NDE application of air-coupled array for thickness measurement of concrete slab

摘要

In this paper, we describe the improvement of Impact-Echo (IE) using developed air-coupled array system. The air-coupled array system utilizes microelectromechanical systems (MEMS) to receive leaky waves in concrete-air media without physical coupling process. The air-coupled array system benefits of Lamb wave analysis. It is known that thickness mode frequency measured by IE test is emerged from S1-ZGV (zero group velocity at the first symmetric mode) among Lamb waves. Lamb wave analysis is experimentally evaluated through the air-coupled sensing and two-dimensional fast Fourier transform. The contour map of frequency-wave number domain (f-k domain) clearly provides thickness mode frequency of tested slab among noise components, indicating the thickness information of concrete slab with minimal error. The developed air-coupled array system has a great potential to provide thickness mode frequency of concrete slab, which has been practically limited at air-coupled IE.