Tuesday, 12 October 2004 - 4:20 PM

This presentation is part of : Active Materials

What Can We Learn from Compressibility Experiments?

Lynn S. Bennethum, University of Colorado at Denver, University of Colorado at Denver, Department of Mathematics, Campus Box 170, P.O. Box 173364, Denver, CO 80217-3364

We examine typical experiments performed on soils (swelling and non-swelling) which can be performed on any liquid-solid porous material and relate them to thermodynamic quantities. Compressibility experiments typically take a porous material sample and control two of the following four parameters: electro-chemical potential of the liquid phase, pressure of the sample, volume of the sample, and volume of liquid leaving the porous sample. The other two variables are measured at equilibrium. In this talk the results of a thermodynamic analysis (with no constitutive assumptions) are presented assuming that the liquid phase is a function of an internal variable, the volume fraction. The results relate thermodynamic quantities (such as the compressibility of each phase and difference in the solid and liquid phase pressures) to what is practically measurable via compressibility experiments. Because minimal constitutive assumptions are assumed (the behavior of the liquid is a function of the volume fraction as well as other variables) the results apply to any isotropic liquid-solid porous material such as electro-active polymers.

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