Failure and thermal-mechanical coupling analysis of exhaust manifold of a gasoline engine

Exhaust manifold is an important component of the engine system, and the failure of manifold can cause faults such as reducing power and increasing noise. This study explores the initiation and propagation characteristics of manifold failure through experimental methods such as high-temperature tensile testing, metallographic analysis, and fracture morphology of the manifold material. Finite element simulation method is adopted to investigate stress characteristics under mechanical and thermal-mechanical coupling loads. The maximum thermal-mechanical coupling stress of the exhaust manifold reaches 150 MPa, and it located coincides with the failure point. The high stress distribution of thermal-mechanical coupling is consistent with the failure experimental study results. The combination of simulation and experiment identified the causes of manifold failure and provided measures to improve the thermal fatigue resistance of the manifold.