol. 2019 IS - 10 SP - 1063 EP - 1066 ER - TY - GEN A1 - Evdokimov, Anton A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Obrosov, Aleksei A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Thermomechanical laser welding simulation of dissimilar steel-aluminum overlap joints T2 - International Journal of Mechanical Sciences N2 - Mixing of steel and aluminum within the weld pool during keyhole laser welding results in a complex dissimilar microstructure, which in turn, initiates a shift in weld metal mechanical properties. In this study, a numerical model for computation of distortions in laser-welded dissimilar overlap joints (austenitic stainless steel 304 – 6082-T6 aluminum alloy), which considers properties of the mixed steel-aluminum weld metal was developed. The required yield strength, Young's modulus, and strain hardening exponent of the weld metal were experimentally determined using the indentation technique coupled with energy-dispersive X-ray spectroscopy. The designed material model calculates the weld elastic-plastic properties as a function of the aluminum concentration. The softening of the alloys in the heat-affected zone was determined by physical simulations and considered as a function of maximum temperature. Computed and measured distortions showed good agreement for various welding regimes with an average deviation of 18.4%. The sensitivity analyses indicated that the application of the developed weld material model significantly improves the accuracy of the thermomechanical simulations. Y1 - 2021 U6 - https://doi.org/10.1016/j.ijmecsci.2020.106019 SN - 1879-2162 VL - 190 ER - TY - GEN A1 - Ginzburg, Svetlana A1 - Morozova, Iuliia A1 - Kloshek, Alexander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Bobrynina, Elizaveta A1 - Koltsova, Tatiana S. A1 - Tolochko, Oleg V. A1 - Koçak, Mustafa A1 - Ozbek, Sunullah A1 - Morozova, Iuliia T1 - Addition of nanoparticles to flux cored wires for the nucleation of acicular ferrite microstructure in weld metals of the high-strength low-alloy steel T2 - Welding and Cutting N2 - For the reliability of many welded structures like pipelines or offshore wind parks, it is necessary to ensure high mechanical properties such as strength and toughness of the entire material. In order to improve quality of weld joints, flux cored rods and wires containing different nanoparticles (ZrO2, LaB6 and Al2O3) were manufactured and welded with the TIG and MAG welding processes. Influence of these nanoparticles on the microstructure and mechanical properties of the weld joints were investigated. The acicular ferrite and improved strength of the weld metals were observed by the addition of 0.2 wt.% of iron powder with ZrO2 nanoparticles to the filling of flux cored wires. Y1 - 2020 SN - 1612-3433 VL - 19 IS - 1 SP - 48 EP - 53 ER - TY - GEN A1 - Morozova, Iuliia A1 - Obrosov, Aleksei A1 - Naumov, Anton A1 - Królicka, Aleksandra A1 - Golubev, Iurii A1 - Bokov, Dmitry O. A1 - Doynov, Nikolay A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Impact of Impulses on Microstructural Evolution and Mechanical Performance of Al-Mg-Si Alloy Joined by Impulse Friction Stir Welding T2 - Materials N2 - Impulse Friction Stir Welding (IFSW) was utilized to join 6082–T6 alloy plates at various impulse frequencies. A distinctive feature of IFSW is the generation of mechanical impulses that enhances the forging action of the tool, and thereby, alters the weld microstructure. The microstructural evolution in the Stir Zone (SZ) with special focus on the strengthening precipitation behavior, and overall mechanical properties of the IFSW joints have been investigated. It was demonstrated that the strengthening β″ precipitates reprecipitated in the SZ of the IFSW joints during natural aging. In contrast, no precipitates were found in the SZ of the Friction Stir Welding (FSW) weld. Partial reversion of β″ after IFSW is supposed to occur due to more developed subgrain network and higher dislocation density introduced by impulses that accelerated precipitation kinetics. Dynamic recrystallisation was facilitated by impulses resulting in a fine, homogeneous structure. There was no significant difference between the microhardness in the SZ, tensile and yield strength of the FSW and IFSW joints. However, the application of impulses demonstrated the smoothing of the hardness reduction in the transition region at the advancing side. The shift of the fracture location from the Heat-Affected Zone (HAZ) by FSW to the SZ as well as higher elongation of the joints by IFSW of lower frequencies could be related to the grain refinement and the change of the grain orientation. KW - Al-Mg-Si alloy KW - impulse friction stir welding (IFSW) KW - precipitation KW - microstructure evolution KW - mechanical properties Y1 - 2021 UR - https://www.mdpi.com/1996-1944/14/2/347/htm U6 - https://doi.org/https://doi.org/10.3390/ma14020347 SN - 1996-1944 VL - 14 IS - 2 ER - TY - GEN A1 - Baena-Moreno, Francisco Manuel A1 - González-Castaño, Miriam A1 - Navarro de Miguel, Juan Carlos A1 - Miah, Kamal Uddin Mohammad A1 - Ossenbrink, Ralf A1 - Odriozola, José Antonio A1 - Arellano-García, Harvey T1 - Stepping toward Efficient Microreactors for CO2 Methanation: 3D Printed Gyroid Geometry T2 - ACS Sustainable Chemistry & Engineering N2 - This work presents a comparative study towards the development of efficient micro-reactors based on 3D-printed structures. Thus, the study evaluates the influence of the metal substrate geometry on the performance of structured catalysts for the CO2 methanation reaction. For this purpose, 0.5%Ru–15%Ni/MgAl2O4 catalyst is wash coated over two different micro-monolithic metal substrates: a conventional parallel channel honeycomb structure and a novel 3D-printed structure with a complex gyroid geometry. The effect of the metal substrate geometry is analyzed for several CO2 sources including ideal flue gas atmospheres, the presence of residual CH4 and CO in the flue gas, as well as simulated biogas sources. The advantages of the gyroid-3D complex geometries over the honeycomb structures are shown for all evaluated conditions, providing at the best-case scenario a 14% improvement of CO2 conversion. Moreover, this contribution shows that systematically tailoring geometrical features of structured catalysts becomes an effective strategy to achieve improved catalysts performances independent of the flue gas composition. By enhancing the transport processes and the gas-catalyst interactions, the employed gyroid 3D metal substrates enable boosted CO2 conversions and greater CH4 selectivity within diffusional controlled regimes. KW - CO2 methanation KW - gyroid geometry KW - CH4 selectivity KW - gyroid-3D complex Y1 - 2021 U6 - https://doi.org/10.1021/acssuschemeng.1c01980 SN - 2168-0485 VL - 9 IS - 24 SP - 8198 EP - 8206 ER - TY - GEN A1 - Shapovalov, Oleg A1 - Shapovalova, Mariia A1 - Ossenbrink, Ralf A1 - Heckel, Thomas A1 - Michailov, Vesselin A1 - Weiß, Sabine A1 - Gaal, Mate T1 - Verbessern der Korrosionsbeständigkeit eines hochtemperaturbeständigen Ultraschalldämpfungskörpers mittels Laserstrahl-Auftragschweißen T2 - DVS Berichte 2021 N2 - Während in einem konventionellen Ultraschallprüfkopf ein Kunststoffdämpfungskörper mit Kleber oder Öl an einen Piezoschwinger angekoppelt ist, werden als Hochtemperaturlösung feinporöse sintermetallische Dämpfungsmaterialien mit einer Flüssigglasankopplung eingesetzt. Um dabei das Sintermetall vor dem korrosiven Angriff der Glasschmelze zu schützten, wird am Dämpfungskörper gegenwärtig Gold- oder Platinfolie zeit- und kostenaufwendig appliziert. In der aktuellen Arbeit wurde eine Methode zum Korrosionsschutz der sintermetallischen Oberfläche aus rostfreiem Stahl mittels Laser-Pulverauftragschweißen entwickelt. Im Laufe einer Schweißparameterstudie auf dem Substratmaterial aus massivem rostfreiem Stahl wurde die Eignung unterschiedlicher Auftragsmaterialien auf Nickel- und Kobaltbasis untersucht. Dabei wurde zunächst der Einfluss verschiedener Schweißparameter wie Laserleistung, Vorschubgeschwindigkeit und Pulvermenge auf die Auftragsqualität (Nahtform, Vermischungsgrad, Porosität) metallografisch bewertet. Anschließend wurden die aufgetragenen Schichten hinsichtlich ihrer Korrosionsbeständigkeit getestet. Der Kontakt mit einer flüssigen Glasmischung bei 500 °C hat bei keiner der beschichteten Proben sichtbare Korrosionswirkung gezeigt. Als Resultat der Schweißparameterstudie haben sich besonders die nickelbasierten Pulver als gut geeignete Materialien für den Prozess gezeigt. Die identifizierten Schweißparameter wurden im nächsten Schritt erfolgreich an das sintermetallische Substrat angepasst. Y1 - 2021 UR - https://www.dvs-ev.de/call4papers/abstract.cfm?vid=109&pid=7032 SN - 978-3-96144-147-1 SP - 370 EP - 377 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Kaneneks, Michael A1 - Kloshek, Alexander A1 - Morozova, Iuliia A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Sembol, Ronny T1 - WAAM eines Zwischenstücks für die Bergbauausrüstung T2 - DVS Bericht 2021 N2 - Die lichtbogenbasierte additive Fertigung (WAAM) ist ein vielversprechendes Werkzeug, um die Ersatzteilbereitstellung von schwer verfügbaren oder aufwendig herstellbaren Einzelkomponenten in kürzester Zeit zu gewährleisten. Die Straffung innerbetrieblicher Abläufe sowie die Minimierung von Herstellungs- und Lagerkosten sind eine direkte Folge. Vor dem Einsatz im Betrieb muss sichergestellt werden, dass die Bauteile fehlerfrei additiv herstellbar sind und die mechanischen Eigenschaften den Anforderungen konventionell gefertigter Werkstücke entsprechen. Ein solcher Nachweis konnte am Beispiel eines additiv hergestellten Zwischenstücks für die Bergbauausrüstung mit einer abschließenden Charakterisierung der Werkstoffeigenschaften erfolgreich geführt werden. Das Zwischenstück mit einem Gewicht von ca. 31 kg zur Verbindung von geometrisch unterschiedlichen Profilen wurde ausgehend von einer Grundplatte aus S355-J2+N beidseitig additiv mit einem Massivdraht G3Si1 aufgebaut. Die Ermittlung geeigneter Parameter, Schweißfolgen und Zwischenlagentemperaturen erfolgte experimentell mit begleitenden metallografischen Untersuchungen. Nach erfolgreicher Fertigung wurden die mechanischen Eigenschaften des Zwischenstücks bestimmt sowie die Festigkeit und Zähigkeit mit den geforderten Werkstoffkennwerten des bisher eingesetzten konventionellen Konstruktionsmaterials verglichen. KW - Schweißtechnik KW - WAAM KW - Wire Arc Additiv Manufacturing KW - Additive Fertigung KW - Lichtbogenauftragschweißen Y1 - 2021 UR - https://www.dvs-ev.de/call4papers/abstract.cfm?vid=109&pid=7030 SN - 978-3-96144-147-1 VL - 2021 SP - 315 EP - 323 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Jokisch, Torsten A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Heat source model for electron beam welding of nickel-based superalloys T2 - Materials testing : Materialprüfung Y1 - 2021 U6 - https://doi.org/10.1515/mt-2020-0002 SN - 2195-8572 SN - 0025-5300 VL - 63 IS - 1 SP - 17 EP - 28 ER - TY - GEN A1 - Valkov, Stefan A1 - Kotlarski, Georgi A1 - Ormanova, Maria A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Petrov, Peter A1 - Michailov, Vesselin T1 - Crystallography and Mechanical Properties of Wire Arc Additively Manufactured Al5356 Components T2 - Comptes Rendus de L'Academie Bulgare des Sciences N2 - In this study, we present results of the evolution of the crystallographic texture and imperfections, as well as the corresponding mechanical properties of wire and arc additively manufactured (WAAM) Al5356 specimens, studied by X-ray diffraction (XRD) and tensile testing, respectively. The results show that the phase composition is in the form of a face-centred cubic (fcc) crystal structure, corresponding to the base material, as well as some traces of oxide phase Al2O3. The WAAM specimen growing is accompanied by a slight change in the preferred crystallographic orientation, from (111) to (200) and a decrease in the imperfections concentration. Also, it was found that the ultimate tensile strength (UTS), yield strength (YS), and elongation slightly decrease from the initial to the more advanced stages of growth. KW - wire arc additive manufacturing KW - Al5356 alloy KW - crystallography KW - mechanical properties Y1 - 2021 U6 - https://doi.org/10.7546/CRABS.2021.06.03 SN - 1310-1331 VL - 74 IS - No. 6 SP - 820 EP - 827 ER - TY - GEN A1 - Wasilewski, Eric A1 - Kaneneks, Michael A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Laserstrahlschweißen – Verzugs- und Kaltrissminimierung durch simulationsbasierte Steuerung T2 - DVD Congress 2020 : Große Schweißtechnische Tagung : DVS Campus : Vorträge der Online-Veranstaltungen vom 14. bis 18. September 2020 N2 - Leichtbau und das Streben nach Ressourcen- und Energieeffizienz fördern in den letzten Jahren vermehrt den Einsatz hochfester Stähle. Das Laserstrahlschweißen dieser Werkstoffe wird in der industriellen Großserienferti-gung zur effizienten Herstellung hochpräziser Bauteile und Komponenten mit höchsten Qualitätsanforderungen eingesetzt. Die Vermeidung schweißbedingter Fehler wie Schweißverzug und Kaltrissbildung sind dabei von ent-scheidender Bedeutung. Konventionelle Anwendungen erfüllen diesen Anspruch derzeit bedingt durch sehr enge Prozesstoleranzen und die Auswahl unkritischer Werkstoffe, was die Potentiale der Fügeverbindung begrenzt. Auf Basis von FE-Schweißprozesssimulationen konnten Konzepte entwickelt werden, welche eine Verzugs- und Riss-minderung durch aktive Steuerung des Laserschweißprozesses ermöglichen. Die zugrundeliegenden Modelle be-rücksichtigen zum einen das schweißbedingte Temperaturfeld, Gefügeumwandlungen und Eigenspannungen für die Berechnung des Verzugs. Zudem wird die lokale Wasserstoffkonzentration berechnet und die Ergebnisse der Schweißprozesssimulation mittels eines Kaltrisstools bewertet, welches werkstoffspezifische Risskriterien enthält. Die Fähigkeit das Verzugs- und Kaltrissverhalten abzubilden, eröffnet die Möglichkeit zur Parametervariation. Aus den erhobenen Daten wurden Konzepte der aktiven Krafteinleitung mit einer dynamischen Werkstückeinspannung abgeleitet, die zu Verzugs- und Kaltrissminimierung führen und die Schweißbarkeit hochfester Werkstoffe fördern. Y1 - 2019 SN - 978-3-96144-098-6 SP - 9 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Jokisch, Torsten A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Böttger, Bernd A1 - Senger, Aleksej T1 - Analysis of temperature field during electron beam welding of hot crack sensitive nickel base alloy T2 - IEBW International Electron Beam Welding Conference: lectures of the 6th International Conference taking place online on 9 to 10 March 2021 N2 - The use of temperature-resistant nickel-based superalloys in the field of industrial gas turbines is increasing due to constantly rising operating temperatures. Among different joining methods the electron beam welding is commonly used for manufacturing of turbine components because it provides a reduced heat input. However, the highly localized beam impact causes high temperature gradients and leads to the formation of hot cracks. Welding of such material with a high brittle temperature range is challenging and needs an increasing effort of process adaption. Experiments indicate a significant improvement of hot crack susceptibility when welding outside the common welding parameter range. To understand these observations a study of the temperature field in the specimens using numerical simulations was carried out. For this purpose, a validated simulation model was used. Special attention was paid to the domain in close vicinity of the weld pool. The results illustrate the velocity of solidification isotherm as well as the temperature rates when crossing the melting point. Finally, the relations between thermal fields, crack types and distributions in the different specimens are discussed. Y1 - 2021 UR - https://www.dvs-media.eu/media/pdf/DVS_Bericht_368_Inhalt.pdf SN - 978-3-96144-133-4 SP - 81 EP - 87 PB - DVS Media GmbH CY - Düsseldorf ER - TY - BOOK A1 - Pasternak, Hartmut A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Michailov, Vesselin A1 - Doynov, Nikolay T1 - Ermittlung der Tragfähigkeit neuartiger stählerner Schalenbauwerke unter realitätsnaher Berücksichtigung des Schweißverzugs Y1 - 2020 SN - 978-3-946885-89-4 PB - Forschungsvereinigung Stahlanwendung e. V. CY - Düsseldorf ER - TY - GEN A1 - Piott, Michael A1 - Werber, Alexandra A1 - Schleuss, Leander A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Numerical and experimental analysis of heat transfer in resistance spot welding process of aluminum alloy AA5182 T2 - International Journal of Advanced Manufacturing Technology N2 - In this work, a numerical model and experiments are used to investigate heat transfer processes during resistance spot welding process of aluminum. For this purpose, calibrated heat transfer conditions and thermal contact conductance are transferred from a previous work to a coupled thermal-electrical-mechanical finite element model. First, all domains of the numerical model are validated by an experimental study. The experimental setup includes the measurement of current, voltage drops, electrode force, electrode displacement, and temperatures while two sheets of aluminum alloy AA5182 are joined. Computational results show that most of the generated Joule heat (78%) is stored in the electrodes or transferred to cooling water until the end of weld time. Heat transfer by natural convection and thermal radiation is very small and can in general be neglected for complete process. Afterwards, the influence of electrode water-cooling on welding process is investigated numerically. The results indicate that the generation of Joule heat and thermal energy of the sheets during weld time is only slightly affected by electrode water-cooling. As a consequence, water-cooling conditions do not affect nugget formation. In contrast, electrode water-cooling highly influences cooling conditions during hold time. KW - Aluminum resistance spot welding KW - Heat transfer KW - FE-simulation KW - Electrode water-cooling KW - Instrumented experiments Y1 - 2020 U6 - https://doi.org/10.1007/s00170-020-06197-7 SN - 0268-3768 SN - 1433-3015 VL - Vol. 111 IS - 5-6 SP - 1671 EP - 1682 ER -