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2 Journal of KONES

2 2006

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Comparative study of a few fem models of a surface coating system

100%

Szymczyk W.

tom Vol. 13, No. 4

41-49

Multilayered coatings established on parts of internal combustion as well as jet engines may be used as TBC systems providing their better thermal-mechanical efficiency, tribological properties, wear resistance and an ability to withstand the influence of aggressive media. A comparative review of a few different FEM models of a surface coating system is presented which can be used for the needs of designing improved parts of engines. The coating system was established on a beryllium copper substrate and consisted of the NiCr midsurface and TiN external layers. The system was analyzed as a graded as well as functionally gradient material (FGM) with an assumed gradient function of material properties. The more advanced models use a micromechanical technique of modeling which enables consideration of microstructure influence on the residual stress distribution. They contain transition zones between the pure material volumes where the material properties change accordingly to the linear gradient function. Simulations of microstructural effects in the area of surface coating are strongly recommended. The results of micromechanical calculations are affected locally too strong to be excluded from considerations.

Thermal barrier influence on temperature and stress fields in an internal combustion engine piston

51%

Kurowski Z. , Niezgoda T. , Szymczyk W.

tom Vol. 13, No. 2

259-266

The paper presents results of numerical Finite Element analysis of an internal combustion engine piston with a thermal barrier made of zirconia, subjected to thermal and thermo-mechanical loadings. Special emphasis was laid on investigation of the impact of the surface coating on the fields of temperature, heat fluxes, residual stresses and stresses in the coated piston in the working conditions. For this a purpose, a methodology of developing FEM numerical models of a piston with a surface coating was elaborated, several 2D and 3D FEM models of the piston with the coating were built, and FEM analysis of the models, subjected to thermal and thermo-mechanical loadings was performed. The results of computations proved high efficiency of the coating as a thermal barrier. The working temperature in some areas inside the piston with a coating showed a huge decrease and was 40% lower as compared with the temperature for the same piston without a coating. At the same time, the heat fluxes inside the piston were reduced almost ten times. The developed methodology of modelling and simulation may lead to obtain higher thermal resistance, strength and durability of internal combustion engines and their elements with thermal barriers in all fields of application, including aviation.