Separation of modes in the thickness mode vibration of the piezoelectric thin plates

An improved procedure for analyzing the thickness resonance of piezoelectric thin plates is examined. The initial measurement is the admittance as a function of frequency, which can be expressed in the form of a deformed circle. This circle is used to calculate the optimum measurement positions of the fundamental thickness resonance. All the parameters are calculated by least-squares curve fitting of the variation of phase around the circle with frequency. The admittance curve related with the fundamental thickness resonance of a thin plate is reconstituted with calculated parameters. Other modes, such as bending mode and high-order harmonics of radial mode, are separated by removing the fraction of the reconstituted admittance of the thickness mode from the initial measurements of admittance. The positions and the origins of the parasitic modes are discussed with the diagram of admittance with frequency