Theoretical Study for Deformation Kinetics of Glassy Solid Helium within Cylindrical Microtubes

TL;DR

This theoretical study models the deformation kinetics of glassy solid helium in microtubes at very low temperatures, revealing near frictionless flow conditions influenced by surface roughness and slip effects.

Contribution

It introduces a transition-rate model considering shear thinning and boundary perturbation to analyze deformation kinetics in confined glassy helium at low temperatures.

Findings

Shear stress approaches zero at high shear rates in microtubes.

Surface roughness and slip significantly affect deformation kinetics.

Results show qualitative similarity with experimental observations by Ray and Hallock.

Abstract

The deformation kinetics for glassy solid helium confined in microscopic domain at very low temperature regime was investigated using a transition-rate model considering the shear thinning behavior which means, once material being subjected to high shear rates, the viscosity diminishes with increasing shear rate. The preliminary results show that there might be nearly frictionless fields for rate of deformation due to the almost vanishing shear stress in microtubes at very low temperature regime subjected to some surface conditions : The relatively larger roughness (compared to the macroscopic domain) inside microtubes and the slip. As the pore size decreases, the surface-to-volume ratio increases and therefore, surface roughness will greatly affect the deformation kinetics in microtubes. By using the boundary perturbation method, we obtained a class of temperature and activation energy dependent fields for the deformation kinetics at low temperature regime with the presumed small wavy roughness distributed along the walls of an cylindrical microtube. The critical deformation kinetics of the glassy matter is dependent upon the temperature, activation energy, activation volume, orientation dependent and is proportional to the (referenced) shear rate, the slip length, the amplitude and the orientation of the wavy-roughness. Finally, we also discuss the quantitative similarity between our results with Ray and Hallock [Phys. Rev. Lett. {\bf 100}, 235301 (2008)].