Munro, Effective Medium Theory of the Porosity Dependence of Bulk Moduli
The article presented a new technique to monitor shear and bulk moduli of rubber for FEA.
* Current relaxation methods in the rubber industry are compressive, whereas finite element codes require decay in shear and bulk moduli;
where [micro] and K are the shear and bulk moduli for the composite, [phi] is the volume fraction, [less than][epsilon][greater than] is the average shear strain, [less than]e[greater than] is the average dilatational strain, and subscripts m and i refer to the matrix and the inclusion respectively.
These equations are numerically solved to yield the values of effective shear and bulk moduli for the composite.
Relaxation tests allow the measurement of shear and bulk moduli
at different temperatures, for instance at T = [T.sub.o] and T = [T.sub.o] [+ or -] [Delta]T where [T.sub.o] is a reference temperature for which h([T.sub.o]) = 0.
The bulk moduli
of PS and PVAc calculated from the excess enthalpy/volume data are in a relatively good agreement with normally reported K values usually obtained by hydrostatic means.
E, G, K and [Nu] = Young's modulus, shear and bulk moduli
and Poisson's ratio of the isotropic phases, respectively.