FEM Modeling of Vibro-Impact Response of Metal Plates Excited by a High-Power Ultrasonic Transducer

2012 ◽  
Vol 197 ◽  
pp. 278-282
Author(s):  
Zhao Jiang Chen ◽  
Shu Yi Zhang ◽  
Zhi Liang Zhang
Keyword(s):  
Contact Force ◽  
High Power ◽  
Ultrasonic Transducer ◽  
Vibration Velocity ◽  
Nonlinear Phenomena ◽  
Fem Modeling ◽  
Frequency Spectra ◽  
Metal Plates ◽  
Power Ultrasonic ◽  
Subharmonic Vibration

When thin metal plates are excited by a high-power ultrasonic transducer, superharmonic and high-order subharmonic vibration phenomena of the plates are observed in our experiments. However, the nonlinear mechanism in the system is still not fully understood. In this paper, a finite element model is established based on the experimental conditions and numerical simulations are performed to explore the generation mechanism of the nonlinear vibration. By comparing the waveforms and frequency spectra of the vibration velocity of the plate to these of the contact force between the ultrasonic horn tip and the plates, it can be found that waveform distortion of the contact force is the main reason for generating the superharmonic vibration, while the intermittent contact-impact between the horn tip and the plate is the reason for subharmonic vibration in the plate. The FEM simulation results can explain reasonably the observed experimental phenomena, which are useful to help to improve the effects of the nonlinear phenomena occurred in ultrasonic processing.

Investigation of the nonlinear phenomena of a Langevin ultrasonic transducer caused by high applied voltage

2021 ◽  
pp. 095440622110093 ◽  
Author(s):  
Shibo Zhang ◽  
Yang Li ◽  
Sisi Li ◽  
Yongbo Wu ◽  
Jiang Zeng
Keyword(s):  
Nonlinear Model ◽  
Longitudinal Vibration ◽  
Ultrasonic Transducer ◽  
Linear Functions ◽  
Vibration Velocity ◽  
System Response ◽  
Nonlinear Phenomena ◽  
Amplitude Curve ◽  
Nonlinear Phenomenon ◽  
Physical Point

In the field of power ultrasound, Langevin ultrasonic transducers (LUTs) usually operate at a large displacements output power by applying high voltages. However, empirically, a LUT exhibits nonlinearities such as amplitude jumping and peak hysteresis for high voltages in actual operations. The nonlinearities would reduce the efficiency and output accuracy of an LUT. In this research, the burst-mode method was used to measure the longitudinal vibration velocity of the LUT, which gradually decreased with time after the excitation voltage was turned off. The equivalent mechanical losses and equivalent spring constants were determined using the velocity attenuation rate and resonant frequency and they were found to be the linear functions of velocity, helping to develop a novel nonlinear model. This model contained two quadratic nonlinear terms based on the linear model. Furthermore, the developed nonlinear model was analyzed using the Lagrangian method as well as the multiscale method, which confirmed that the model was effective in describing the nonlinear behavior. It was also found that the frequency-amplitude curve bent when the nonlinear term was taken into account, which resembled the nonlinear phenomenon tested experimentally. From a physical point of view, this bending was meaningful because it led to the formation of multi-valued response regions with jumping phenomena. Additionally, according to the obtained results, the maximum value of the system response was independent of the degree of nonlinearity of the system.

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