Ozaki Ryotaro, Aoki Masashi, Yoshino Katsumi, Toda Kohji, Moritake Hiroshi
Department of Electrical and Electronic Engineering, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 Jun;81(6 Pt 1):061703. doi: 10.1103/PhysRevE.81.061703. Epub 2010 Jun 18.
We investigate the effective viscosity of a nematic-liquid-crystal (NLC) for viscosity measurement using a shear horizontal (SH) wave propagating through a glass substrate loaded with the NLC. The phase measurement of the SH wave determines the NLC viscosity because SH wave propagation depends on loaded material viscosity. Using this viscosity measurement, we can also determine the viscosity anisotropy of the NLC with director reorientation. In experiment, phase shifts are detected when voltages are applied to a NLC layer. The measured phases show an unpredictable shift which cannot be explained by conventional director angular dependence of viscosity. To analyze the phase shifts quantitatively, we introduce average effective viscosity for the viscosity measurement using SH wave. This effective viscosity is calculated considering the NLC director configuration and SH wave penetration into the NLC layer. The phase shifts calculated from the effective viscosity well agree with the measured phase shifts. The use of effective viscosity enables quantitative analysis for NLC viscosity measurement using the SH wave and also clarifies the mechanism of the unpredictable SH wave phase shift with director reorientation.
我们研究了向列型液晶（NLC）的有效粘度，通过使用在负载有NLC的玻璃基板中传播的水平剪切（SH）波来进行粘度测量。SH波的相位测量可确定NLC的粘度，因为SH波的传播取决于负载材料的粘度。利用这种粘度测量方法，我们还可以通过指向矢重新定向来确定NLC的粘度各向异性。在实验中，当向NLC层施加电压时会检测到相移。测量到的相位显示出不可预测的偏移，这无法用传统的粘度与指向矢角度的依赖关系来解释。为了定量分析相移，我们引入了用于SH波粘度测量的平均有效粘度。这种有效粘度是在考虑NLC指向矢构型和SH波穿透到NLC层的情况下计算得出的。由有效粘度计算出的相移与测量到的相移非常吻合。有效粘度的使用使得利用SH波对NLC粘度测量进行定量分析成为可能，并且还阐明了指向矢重新定向时SH波不可预测相移的机制。
