Finite Element Simulation And Optimization Design Of Slotted Circular Tube Ultrasonic Transducer

As the key part of ultrasonic equipment,piezoelectric ultrasonic transducer has been widely used.Power ultrasonic technique,such as ultrasonic cleaning,ultrasonic machining,ultrasonic machine,ultrasonic welding,ultrasonic wastewater treatment,ultrasonic drug extraction,ultrasonic viscosity reduction of crude oil and sonochemical reaction and so on,with high efficiency,energy saving,environmental protection etc,has broad application prospect in the defense industry,mechanical engineering,aerospace,petrochemical industry,energy and environment,electronics and package of biological medicine,and other fields.In order to adapt to different application requirements,ultrasonic transducers with different structures and vibration modes need to be designed.There are many kinds of ultrasonic transducers,including longitudinal,torsional,bending and composite vibration modes.Bending vibration ultrasonic transducers are widely used in the field of ultrasonic technology.Because of the dispersion characteristics of the bending vibration wave velocity,wave velocity of bending vibration can be adjusted by changing the geometry of the vibrator,and the wave velocity can be much smaller than the longitudinal wave velocity.Therefore,compared with the longitudinal oscillator,the curved oscillator has a higher peak density and higher acoustic radiation uniformity,which is especially suitable for liquid ultrasonic processing and other fields.Based on this,a new type of slit round tube composite piezoelectric ultrasonic transducer with longitudinal and bending vibration mode conversion is proposed in this paper.The transducer is composed of longitudinal vibration piezoelectric ultrasonic transducer,ultrasonic horn and slit metal round tube radiator.The purpose of this study is to improve the acoustic radiation efficiency of the transducer by converting the longitudinal vibration of the transducer into the high-order and high-amplitude bending vibration of the tube wall through a series of slits with equal arc intervals on the cylinder of the thin-walled tube oscillator.The vibration characteristics of each component of composite piezoelectric transducer are analyzed theoretically and simulated by finite element method based on resonance design principle.The results show that the theoretical and simulation results agree well.On this basis,the structure and vibration modes of the slit tube composite piezoelectric transducer are optimized.The main research contents of this paper are as follows:1.Based on the analysis of the structure and performance characteristics of the existing similar ultrasonic transducer,a new type of circular tube composite piezoelectric ultrasonic transducer with slit structure is proposed,and its vibration characteristics are systematically studied by theoretical and numerical simulation.2.Based on the resonance design method,the sandwich piezoelectric ultrasonic transducer,stepped horn and slit pipe vibrator were used as independent resonance units for theoretical analysis.The end cover of a circular tube is approximated as a thin disc,and the wall of a slit circular tube is approximated as a slender rectangular beam.The resonance frequency equation of the circular tube under different boundary conditions is solved.3.Based on the finite element simulation software COMSOL Multiphysics 5.4,the vibration characteristics of round tube transducer and slit round tube transducer were studied.The vibration mode,vibration displacement,volumetric deformation and radiation sound field distribution characteristics are compared and analyzed.The results show that the sound radiation efficiency and the uniformity of the radiation sound field of the circular tube composite piezoelectric ultrasonic transducer are improved compared with the current seamless circular tube piezoelectric ultrasonic transducer and the column transducer.The influences of the geometrical dimensions,the number of cracks and the length of cracks on the vibration characteristics of the transducer are studied by simulation.The results show that the resonant frequency of the transducer decreases with the increase of tube length.It increases with the thickness of the end cover.Increases with the increase of tube wall thickness;It decreases with the increase of radius;It increases with the increase of slit length;It decreases with the increase of the number of seams.The volume shape of the oscillator increases with the increase of the slit length and the number of the slit.4.The error of theoretical analysis and simulation analysis of slit tube composite piezoelectric ultrasonic transducer is analyzed.The result show that the theoretical and simulation results are in good agreement with each other,which verifies the correctness of the theory.At the same time,the size of the transducer is optimized according to the analysis of its simulation vibration characteristics.