Dynamic coupling and experimental study on flexural transducer used in near field acoustic levitation

Abstract

Acoustic transducers with large radiation surfaces are used to handle planar object without any physical contact. To more accurately describe the dynamic performance of such transducer with strong coupling effect due to the large lateral scales, a mathematical model with flexural boundary conditions and gas inertia is presented in this paper. A coupled 3D finite element method model has been built and simulated with an identical experimental condition. The influences of dynamic coupling on the transducer performances and the levitation behaviors have been studied. We have found that under the strong dynamic coupling between the PZT and the large vibrator, the lowest impedance of the transducer shifts to the 2 nd resonant frequency, instead of locating at the 1 st resonant in a general case. Experiments have been set up to validate the coupling effects.Good agreement between the calculations and the experimental results indicates that the coupling plays an important role in the dynamic behaviors of the transducers with large lateral scales. Our work has improved the model's precision and provides an optimization tool to construct acoustic transducers used in the Near Field Acoustic Levitation.

Benefits of controlled inclination for contactless transport by squeeze-film levitation

“…Active feedback control of the excitation signal has been implemented to account for slight, unpredictable drifts of the natural frequency (Ilssar, Bucher, & Flashner, 2017). The drastic increase in the amplitude of oscillations near resonance magnifies substantially the repulsive levitation force (Li, Liu, & Ding, 2014; Matsuo, Koike, Nakamura, Ueha, & Hashimoto, 2000). The effective flexural amplitude can be improved by reducing the stiffness of the oscillator through careful selection of material(s) (Shi, An, Feng, Guo, & Liu, 2018; Wang & Au, 2013) and geometry (Stolarski, Gawarkiewicz, & Tesch, 2015).…”