Low-cost electromechanical impedance testing for civil structures

Electromechanical (E/M) impedance testing using piezoceramic (PZT) patches adhered to the surface of a host structure has been shown to be a promising structural health monitoring (SHM) technique. E/M impedance testing can detect incipient and local damage in engineering structures by taking advantage of the coupling between the electrical impedance of the PZT patch and the mechanical impedance of the host structure. Research in this field so far has largely been laboratory based in ideal environmental conditions. Moreover, an impedance analyzer is typically used to make measurements; typically, these analyzers are expensive and not portable, and thus do not lend themselves to field applications. This paper explores an expansion in the application of E/M impedance testing that aims to close the critical gap between laboratory development of this SHM method and its deployment in the field. To reduce the cost associated with this technique, a single-board computer (SBC) is used to make measurements. The SBC used, called Red Pitaya (RP), does not require further hardware development, can make high fidelity impedance measurements, and can wirelessly communicate with a PC. Additionally, the scope of most research conducted to date has been on structures in a laboratory setting or simple outdoor exposure. Work has not been done yet on extreme environments, such as under water. To expand the range of environments in which the E/M impedance technique is employed, damage detection tests are conducted on one-dimensional beams submerged under water.