NFAL Prototype Design and Feasibility Analysis for Self-Levitated Conveying

Abstract

：In order to avoid friction and scratching when conveying objects, a squeeze-film levitation prototype was designed to verify the feasibility. The modal shapes and the forced harmonic shapes of the prototype are obtained by an ANSYS coupled field computation with a ¼ symmetry model and the levitation capacity was assessed by the use of groups of simulation and physical testing. The simulation results show that the pure flexural and mixed flexural wave shapes with different wave number exist at specific frequencies. The amplitude of the central point of an aluminium plate having four piezo-electric discs glued to the bottom surface was simulated for a frequency spectrum. The experimental results confirm the theoretical results and the feasibility of the prototype, and also confirm that objects can be floated at several resonant frequencies under forced vibration conditions. The system provides the largest levitating capacity when both the piezo-electric disc and the plate resonances coincide.

Acoustic Journal Bearing With Changeable Geometry and Built-in Flexibility

“…The subsequent studies by Ilssar et al [15] improved efficiency of the levitation process and contributed to increasing accuracy required by high precision positioning in micro fabrication. Chang et al [16] constructed a device containing a plate subjected to vibration produced by round type PZTs attached to it. They demonstrated that modal shapes together with harmonic shapes play an important role in resulting levitation parameters.…”

Influence of design embodiment on the performance of squeeze-film levitation contacts

“…Investigation of an NFAL-based device consisting of a vibrating plate excited by round piezoelectric actuators attached to the underside of the plate is described in Chang et al. 17 It was found that plate modal and forced harmonic shapes were important determinants of levitation characteristics.…”

Tangential motion mechanism and reverse hydrodynamic effects of acoustic platform with nonparallel squeeze film

“…Accompanied by the development of acoustic squeeze film theory, various kinds of prototypes and experiments are also gradually updated. In general, summarizing from the experiments, the main driving modes included standing 9,12,14 and traveling waves; 5,15,16 the movement modes included straight and rotation; the driving units included a compact piezoelectric actuator and transducer with horn.…”