Thermoelastic Analysis On Functional Gradient Thermal Barrier Coating Engine Cylinder Linear With Temperature Dependence

In this paper, functional gradient material is used to the inner surface of engine cylinder linear, which is composed of ceramic and metal. Ceramic layer structure has a strong capacity of insulation thermal. Functional gradient layer structure can reduce the thermal stress of engine cylinder because the expansion coefficients of metals and the expansion coefficients of ceramics mismatch. This engine cylinder liner possesses the ability of high temperature oxidation resistance, and can meet the mechanic demand of metal material. So it has very good development prospect. The concrete work of this paper can be summarized as the following:1. Using the empirical formula and the existing experimental curves, the average heat transfer coefficients and average gas temperature inside the cylinder liner are calculated, the distribution of heat transfer coefficients along axial direction of the cylinder liner is studied in the steady heat transfer process, and the heat transfer coefficient is determined between cylinder liner and frame.2. Using ceramic ZrO2 materials as heat insulation coating for cylinder liner, alloy steel as matrix material, and assuming the material parameters of functional gradient coatings change as an exponential function along the thickness direction. For various distribution index of material parameters, the corresponding materials parameters (including elastic modulus, thermal conductivity and Poisson's ratio, linear expansion coefficients) are. respectively, calculated and thermoelastic analysis are, respectively, carried on. Analyzing comprehensively on the insulation effect, the value of thermal stress and the rate of change of thermal stress along the thickness direction, the reasonable distribution index of material parameters are discussed.3. Considering the stability of coating and costs in the practical work, it is necessary to determine reasonable gradient transition layer thickness. In this paper, the cylinder liners with functional gradient coatings of different thickness are simulated and the results obtained are analyzed by comparing with the corresponding results of cylinder liner without coating. The rational gradient transient layer thickness is determined.4. Cylinder liners are under high temperature in practical work. Material parameters are influenced by temperature changes. In order to obtain more practical analysis results, in the condition of considering temperature dependence of material, the thermoelastic analysis is done in this paper for cylinder liner with functional gradient thermal barrier coatings and accurate analysis results are obtained.