Failure Simulation Study of Double-Layer Exhaust Manifold for Turbocharged Engine Under LCF & HCF

With the high requirements of turbocharged engine fuel efficiency and high exhaust gas temperature and continuous improvement of emission standards, the structure of automobile exhaust manifold needs to be continuously optimized on the premise of ensuring durability and reliability. Taking the exhaust manifold of a four cylinder turbocharged engine as the research object, the low cycle fatigue and high cycle fatigue at high temperature were studied as follows. Firstly, Hyper-mesh is used for modeling, STARCCM + is used for CFD calculation, and ABAQUS is used for thermal stress calculation and thermal mode calculation under standard conditions. The failure point of the system is preliminarily judged according to the FEM calculation results, and then compared with the durability test results to verify the reliability of the FEM calculation results. Finally, the optimal design scheme of exhaust manifold is proposed and verified by simulation calculation. The results show that the DPEEQ value of the outer ring is 1.06%. The elastic strain energy under thermal mode calculation is 49.4J, which is consistent with the cracking point in the durability bench test results. By optimizing the outer ring design, the elastic strain energy is reduced by 20.9%. Our research provide theoretical support and reference for the analysis method of exhaust manifold failure under low cycle fatigue and high cycle fatigue.