Non-Newtonian viscous flow in glass

Abstract

The viscosity of a soda-lime silica glass was measured at high strain rates. The data show non-Newtonian viscous flow in this inorganic oxide glass with the viscosity values below the expected Newtonian value. Following the imposition of large, steady strain rates, the observed stress increases with time to a maximum and then decreases to a time-independent value. A comparison of the viscosity behavior of this glass with the molecular dynamics results in a ’’Lennard-Jones’’ glass shows a number of points of correspondence and suggests the interpretation of the non-Newtonian behavior as resulting from structural rearrangements in the material. The combined data show that the sustained, steady-state stress asymptotically approaches a maximum at very high strain rates. This limiting stress is interpreted as the actual cohesive strength of the material and is calculated to be 1.4×108N/m2 (20,000 psi) for the glass under study.