Impedance-based structural health monitoring considering temperature effects

This paper presents an impedance-based structural health monitoring (SHM) technique considering temperature effects. The temperature variation results in a significant impedance variation, particularly a frequency shift in the impedance, which may lead to erroneous diagnostic results of real structures such as civil, mechanical, and aerospace structures. A new damage detection strategy has been proposed based on the correlation coefficient (CC) between the reference impedance data and a concurrent impedance data with an effective frequency shift which is defined as the shift causing the maximum correlation. The proposed technique was applied to a lab-sized steel truss bridge member under the temperature varying environment. It has been found, however, the CC values are still suffering from the significant fluctuation due to the temperature variation. Therefore, an outlier analysis providing the optimal decision boundary has been carried out for damage detection. From an experimental study, it has been demonstrated that a narrow cut inflicted artificially to the steel structure was successfully detected using the proposed SHM strategy.