Abstract
The performance of a system consisting of a thin rectangular plate under plane stress due to the action of PZT actuators, thus subjected to the Poisson’s contraction effect, and a light circular object freely floating over it was studied both numerically and experimentally. The results show that performance of the system is influenced by a few factors, including the magnitude of elastic deformation of the plate and the electrostatic action of the PZTs attached to the plate, which combine to form oscillating dimples created by the Poisson’s effect to separate the object from the plate with a film of compressible fluid. The importance of operating frequency of PZTs, shape and size of the dimple, offset and amplitude voltage under which PZTs operate, and distribution of PZTs on the plate’s surface were all examined theoretically and verified experimentally. The plate was made of aluminium and stainless steel in order to find out the importance of the material’s energy absorption rate for the effectiveness of squeeze-film induced levitation. The agreement between theoretical models and experimental measurements proved to be quite satisfactory.
Highlights
Frictionless or non-contact transportation is essential for manufacturing ultra-precision products in microfabrication and nanotechnology, for example, silicon wafers and integrated circuits, where tiny flaws, infinitesimal scratches and contamination must be avoided
The literature review reveals that levitation comprises three main categories, namely: Standing Wave Levitation (SWL), Near-Field Acoustic Levitation (NFAL) and Squeeze film levitation (SFL)
In a near-field acoustic levitation (NFAL) system, there is no need for the reflector as it is represented by the floating item itself
Summary
Frictionless or non-contact transportation is essential for manufacturing ultra-precision products in microfabrication and nanotechnology, for example, silicon wafers and integrated circuits, where tiny flaws, infinitesimal scratches and contamination must be avoided Techniques such as air–bed flotation and magnetic levitation, have been utilised for frictionless, non-contact production–line transportation. Squeeze-film levitation (SFL) relies on a similar working principle to NFAL, occurring when the object to be floated is located adjacent to a vibrating structure. It is the viscosity and compressibility of a thin film of air (squeeze-film) that is trapped between the two surfaces (vibrating surface and floating object) that is the basis of SFL rather than sound pressure. While there is some similarity between NFAL and SFL, they differ as mentioned above and this paper is concerned with the SFL effect
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