Lifetime prediction of thermo-mechanical fatigue for exhaust manifold

In this research, the non-linear thermo-mechanical simulation, experimental study and lifetime prediction of engine exhaust manifold were systematically analyzed. Fluid-structure coupled method was employed in the simulation. Heat transfer analysis simultaneous considered radiation, convection and conduction. Inelastic properties of the materials used for the thermomechanical analysis included kinematic hardening and creep. Some models were introduced and used to predict lifetime of the manifold. Temperature data obtained during the engine bench tests can be accurately matched with the analysis results. The results indicated that the highest temperature located on the confluence of exhaust manifold and the plastic dissipated energy field caused by the cyclic thermal loading can be matched with the crack zone of exhaust manifold.