Low-Cycle Thermal Fatigue Life Calculation of an Aluminum Alloy Cylinder Head

When calculating the low-cycle thermal fatigue life of the heated components by applying the finite element method, the energy featured by the cyclic response of material was considered to be the most reasonable damage parameter. Therefore, the use of the energy method to assess the low-cycle thermal fatigue life of the cylinder head can obtain more accurate results. The low-cycle fatigue test at high temperature condition was conducted on the aluminum alloy material of a cylinder head, which employed the alternating load with equal amplitude and constant strain. The tested results revealed the low-cycle fatigue life prediction model and the parameters were also obtained based on the energy law. The low-cycle thermal fatigue life and its distribution on the firepower surface of the cylinder head were also obtained. The results show that the combustion pressure contributes less to the stress load on the firepower surface than the thermal load does. The regions with the lowest fatigue life on the firepower surface of each cylinder are located at the edge of the exhaust valves. Besides, in each cylinder, the fatigue life is shorter at the nose area of the exhaust valves, the nose area between the valves and the injection hole, and the regions near the nose area of the exhaust valves.