Apparatus for measuring viscoelastic properties over ten decades: Refinements

M. Brodt, L. S. Cook, R. S. Lakes
1995 Review of Scientific Instruments  
This article describes refinements to an instrument for determining the viscoelastic properties of a solid material isothermally, with a single apparatus, over 10 decades of time and frequency. Torque is applied electromagnetically to a specimen fixed at one end. Specimen deformation 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 lock in amplifier at high frequency and by the use of Lissajous figures to
more » ... e phase, allowing study of materials of moderate loss (0.008 ≤ tan δ ≤ 0.2) in addition to materials with high loss (tan δ ≈ 1). The rigidity of the instrument is increased by modifications in the specimen support geometry. The range of equivalent frequency for torsion is from less than 10 -6 Hz to more than 10 4 Hz. Digital methods are incorporated in the creep measurements and in phase measurements.
doi:10.1063/1.1146101 fatcat:itg5nvd2gjblbajewda2trahli