Study of squeeze film damping characteristics in damper of linear rolling guide

2015 ◽  
pp. 343-348
Keyword(s):  
Squeeze Film ◽  
Damping Characteristics ◽  
Squeeze Film Damping ◽  
Rolling Guide

Effect of random surface roughness on squeeze film damping characteristics in damper of linear rolling guide with a fractal-based method

2015 ◽  
Vol 67 (6) ◽  
pp. 549-556 ◽  
Author(s):  
Linlin Li ◽  
Jiajun Yang ◽  
Wenwei Liu
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Squeeze Film ◽  
Roughness Effect ◽  
Random Surface ◽  
Content Type ◽  
Damping Characteristics ◽  
Squeeze Film Damping ◽  
Rolling Guide ◽  
Effect Of Surface

Purpose – The purpose of this paper is to explore the effect of surface roughness characterized by fractal geometry on squeeze film damping characteristics in damper of the linear rolling guide, which has not been studied so far. Design/methodology/approach – The stochastic model of film thickness between rail and damper is established by using the two-variable Weierstrass–Mandelbrot function defining multi-scale and self-affinity properties of the rough surface topography. The stochastically averaged Reynolds equation is solved by using the variables separation method to further derive the film pressure distribution, the damping coefficient, the damping force and squeeze film time. The effect of surface roughness on squeeze film damping characteristics of the damper is analyzed and discussed through simulation. Findings – By comparing cases of the rough surface for different fractal parameters and the smooth surface, it is shown that for the isotropic roughness structure, the presence of surface roughness of the damper decreases the squeeze film damping characteristics. It is found that roughness effect on the damping coefficient is associated with the film thickness. In addition, the vibration amplitude effect is negligible for the damper of the linear rolling guide. Originality/value – To investigate the random surface roughness effect, the rough surface topography of damper of the linear rolling guide is characterized by using the fractal method instead of the traditional mathematical statistics method.

The Squeeze Film Damping Effect on Dynamic Responses of Micro-Electromechanical Resonators

2013 ◽  
Vol 284-287 ◽  
pp. 1961-1965 ◽  
Author(s):  
Shih Chieh Sun ◽  
Chi Wei Chung ◽  
Chao Ming Hsu ◽  
Jao Hwa Kuang
Keyword(s):  
Dynamic Responses ◽  
Squeeze Film ◽  
Assumed Mode Method ◽  
Damping Effect ◽  
Lagrange’S Equation ◽  
Damping Characteristics ◽  
Squeeze Film Damping ◽  
Mode Method ◽  
Eigen Solutions ◽  
Assumed Mode

The air squeeze film damping effect on the dynamic responses of clamped micro- electromechanical resonators is investigated in this study. A dynamic model for a clamped micro- electromechanical resonator with the damping consideration is derived using Lagrange’s equation. The corresponding resonator eigen solutions are formulated and solved by employing the assumed-mode method. The effect of different parameters; i.e. the resonator size, ambient temperature and pressure on the squeeze film damping characteristics were simulated and investigated. The results indicate that the squeeze film damping effect may significantly affect the dynamic responses of micro-scale electromechanical resonator.

Coupled effects of surface interaction and damping on electromechanical stability of functionally graded nanotubes reinforced torsional micromirror actuator

2021 ◽  
pp. 030932472110368
Author(s):  
Weidong Yang ◽  
Menglong Liu ◽  
Linwei Ying ◽  
Xi Wang
Keyword(s):  
Casimir Force ◽  
Volume Fraction ◽  
Nonlocal Parameter ◽  
Saddle Points ◽  
Functionally Graded ◽  
Heteroclinic Orbits ◽  
Phase Portraits ◽  
Squeeze Film ◽  
Squeeze Film Damping ◽  
Tilting Angle

This paper demonstrated the coupled surface effects of thermal Casimir force and squeeze film damping (SFD) on size-dependent electromechanical stability and bifurcation of torsion micromirror actuator. The governing equations of micromirror system are derived, and the pull-in voltage and critical tilting angle are obtained. Also, the twisting deformation of torsion nanobeam can be tuned by functionally graded carbon nanotubes reinforced composites (FG-CNTRC). A finite element analysis (FEA) model is established on the COMSOL Multiphysics platform, and the simulation of the effect of thermal Casimir force on pull-in instability is utilized to verify the present analytical model. The results indicate that the numerical results well agree with the theoretical results in this work and experimental data in the literature. Further, the influences of volume fraction and geometrical distribution of CNTs, thermal Casimir force, nonlocal parameter, and squeeze film damping on electrically actuated instability and free-standing behavior are detailedly discussed. Besides, the evolution of equilibrium states of micromirror system is investigated, and bifurcation diagrams and phase portraits including the periodic, homoclinic, and heteroclinic orbits are described as well. The results demonstrated that the amplitude of the tilting angle for FGX-CNTRC type micromirror attenuates slower than for FGO-CNTRC type, and the increment of CNTs volume ratio slows down the attenuation due to the stiffening effect. When considering squeeze film damping, the stable center point evolves into one focus point with homoclinic orbits, and the dynamic system maintains two unstable saddle points with the heteroclinic orbits due to the effect of thermal Casimir force.

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