A torsional creep instrument and a torsional pendulum, both with accurate temperature control
article
This paper describes a torsional pendulum and a torsional creep instrument. With the pendulum shear moduli between 10^6 and 10^10 N/m^2 can be measured at frequencies from 0.1 to 20 Hz. The creep instrument is suitable for measurement of shear compliances lower than 10^−7 m^2/N in the time range from 1 to 10^5 seconds. In both instruments, specimens are kept at the right temperature by blowing heated nitrogen gas through a surrounding thermostatic chamber. The signal of a platinum resistance thermometer, provided in each chamber, automatically controls the heating of the gas. Temperatures from −180 to +300 °C can be maintained with an absolute accuracy of ±1 °C and a long term stability of ±0.05 °C. It is shown that one cannot directly compare one and the same shear property, calculated from the shear modulus as measured with the pendulum as well as from the shear compliance as measured with the creep instrument. This is due to differences in the temperature of one thermostatic chamber over against the other. Finally, the paper presents a method to reduce these differences to ±0.1 °C, although the absolute accuracy of temperature control remains ±1 °C.
TNO Identifier
283151
Source
Rheologica acta, 8(2), pp. 130-133.
Pages
130-133
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