Vibrating Disc The Same Size Curved Design

Thin plate in flexural vibration is an important part of ultrasonic vibration system. Its thickness is much smaller than the length. There are three boundary conditions:free, simply-supported and fixed. It has large radiation surface and low radiation resistance. The use of thin plate has increased with the development of ultrasonic technique in recent years,such as ultrasonic levitation, drying, agglomeration, aerosol particle precipitation in gauging. The main problems concerning the ultrasonic generation and propagation in gases are a match between the transducer and the gases.Because the gases are the low acoustic impedance and the high absorption of the medium, it is necessary to produce high directivity and achieve a good impedance match. The compound ari-coupled transducer consisting of a sandwich longitudinal piezoelectric vibrator and a circular thin plate in flexural vibration has the advantages of large radiation surface and improved impedance matching and has used in producing ultrasound of high directivity in air.In this paper,the radiation impedance and sound field of the flat in flexural vibration as an ultrasonic radiator are studied.The research results include severral aspecte as following:(1) Research for the directivity of the flat circular plate in fiexural vibrationFlexural vibration and radiated sound field of a flat circular plate were study,the directivity pattern of a flat circular plate with flexural vibration under the three boundary condition is derived. And a computer program is developed by matlab,which can study on the radiated sound field.The curves of the directivity varying with the flat's size and order are plotted.The directivity of the flat is not only the function of the flat's size,but also concerned with the boundary condition and the vibration mode of the flat. The results showed that the acuity of the directivity patterns is different under the same size of the flat circular plate,that fixed conditions is best,and free boundary conditions is worst.However,the directivity pattern of flat circular plate becomes poor when the vibrational order and the size of the flat circular plate in flexural are increased. (2) Research for radiation impedance of the flat circular plate in anharmonic vibrationFlexural vibration and radiated sound field of a flat circular plate were study,the expressions for radiation impedance of the flexural circular plate in three boundary conditions are derived. The values of radiation impedance for the flat circular plate in anharmonic vibration are calculated by using high precision numerical numerical method of integration, Gauss quadrature formula and mathematica. The curves of resistance and reactance varying with frequency are plotted by cubic spline.Radiation impedance of of the flat circular plate in anharmonic vibration is not only the frequency of the flat,but also concerned with the vibration mode of the flat.The values of resistance decrease with the number of nodal circle increasing, howerve, the values of reactance increase. When the flexural plates are in different boundary conditions,the values of resistance are different although the same vibration mode. The fewer nodal circles is,the values of radiation resistance of the flexural circle plate with simple supported edge are largest, the values of circle plate with fixed boundary are lest,and the values,with free boundary,are middle. The values of radiation reactance of the flexural circle plate with free boundary are larger than the simple supported edge,howeren,, the values of circle plate with fixed boundary are not obvious change.These provide the scientific theoretical foundation for utilizing these types of vibrators intentionally and efficiently in practical applications.