Because the exhaust manifold of the high-power and large-bore diesel engine is in a high-tem⁃ perature，high-pressure and high-impact working environment，it is subjected to complex and harsh thermome⁃ chanical loads，making the problem of fatigue failure increasingly prominent. To solve the exhaust manifold fa⁃ tigue failure in engineering design，the fatigue damage mechanism and low cycle fatigue life of a multiple exhaust manifold under three different conditions of thermal load，mechanical load and thermomechanical coupled load are studied through the method of CFD-FE coupling simulation. The results show that the pure alternating ther⁃ mal load is not enough to cause low-cycle fatigue failure of the exhaust manifold，and the alternating thermome⁃ chanical coupled load causes the exhaust manifold life to drop sharply. The importance of the inner wall pressure and the end thrust are 4.34 and 0.88. The plastic strain of the exhaust manifold is further increased，and the fa⁃ tigue life is reduced to 3710 times，which is only 29% of the original，under the design condition of high boost pressure where the exhaust pressure is increased by 60% and the temperature is unchanged. © 2022, Editorial Department of Journal of Propulsion Technology. All right reserved.
