Complex Frequency-power Ultrasonic Transducer Design And Research

High power ultrasound has been widely used for ultrasonic welding, ultrasonic soldering, ultrasonic machining and ultrasonic cleaning. Ultrasonic energy performs a especial physical function in the process of cleaning that can be obtained by no other industrial tool. Ultrasonic cleaning is usually sorted as low-frequency cleaning and high-frequency cleaning. The low-frequency cleaning, whose cleaning mechanism is based on the cavitations, is suitable for removing dirty mote of several microns, and the high-frequency cleaning, whose cleaning mechanism is based on the acceleration force, is suitable for cleaning much small particles. The ultrasonic transducer is usually designed to have one working frequency in traditional ultrasonic cleaning, so it is easy to build a standing wave, and it is difficult to enhance the quality of ultrasonic cleaning. However, the situation is different in the case of multi-frequency ultrasonic cleaning. To produce ultrasound with different frequencies for one transducer in the tank, a multi-frequency ultrasonic transducer should be designed and used. Based on coupled vibration, some multi-frequency ultrasonic transducers are designed and analyzed in this paper.The main content and work of this paper are as follows:1. A new type of multi-frequency ultrasonic transducer is analyzed in this paper. The multi-frequency ultrasonic transducer consists of two sandwiched ultrasonic transducers and a rectangular radiator. Because of the coupling between longitudinal vibration of the sandwiched ultrasonic transducers and flexural vibration of the rectangular, the multi-frequency ultrasonic transducer has several resonance frequencies. The vibrational characteristics of thick and thin plates are analyzed especially. Some multi-frequency ultrasonic transducer are designed and simulated by finite element method, and modal analysis and harmonic response analysis are also done utilizing finite element method. The multi-frequency ultrasonic transducers are designed and manufactured according to finite element analysis. The effect of the geometrical dimension of the multi-frequency ultrasonic transducer and the location of two sandwiched ultrasonic transducers on the multi-frequency ultrasonic transducer is discussed.2. A new kind of multi-frequency transducer with a rectangular radiator is analyzed in this paper. The transducer consists of metal cylinder, piezoelectric ceramic pile and rectangular radiator. The fundamental modes of the coupled vibration of rectangular radiator are analyzed, and the frequency equations of the fundamental modes in the transverse directions are given by means of the apparent elasticity method. Meantime, based on the one dimensional longitudinal vibration theory, the resonance frequency equation in longitudinal direction of the multi-frequency ultrasonic transducer is derived out. One ultrasonic transducer of this kind is designed and simulated by finite element method, and modal shapes and harmonic response are analyzed. The ultrasonic transducer is also designed and manufactured. The resonance frequencies are measured and compared with the theoretical results. It is shown experimentally and theoretically that the compound multi-frequency ultrasonic transducer has several resonance frequencies.3. The methods for designing broadband ultrasonic transducers based on optimizing the multi-frequency ultrasonic transducers are introduced, and the theories of these methods are discussed.4. The process of analyzing a transducer by finite element method ANSYS is explained, and some issues that should be paid attention to when simulating the transducer by ANSYS and analyzing a transducer in fluid are pointed out.