1-Dimensional Analysis of Ultrasound at Closed Interface of Solid

Abstract

As a first step to investigate mechanism of nonlinear ultrasonic generation at closed cracks, computer simulation for ultrasonic propagation in 1 -dimensional solid including closed interface was examined using Improved-FDM. Fundamental calculation model which described interaction between open / closure motion of the interface and ultrasonic stress was developed. In the model, compression stress is distributed over the entire solid, as motive force for closure of the interface. The interface is exhibited by the small region, and its open / closure are determined using calculated strain of the region. As a result, motion of the interface causing generation of saw-tooth like displacement waveform was observed. Amplitude modulation of displacement waveform was also observed, and it indicated possibility that small fluctuation of open / closure timing caused the modulation of the amplitude.