An Ultrasonic Flextensional Array for Acoustic Emission Techniques on Concrete Structures

The monitoring of concrete buildings is important to assess their solidity and promptly intervene in case of damage. Concrete structures suffer the formation of micro-cracks and the propagation of macro-cracks, due to ageing or to mechanical stresses. These cracks are sources of acoustic emission, and can be distinguished according to the frequency and intensity of the acoustic wave they generate; thus, transducers with high sensitivity and wide bandwidth are needed. Flextensional piezoelectric transducers are known for these characteristics, which make them suitable for acoustic emission applications. For this reason, we designed a flextensional transducer optimized for acoustic emission techniques applied to concrete structures. The performance of the device in receive mode in concrete-coupled operation was investigated by running harmonic analyses on a finite element model. The geometrical parameters of the device were designed in order to obtain a broadband receive sensitivity.