BEM ANALYSIS OF CRACK DEPTH EVALUATION IN THE ULTRASONIC SPECTROSCOPY

Abstract

The ultrasonic spectroscopy is known to be one of promising techniques for non-destructive evaluation of defects in structures. Conventional ultrasonic testings have an essential drawback on the applicability to composite structures, because the technique is basically associated with the arrival time measurement. The spectroscopy deals with information in the frequency domain, instead of the arrival times in the time domain. As a result, spectral responses of composite members possibly identify crack information without stained by the inhomogeneity effect.
In the present paper, the spectral responses of plain concrete and reinforced concrete (RC) members are investigated analytically by the three-dimensional boundary element method (BEM) and are compared with experimental results. To analyze a notched concrete member, a multi-domain BEM procedure is employed. In addition, BEM-FEM coupling procedured is applied to model a RC member with a notch. Spectral responses between 1kHz and 20kHz are determined on plain concrete and RC specimens with artifical cracks of several depths. Analytical results show close correlation with experimental results. It implies that the present method is promising for the evaluation of crack depth in composite materials.