Thermal barrier coating effect on stress distribution of a diesel engine cylinder head

In the present paper, a finite element analysis of a coated and un-coated cylinder head is performed to find stress distributions. A thermal barrier coating (TBC)system which is applied on the combustion chamber, consists of two-layer systems: a ceramic top coat (TC), made of yttria stabilized zirconia (YSZ), ZrO2-8%Y2O3and also a metallic bond coat (BC), made of Ni-Cr-Al- Y. A three-dimensional finite element model of the cylinder head is simulated in ABAQUS software andtwo-layer elastic-visco-plastic material behavior is used for aluminum alloy. For BC and TC layers, elastic andplastic properties are considered. Then, the coating effect on stress distributions is investigated. The purpose of this work is to ompare stress distributions in the cylinder head, with and without the TBC system under thermo-mechanical loadings. The TBC system provides a temperature drop of about 100°C due to itslow thermal conductivity. The results show that stress values decrease in the coated cylinder head due to lowertemperature gradient below coating areas. This reduction in the stress of the substrate is about 20 (MPa) which can lead to higher fatigue lifetime. As anotherresult, the temperature of the TC face has no significant effects on temperature and stress distributions of the coated cylinder head.

کلیدواژه ها:

cylinder head ، thermal barrier coating ، thermo-mechanical loading ، finite element method ، numerical stress distribution