Over-Speed Preloading And Shakedown Analysis Of Rotating Bladed-Disk

Rotating bladed-disk are the core rotating component of the centrifugal compressors.Its structure and work condition are both complicated and its work status directly affects the safety of the whole compressor unit.With the advance of the design parameters for compressor,the work condition and static character of the rotating bladed-disk become more critical.A detailed and reliable strength analysis provides designers a solid foundation, ensures the safety of compressor operation and is of great significance of theory and engineering value for design and production of important industrial equipment with self-owned intellectual property right.The present paper studies several important mechanical performances of the rotating bladed-disk as follows:(1) Making a comprehensive consideration of the computational accuracy,model size and efficiency,we apply the adaptive finite element method to carry out refined static elastic-plastic strength analysis for the rotating bladed-disk.The over-speed preloading techniques process is simulated;the evolution of von Mises stress and equivalent plastic strain with time is studied.The contrast of stress levels between the over-speed preloading disk and the no over-speed preloading disk in normal working condition reveals the mechanism of the over-speed preloading techniques.The concept of structural hot spot stress is introduced which is not sensitive to the mesh-size,and the method how to get the structural hot spot stress is discussed.With the comprehension of these problems,we can use the result of the finite element calculation to predict its fatigue life.(2) The residual stress obtained by loading the rotating bladed-disk into plastic deformation and unloading is proposed as the self-equilibrium stress basis.Based on the lower-bound theorem of limit analysis and lower-bound theorem of shakedown analysis,we developed the mathematical formulation of limit load and shakedown load,and solved with mathematical programming.The shakedown analyses of two simple structures are studied to verify the correctness of our method.The shakedown analysis of rotating bladed-disk is carried out.On the basis of mathematical programming formulation,we further prove that safety load factor and shakedown load factor is equal if the elastic envelop for every point in the structure is simultaneously attained at the maximum(or minimum) load factors.