Finite Element Numerical Simulation Of Structure Design For Magneto-electrical Composite Ultrasonic Levitation Device

With the development of the space science and the material science,the demand for testing conditions is also increasing,and the space environment is such a special experimental environment.As a technical meanings to realize the simulation of the space environment,ultrasonic levitation plays an important role in the fields of material technology,droplet dynamics research,and biopharmaceuticals,etc.The simulation of acoustic levitation is very important for engineering application.However,at present,the simulation optimization of the ultrasonic levitation device is more in the one-way coupling stage,and the multi-physics coupling effect of the physical field inside the transducer and the sound field is not considered.In this paper,based on the magnetoelectric composite material as an ultrasonic transducer,a multi-physical field coupling model including magnetic field,electric field,displacement field,and sound field are established to simulate the magnetoelectric composite ultrasonic levitation device.The main research results achieved in this paper are as follows:(1)Based on the acoustic levitation theory,magnetostrictive theory,piezoelectric theory,and combined with the working principle of magnetoelectric composite ultrasonic levitation device,a multi-physical field coupling model for the ultrasonic levitation device including the magnetic field,electric field,sound field,and displacement field is established and simulated.Due to the existence of the demagnetizing field,the physical mechanism that the transducer produces the difference of amplitude is clarified,which affects the sound pressure output of the transducer.It is obtained that the transducer can output the maximum sound pressure for the piezoelectric material with the width of 4 mm and the height of 2 mm,and the magnetostrictive layer with the width of 4 mm and the height of 8 mm as well.The modal analysis is carried out,and the model mode shape corresponding to the frequency of 79.706 k Hz is obtained as a longitudinal vibration form,which is close to the frequency of the external excitation magnetic field at 80 k Hz,so this frequencey is an ideal frequency for the transducer.(2)The multi-physics coupling model simulation of ultrasonic levitation devices with different resonant cavity heights and reflecting surface lengths is performed,and it is found that the resonating cavity has the largest acoustic levitation capability with the resonant cavity height 11 mm and the reflecting surface length 10 mm.The levitation device with a reflection surface length of 27 mm is conducted to operate a reseach of the multi-physics finite element numerical simulation for the suspended particles.The results show that the particles in the air cavity can be quickly and stably suspended in the nodal potential well with zero sound pressure.The energizer can effectively achieve the acoustic levitation for the particles,which provides a new way for the acoustic waves to manipulate particle motion.(3)The parametric finite element model simulation analysis is carried out for the cylindrical resonance tube resonator with different resonance tube radius R_r,and it is obtained that the resonance cavity can provide the maximum sound pressure with the cylindrical resonance tube radius R_rof 7 mm.By changing the control parameter R_B,the finite element simulation analysis of the resonant tube with different degrees of concave and convex bending is carried out.It can be seen that the resonant cavity of the resonant tube has a large suspension capacity with the control parameter R_Bclosing to 7 mm.the cylindrical resonance tubes and the Bezier curve resonance tubes with different bending degrees with the same resonance tube radius are compared for the acoustic levitation capability and the acoustic levitation stability.It is found that the effect of the resonant tube on the sound field is more obvious as the length of the resonant tube is small,the difference of the sound field with or without the resonant tube decreases with increasing the length of the reflecting surface,and there is a higher sound suspension ability and acoustic suspension stability with the control parameter R_Bof 6 mm.Therefore,in the multi-physics coupling acoustic levitation device,the acoustic levitation performance of the acoustic levitation device can be improved by designing and introducing a resonant tube with reasonable structure.