Calculation And Analysis Of Structure Strength And Fatigue Life About Heavy Duty Diesel Engine Cylinder Head

With the improvement of the engine’s strengthening degree, the engine power preliter is higher and higher, the heat load of heated parts also will increase. In the workingprocess of the engine, when the cylinder head is under large mechanical load (bolttightening force, gas explosion pressure, etc.), it also has high heat load, that makes thecylinder head is often working in alternating hot and cold conditions, static and dynamicload conversion process, so it is one of the worst working conditions in the internalcombustion engine parts. As a result, the strength reliability of cylinder head problem hasalways been a key problem in design of the engine, and the analysis of cylinder headstructure strength and reliability to ensure the safe operation of diesel engine has veryimportant significance.This article takes a six-cylinder engine cylinder head as the research object, by meansof finite element analysis, firstly building meshes by HYPERMESH, then finishing themodal analysis and stress analysis by ABAQUS, after that using frequency and vibrationmode of various boundary conditions to get critical speed and vibration response ofcylinder head on the basis of modal analysis, and estimating high or low cycle fatigue lifeby FEMFAT on the basis of stress analysis, at last using probability theory to evaluate thereliability of stress level.The research results show that the rigidity of the engine cylinder head in anydirection the direction is alright, don’t have obvious weak seismic zone. The critical speedis much higher than normal working speed, will not happen resonance phenomenon. Thepeak stress value under dynamic loading is higher than at the static stress value29.47%.The most dangerous area of high cycle fatigue life located in the lower waterway nearbythe cylinder head thread hole is2.14e8times, and the low cycle fatigue damage located inbridge of the nose area is13679times, both at a safe level. The reliability of the low cyclefatigue are far below the high cycle fatigue, should focus on the low cycle fatigue damage.