Thermal-mechanical Coupling Finite Element Strength Analysis Of Typical Parts Of Aviation Engine

The cylinder head and piston constitute the combustion chamber of the engine, they are keyparts of engine under complicated working conditions. Under the working conditions, the pistonstands periodic loadings, such as high gas-pressure, inertia-pressure and side direction pressure,which produced by combustion gas pressure and high speed and produces mechanical stress anddistortion. As a part of combustion chamber, the cylinder head produces distortion easily on thefire deck combustion face and bolt surface, which produced by high mechanical pressure, such asgas-pressure and pre-load. Consequently, there is great significance to analyze thethermal-mechanical coupling strength of the piston and the cylinder head.First, pistons are one of the most complex components of engines, enduring thermal andmechanical loadings when engines are working. This work is based on the analysis of loadings ofa type of aviation piston, the boundary conditions are given. The contacts between piston andpiston pin, piston pin and connecting rod, and connecting rod and part of crankshaft areestablished. The temperature filed, the thermal stress, mechanical stress, coupling stress andcontact stress are analyzed by using the finite element method. The simulative results indicate thatthe temperature and coupling stress are accorded with practical running instance. The numericalvalues are in the limits of material parameter, the mechanical loading as the dominant loadingwithin the piston’s loadings. The temperature changes along with engine’s working conditions.Second, this work makes the cylinder head and coolant as a whole and analyzes the cylinderhead temperature distribution. The simulative results indicate that temperature at the cylinderbridge is high，and the temperature of the cylinder head are reduced along with increasing altitude.The mechanical stress of the cylinder head is analyzed by using the finite element method.Calculated results show that the pre-load affects the stress on the bolt holes and gas-pressureimpacts the contact stress between fire deck combustion face and cylinder body. Finally, thethermal-mechanical coupling stress is analyzed, the results indicate that the numerical values andstress distribution are consistent with the thermal stress. In the cylinder head, thermal loading aremain source of total stress, and the remainder is due to pressure loading and mechanicalconstraints.The thermal-mechanical strength analysis of piston and cylinder head will get their stressdistribution and centralized position and provide theoretic basis for optimizing structure of pistonand cylinder head.