Fatigue Life Prediction Of The Centrifugal Compressor Impeller Based On Fracture Mechanics

Impellers are core components of high-speed rotors of centrifugal compressors. Because of the complexity of the structure and the working environment, the impeller often occurs fatigue failure phenomenon. Recently, with the increase of the components of the compressor impeller structure and the diameter of the impeller outlet width, the phenomenon that the impeller crack and gradually extended to the fracture is more and more frequent and seriously affect the safety and reliability of compressor unit, which has aroused strong concern. The study of crack propagation life is objected on the centrifugal compressor shrouded impeller and based on fracture mechanics in this article, which is for laying the theoretical foundation for the research of simulation and safety design of impeller fracture further.First of all, the centrifugal compressor impeller is established 3D solid model, and has been carried on the strength analysis, obtain the stress distribution between blade and the wheel cover In order to study the impeller structure of crack, simplify the welded part between the blade and the wheel cove by using local stress strain similar method, provide the feasibility of solving the stress intensity factor.Then, use the two-dimensional simplified equivalent model to calculate the stress intensity factor. From the point of view of linear elastic fracture mechanics, use the ANSYS software to calculate the stress intensity factor of the center crack and edge crack,obtain the function relation between the crack length and the stress intensity factor by curve fitting.Finally, in the research on the crack growth process, use the maximum surrounding primary stress theory to calculate the crack angle; use the composite fatigue crack propagation life model, estimate the fatigue crack propagation life of impeller structure whose crack form is edge crack, show the relationship of crack propagation life with initial crack length, sum up a set of prediction fatigue life method and procedure of impeller structure based on fracture mechanics approach.