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Abstrakt

The behaviour of porous sinters, during compression and compression with reverse cyclic torsion tests is investigated in the article based on the combination of experimental and numerical techniques. The sinters manufactured from the Distaloy AB powder are examined. First, series of simple uniaxial compression tests were performed on samples with three different porosity volume fractions: 15, 20 and 25%. Obtained data were then used during identification procedure of the Gurson-Tvergaard-Needleman finite element based model, which can capture influence of porosity evolution on plasticity. Finally, the identified Gurson-Tvergaard- Needleman model was validated under complex compression with reverse cyclic torsion conditions and proved its good predictive capabilities. Details on both experimental and numerical investigations are presented within the paper.
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Abstrakt

Detailed studies of the movement of liquid steel (hydrodynamics) on a real object are practically impossible. The solution to this problem are physical modelling carried out on water models and numerical modelling using appropriate programs. The method of numerical modelling thanks to the considerable computing power of modern computers gives the possibility of solving very complex problems. The paper presents the results of model tests of liquid flow through tundish. The examined object was model of the twonozzle tundish model. The ANSYS Fluent program was used to describe the behavior of liquid in the working area of the tundish model. Numerical simulations were carried out using two numerical methods of turbulence description: RANS (Reynolds-Averaged Navier-Stokes) – model k-ε and LES (Large Eddy Simulation). The results obtained from CFD calculations were compared with the results obtained using the water model.
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Abstrakt

A numerical model of binary alloy crystallization, based on the cellular automaton technique, is presented. The model allows to follow the crystallization front movement and to generate the images of evolution of the dendritic structures during the solidification of a binary alloy. The mathematic description of the model takes into account the proceeding thermal, diffusive, and surface phenomena. There are presented the results of numerical simulations concerning the multi-dendritic growth of solid phase along with the accompanying changes in the alloying element concentration field during the solidification of Al + 5% wt. Mg alloy. The model structure of the solidified casting was achieved and compared with the actual structure of a die casting. The dendrite interaction was studied with respect to its influence on the generation and growth of the primary and secondary dendrite arms and on the evolution of solute segregation both in the liquid and in the solid state during the crystallization of the examined alloy. The morphology of a single, free-growing dendritic crystal was also modelled. The performed investigations and analyses allowed to state e.g. that the developed numerical model correctly describes the actual evolution of the dendritic structure under the non-equilibrium conditions and provides for obtaining the qualitatively correct results of simulation of the crystallization process.
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Abstrakt

In the paper the use of the artificial neural network to the control of the work of heat treating equipment for the long axisymmetric steel elements with variable diameters is presented. It is assumed that the velocity of the heat source is modified in the process and is in real time updated according to the current diameter. The measurement of the diameter is performed at a constant distance from the heat source (∆z = 0). The main task of the model is control the assumed values of temperature at constant parameters of the heat source such as radius and power. Therefore the parameter of the process controlled by the artificial neural network is the velocity of the heat source. The input data of the network are the values of temperature and the radius of the heated element. The learning, testing and validation sets were determined by using the equation of steady heat transfer process with a convective term. To verify the possibilities of the presented algorithm, based on the solve of the unsteady heat conduction with finite element method, a numerical simulation is performed. The calculations confirm the effectiveness of use of the presented solution, in order to obtain for example the constant depth of the heat affected zone for the geometrically variable hardened axisymmetric objects.
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