| The integral bladed blisk structure is a core component that meets the continuous performance requirements of aviation engines.Due to long-term exposure to extreme working environments such as high temperature and high centrifugal force,as well as frequent starting and acceleration conditions,the compressor’s integral bladed blisk can withstand complex cyclic loads and a large amount of elastic stress cycling,leading to the susceptibility of the integral bladed blisk to crack failure.The existing research mainly focuses on the analysis of the vibration characteristics of the blisk due to mass and stiffness detuning,single sector blade detuning,and opening cracks.However,there is relatively little research on the effects of breathing cracks,crack distribution,and blade angle on the localization and nonlinear characteristics of the overall blisk vibration.Therefore,this article adopts finite element numerical simulation analysis method and vibration testing test method to analyze the impact of breathing cracks on the vibration characteristics of the overall bladed blisk.The main research content is as follows:(1)Based on the ANSYS platform,modal analysis and transient response analysis were conducted on the simplified finite element model of the entire bladed blisk,and it was found that the location where cracks are prone to occur is located near the exhaust edge of the blade root,thereby determining the location of crack initiation.Analyzed the effects of the length,position,and rotational speed of breathing cracks on the natural characteristics,frequency steering,and mode transition of simplified integral bladed blisks;A study was conducted on the vibration response of a simplified integral bladed blisk under three operating conditions: no speed,constant speed,and variable speed.It was found that there are respiratory effects,subharmonics,superharmonics,and superharmonics under variable operating conditions.(2)The resonance method is used to conduct vibration testing on the simulated test piece of the entire bladed blisk with or without cracks,in order to verify the correctness of the finite element numerical simulation.By comparing with the finite element simulation values,it was found that the error rate between the simulation values and the experimental values was within the allowable engineering error range,confirming the correctness of the finite element simulation method;By comparing the acceleration response and waterfall plot of the simulated test piece with different accelerations,it was found that the occurrence of cracks can lead to a decrease in natural frequency and an increase in amplitude.(3)The effects of crack distribution and blade rotation angle on the inherent characteristics of blisks with breathing cracks were investigated.The impact of pitch diameter on natural characteristics such as "frequency steering" and modal localization was further evaluated and analyzed.The modal localization was quantified by introducing a modal localization factor.When the crack distribution is different,it is found that the mode order near the frequency steering region is prone to mode localization,and only one or several blades have a large mode localization factor;When the blade angle is 45 ° and the blade angle is different,the modal localization quadrant is significant,and the modal localization factor is the largest.(4)The effects of crack distribution and blade rotation angle on the response characteristics of blisks with breathing cracks were investigated.The response characteristics of the entire bladed blisk before and after the occurrence of cracks were analyzed by comparing the response amplitude of each blade tip with the response spectrum and waterfall diagram of the blade with breathing cracks.When the distribution of cracks is different,it is found that the response amplitude of each blade of an integral blade blisk is the largest,and the response with a peak value after the occurrence of cracks shifts to a low frequency,the frequency band becomes wider and larger,and small peaks appear at multiple locations,resulting in increasingly significant response localization;The vibration response of a cracked blisk with an angle of 45° presents a typical nonlinearity and the response localization is the most significant. |
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