Experimental Study on Applicability of Triboelectric Film Sensors for Integrity Monitoring of Shear Bolted Joints

Abstract Many structures such as bridges, buildings, or automobiles use various joining methods such as screws, rivets, welding, gluing, and caulking to join members together. In particular, the shear bolted joints is widely used as a joining method that facilitates assembly and disassembly, while being accompanied by a troublesome problem of bolt loosening due to repeated shear force. In the previous study, we proposed a self-powered film-shaped triboelectric sensor made of inexpensive materials, being installed between the contact surfaces at the joint, to monitor the loosening of tensile bolted joints. The principle of the sensor is that it detects microscale relative motions between the contacting surfaces at the joint as the triboelectric induced voltage, when the integrity of the joint is deteriorated due to the decrease in the bolt’s fastening force. In this study, we apply our sensor to shear bolted joints. A sensor is designed, fabricated, and tested in a single-bolt shear joint subjected to lateral shear forces. As a fundamental experiment, we designed a drop test to apply a lateral impact to bolted structures, simulating the lateral loads experienced by bolted assemblies in real-world situations. Under various fastening forces of the bolt, we observed the sensor’s voltage output when subjected to the same impact force or lateral load. The analysis focuses on the relationship between the sensor’s voltage output signal, the impact, and the fastening force of the bolted structure.