Thermal-mechanical coupling failure analysis and optimization of an exhaust manifold

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 adopted finite element simulation and experimental methods such as high-temperature tensile testing, metallographic analysis to investigate stress characteristics under mechanical and thermal-mechanical coupling loads. The Mises stress of the exhaust manifold under thermal-mechanical coupling load reaches 150MPa, and it closes to yield stress of material at the temperature of 600°C. High temperature and installation constraints restrict the expansion of the exhaust manifold and results in significant high stress and stress concentration. The thermal-mechanical load is the main reason leading to the failure of the exhaust manifold. Constraints optimization is applied to redesign the structure and installation constraints. It is an effectively method to reduce structural stress and improve the fatigue resistance of the manifold. • Geometric scanning method is applied to analyze the manufacture deviation of the exhaust manifold. • Material failure analysis and material testing with different temperature are applied in the study. • Constraint conditions and high temperature mainly effect the stress of the exhaust manifold.