Abstract
Nowadays ultrasonic and electromagnetic waves are often used for the quantitative nondestructive testing of concrete. The evaluation of material deterioration and detection of defects in concrete are carried out using the ultrasonic wave. On the other hand, the position of reinforced bars can be reconstructed by using the electromagnetic wave. In order to obtain a better understanding of propagation of both ultrasonic and electromagnetic waves in concrete, it is effective to model the wave propagation and scattering process explicitly in the time domain. This study presents a numerical time domain modeling of ultrasonic and electromagnetic waves. Our simulation tool is based on the finite integration technique (FIT) and combined with an image based modeling approach. The FIT is a grid-based spatial discretization method that works in conjunction with a leap-frog type explicit scheme. In the image based modeling, geometries of concrete are determined by a digital image, e.g. a cross-sectional picture, CT data, etc. Then the processed pixel or voxel data are directly fed into the FIT. Here simulations of the contact ultrasonic method and electromagnetic radar method for concrete are demonstrated.
