Identification of the location and size of cracks in beams by a piezoceramic actuator–sensor

This paper presents an application of the modal identification technique employing piezoceramic (PZT) material to identify the location and size of cracks in beams. A PZT patch can be used both as an actuator and a sensor by utilizing its electro-mechanical coupling property. Measuring the impedance at a location where a PZT is bonded to a beam, modal frequencies of the beam are identified from the measured impedance. In this technique, the beam can be excited at high frequencies in order to obtain information of high-frequency modes that are sensitive to local damage. The location and size of the cracks can be identified from the measured impedance as well as using a cracked beam model formulated from a spectral element method (SEM). The SEM is used in the structural modelling because of its high accuracy in modelling of beam in high-frequency range. An experiment was performed on a set of cracked aluminium beams and it is demonstrated that the location and depth of the cracks could be accurately identified using the proposed technique.