Bispectra-based impact acoustic non-destructive evaluation

This paper presents a novel cost-effective non-destructive evaluation (NDE) method for detecting defects in tiled-walls of high-rise buildings. The method is based on impact acoustic technique which identifies the bonding quality of tiles by analyzing the acoustic vibration signals generated by tapping a structure with an impacting device. However, the basic impact acoustic method, which uses a single impacting device, can only provide a single-point inspection and will take time to inspect a large high-rise building. To speedup the evaluation process, impacting the structure simultaneously with multiple impacting devices are being developed to increase the coverage area of the inspection. However, the sound signals generated by multiple impacting devices are more complicated than those from a single impacting device. Through the analysis of the raw sound data, this paper proposes a regional integrated bispectra method to extract the feature vector and a threshold method for classifying the bonding quality of tiles for multiple impacting devices. The experimental results confirm the validity of the proposed method.