Research On Diagnosis Method Of Fan Blade With Single Crack

Ventilators is widely used in mining,metallurgy,energy pharmacy,petrochemical,aerospace,and other national economic industries.It is used to ensure the air quality of the working environment through dust removal,dehumidification,air volume adjustment,and reduction of harmful gas concentrations,thereby ensuring air quality.Life safety of workers and production safety of industry operations.The blade is an important part of the rotor system of the fan.During long-term operation,it is subjected to the combined effects of centrifugal force,fluid dynamics,vibration,temperature difference,and media,etc.,and cracks will occur to varying degrees.Therefore,the research on the diagnosis method of the fan blade crack fault is carried out to obtain the damage information of the blade crack as early as possible,and the blade is repaired or replaced before the crack failure is upgraded to avoid major accidents,which has huge safety benefits,social benefits and economic benefits.In view of this,in view of the characteristics of the singularity of the signal corresponding to the local damage of the blade crack,this paper proposes a fan blade crack fault diagnosis method based on the Hilbert-Huang transform to realize the diagnosis of the fan blade crack position and depth,and through the modal Experiments verify the feasibility of the method.main tasks as follows:a)Simplify the fan blade model and analyze its dynamics.Combine the theory of damage mechanics and the principle of damage detection based on signal singularity to derive the shape function of the blade.The mathematical relationship between the blade shape and crack position is obtained through theoretical analysis.b)A three-dimensional modeling software Solid Works was used to establish a model of a fan blade with cracks.A total of 25 groups were set up in the model:blade cracks were set to 6 different positions and 4 different depths,for a total of 24 groups,plus 1 type of crack-free blade model.The 25 sets of models were imported into ANSYS Workbench finite element software for modal analysis,and the first six modes of the blade model were obtained.c)Using MATLAB to perform EMD decomposition and Hilbert spectrum analysis on the mode data of the blade model,making full use of the adaptive characteristics of the Hilbert-Huang transform method and the ability of time-frequency analysis,this signal processing method is changed from time domain to space domain.The damage identification of blade crack model position and depth is realized.d)The modal test of the cracked blade of the fan is performed.The bladewith cracks is excited by the hammer method to obtain the acceleration response.The modal test DASP software is used to obtain the natural frequency and mode data.Processed to identify the location and depth of blade cracks.The test results prove the effectiveness and feasibility of the proposed method for identifying the location and depth of blade cracks.