Design And Characterization Of Longitudinal-Torsional Ultrasonic Transducer

As a typical sandwich cellular lattice core material,honeycomb aramid material has higher stiffness-to-weight ratio and strength-to-weight ratio properties due to its larger pores and lower bulk density,and its excellent performance in fracture toughness,impact resistance,heat dissipation,vibration damping and noise reduction,and the application scenario is no longer limited to the aerospace satellite field.However,due to the mechanical anisotropy between the spatially interconnected cells inside the honeycomb,conventional processing methods can lead to defects such as deformation and cracking of the matrix fibers.Therefore,this paper designs a longitudinal-torsional ultrasonic transducer for honeycomb aramid material processing that can generate vibration displacement in both axial and transverse directions.Based on the longitudinal-twist composite vibration mode conversion theory,the mechanism of longitudinal twist is analyzed and derived,the vibration state of the crystal stack of piezoelectric ceramics is analyzed,the frequency equation,vibration velocity equation and stress state equation of the left and right sides of the transducer nodes are derived,the theoretical design dimensions of the transducer are solved,and the intrinsic frequency and vibration pattern of the transducer are further analyzed by the finite element method.The N-ICPT technology is used to design the transducer power supply system for the high-speed rotating conditions of the longitudinal-torsional ultrasonic transducer.In this paper,the physical structure model of the up-and-down type rotating N-ICPT system is designed,the mutual inductance model of the N-ICPT system is derived,and the entire transducer is treated as an electromechanical equivalent circuit to facilitate further circuit analysis.In order to improve the energy transfer efficiency,the impedances of four circuit matching compensation topologies are analyzed.The simulation results show that the energy loss is only 1.2W under the condition of 0.3mm air gap.The characteristics of the longitudinal-torsional ultrasonic transducer are investigated.The acoustic characterization parameters of the longitudinal torsional ultrasonic transducer-assisted processing system are derived from the electrical conductivity circle diagram;the acoustic field distribution of the transducer is analyzed,and the pointing characteristics of the transducer are studied.The temperature rise of the transducer was studied,and the problem of temperature rise of the transducer was solved by the analysis of the flow field distribution of the transducer and the installation of a heat sink for the transducer.The process characteristics and dynamic load characteristics of the transducer were studied,and the influence model of the clamping nut preload and cutting dynamic load on the internal acoustic parameters of the transducer was constructed on the basis of the experiment,which provided some guidance for the adjustment of the acoustic characterization parameters of the transducer.Based on the longitudinal-torsional ultrasonic transducer-assisted machining system,the performance of the longitudinal-torsional ultrasonic transducer for machining honeycomb aramid material was tested.The experiments show that the longitudinal vibration amplitude can reach 13.0μm and the torsional vibration amplitude can reach5.89μm.The longitudinal and torsional amplitude fluctuations are relatively small and the system is relatively smooth;the milling force tests show that the longitudinal and torsional ultrasonic transducer-assisted processing can effectively reduce the milling force and improve the effective milling time,which provides a new idea for the processing of honeycomb aramid material.