Evaluation of Small Defects by Wavelet Analysis of Scattering Ultrasonic

Nondestructive evaluation method of the density and mean diameter of small defects in the material using wavelet analysis of scattering ultrasonic waves was developed. The relationship between scattering ultrasonic frequancy characteristics (noise energy and center of the frequency) and defects characteristics (diameter and volume density) was determined by numerical calculations. Scattering ultrasonic was detected using 50 MHz forcused transducer for Al-Si sintered materials ; relative density were 99.56%, 99.52% and 99.22%, mean pore diameter were about 2 μm. From the experimental results, it was found that the defects characteristics can be evaluated from the wavelet analysis of scattering ultrasonic.