Key words Thermal instability, functionally graded materials, non-stationary heat flux, frictional heat sources, nonstationary heat convection. This paper deals with study of the global thermoelastic instability of brake disk made of either the isotropic homogeneous metal matrix composite (MMC) or the isotropic inhomogeneous functionally graded material composite (FGM). The main idea of the FGM composite is a smooth variation of material properties due to continuous change in microstructure. The estimates in diffusion equation are characterized both by non-stationary heat flux and non-stationary heat convection terms enhanced by the characteristic frictional heat sources. Global instability is characterized by the Schaefer-Papkovich condition. Application of functionally graded A356R-based composite to brake disk structure prevents loss of global stability in contrast with homogeneous A356R composite and stainless steel ASTM321 brake disk which guaranties safety and durability of the braking system.
The aim of this paper is the numerical analysis of the one of main part of car engine – piston sleeve. The first example is for piston sleeve made of metal matrix composite (MMC) A356R. The second improved material structure is layered. Both of them are comparison to the classical structure of piston sleeve made of Cr-Ni stainless steel. The layered material structure contains the anti-abrasion layer at the inner surface of piston sleeve, where the contact and friction is highest, FGM (functionally graded material) interface and the layer of virgin material on the outer surface made of A356R. The complex thermo-elastic model with Archard's condition as a wear law is proposed. The piston sleeve is modelling as a thin walled cylindrical axisymmetric shell. The coupled between the formulation of thermo-elasticity of cylindrical axisymmetric shell and the Archard’s law with functionally changes of local hardness is proposed.
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