Monitoring of corrosion-induced damage to bolted joints using an active sensing method with piezoceramic transducers

Ensuring adequate tightening of bolted joints is necessary since they are more prone to corrosion in a harsh environment under insufficient preload. To this end, this paper first conducted an accelerated electrochemical corrosion experiment to expedite the corrosion process of bolted connections over different periods. The results show that as the corrosion time is extended, the overall dimensions of the bolt system remarkably decrease. Moreover, according to the mass loss of the bolted joints in 3.5% NaCl solution, the rate of corrosion continuously changes. Then, a real-time monitoring approach based on active sensing was utilized to evaluate the corrosion conditions of bolted joints. The stress wave generated by one piezoceramic transducer propagates through the bolted joints and is captured via another transducer that acts as a sensor. The energy corresponding to the stress wave signal declines during the corrosion process, and the normalized wavelet packet energy index is used to evaluate the degree of damage to the bolted joints. Overall, the health status of the bolted joints is significantly affected by the corrosion time. The proposed active sensing method can accurately monitor the corrosion process of bolted joints. The experimental results verify the feasibility and practicality of the real-time, piezoceramic transducer-enabled method for monitoring the structural health of corroded bolted joints.