[P01-06] A Study on the Propagation Characteristics of Surface Waves in a Granite Based on Ultrasonic Measurement
Keywords:surface wave, granite, ultrasonic wave, heterogeneous material
This study investigates the propagation characteristics of high frequency surface wave in a granite block by ultrasonic measurement. In the experiment, a surface wave field excited by a line-focus transducer is scanned finely over a rectangular aperture with a laser Doppler vibrometer. From the measured waveforms, the spatial distribution of Fourier phase is reconstructed, and the structure of the wave front configuration is investigated. Due to the heterogeneity of the granite, we find the fluctuation of the wave front measured by the distribution of spatial gradient of phase. The intensity of the fluctuation is quantified as a local wavenumber vector. As the result it is found that the granite sample can be characterized by a stochastic wave number whose probability density is frequency dependent, asymmetric and non-Gaussian with a finite support.