| Ultrasonic is a kind of mechanical wave whose frequency is upper20kHz. Ultrasonic has many advantages, such as carrying large amount of information, strong penetrability, good cluster. Ultrasonic propagate in the medium will produce physical effect, chemical effect, and biological effect, etc. Ultrasonic cleaning uses the cavitation effect which ultrasonic produce in the medium, in need of cleaning workpiece with ultrasonic. Compared with traditional cleaning methods, ultrasonic cleaning has the following advantages:high speed; high quality; broad cleaning range; saving the cost and reducing the pollution. Due to the advantages of ultrasonic cleaning, this technology has been widely applied in chemical industry, textile, machinery, electronics and other fields. Using in ultrasonic cleaning equipment, usually also called ultrasonic cleaning machine. Ultrasonic cleaning machine is consists of ultrasonic generator, cleaning tank, ultrasonic transduce.In traditional ultrasonic cleaning equipment, sandwich type piezoelectric ceramic transduce radiate directly ultrasonic wave to the cleaning fluid. So there are small radiation area, poor acoustic matching, uniform radiation acoustic field and so on some disadvantages. In order to improve these disadvantages, in this paper, we study a kind of composite transducer which are composed of longitudinal vibration transduce and flexural vibration circular plate. Longitudinal vibration transduce don’t radiate directly ultrasonic wave to the cleaning fluid, but it stimulate circular plate to flexural vibration, circular plate radiate ultrasonic wave to the cleaning fluid. The size of flexural vibration circular plate is larger, thus radiating surface area is larger, increasing acoustic matching and the uniformity of radiation acoustic field.This paper studies and discuses the problems on the following aspects:1. On the basis of the thin plate theory, by using the equalization of kinetic energy of the distributed parameter system and lumped parameter system, the equivalent mass of flexural vibration circular plate is derived; by using the equalization of potential energy of the distributed parameter system and lumped parameter system, the equivalent elasticity coefficient of flexural vibration circular plate is derived. The equivalent circuit diagram of the flexural vibration circle plate is derived.2. The equivalent circuit of piezoelectric ceramic crystal heap, back shroud, and circle plate are arranged series connected. When resistance part is zero, the resonance frequency equations for the buckling of composite transducer is derived. A buckling of composite transducer is designed, then the transducer is simulated with modal analysis by finite element software ANSYS, between the frequency of10000Hz to50000Hz, various vibration modes and the corresponding vibration map are presented. Theoretical results and experimental numerical results are basically identical. The transducer is simulated with harmonic response analysis by finite element software ANSYS, and the buckling of composite transducer of admittance curve is presented. The radius and thickness of circular plate affect resonant frequency of composite transducer. Effective electromechanical coupling coefficient of different types of transducers are calculated. It is expected that the result of this paper is used for reference to the vibration characteristics of buckling of composite transducer.3. In the composite transducer for ultrasonic cleaning, back shroud is empty, circular plate contact with liquid medium, and it radiates ultrasonic wave to the cleaning fluid. The equivalent circuit of load, piezoelectric ceramic crystal heap, back shroud, and circle plate are arranged series connected. When resistance part is zero, the resonance frequency equation buckling of composite transducer with load is derived. When effective electromechanical coupling coefficient of composite transducer is larger, radiation wave, radiation surface, and the radiation ability in the water is the best. The transducer is simulated with modal analysis by finite element software ANSYS between the frequency of10000Hz to30000Hz, various vibration modes and the corresponding vibration map are presented. Theoretical results and experimental numerical results are basically identical. Compare with composite transducer with no load, resonance frequency and vibration amplitude are reduced. The transducer is simulated with harmonic response analysis by finite element software ANSYS, and the buckling of composite transducer of admittance curve and radiation beam are presented. It is expected that the result of this paper is used for reference to the vibration characteristics of buckling of composite transducer with load. |
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