Thickness Control of Liquid Crystal Film in a Step Bearing by Electric Field Under Dynamic Loading Condition

Tribology ◽  
2005 ◽  
Author(s):  
Yoshiki Matsumura ◽  
Toshihiko Shiraishi ◽  
Shin Morishita
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Pid Controller ◽  
Molecular Orientation ◽  
Organic Liquid ◽  
Orientational Order ◽  
Earthquake Excitation ◽  
Crystal Film ◽  
Dynamic Loading Condition ◽  
Viscosity Variation

This paper describes the viscosity variation of a liquid crystal under electric field, and its application to a controllable step bearing. Liquid crystal is known as a homogeneous organic liquid characterized by the long-range order of its molecular orientation. When an electric field is applied to a liquid crystal film as lubricant, the orientational order of molecules becomes parallel to the applied field, which causes apparent viscosity variation. In this paper, a controllable step bearing system was constructed and its dynamic characteristics were studied. When a step load, sinusoidal or earthquake excitation was applied to the bearing pad, the film thickness was successfully controlled to the appointed value by a conventional PID controller. The response frequency was also studied in the experiment.

Development of an Electrically Controllable Damper Using a Liquid Crystal

1996 ◽  
Vol 118 (3) ◽  
pp. 510-515 ◽  
Author(s):  
S. Morishita
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Molecular Orientation ◽  
Nematic Phase ◽  
Organic Liquid ◽  
Working Fluid ◽  
Damping Force ◽  
Electric Voltage ◽  
Electroviscous Effect ◽  
Display Devices

This paper describes a new electrically controllable damper that uses a liquid crystal (LC) as the working fluid. LC is a homogeneous organic liquid characterized by the long-range order of its molecular orientation. The sample LC used in this work is a thermotropic, low molecular-weight LC which appears in the nematic phase, and was originally developed for display devices. The molecular orientation of the nematic phase is characterized by slender ellipsoidal shape molecules, the main axis of which can be controlled by applying an electric or magnetic field. When an electric field is applied to a LC, the orientation order of the molecules becomes parallel to the applied electric field, causing the apparent viscosity to increase. This phenomenon is known as the electroviscous effect. To study the application of the electroviscous effect of a LC to a controllable mechanical damping device, a prototype controllable damper was constructed and its performance was examined. In this damper, a piston, equipped with several concentric cylindrical electrodes attached to the piston rod, moves in the liquid crystal. During the reciprocal movement of the electrodes, LC flow through the electrodes is controlled by applying electric voltage to the latter. Damper performance was investigated under various DC electric field strengths, piston oscillation amplitudes and frequencies. The results show that the controllable damping force was three times larger with the application of an electric field than that without, and that the range of force variation was kept at the same level regardless of the frequency and amplitude of piston motion.

Pressure-induced insulator–conductor transition in a photoconducting organic liquid-crystal film

Nature ◽  
2002 ◽  
Vol 418 (6894) ◽  
pp. 162-164 ◽  
Author(s):  
Chong-yang Liu ◽  
Allen J. Bard
Keyword(s):  
Liquid Crystal ◽  
Organic Liquid ◽  
Crystal Film

The orientational behaviour of dichlorobenzenes in nematic liquid crystal solvents

1989 ◽  
Vol 67 (1) ◽  
pp. 54-59 ◽  
Author(s):  
C. T. Yim ◽  
D. F. R. Gilson
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Potential Energy ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Short Range ◽  
Orientational Order ◽  
Energy Parameters ◽  
Average Electric Field ◽  
Shape And Size

The orientational order parameters of ortho-, meta-, and para-dichlorobenzene, dissolved in the nematic solvents EBBA and 1132, have been measured as functions of temperature and concentration, and used to determine the values of the potential energy parameters for each solute–solvent pair. These potentials have been interpreted in terms of a short-range contribution, which depends upon the shape and size of the solute molecule, plus a long-range term due to the interaction between the average electric field gradient from the solvent and the molecular quadrupole moment of the solute. Keywords: dichlorobenzenes, nematic solvents, liquid crystals, orientation, potential energy parameters.

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