<title>Structural modal analysis using collocated piezoelectric actuator/sensors: an electromechanical approach</title>

Abstract

This paper presents a modal analysis technique based on the measurement of electric admittance of collocated actuator/sensors. The technique utilizes thin piezoelectric patches bonded on structures as both sensor and actuator. A commercial electrical impedance analyzer is used to measure the electrical admittance of the PZT patch. An SDOF model governing the electromechanical interaction is derived and then used to extract the mechanical impedance of the structures from the measured electrical admittance. Two corresponding algorithms, revised inverse Nyquist plane curve fitting and admittance matching-half power bandwidth approaches are presented for the extraction of modal parameters. Both approaches exclude the stiffening effect of PZT on structure yielding better estimations of extracted structure natural frequencies. The placement of PZT on structure is also studied. An experimental example is given on a small flexible beam. The results show the advantages of this technique in modal test of lightweight and flexible structures whose modal parameters are extremely sensitive to the stiffening of the transducers and shaker.