Time and Frequency domain analysis of elastic waves in Scanning Laser Source Technique

Abstract

This study investigates the propagation characteristics of elastic waves in a metal plate with a sub-surface defect. Dynamic force simulating a laser ultrasonic source was applied on the surface of the structure, and the energy transmitted around the defect was calculated in the time domain. The numerical results revealed that the energy of the acoustic wave transmitted around the defect close to the edge of the structure is larger than that around the defect located at the center of the structure. Next, natural vibration analysis was performed assuming that the defect is located near the left wall of the structure and at the center of the structure. The frequency components of the elastic wave transmitted around the defect were also calculated. The results show that the form of defect resonance and the resonance frequency are different depending on the defect location.