The Analysis Of Service Environment And Fatigue Crack Growth In Determination Of Critical Threshold Of Impeller Remanufacturing

The general designation of the remanufacture engineering is to maintain and to the rebuild worn products, which is taking the productive whole life period theory as instruction, taking the great upgrade of the performance of waste productions as goal, taking the good quality, energy-saving, high efficiency, environmental protection as principle, as well as taking the advanced techniques and industrializing process as measures. As the key component of the centrifugal compressor, the determination of the critical threshold of impeller remanufacturing depends on the service environment, the fatigue crack growth and the residual life of the impeller. Therefore, the researches on the service environment and the crack growth in impellers are very important in the remanufacturing industries of impeller.The main research of this article is listed as follows:In chapters1and2, the significance for the determination of the critical threshold of the remanufacture of the impeller is introduced. The researchers and the developments on the contact mechanics and the fracture mechanics are reviewed. The basic concepts and the computational methods in nonlinear contact problems and in fracture mechanics are reviewed. The finite element numerical methods are compared.In chapter3, a3D model of impeller is creased based on the geometry of the impeller in compressor by ABAQUS. The effects of the fit tolerance, the frictional coefficient and the rotational speed on the contact stress of the interference-fitting surface are discussed in detail in this paper.187cases for impeller have been studied to obtain the fitting formula on the contact area. The optimal interference fit can be then obtained by this formula. The effect of the pre-over loading technique is further considered. The work can be useful for the initial design and the re-design for the impeller in the manufacture and the remanufacture.In chapter4, based on the2-D model of impeller contact surface, the stress intensity factor (SIF) of the cracks on different locations is calculated by using J-integral method. The comparison of different models shows validity of the established model. The crack growth rate and residual life of the cracks in different rotational speeds are computed by using of the Paris formula. The computations can make a contribution to the determination of the critical threshold of the impeller remanufacturing.