Embedded self-sensing piezoelectric for damage detection

A method for damage detection based on self-sensing piezoelectrics is presented. When a piezoelectric actuator is electronically excited, it causes stress in the structure to which it is attached. As the structure deformation is influenced by the presence of damage, so will be the response of the sensor. The goal of the method is to use the same piezoelectric element as both actuator and sensor, by analyzing the electro-mechanical response of the system in the frequency domain. In this way, damaged and undamaged structures can be distinguished and the extent of damage estimated. The distinction between the excitation and the response signals is achieved by an electronic bridge circuit. A comparison between this self-sensing method and the more common cross-talk method is performed, showing the similarity of the two methods and the validity of our technique. A method to differentiate among the spectrum changes due to actual damage and those due to temperature shifts is also presented. As the temperature rises, the PZT characteristics change and the resonance frequencies of the spectrum shift. However, the acquired signal can be processed to compensate for the temperature changes.