Identification of temperature variation and vibration disturbance in impedance-based structural health monitoring using piezoelectric sensor array method

Impedance-based structural health monitoring (ISHM) using piezoelectric materials has been extensively developed to provide a structure health indicator. In practice, due to the environmental disturbances, the received signal in different surrounding conditions may be different from intact structure received signal. In the past, any difference was assumed being caused by damage even changes such as temperature effects on the received signal. In ISHM, the received signal is different from the intact structure received signal; however, there is not necessarily damage in the system. So, the validity of ISHM depends on the identification of environmental disturbances in order to extract the real results from disturbed results. In this article, a new method using sensor array and statistical metric analysis has been proposed to identify signal changes derived from damage and/or environmental change. Using this method, it is expected that the environmental variations affect similarly on output signals of different row sensors, whereas changes caused by damage will not be similar for all row and column sensors. This expectation is a general fact because there would be no sensible difference in the environmental variations from one side to other sides of the structure. To identify environmental disturbance from damage detection, an analysis is developed using statistical metrics. Experimental results show that this method is reliable to identify damage.