A novel approach to alloy-based bonding for piezoelectric sensor integrated in impedance-based structural health monitoring

Abstract

Structural health monitoring aided with the electromechanical impedance technique (EMI) is gaining popularity among researchers due to its dual sensing application and noise-free sensor results, and it is very sensitive to inceptive structural alternation. A thin coat of adhesive permanently bonds the piezoelectric transducers to the host structure. The bonding layers effect the mechanical interaction between the structure and the piezoelectric material as they act as a pure shear connector. Furthermore, the presence of shear alters the actuation and sensing capability of the PZT (Piezoelectric Transducer) patch, hence the efficiency of EMI technique. In this paper, a novel alloy (Sn-Ag) based bond is introduced for sensor integration and studied for bond behaviour in order to improve the bond’s quality in the EMI approach for structural health monitoring. The first part of experiment deals bond geometry degradation deals with the effect of disbond towards impedance-based coupled signature. The last part of experiment focuses on bond exposure to environmental degradation and it’s durability. From the experimental results, it is found that the Sn-Ag alloy-based bond formed between the structure and the piezoelectric transducer with the help of thermos-activated process is extremely strong and establishes a unique bond layer connection to the structure, which has a more resistive capacity towards moisture, chemical, and also temperature, compared with the epoxy-based bond.

Keywords

• alloy bonding
• debonding
• piezoelectric transducer (pzt)
• electro-mechanical impedance (emi) technique
• sn-ag alloy