Dynamic tensile strength of glycerol

Abstract

By use of a tensile stress wave 0.1 to 0.4 μsec in duration, generated by pulsed electron−beam energy deposition, the dynamic tensile strength (TS) of glycerol was determined in the 220−350 K temperature range. The TS curve is clearly divided into high− and low−temperature segments at about 262 K. Above this temperature, the TS decreases uniformly from 250 MPa (2.5 kbar) to 34 MPa at 350 K and failure appears to occur by void nucleation and growth. The experimental results are explained by a theory of homogeneous bubble nucleation which takes into account the non−steady−state nature of the experiment. Below the transition temperature, the TS is constant at about 250 MPa and failure is believed to occur by crack nucleation and growth.

Dynamic tensile strength of silicone oils

“…The rate of homogeneous void nucleation is only weakly related to liquid viscosity [8]. It is only when the relaxation time needed to reach a steady void nucleation rate is comparable to the timescale of the experiment that viscosity affects the void nucleation rate [8].…”

“…Also shown in Figure 2b are previously published data sets for spall experiments performed on water [21] and glycerol [22,10,8]. Glycerol data has been included for comparison because it has a viscosity of 1.4 Pa s at room temperature and is therefore the closest widely studied analog to the viscous silicone oils used in this work.…”

“…They observed that the spall strength in hexane had a very weak dependence on strain rate, while the spall strength of the more viscous glycerol increased by a factor of 2.5 over a strain rate of 1.5 × 10 4 to 2.0 × 10 5 s −1 . Both Carlson and Utkin attributed the variation in the spall strength observed in their experiments to the effect of viscosity and strain rate on homogeneous nucleation [8,12]. They claimed that for nearly pure liquids placed in tension at sufficiently high strain rates, the dominant cavitation mechanism was that of homogeneous void nucleation [8,12].…”

“…These cavities may nucleate from random molecular fluctuations [5,6] (homogeneous nucleation) or from pre-existing cavities: including free bubbles or bubbles located on impurities within the liquid [7] (heterogeneous nucleation). At low strain rates or in contaminated liquids, heterogeneous nucleation is likely to dominate void formation and growth, however for pure liquids undergoing dynamic stretching within the bulk liquid, homogeneous nucleation may play a significant role in the cavitation process [8].…”

“…Carlson used an electron beam to perform spall experiments on glycerol at a wide range of temperatures (491 to 623 K), over which the liquid exhibits a five order of magnitude variation in viscosity [8]. Carlson noted a factor of eight decrease in spall strength as temperature was increased.…”