Lawrence Berkeley National Laboratory
United States. Department of Energy. Office of Basic Energy Sciences.
The effective thermal expansion coefficient beta* of abinary viscoelastic composite is shown to be frequency dependent even ifthe thermal expansion coefficients beta A and beta B of both constituentsare themselves frequency independent. Exact calculations for binaryviscoelastic systems show that beta* is related to constituent valuesbeta A, beta B, volume fractions, and bulk moduli KA, KB, as well as tothe overall bulk modulus K* of the composite system. Then, beta* isdetermined for isotropic systems by first bounding (or measuring) K* andtherefore beta*. For anisotropic systems with hexagonal symmetry, theprincipal values of the thermal expansion beta*perp and beta*para can bedetermined exactly when the constituents form a layered system. In allthe examples studied, it is shown explicitly that the eigenvectors of thethermoviscoelastic system possess non-negative dissipation -- despite thecomplicated analytical behavior of the frequency dependent thermalexpansivities themselves. Methods presented have a variety ofapplications from fluid-fluid mixtures to fluid-solid suspensions, andfrom fluid-saturated porous media to viscoelastic solid-solidcomposites.
ark: ark:/67531/metadc901856
Symmetry
Composites Thermal Expansion Viscoelasticity
osti: 932704
Journal Name: Mechanics of Materials; Journal Volume: 0; Journal Issue: 0; Related Information: Journal Publication Date: 0
2007-12-01
Mixtures
Frequency dependent thermal expansion in binary viscoelasticcomposites
Berryman, James G.
Eigenvectors
rep-no: LBNL--63655
grantno: DE-AC02-05CH11231
54
Thermal Expansion Composites Thermal Expansion Viscoelasticity