Development of a portable damage detection system based on electromechanical impedance technique for monitoring of bolted joint structures

Structural health monitoring of structures in general usually require an expert to permanently attach a sensor onto a specific area. This would be important for mechanical structures with bolted joints, such as in aircrafts or even machines as human lives depend on its structural integrity. However, for large civil infrastructures with bolted joints, such as in cable stayed bridges, installing a monitoring system with a large number of sensors would be unrealistic as the cost of the system would be significantly high. In addition, the time frame for certain bolts to loosen for civil structures can be quite long and one could say that a real time monitoring system is unnecessary as a routine maintenance is conducted for civil structures. An effective way of identifying bolt loosening would be vital for safety inspectors to inspect the target structure with minimized time. Thus, in this study, a piezoelectric transducer based non-destructive testing method is introduced to identify bolt loosening. The concept of real time online monitoring could be replaced with the portable damage detection concept shown in this study as the proposed idea could minimize the overall cost of the maintenance process.