Numerical investigation on the oscillation performance of an acoustically suspended plate using flexural vibration

Near-field acoustic levitation (NFAL) technology holds significant promise for applications in the manufacturing processes of wafers and other delicate components, owing to its advantages such as compactness, environmental friendliness, and unlimited materials for suspended objects. NFAL relies on high-frequency vibrations to generate the squeeze film that suspends objects, which inherently leads to oscillations of the suspended objects. To date, no research has been conducted to predict the oscillation performance of a suspended object under a flexural radiator. The objective of this study is to address this challenge and thereby expand the application of NFAL in precision fields. First, the pressure and thickness distributions of the squeeze film at steady state are obtained by solving the governing equations using the finite difference method. Subsequently, the stiffness and damping coefficients of the squeeze film are computed by employing the infinitesimal perturbation method. Second, a predictive model for the oscillation displacement of suspended objects is developed based on the transfer function method. The numerical results show good agreement with measurements from the experimental setup constructed for this study. Finally, the results of the parametric study indicate that higher levitation accuracy is achieved with an increased weight of the reflector. Moreover, the influence of the radiator's vibration amplitude and air temperature on levitation accuracy is found to be limited within certain parameter ranges.