Analysis on identifying thin-plate void parameters in concrete based on vibro-acoustic method

Thin-plate voids are common defects found in concrete structures, such as tunnel vaults. Parameter identification for concrete thin plates using the vibro-acoustic method is a crucial approach for rapid and accurate detection in specific locations. In this study, a fixed-support rectangular thin-plate vibration model was developed, and the vibro-acoustic echo components were derived under external excitation. Based on this model, a method for identifying horizontal dimensions was proposed, utilizing the power spectrum frequency distribution. Subsequently, a digital filter based on Wavelet Synchronous Squeezing Transform (WSST) was constructed to obtain the modal vibration echo. A fitting method for the vibro-acoustic echo attenuation coefficient and a correction for thin-plate thickness were implemented. Finally, the accuracy and applicability of identifying the size parameters of thin plates were verified using square specimens with thicknesses of 12 mm, 21 mm, and 30 mm, as well as circular specimens with a thickness of 15 mm.