Abstract : In order to test the fluctuation-dissipation relation on rheological properties of soft materials, we built an experiment to measure thermally excited strain in a sample and compare it to the classical response to an external stress. The rheometer is based on a cylindrical Couette geometry. We use differential interferometry to achieve better than 10(-10) rad/rootHz sensitivity in angular position above 0.5 Hz. The forcing method, based on electrostatic interaction in a capacitor, generates torques comparable to that of thermal noise. Experiments on a calibrated silicon oil show good agreement between response and fluctuation measurements.
https://hal-ens-lyon.archives-ouvertes.fr/ensl-00179779
Contributor : Ludovic Bellon
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Submitted on : Tuesday, October 16, 2007 - 4:07:37 PM
Last modification on : Wednesday, November 20, 2019 - 8:18:32 AM
Ludovic Bellon, Lionel Buisson, Sergio Ciliberto, Franck Vittoz. Zero applied stress rheometer. Review of Scientific Instruments, American Institute of Physics, 2002, pp.3286-3290. ⟨10.1063/1.1499210⟩. ⟨ensl-00179779⟩
