Grosso M, Crescitelli S, Somma E, Vermant J, Moldenaers P, Maffettone P L
Dipartimento di Ingegneria Chimica, Universitá Federico II di Napoli, Piazzale Tecchio 80, I-80125, Napoli, Italia.
Phys Rev Lett. 2003 Mar 7;90(9):098304. doi: 10.1103/PhysRevLett.90.098304. Epub 2003 Mar 5.
Experimental observations of sustained oscillations of both shear stress and first normal stress differences are reported in flowing liquid crystalline polymers in a limited range of shear rates. The results can be described by considering the response of a rigid-rod model. Depending on the initial conditions, the frequency spectrum of the stress signal contains either one or two characteristic frequencies. This can be explained by the occurrence of either pure "wagging" or the coexistence of wagging and "log-rolling" behavior of the director.
在有限的剪切速率范围内，对流动的液晶聚合物中剪切应力和第一法向应力差的持续振荡进行了实验观察。通过考虑刚性杆模型的响应可以描述这些结果。根据初始条件，应力信号的频谱包含一个或两个特征频率。这可以通过指向矢的纯“摆动”或摆动与“滚动”行为的共存来解释。
