Study On Ultrasonic Rayleigh Wave Detection Of Micro-crack In Blade

Turbine blades are key components in aircraft engine,its extreme high temperature and high pressure conditions,the blade will produce thermal barrier coating peeling,high temperature oxidation corrosion surface and metal fatigue damage,which formed by fatigue damage and micro cracks are the most susceptible to leaf under extreme conditions of defects,the quality of turbine blade performance directly affects the normal work of the engine.Therefore,it is very important to inspect engine turbine blade regularly to prevent safety accidents.In this paper,the existing non-destructive testing methods for turbine blade defects are summarized,and a turbine blade microcrack detection method based on ultrasonic Rayleigh wave is proposed.The location and size of defects are quantitatively evaluated through signal processing and analysis of detected signals.According to the shortcomings of the existing non-destructive detection methods for micro-cracks on turbine blade surface,this paper proposes a double-probe Rayleigh wave detection method for micro-cracks on blade surface,which can improve the detection efficiency and detection accuracy of micro-cracks on blade surface.In this paper,Rayleigh wave is used to detect microdefects on turbine blade surface.The Rayleigh wave propagation model on turbine blade surface was established by COMSOL Multiphysics 5.6,and the defects were quantitatively analyzed by using Rayleigh wave.Because the water-immersion focusing probe is used in this experiment,a finite element simulation model of "liquid-solid" interface Rayleigh wave is established.The relationship between defect size and position and normalized amplitude of received signal was quantitatively evaluated by simulation analysis of defects with different widths,depths,positions,tilting angles and curvature models.The line laser profilometer is utilized to measure the blade profile.Based on the module of 3D modeling software CATIA,the data set of the measured blade profile point cloud is utilized to reconstruct the blade profile.The C# programming language is used to extract the data set of the blade shaped point cloud and solve the included Angle between the normal direction and the vertical direction of any point on each section of the blade,so as to determine the Angle of the transmitting probe and the receiving probe at different positions of the blade.Net Framework based on the Win Form Framework to complete the software development of the ultrasonic testing experimental platform,the ultrasonic testing experimental platform for micro-cracks on the surface of turbine blades detection function of Pitch-Catch double probe Rayleigh wave.Finally,based on artificial defects,the quantitative characterization of the size and position of blade surface defects was completed through experiments.