M. Brodt et al., APPARATUS FOR MEASURING VISCOELASTIC PROPERTIES OVER 10 DECADES - REFINEMENTS, Review of scientific instruments, 66(11), 1995, pp. 5292-5297
This paper describes refinements to an instrument for determining the
viscoelastic properties of a solid material isothermally, with a singl
e apparatus, over 10 decades of time and frequency. Torque is applied
electromagnetically to a specimen fixed at one end. Specimen deformati
on is determined via a laser beam reflected from the other end upon a
split diode detector. Phase resolution is improved by the use of a loc
k-in amplifier at high frequency and by the use of Lissajous figures t
o measure phase, allowing the study of materials of moderate loss (0.0
08 less than or equal to tan delta less than or equal to 0.2) in addit
ion to materials with high loss (tan delta approximate to 1). The rigi
dity of the instrument is increased by modifications in the specimen s
upport geometry. The range of equivalent frequency for torsion is from
less than 10(-6) Hz to more than 10(4) Hz. Digital methods are incorp
orated in the creep measurements and in the phase measurements. (C) 19
95 American Institute of Physics.