Dynamic rheometer
AssigneeCalifornia Institute of Technology
InventorNicholas W. Tschoegl
Life of this patent
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Abstract
The dynamic mechanical properties of polymeric materials can be measured either in uniaxial compression or in flexure as a function of frequency over a wide frequency as well as temperature range, by using a piezoelectric driver to apply a displacement to a sample and a piezoelectric pickup to pick up the forces transmitted through the sample together with electrical circuitry whereby the amplitude ratio and phase angle between drive and pickup signals may be read.
Claims9
A dynamic rheometer comprising:
- a support base,
- a piezoelectric transducer means supported on said support base,
- means for supporting a specimen to be tested on said piezoelectric transducer means,
- a force pickup transducer,
- means for supporting said force pickup transducer on top of said specimen to be tested for generating signals responsive to motion of said specimen,
- power means for driving said piezoelectric transducer means for causing compression deflections and flexure deflections to said specimen, and
- means for comparing the phase and amplitude of the signals applied by said power means to said piezoelectric transducer means and the signals generated by said force pickup means in response to compression and deflection of said specimen.
A system for measuring the dynamic mechanical properties of material in either compression or in flexure as a function of frequency comprising a dynamic rheometer including:
- a support base,
- a stack of piezoelectric discs mounted on said support base,
- means for supporting a specimen to be tested on said stack of piezoelectric discs,
- a cylindrical piezoelectric force pick up transducer,
- means for supporting said cylindrical piezoelectric force pick up transducer on said specimen to be tested, with its cylindrical axis normal to the plane established by said specimen to be tested,
- a source of signals having a desired frequency and amplitude,
- means for applying signals from said source to said stack of piezoelectric discs for applying flexure deflections and compression deflections to said specimen,
- means for measuring the phase angle and amplitude ratio between the signals applied to said stack of piezoelectric discs and signals generated by said cylindrical force pickup transducer responsive to deformations of said specimen, and
- means for applying signals from said source and from said cylindrical piezoelectric force pickup to said means for measuring.
Dependencies are inferred from the claim text.