Research On High Cycle Fatigue Prediction Method Of Rotating Machinery Blade

Rotating machinery is an indispensable power equipment in the industry nowadays.The safety of its main component blades is extremely important for the normal industry and production life.The numerical simulation of vibration analysis of rotating blades,vanes and safety analysis under the influence of aerodynamic factors,is a useful tool in the design and operation of the blade failure.This paper described the finite element method,modal analysis for a typ-ical turbomachinery blade at the design stage to calculate the static blade/dynamic modal frequencies.The results show that the static/dynamic fre-quency change of the blade in the low-order(first-order)mode is relatively larger than that in the high-order mode.At the same time,a Campbell diagram is drawn to determine whether the blade resonates.Then by simulating an axial fan rotor blade under a large rotation angle,the blade crack fault analysis.The process of deriving the modal aerodynamic damping ratio from the "energy method" and the positional relationship of each blade under different phase angles between blades are introduced.The aerodynamic damping ratios of the various modes of the moving blade at dif-ferent rotation angles and different inter-blade phase angles are calculated.Analyze the Campbell diagram of the blade,fine-tune the rotation speed under the possible resonance state,and explore the relationship between the rotation speed and the unsteady aerodynamic force of the blade and the dynamic stress.Through calculation,it is found that fine-tuning the rotation speed near the rated rotation speed can reduce the dynamic stress of the blades accordingly,and at the same time prevent the fan blades from running at a large rotation angle for a long time.For the high-speed impeller vibration test bed,the connection part of the impeller and the shaft-the expansion sleeve is selected for corresponding strength analysis,and the structure and working characteristics of the expan-sion sleeve are introduced.Choose different materials,calculate the static structural strength of the expansion sleeve and the impeller at different speeds,and the relationship between the axial displacement of the expansion sleeve jacket under different pretensions.In the subsequent experiments,it is neces-sary to further rationalize the expansion sleeve to connect the impeller.Speed for further experiments.Finally,the non-contact measurement method was used to monitor the vibration of the three blades A,B and C,and compared with the modal strain-amplitude results of the finite element analysis.The results show the feasibility of the finite element calculation,but the experimental part needs to be further optimized to achieve error reduction.