High accuracy and resolution damage detection for concrete based on novel virtual correlation imaging method and embedded piezoelectric sensing technology

This paper presents a novel virtual correlation imaging (VCI) method to reduce the adverse effects of stress wave distortion and realize high accuracy and resolution damage imaging based on the sparse stress wave data collected by embedded piezoceramic transducers. Specifically, a compensation function is first constructed in the VCI method based on the frequency response characteristic of damage-induced scattering signals. Then, the constructed compensation function is emitted as the virtual excitation signal in the simulation space via virtual channels. To automatically compensate for the effect of waveform distortion, a virtual correlation operator is developed based on the scattering signal and its corresponding virtual received signal to design the imaging function. Finally, the practicability of the proposed VCI method is investigated on a concrete specimen with two successively drilling holes under laboratory conditions. The results indicate that, compared with the conventional damage imaging methods, the proposed VCI method can effectively decrease the adverse effect of distorted probing stress waves on damage localization accuracy and spatial resolution during the imaging process.