The Fatigue Life Prediction For Thin-walled Parts Of Engine

With the growth of thermal and mechanical load of the components, the design ofmodern engine parts pay more attention to fatigue failure problem due to the criticalrequirement. As a typical example of thin-walled iron parts, exhaust manifold wasresearched in this paper. By combined means of simulation and experiment, thethermal load and mechanical strength were calculated, and the fatigue life predictionwas carried out，in order to provide the calculation basis for the improvement andoptimization design.Firstly using AVL software BOOST and FIRE, parameter of the enginethermodynamics along with interior and exterior flow field of exhaust manifold werecalculated by computational fluid dynamics (CFD) analysis. Then a fluid-structurecoupling was proceeded in FIRE, the temperature field and thermal stress werecalculated by using the software ABAQUS. The temperature field was tested contrastwith finite element analysis results. Using FEMFAT and MSC.Fatigue software,fatigue safety coefficient and fatigue life were obtained.For crack of an engine exhaust manifold, the simulation was carried on to find thereasonable boundary condition and a way of load applying. On the basis of that, theimprovement schemes were put forward and fatigue life was simulated by using thesoftware FEMFAT. The simulation results show that the fatigue factor of safety of theimprovement schemes was obviously increased.