Damage Detection Based on Voltage Transfer Ratio Approach and Bayesian Classifier

Structural damage can result in observable changes of the signal acquired by network of PZT sensors, due to elastic wave interaction with damage. There are two approaches how to utilize PZT sensors for SHM purposes. One of the approaches follows closely classical ultrasonic testing. In that case, short-pulse excitation of PZT transducers is used, thus guided wave packets can be scattered on different elements of structure, eventually also on the damage itself. The disturbance of the scattered wavefield is the basis of damage detection and evaluation. In the different approach harmonic excitation of PZT is used, thus steady elastic waves are excited in the structure. The signal can be gathered in the pulse-echo scheme, i.e., when a single transducer is used both as an actuator and a receiver of waves, as well in the pitch-catch scheme, when a pair of transducers is used. An approach for damage detection with use of a network of PZT sensors excited with harmonic signals in the pitch-catch scheme will be presented and its properties and damage detection capabilities will be discussed. In addition method for data classification based on the Bayesian approach will be demonstrated and compared to other approaches to data classification.