Slip model for the ultra-thin gas-lubricated slider bearings of an electrostatic micromotor in MEMS

Abstract

A new slip model derived by molecular dynamics has been used to investigate the ultra-thin gaslubricated slider bearings beneath the three bushings of an electrostatic micromotor in micro-electro-mechanical systems (MEMS). Modified Reynolds equation is proposed based on the modified slip model. Analytical solutions for flow rate, pressure distribution, load carrying capacity and streamwise location using the modified Reynolds equation are obtained and compared with the results gained from those in the literature. It demonstrates that the new secondorder slip model is of greater accuracy than that predicted by the first-order, second-order slip models and MMGL model and produces a good approximation to variable hard sphere (VHS) and variable soft sphere (VSS) models, which agree well with the solution obtained from the linearized Boltzmann equation. It is indicated that the slip effect reduces the pressure distribution and load carrying capacity, and shifts the streamwise location of the load carrying capacity, which should not be ignored to study the step-shaped slider bearings in micromotors for MEMS devices.

Dynamic characteristics of rotor system and rub-impact fault feature research based on casing acceleration

“…Sinou [10] researches the non-linear dynamic characteristics of a flexible rotor excited due to unbalance force and supported by ball bearings, detecting that the nth Fourier components are important when the rotor passes through the 1/n sub-critical resonances and critical speeds. Zhang and Meng [11][12][13][14][15] conduct a variety of researches on the non-linear Micro-Electro Mechanical Systems (MEMS), such as stability, bifurcation and chaos. Meanwhile, a set number of specific researches on the effects of several non-linear variables to rotor systems are also carried out.…”

Experimental validation of impact energy model for the rub–impact assessment in a rotor system

“…Zhang et al [7] analyzed the rub-impact fault caused by geometric asymmetry between the rotor and stator, and discussed the grazing phenomenon of the single point rubbing in detail. Zhang and Meng [8][9][10][11][12][13][14][15][16] give a series of researches on the nonlinear Micro-Electro Mechanical Systems (MEMS), including stability, bifurcation and chaos. Also they do a number of detail researches on the influence of several nonlinear parameters to rotor systems.…”

An energy analyzing method for the assessment and diagnosis of rub–impact fault in a rotor system

“…Zhang et al (1998) analyzed the rub–impact fault caused by geometric asymmetry between the rotor and stator, and studied the grazing phenomenon of the single point rubbing in detail. Zhang, Meng and coworkers (Meng et al, 2009; Zhang and Meng, 2005, 2006a, 2006b, 2009; Zhang et al, 2005, 2008a, 2008b, 2009) have published a series of research on the nonlinear micro-electro-mechanical systems (MEMSs), including stability, bifurcation and chaos. Also they presented a variety of detailed research on the influence of several nonlinear parameters on the rotor system.…”