Browsing by Author "Burbelko, Andrej"

Now showing 1 - 2 of 2

Access status: Open Access ,
Model krystalizacji w układzie dwuskładnikowym z udziałem trzech faz z wykorzystaniem automatu komórkowego
(Data obrony: 2011) Gurgul, Daniel
Wydział Odlewnictwa
In the first part of thesis an overview of modeling of cast iron solidification is presented. It is a short historical re-view, starting with analytical models and ending with fully numerical. The characteristics of individual models are briefly described. Chapter "Model description" presents a detailed description of the model of ductile iron solidification. It is based on cellular automaton technique. Its characteristic feature is that the shape of growing austenite and graphite grains is not supposed a priori, but is the result of model calculations. The model takes into account such phenomena as heat transfer, diffusion of carbon in liquid and austenite, release of latent heat and its impact on the conditions prevailing at the front of solidification, nucleation of austenite and graphite. The model takes into consideration nonequilibrium nature of phase transformations and the effect of curvature of the interphase boundaries on the temperature of thermodynamic equilibrium. In the experimental part simulations of ductile iron solidification were performed for hypoeutectic, eutectic and hypereutectic composition. The modeling results were compared with experimental results which were obtained for ductile iron with hypoeutectic composition and for so called transparent model substance. The modeling cooling curve was compared with the real cooling curve. In order to qualitatively comparison of calculated microstructures they were compare with real microstructures of the experimental castings.
Access status: Open Access ,
Reduction of the calculation time in the modeling of the microstructure formation by CAFD method
(2011) Burbelko, Andrej; Początek, Jacek
In the CAFD solidification modeling (Cellular Automaton + Finite Difference) as the growing grains shape, as the final microstructure of the alloy were not superimposed beforehand but were obtained in the simulation. CAFD models take into account heat transfer, components diffusion in the solid and liquid phases, nucleation kineties, solid border migration and liquid phase vanishing etc. Computer methods that include the solutions for all above mentioned phenomena are very time-consuming. The 'bottleneck' of the models is the temperature field calculation. Acceleration of the well-known Gauss-Seidel (GS) iterative method of the numerical solution of the difference equations set was proposed by mean the selective reduction of the iteration number for the different equations used in the temperature field modeling. Computer modeling results obtained by the known GS method and results of the proposed reduced scheme using were compared with the known analytical solution of the Schwarz task. It was shown that the reducing of the solution tolerance results in the substantial increase of the solution time but has a smali influence on the mean quadrate deviation between the numerical results and the analytical one. Proposed solution scheme results in the significant reduction of the calculation quantity and the simulation time.