Next Article in Journal
A Novel Button-Type Micro Direct Methanol Fuel Cell with Graphene Diffusion Layer
Previous Article in Journal
3D-Printed Soft Structure of Polyurethane and Magnetorheological Fluid: A Proof-of-Concept Investigation of its Stiffness Tunability
Open AccessArticle

Combined Effect of Rarefaction and Effective Viscosity on Micro-Elasto-Aerodynamic Lubrication Performance of Gas Microbearings

by Yao Wu 1,2,3, Lihua Yang 1,2,3,*, Tengfei Xu 1,2,3 and Haoliang Xu 1,2,3
1
State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an 710049, China
2
Shaanxi Key Laboratory of Environment and Control for Flight Vehicle, School of Aerospace, Xi’an Jiaotong University, Xi’an 710049, China
3
School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an 710049, China
*
Author to whom correspondence should be addressed.
Micromachines 2019, 10(10), 657; https://doi.org/10.3390/mi10100657
Received: 13 August 2019 / Revised: 25 September 2019 / Accepted: 25 September 2019 / Published: 29 September 2019
Elastic deformation and gaseous rarefaction effects are of great importance to the static and dynamic characteristics of gas microbearings. Based on the effective viscosity model of Veijola, the governing equations can be solved by the partial derivative method, finite element procedure, and relaxed iterative algorithm. The numerical results showed that the maximum gas pressure is relatively lower compared to a microbearing with a rigid liner at a local pressure peak region, owing to the film thickness of two converging-diverging profiles and the existence of bimodal pressure inside the elastic microbearing liner. However, the effect of bearing flexibility provides a marginal increase in the load capacity on account of the integral area of pressure distribution is larger than the rigid bearing liner. The friction coefficient and direct stiffness coefficients increase as the elastic modulus decreases while the direct damping coefficients become smaller at high eccentricity ratios and bearing numbers. Since the Poiseuille flow rate increases in connection with an increasing Knudsen number, the effective viscosity of the lubricant leads to a decreased load carrying capacity, friction coefficient, and direct stiffness coefficient, which produces an increase in the direct damping coefficients. View Full-Text
Keywords: gas rarefaction; micro-elasto-aerodynamic lubrication; compliance matrix; effective viscosity; bearing characteristics gas rarefaction; micro-elasto-aerodynamic lubrication; compliance matrix; effective viscosity; bearing characteristics
Show Figures

Figure 1

MDPI and ACS Style

Wu, Y.; Yang, L.; Xu, T.; Xu, H. Combined Effect of Rarefaction and Effective Viscosity on Micro-Elasto-Aerodynamic Lubrication Performance of Gas Microbearings. Micromachines 2019, 10, 657.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop