An ultrasonic levitation journal bearing able to control spindle center position

Zhao, Su; Mojrzisch, Sebastian; Wallaschek, Jörg

doi:10.1016/j.ymssp.2012.05.006

Cited by 63 publications

(26 citation statements)

References 28 publications

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“…The relation between average levitation gap u − u 0 and vibration amplitude does not seem to follow a linear relationship as predicted when squeeze film theory is applied to a flat, rigid plate (30,32). One possible explanation is that the interfacial separation is strongly affected by the dynamics of the fingertip.…”

Section: Resultsmentioning

confidence: 76%

“…For smooth planar objects, stable levitation can occur when the acoustic radiation pressure balances the weight (29,30). For levitation distances significantly smaller than the wavelength of sound (i.e., by at least three orders of magnitude), the behavior becomes dominated by the elasticity and viscosity of the fluid trapped between the actuator and the reflector surface (31,32). This trapped fluid is known as a squeeze film.…”

Section: Significancementioning

confidence: 99%

See 1 more Smart Citation

Partial squeeze film levitation modulates fingertip friction

Wiertlewski

Friesen

Colgate

2016

Proc. Natl. Acad. Sci. U.S.A.

119

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When touched, a glass plate excited with ultrasonic transverse waves feels notably more slippery than it does at rest. To study this phenomenon, we use frustrated total internal reflection to image the asperities of the skin that are in intimate contact with a glass plate. We observed that the load at the interface is shared between the elastic compression of the asperities of the skin and a squeeze film of air. Stroboscopic investigation reveals that the time evolution of the interfacial gap is partially out of phase with the plate vibration. Taken together, these results suggest that the skin bounces against the vibrating plate but that the bounces are cushioned by a squeeze film of air that does not have time to escape the interfacial separation. This behavior results in dynamic levitation, in which the average number of asperities in intimate contact is reduced, thereby reducing friction. This improved understanding of the physics of friction reduction provides key guidelines for designing interfaces that can dynamically modulate friction with soft materials and biological tissues, such as human fingertips.acoustic | squeeze film | biotribology | roughness | haptics H olding a glass of wine, searching for keys in one's pockets, and assessing the quality of fabric are everyday tasks that involve precise and unambiguous perception of the friction between the skin and the environment. The somatosensory and motor control systems integrate multiple neural signals to determine the state of adhesion of the surface in contact with the skin, thus enabling perception (1-3) and in the context of grasp, ensuring that slippage is under control (4-6). Considering the central role of fingertip-surface friction in both manipulation and tactile perception, it is not surprising that many technologies attempt to control this effect to produce artificial and programmable tactile sensations (7-9). The use of transverse ultrasonic vibrations to reduce tactile friction (10) has proven to be a strong candidate for surface haptic displays that might be integrated with the ubiquitous touchscreen interface (11-13). A typical architecture consists of a glass plate-which may be placed in front of a graphical display-with piezoelectric actuators glued along one edge and used to excite a 0 × n flexural resonance. The resonant frequency may be ∼30 kHz and the peak to peak vibration amplitude may be up to 5 μm at the antinodes. A finger placed on the plate experiences markedly reduced friction as the vibration amplitude is increased as shown in Movie S1.A full understanding of the physical principle behind friction reduction has proven elusive. Two leading hypotheses have been put forward. The first hypothesis stems from an application of Reynolds' lubrication theory to the thin film of air between the fingertip and vibrating plate. The vibrations lead to time-averaged compression of the air, thereby creating an overpressure that levitates the skin. The second hypothesis postulates that the skin does not stay in close contact with the surfa...

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Section: Resultsmentioning

confidence: 76%

Section: Significancementioning

confidence: 99%

Partial squeeze film levitation modulates fingertip friction

Wiertlewski

Friesen

Colgate

2016

Proc. Natl. Acad. Sci. U.S.A.

119

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“…A steel spindle with a diameter of 50 mm had been successfully levitated and driven at low rotational speed. Each of the three ultrasonic transducers can provide a load carrying force up to 51 N at an input power of 50 W [24,25]. Zhigang Yang et al focused the study on supporting patterns of ultrasonic bearings and successfully developed ultrasonic thrust bearings, bidirectional supported ultrasonic bearings and hybrid-levitation bearings integrating ultrasonic levitation into gas bearings [26][27][28].…”

Section: Structure and Operating Principlementioning

confidence: 99%

A Novel Noncontact Ultrasonic Levitating Bearing Excited by Piezoelectric Ceramics

Quan

Deng

et al. 2016

Applied Sciences

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A novel ultrasonic levitating bearing excited by three piezoelectric transducers is presented in this work. The transducers are circumferentially equispaced in a housing, with their center lines going through the rotation center of a spindle. This noncontact bearing has the ability to self-align and carry radical and axial loads simultaneously. A finite element model of the bearing is built in ANSYS, and modal analysis and harmonious response analysis are conducted to investigate its characteristics and driving parameters. Based on nonlinear acoustic theory and a thermodynamic theory of ideal gas, the radical and lateral load-carrying models are built to predict the bearing's carrying capacity. In order to validate the bearing's levitation force, a test system is established and levitating experiments are conducted. The experimental data match well with the theoretical results. The experiments reveal that the maximum radical and axial levitating loads of the proposed bearing are about 15 N and 6 N, respectively, when the piezoelectric transducers operate at a working frequency of 16.11 kHz and a voltage of 150 V p-p .

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“…(37), (38) represent the slow dynamics of an acoustically levitated object under the enforced fast oscillations indicated by (3). The former is a nonlinear ordinary differential equation in terms of the slow evolution of the levitated object, which is a function of the initial conditions and the fast driving excitation.…”

Section: Adding the Effect Of Energy Loss And Dampingmentioning

confidence: 99%