Research On Hemispherical Shell Cymbal Transducers

Piezoelectric transducer is an energy conversion device that uses the piezoelectric effect of materials to convert between electrical energy and sound energy.It is an important part of ultrasonic technology.Piezoelectric transducers have many different vibration modes.The flextensional transducer contains both bending and extensional vibration modes,and has a wide range of applications in underwater acoustic communications,ultrasonic motors,energy harvesters,piezoelectric accelerometers,etc.As a typical flextensional transducer,the cymbal transducer has the characteristics of small size,simple structure,and easy processing.However,the truncated cone-shaped end cap of the traditional cymbal transducer results in a smaller radiation area.Based on the structure of the traditional cymbal transducer,this paper proposes a new structure of the hemispherical cymbal transducer.The end cap is a hemispherical shell with a larger radiation area.In this paper,the hemispherical cymbal transducer with a piezoelectric ring and the hemispherical cymbal transducer with a combined piezoelectric ring and metal ring are studied respectively.The research work of this paper includes the following:(1)Based on the electromechanical equivalent circuit of the radial vibration of the thin metal ring and the piezoelectric ceramic thin ring and the theoretical study of the elasticity of the metal thin spherical shell,carry on theoretical analysis to the hemispherical cymbal transducer with a piezoelectric ring and the hemispherical cymbal transducer with a combined piezoelectric ring and metal ring,get its electromechanical equivalent circuit and resonance/anti-resonance frequency respectively.(2)Using finite element analysis software,the resonance frequency and vibration characteristics of the hemispherical cymbal transducer with a piezoelectric ring are studied,the first two vibration modes are obtained.We analyzed the influence of different dimensions of the transducer on its resonance,anti-resonance frequency and effective electromechanical coupling coefficient,and obtained a theory conducive to optimal design.The vibration in the underwater acoustic field of a hemispherical cymbal transducer with a piezoelectric ring is simulated,and the sound pressure distribution and sound pressure level of its first and second vibration modes were obtained.The transmit emission voltage response of the transducer in the underwater acoustic field is studied,and the influence of the thickness of different metal end caps on the transmit emission voltage response is analyzed.Finally,a hemispherical cymbal transducer with a piezoelectric ring was designed and processed,and its frequency response curve and resonance/anti-resonance frequency were measured by Precision Impedance Analyzer.The experimental results were compared with the theoretical results.(3)Based on the hemispherical cymbal transducer with a piezoelectric ring,a metal ring is compounded outside the piezoelectric ring to obtain the hemispherical cymbal transducer with a combined piezoelectric ring and metal ring,which can get rid of the size limitation and power limitation of traditional cymbal transducers.The finite element analysis software was used to study the resonance frequency and vibration characteristics of the hemispherical cymbal transducer with a combined piezoelectric ring and metal ring,and the influence of different dimensions of the transducer on its resonance/anti-resonance frequency and effective electromechanical coupling coefficient is analyzed,and a theory conducive to optimal design is obtained.The vibration in the underwater acoustic field of the hemispherical cymbal transducer with a combined piezoelectric ring and metal ring is simulated,and the sound pressure distribution and sound pressure level of the first and second vibration modes are obtained.The transmit emission voltage response of the transducer in the underwater acoustic field is studied,and the influence of the thickness of different metal end caps on the transmit emission voltage response is analyzed.Finally,a hemispherical cymbal transducer with a combined piezoelectric ring and metal ring was designed and processed,and its frequency response curve and resonance/anti-resonance frequency were measured by Precision Impedance Analyzer.The experimental results were compared with the theoretical results.