A Study on Evaluation Method for Micro Defects on Surface based on Leaky Rayleigh Wave

Among the various non-destructive test techniques, one of the ultrasonic techniques, ultrasonic testing using leaky Rayleigh wave, are very useful for measuring micro-defects that occur on surfaces. However, it is difficult to determine the depth of the actual flaw, because the amplitudes of the collected signals vary depending on the location of the signal acquisition due to the characteristics of the leaky Rayleigh wave occurring at liquid-solid interface. Therefore, in this study, the phenomenon and characteristics of leaky Rayleigh wave were analyzed through FEM simulation. In addition, transmissions factors that depend only on the size of the defect and leaky factors that depend only on the collection distance were distinguished. Then, a defect calculation algorithm has been developed that can quantitatively assess the depth of defects regardless of its acquisition location.