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Mechanics of liquid crystals and application to micro-actuators

液晶力学及其在微执行器中的应用

基本信息

批准号：
17360084
负责人：
CHONO Shigemi
金额：
$ 9.98万
依托单位：
Kochi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360084/
关键词：
Liquid Crystal Micro-Actuator Back Flow Molecular Orientation

项目摘要

When a liquid crystal is filled between two parallel plates and a voltage is applied to the liquid crystal with all molecules initially orienting parallel to the plates, the molecules except for wall vicinity rotate around their center of gravity and reorient to the direction perpendicular to the plates. As a result, a flow is induced between the plates. Application of this phenomenon leads to development of new actuators which have completely different mechanism from that in a past; that is, because a liquid crystal behaves like a liquid, the new actuators have some advantages such as simple mechanism, shape compatibility, easy downsizing, and low-voltage driving.In this study, we have studied the effect of applied voltage, gap of the plates, and twist and tilt angles on the induced velocity, flow rate, and shear stress acting on the plate. When the twist angle is 0 deg, the induced flow is planar, and when the twist angle is not 0 deg, on the other hand, the flow has an out of plane … More component. With increasing the applied voltage, the shear stress acting on the plate, the velocity, and the flow rate are increased and the response is improved. The effect of the gap of the plates is large, while the tilt angle has comparatively little effect.In addition, we have performed an experiment with using a cell device, in which the upper plate is kept movable, while the lower one is fixed. Furthermore, numerical simulation of motion of the upper plate has been done using the Leslie-Ericksen theory as a constitutive equation. Since the rotation of molecules on applying a voltage is opposite to the rotation when we release the voltage, the upper plate repeats forward and backward movements. However, the rotation speed on applying the voltage is larger, so that the upper plate resultantly moves forward. The maximum speed of the plate is 90 μ m/s at the frequency of the applied voltage of 100 Hz. Numerical predictions show the step-like movement, which is qualitatively agreed with the experiments. However, the predictions are larger than the experiments because in simulations we have ignored the friction between the upper plate and particles used for keeping the gap of the plates constant. Less

当液晶被填充在两个平行板之间，并且向液晶施加电压，并且所有分子最初取向平行于平板时，除了壁面附近的分子围绕其重心旋转，并重新定向到垂直于平板的方向。结果，在两块板之间产生了流动。这种现象的应用导致了与过去完全不同的机理的新驱动器的发展，即由于液晶的行为像液体，所以新的驱动器具有机制简单、形状兼容、易于缩小和低电压驱动等优点。在本研究中，我们研究了外加电压、板的间隙、扭转和倾斜角度对作用在板上的诱导速度、流量和剪应力的影响。当扭转角为0度时，诱导流为平面流动，而当扭转角不为0度时，流有平面外…更多的组成部分。随着外加电压的增加，作用在平板上的剪应力、速度和流量都增大，响应也随之改善。板间间隙的影响较大，倾角的影响相对较小。此外，我们还进行了电池装置的实验，在该装置中，上平板保持移动，而下平板固定。以Leslie-Ericksen理论为本构方程，对上板块的运动进行了数值模拟。由于施加电压时分子的旋转与我们释放电压时的旋转相反，因此上平板重复向前和向后移动。然而，施加电压时的转速较大，从而导致上极板向前移动。在外加电压为100HZ的频率下，极板的最大速度为90μm/S。数值预测显示了阶梯状的运动，这与实验定性地吻合。然而，由于在模拟中我们忽略了上平板与用于保持平板间隙恒定的颗粒之间的摩擦，所以预测比实验更大。较少