Inclusions On The Powder Metallurgy Turbine Disk Stress Intensity Factor And Crack Propagation Life

Powder metallurgy turbine disks are worldwide adopted in most advanced aeroengine nowadays. The research of engineering application of them is actively being carried out in our country, and the key problem urgently needed to solve is their low cycle fatigue life prediction.The low cycle fatigue failure of powder metallurgy turbine disks is mainly caused by inclusions,so it's important to study the effect of inclusion on the stress intensity factors (SIF) initiation and development of crack in powder metallurgy turbine disks.The effect of inclusion on SIF and growth life of crack in powder metallurgy are investigated using the finite element method (FEM).The results indicate that the inclusion can effect the SIF of crack in powder metallurgy when the crack is in the place of three time of inclusion's radius and it can't if the crack overstep this place. For soft inclusion,the SIF of crack with inclusion is smaller than without inclusion, when the radius of the crack approachs the radius of the inclusion. And with the radius of crack increasing, it is uncertain whether the SIF of crack with inclusion is smaller than without inclusion. But they will be approaching. And for rigid inclusions, the direction of effection is opposite to soft inclusions.In the prediction of growth life of crack, the results is safe if a soft inclusion is considered as an initial crack, but for a rigid inclusion, the results is risky. Therefore the calculated life is a safe results, excluding the effect of the inclusion.The control parameters and growth lives of cracks are calculated using the method of submodel. Come to the conclusion that the results of life is safe while the average stress at crack is used as the remote tensile stress. For a turbine disk, the growth life of crack is the shortest when the inclusions are at the edge of the center hole. Plastic deformation arises at the local of mortice. Bodyforce has little effect on the J integral.This thesis calculates the SIFs of circular cracks in a circular bar, writes a computer program to calculate the initial crack's growth life in everywhere of the bar, simulates the evolution course of crack from sub-surface to surface and calculates the growth life of sub-surface crack. So it establishes the essential foundation for studying the crack's initiation life of powder metallurgy turbine disks with inclusions.