@inproceedings{DreibatiZhangWolfetal., author = {Dreibati, Ossama and Zhang, Wei and Wolf, Matthias and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Thermo-mechanical properties of refractory ceramic for the numerical simulation of their thermo-shock behaviour}, language = {en} } @inproceedings{DreibatiOssenbrinkDoynovetal., author = {Dreibati, Ossama and Ossenbrink, Ralf and Doynov, Nikolay and Michailov, Vesselin}, title = {Physical and numerical simulation of thermo-mechanical properties in the weld heat affected zone of an AlMgSi-alloy}, series = {THERMEC 2011, International Conference on Processing \& Manufacturing of Advanced Materials, processing, fabrication, properties, applications, August 1 - 5, 2011, Quebec City, Canada, Vol. 2}, booktitle = {THERMEC 2011, International Conference on Processing \& Manufacturing of Advanced Materials, processing, fabrication, properties, applications, August 1 - 5, 2011, Quebec City, Canada, Vol. 2}, publisher = {TTP, Trans Tech Publ.}, address = {Durnten-Zurich [u.a.]}, pages = {1491 -- 1496}, language = {en} } @inproceedings{DreibatiOssenbrinkMichailov, author = {Dreibati, Ossama and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Hydrogen charging of high strength steel specimens and physical simulation of cold cracking under laser beam welding conditions}, series = {THERMEC 2011, International Conference on Processing \& Manufacturing of Advanced Materials, processing, fabrication, properties, applications, August 1 - 5, 2011, Quebec City, Canada, Vol. 2}, booktitle = {THERMEC 2011, International Conference on Processing \& Manufacturing of Advanced Materials, processing, fabrication, properties, applications, August 1 - 5, 2011, Quebec City, Canada, Vol. 2}, publisher = {TTP, Trans Tech Publ.}, address = {Durnten-Zurich [u.a.]}, isbn = {978-3-0-3785-303-0}, pages = {1391 -- 1396}, language = {en} } @misc{DreibatiOssenbrinkDoynovetal., author = {Dreibati, Ossama and Ossenbrink, Ralf and Doynov, Nikolay and Michailov, Vesselin}, title = {Physical and numerical simulation of thermo-mechanical properties in the weld heat affected zone of an AlMgSi-alloy}, series = {Materials Science Forum}, volume = {706-709}, journal = {Materials Science Forum}, issn = {0255-5476}, pages = {1491 -- 1496}, language = {en} } @misc{GenchevDreibatiOssenbrinketal., author = {Genchev, Gancho Vladimirov and Dreibati, Ossama and Ossenbrink, Ralf and Doynov, Nikolay and Michailov, Vesselin}, title = {Physical and Numerical Simulation of the Heat-affected Zone of Multi-pass Welds}, series = {Materials Science Forum}, journal = {Materials Science Forum}, number = {Vol. 762}, issn = {0255-5476}, pages = {544 -- 550}, abstract = {The paper presents a numerical and experimental approach for the quantification of the thermo-mechanical properties in multi-pass weld's heat affected zone (HAZ) of low alloy steel "S355J2+N". First, the characteristic temperature cycles for multi-pass welds were identified by FE temperature field simulations of welding. Based on the identified temperature cycles, the microstructure in the HAZ has been physically simulated with the simulation and testing system Gleeble 3500 to investigate the influence of multi thermal exposure on the thermo-mechanical properties. Thus, the thermo-mechanical material properties including thermal strain and temperature dependent stress strain behaviour as function of peak temperatures and cooling rates have been determined. These material properties were used to calibrate a developed model for numerical prediction of the material properties of multi-pass weld HAZ.}, language = {en} } @misc{ZhangDoynovWolfetal., author = {Zhang, Wei and Doynov, Nikolay and Wolf, Matthias and Dreibati, Ossama and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Investigation of the Thermal Shock Behavior of Ceramic Using a Combination of Experimental Testing and FE-Simulation Methods}, series = {Advanced engineering materials}, volume = {15}, journal = {Advanced engineering materials}, number = {6}, issn = {1527-2648}, doi = {10.1002/adem.201200241}, pages = {480 -- 484}, abstract = {Thermal shock behavior of ceramics plays a decisive role in their broad industrial applications. For enhanced understanding of damage and failure mechanism under thermal shock loading, in the present work, a combination of experimental testing and numerical simulation methods has been used. The thermal shock behavior of the alumina (99.7\%) disk samples has been investigated by using a plasma test stand: the bottom of the ceramic disks were locally heated in the center by plasma beam; during the heat treatment the temperature distribution at the top of the sample was recorded with a thermographic system. To characterize the thermal shock resistance, a thermomechanical simulation was subsequently carried out. It calculates the temperature and stress distribution within the ceramic disks. The calculated critical thermal tension stresses are reported, which led to the failure of the ceramic disks under thermal shock loading. The effect of the sample thickness on the temperature and stress distribution is presented. Compared with the experimental results the simulated results show excellent agreement. As conclusion, it is possible to determine the thermal shock behavior of ceramic materials by the combination of experimental testing and numerical simulation.}, language = {en} } @misc{DreibatiOssenbrinkMichailov, author = {Dreibati, Ossama and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Quantification of cold cracking parameters of high strength steels by physical simulation under welding conditions}, series = {Quarterly journal of the Japan Welding Society}, volume = {31}, journal = {Quarterly journal of the Japan Welding Society}, number = {4}, issn = {0288-4771}, doi = {10.2207/qjjws.31.148s}, pages = {148 -- 152}, abstract = {Cold cracks in welds are the result of the formation of brittle microstructure as martensite in the presence of diffusible hydrogen as well as of tensile stresses. Cold cracks occur when the combination of cold crack influence parameters (CCIP) overcomes a critical limit. In this study, critical combinations of CCIP were identified with an enhanced test procedure under welding conditions. The test is based on the physical simulation technique of heat affected zone (HAZ) and it is carried out using the test and simulation center Gleeble 3500. Thereby, laboratory special specimens are charged with hydrogen from pure hydrogen atmosphere in the initial stage of the test. Rigidly restraint specimen section is subjected to different weld temperature cycles. Through the thermal exposure, the desired microstructure of HAZ is set in the test zone of the restraint specimen section. A plastic deformation takes place owing to the prevented expansion during heating and contraction of the specimen during cooling. Consequently, compressive or tensile reactions stresses arise in the deformed zone. Cracked specimen represents a critical combination of the CCIP. The quantitative cold crack criterion separates the cold crack susceptible combinations from those non susceptible.}, language = {en} } @misc{MichailovDreibatiOssenbrinketal., author = {Michailov, Vesselin and Dreibati, Ossama and Ossenbrink, Ralf and Schweizer, Frank}, title = {Rechnergest{\"u}tzte Vorhersage der Kaltrissneigung laserstrahlgeschweißter Bauteile aus hochfesten St{\"a}hlen - Teil 1}, series = {Schweißen und Schneiden : Fachzeitschrift f{\"u}r Schweißen und verwandte Verfahren}, volume = {65}, journal = {Schweißen und Schneiden : Fachzeitschrift f{\"u}r Schweißen und verwandte Verfahren}, number = {11}, issn = {0036-7184}, pages = {776 -- 781}, language = {de} } @misc{AtangaZhangDreibatietal., author = {Atanga, Valetine Kubong and Zhang, Wei and Dreibati, Ossama and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin and Scheffler, Michael}, title = {Alumina-mullite Materials for Refractory Applications: Microstructure, Physical and Finite Element Simulation of Thermal Shock Behaviour}, series = {refractories WORLDFORUM}, volume = {4}, journal = {refractories WORLDFORUM}, number = {1}, issn = {1868-2405}, pages = {159 -- 164}, language = {en} }