Research on bolt looseness monitoring based on electromechanical impedance transmissibility technology

Abstract

Centralized damage, such as bolt looseness, is one of the most common types of damage in bridge structures. Thus, early detection of such damage is essential for bridge maintenance. Detection methods based on transmittance functions (TFs) have been widely studied. These functions use a T matrix to calculate damage indicators and reflect changes in dynamic parameters, such as natural structural frequencies. However, existing research has shown that the excitation position significantly impacts the T matrix. Therefore, this study proposes a new method based on electromechanical impedance (EMI) for local damage characterization, namely, EMI-TF. A series of comparative tests shows that the EMI-TF process is more sensitive and accurate than the traditional TFs. In addition, the sensitivity of the EMI-TF and EMI methods is compared. Results show that using EMI-TF technology can achieve the localization of minor damage at lower frequencies, which, to some extent, overcomes the limitations of the traditional EMI method that can only detect minor damage at high frequencies. The repeatability of EMI-TF is also studied separately in experiments, with 10 repeated experiments conducted. Results show that the experimental results of EMI-TF have high repeatability.

Research on the monitoring friction hysteresis for the bolted interface by electromechanical impedance

“…The research on performance monitoring of prestressed structures using electromechanical impedance can be categorized as follows: (1) characterizing changes in structural performance based on indicators [37][38][39], such as root mean square deviation, peak frequency shift, meanabsolute-percentage deviation, and others. (2) Developing intelligent algorithms based on ultrasonic energy methods [40] and transfer functions [41]. (3) Compensating for signal features under the influence of external loads using deep learning, including factors like temperature [42] and tangential forces [25].…”