Low–frequency acoustic waves in nematic elastomers

Abstract

We study the spectral and polarization properties of acoustic waves propagating in nematic liquid-crystalline rubber materials. We apply the viscoelastic theory of nematic elastomers in the low-frequency (hydrodynamic) limit. Dynamic soft elasticity, exhibited by ideal nematic elastomers under certain geometries of shear at low frequencies, leads to anomalous anisotropy of energy transfer and attenuation of transverse waves. The results suggest an application of this class of materials as an acoustic polarizer medium.

Supersonic rupture of rubber

“…However, the frequency dependence of sound attenuation does not resemble experiment any better after inclusion of c 1 . Thus I will simply continue to use the simplest form of Kelvin dissipation, as it is familiar and conventional (Fradkin et al, 2003) and take the dimensionless measure of dissipation,b ¼ bc=a to be of order unity. Fortunately, none of the final results depend much on the value ofb.…”

Edge waves and resonance on elastic structures: An overview

“…A nematic material is a rubber like liquid crystalline elastomer possessing strong anisotropy in both elastic and viscous properties, together with some additional freedom caused by long polymer chains and molecules. Such media can be analysed using an approximate linear low frequency model[64].…”

Transmission of Elastic Waves in Anisotropic Nematic Elastomers

“…The equations of motion of a viscous nematic solid after neglecting the effects of Frank elasticity on the director gradient [16] are…”

“…Fradkin et al [16] studied the visco-elastic theory of nematic elastomers in the lowfrequency limit, which was used to investigate the spectral and polarization properties of acoustic waves propagating in liquid-crystalline nematic elastomers. Gebretsadkan and Kalra [17] investigated the propagation of linear waves in relativistic anisotropic magneto-hydrodynamics, and plotted a Fresnel ray surface.…”