Damage Location for a Steel Plate Using Distributed Sensors Based on EMI Method

The piezoelectric sensor is more sensitive to change in its vicinity than to global changes in the structure. By means of this feature, multiple piezoelectric patches are applied to locate damages in the present experimental investigation based on Electro-mechanical impedance (EMI) method. Two steel plates bonded with distributed piezoelectric patches are respectively drilled a small hole in the certain position to simulate the local damage. Then, EMI signatures are separately obtained from these distributed sensors before and after damage’s generation. The EMI data analysis integrated with non-parametric indices, such as root mean square deviation (RMSD) and covariance (COV), is proposed to locate the damages. In order to improve detection efficiency, a technique by multiplexing the four piezoelectric sensors is applied. However, due to the differences of each piezoelectric patch, there exist some relatively large errors in the detection results. Thus, a data standardization method is adopted to eliminate these errors. From the three-dimensional damage metric charts, the damage position can be detected clearly. This illustrates the present technique integrated with non-parametric indices can be adopted to locate structural damages using multiple piezoelectric sensors.