Research On The Sandwiched Radial Vibartion Piezoelectric Ultrasonic Transducers

The high power ultrasonic transducer is a ultrasonic equipment that electricity energy and sound energy (mechanical energy) can mutual transformation. The longitudinal sandwiched piezoelectric transducer is widely used in the field of ultrasonic technology, and the design theory of this kind of transducer is almost perfect. In order to meet the applications, a high-power radial composite piezoelectric transducer is developed. Because of this kind of transducer has the advantage of high power density, high radiation efficiency and all-direction radiation of ultrasound, so it has widely application prospects in liquid ultrasonic processes, and gradually become a research focus in this field.At present, the radial vibrational mode and longitudinal radial coupling vibrational mode of the dual or ternary radial composite piezoelectric transducer are studied by many scholars. But they are usually assembled by heat bilges cold shrink method, which need to high processing technology, so the magnitude and uniformity of the pre-stressed are always very difficult to control.In view of the above problems, a ternary radial composite piezoelectric transducer is proposed and a preliminary study in this paper. The radial composite transducer mainly consists of an inner and an outer metal pre-stressed tube and a middle piezoelectric ceramic circular tube. But in this paper, the piezoelectric unit of the single-layer ceramic radial composite transducer is composed by thin piezoelectric sheet circular permutation. Based on the design theory of longitudinal sandwiched piezoelectric transducer, the ternary radial piezoelectric transducer has further improvement, the sandwiched radial composite piezoelectric transducer is presented in this paper. We also introduced a cylindrical elastic expansion inner core that don’t need high precision hot process and can be disassembled easily. In this paper, the single and double piezoceramic radial composite transducer are analyzed respectively by the theory, finite element method (FEM) and experiment, the test values and the theoretical results are basically in agreement with each other.1. The radial vibrational characteristic of the isotropic metal thin circular disk, the isotropic thin short ring and isotropic thin-wall pipe was briefly studied respecttively. Based on the electro-mechanical analogy, their equivalent circuits and resonance frequency equations are obtained.2. The radial vibrational characteristics of a single-layer piezoceramic ternary radial composite piezoelectric transducer are studied. Based on the continuity of the boundary conditions, its radial vibrational electro-mechanical equivalent circuit and the frequency equations were derived. the relationships between the performance parameters of the transducer and its wall thickness, the position of piezoelectric ceramic are discussed.3. The multi layers (usually even layers) sandwiched radial piezoelectric ultrasonic transducer was presented. Based on the continuity of the boundary conditions and the network cascade theory, the equivalent circuit, the resonance and anti-resonance frequency equations of the radial vibration of a sandwich radial piezoelectric ultrasonic transducer are derived. the relationships between performance parameters of the transducer and the geometrical dimensions are analyzed.4. The finite element package software ANSYS was used in analyzing the radial vibration of the sandwiched radial composite piezoelectric ultrasonic transducer. The several samples with different wall thickness of the transducers were manufactured, and their resonance frequencies are tested. It’s shown that the results of the theoretical and FEM simulations are in good agreement with that of the measurements.