Rapid evaluation of tile-wall bonding integrity using multiple-head impact acoustic method

In view of the increasing hazards posed by tiles falling from high-rise buildings, a nondestructive testing (NDT) method based on frequency domain features, which are obtained from the sound signals generated by tapping the wall surfaces with a single-head impactor, has been developed to ascertain the tile-wall bonding integrity in our previous investigation. However, the single-point-impact inspection operation will lead to extremely low inspection efficiency in practical implementation, especially considering the large wall area of high-rising buildings. Aiming to develop a significantly faster inspection method that can meet the practical need, a multiple-head impactor consisting of 3 steel spherical heads is proposed; each steel head is constructed with different resonant frequencies in order to ensure correct extraction and analysis of acoustic features related to each steel head when all 3 heads impact the wall surface simultaneously. Based on different spectral patterns related to different bonding qualities at each impact location, a spectral peak identification approach has been developed to automate the inspection process. The proposed method is 3 times faster than the similar method using a single-head impactor. © 2011 Elsevier Ltd.