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Number of results: 4
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Abstract

Mathematical modeling of thermal processes combined with the reversible phase transitions of type: solid phase – liquid phase leads to formulation of the parabolic or elliptic moving boundary problem. Solution of such defined problem requires, most often, to use som sophisticated numerical techniques and far advanced mathematical tools. The paper presents an analytic-numerical method, especially attractive from the engineer’s point of view, applied for finding the approximate solutions of the selected class of problems which can be reduced to the one-phase solidification problem of a plate with the unknown a priori, varying in time boundary of the region in which the solution is sought. Proposed method is based on the known formalism of initial expansion of a sought function, describing the field of temperature, into the power series, some coefficients of which are determined with the aid of boundary conditions, and on the approximation of a function defining the freezing front location with the broken line, parameters of which are determined numerically. The method represents a combination of the analytical and numerical techniques and seems to be an effective and relatively easy in using tool for solving problems of considered kind.

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Authors and Affiliations

R. Grzymkowski
E. Hetmaniok
M. Pleszczyński
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Abstract

Thin metal film subjected to a short-pulse laser heating is considered. The parabolic two-temperature model describing the temporal and spatial evolution of the lattice and electrons temperatures is discussed and the melting process of thin layer is taken into account. At the stage of numerical computations the finite difference method is used. In the final part of the paper the examples of computations are shown.

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Authors and Affiliations

E. Majchrzak
J. Dziatkiewicz
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Abstract

The article concerns the experimental verification of the numerical model simulating the solidification and cooling processes proceeding in the domain of cast iron casting. The approximate course of the function describing the evolution of latent heat and the value of substitute specific heat resulting from its course were obtained using the thermal and derivative analysis (TDA) method The TDA was also used to measure the cooling curves at the distinguished points of the casting. The results obtained in this way were compared with the calculated cooling curves at the same points. At the stage of numerical computations, the explicit scheme of the finite difference method was applied. The agreement between the measured and calculated cooling curves is fully satisfactory.
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Bibliography

[1] Mendakiewicz, J. (2011). Identification of the solidification parameters of casting alloys on the example of grey cast iron. Monografia. Gliwice: Wyd. Pol. Śl. (in Polish).
[2] Jiji, L.M. (2009). Heat conduction. Third Edition. Springer.
[3] Mochnacki, B. & Majchrzak, E. (2007). Identification of macro and micro parameters in solidification model. Bulletin of the Polish Academy of Sciences. Technical Sciences. 55(1), 107-113.
[4] Kapturkiewicz, W. (2003). Modelling of cast iron solidification. Cracow: Akapit.
[5] Majchrzak, E., Mendakiewicz, J. & Piasecka-Belkhayat, A. (2005). Algorithm of mould thermal parameters identification in the system casting–mould–environment. Journal of Materials Processing Technology. 162-163, 1544-1549.
[6] Mochnacki, B., Suchy, J.S. (1995). Numerical methods in computations of foundry processes. Cracow: PFTA.
[7] Ciesielski, M. & Mochnacki, B. (2019). Comparison of approaches to the numerical modelling of pure metals solidification using the control volume method. International Journal of Cast Metals Research. 32(4), 213-220. https://doi.org/10.1080/13640461.2019.1607650
[8] Majchrzak, E., Mochnacki, B., Suchy, J.S (2008). Identification of substitute thermal capacity of solidifying alloy. Journal of Theoretical and Applied Mechanics. 46(2), 257-268.

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Authors and Affiliations

J. Mendakiewicz
1
ORCID: ORCID

  1. Department of Computational Mechanics and Engineering, Silesian University of Technology, Konarskiego18A, 44-100 Gliwice, Poland
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Abstract

The article presents a computational model build with the use of artificial neural networks optimized by genetic algorithm. This model was used to research and prediction of the impact of chemical elements and heat treatment conditions on the mechanical properties of ferrite stainless steel. Optimization has allowed the development of artificial neural networks, which showed a better or comparable prediction result in comparison to un-optimized networks has reduced the number of input variables and has accelerated the calculation speed. The introduced computational model can be applied in industry to reduce the manufacturing costs of materials. It can also simplify material selection when an engineer must properly choose the chemical elements and adequate plastic and/or heat treatment of stainless steels with required mechanical properties.

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Authors and Affiliations

R. Honysz

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