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This work concerns issues of mathematical modelling of phase transformations in steels during a high-speed high-power heat source welding processes. The analysis of the influence of thermal cycle parameters such as: heating rate, cooling rate and the maximal heating temperature on the kinetics of phase transformations during heating and cooling is performed. The verification of classical mathematical and numerical models of phase transformations is presented in relation to advanced welding methods using a high-speed high-power heat source on the basis of data found in the literature and experimental research. [ABSTRACT FROM AUTHOR]

The mathematical model and numerical simulations of the mechanical phenomena in the gantry crane are presented in this paper. The design of modern mechanical constructions is a complex task that requires use of appropriate tools. Such a modern tool, that gives a broad opportunity to analyze strength parameters of designed structures, is numerical simulation which uses the various numerical methods. Here the problem was solved by the finite element method. The analysis of the stresses and strains of the structure of gantry crane was made using the advanced software with highly efficient possibilities of modeling. Motion of the crane trolley along the beam was also taken into account in the study. The research performed, allows the evaluation of the stress state, pointing out the critical areas and values which are made in order to increase the strength of the structure of the gantry crane. The results of numerical simulation are presented in the form of the fields of Huber-Misses stress for the selected location of the crane trolley. [ABSTRACT FROM AUTHOR]

This work concerns experimental research on the determination of deformation during uniaxial tension test of samples made of laser-arc hybrid welded joints. Steel sheet made of S355 steel with thickness 5 mm is butt-welded without gap using hybrid welding technique involving GMAW method with Yb:YAG laser beam. Samples used to the tension test are made from welded joints and base material. Universal strength machine Zwick&Roel Z100 is used with extensometer Multisens in all performed tension tests. The machine works with Dantec Q-400 Istra multi-camera 3D correlation system. System of three cameras mounted on a beam line is used for accurate measurement of the spatial deformations. Presented results of the research include strain fields measured for the entire tension cycle at the frequency 40 Hz. [ABSTRACT FROM AUTHOR]

Numerical modeling of thermal phenomena with the motion of fusion zone in the welding pool taken into account is performed in this study for hybrid welding process using Yb:YAG laser with electric arc in GMAW method. New hybrid heat source model is developed on the basis of classical Goldak model for the electric arc and interpolation model for the laser beam with the experimental data of Yb:YAG laser beam distribution taken into account. Temperature field and melted material velocity field are calculated on the basis of numerical solution into mass, momentum and energy conservation equations in finite volume method with Chorin's projection method. Computer simulations of temperature field and melted material velocity field are performed in the welding pool for different distances between heat sources. The comparison of numerically estimated geometry of characteristic zones of joints with macroscopic pictures of cross sections of welds is made in order to evaluate the suitability of developed numerical model in industrial applications. [ABSTRACT FROM AUTHOR]

Numerical analysis of thermal treatment processes is an important issue to be considered by contemporary laboratories dealing with industrial designing in general. Phenomena associated with heat treatment are complex and not yet adequately explained. Improvement in this field of numerical solutions is particularly forced by industry which, striving for deployment of state of the art technologies and reduction of costs, is demanding continuous enhancement of tool thermal treatment. Phase transformations, in particular in cooling processes, involve considerable changes in kinetics that are not always associated with external thermal impact. Analyses of experimental data allowed developing many mathematical models to measure volume fractions of phase transformations in solid state. The Johnson-Mehl Avrami equation and generalised Kolmogorov equation are the two primary models applied in almost all tests evaluating transformation of austenite into ferrite, bainite and martensite. In order to calculate the martensitic phase volume fraction, usually the Koistinen-Marburger equation, or any of its modified formulas, are used. [ABSTRACT FROM AUTHOR]

The laser-arc hybrid welding is widely used in many industries through the combination of advantages found in welding technologies used in this single process. A significant issue is the determination of the influence of heat source power distribution on welding deformations generated at the interface of joined elements and adjacent zones. Numerical estimation of welding deformations is very important and allows for the proper selection of technological parameters as well as the prediction of welded joints quality. This work concerns numerical simulation of thermomechanical phenomena in hybrid welding of sheets made of X5CRNI18-10 steel using laser beam and electric arc heat sources. Three dimensional discrete model is created in Abaqus FEA in order to estimate welding deformations generated by temperature field in the joint. Additional numerical subroutine is created in Abaqus/Standard module in which the distribution of movable hybrid heat source is implemented. The shape and size of the fusion zone is determined on the basis of numerically obtained temperature field as well as welding deformations occurring in hybrid butt-welded joints. [ABSTRACT FROM AUTHOR]

This work concerns mathematical and numerical modelling of temperature field during hybrid welding process using Yb:YAG laser and electric arc in GMAW method. Numerical analysis is performed taking into account the motion of liquid steel in the fusion zone. Yb:YAG laser power distribution is determined on the basis of experimental research made on TruDisk 12002 laser. Geostatistical Kriging method is used in the interpolation of Yb:YAG laser power intensity distribution. Temperature field and melted material velocity field in the fusion zone of hybrid welded sheets made of S355 steel are obtained on the basis of numerical solution of continuum mechanics equations in Chorin's projection method and finite volume method. Experimental research of laser beam profile is performed in order to verify the correctness of developed heat source model. Fusion zone and heat affected zone geometry is predicted on the basis of calculated temperature field in the cross section of hybrid welded joint. [ABSTRACT FROM AUTHOR]

This paper concerns the modelling of laser beam heat source based on experimental research of Yb:YAG laser. Measurements of the real laser beam power emitted by Trumpf laser head D70 are performed using UFF100 analyser. Developed heat source interpolation model is based on the geostatistical Kriging method. Comparison of experimentally determined Yb:YAG laser power intensity distribution with analytical models and interpolated distribution is carried out in order to determine the accuracy of mapping of the real laser beam heat source distribution. Finally, numerical simulation of laser heating process is performed in finite element method to evaluate the usefulness of presented solutions. [ABSTRACT FROM AUTHOR]