Life Prediction Of Cylinder Head Under The Creep-Thermal Fatigue Interaction

As a kind of heat energy power machinery, the engine is mainly submitted to thermal and mechanical load. The engine's cylinder head always works under the high temperature and pressure effect, it is one of all engine's parts which bear the most heavy and complicated load, its service life is relative to engine's reliability directly. The service life of cylinder head is mainly determined by thermal and creep fatigue, but there are only few studies on life prediction of cylinder head of creep-thermal fatigue interaction until now. Therefore, it is studied by FEM here.The method combining ANSYS with CFX software to transfer loads bidirectionally is specially used for multi-field couple simulation with bigger and more complicated model. The distribution of temperature and displacement can be obtained by transferring thermal or mechanical load automatically. Firstly, the accurate temperature distribution is calculated by this method. Then mechanical-thermal stress field and mechanical stress field are obtained, moreover, it is found that the former is as six times around as the latter, so the latter can be taken no account of. Otherwise, another important ingredient creep is studied deeply. A new life prediction method is brought forward, the creep-thermal fatigue is equaled as mechanical-thermal fatigue of constant stress amplitude and average stress. Thermal-mechanical fatigue test does not need heat preservation time, its test equipment is simple and its efficiency is high. In the end, the P-S-N curve of material ZL702A which is used for cylinder head is gained by thermal-mechanical fatigue test, the life of cylinder head is predicted.