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POROUS ELASTICITY
By defining Poisson’s ratio
Define Poisson’s ratio, . The instantaneous shear modulus is then defined from the instantaneous bulk
modulus and Poisson’s ratio as
where
is the logarithmic measure of the elastic volume change. In this case
Thus, the elastic shear stiffness increases as the material is compacted. This equation is integrated to
give the total stress–total elastic strain relationship.
Input File Usage:
Abaqus/CAE Usage:
*POROUS ELASTIC, SHEAR=POISSON
Property module: material editor: Mechanical→Elasticity→Porous
Elastic: Shear: Poisson
Use with other material models
The porous elasticity model can be used by itself, or it can be combined with:
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the “Extended Drucker-Prager models,” Section 20.3.1;
the “Modified Drucker-Prager/Cap model,” Section 20.3.2;
the “Critical state (clay) plasticity model,” Section 20.3.4; or
isotropic expansion to introduce thermal volume changes (“Thermal expansion,” Section 23.1.2).
It is not possible to use porous elasticity with rate-dependent plasticity or viscoelasticity.
Porous elasticity cannot be used with the porous metal plasticity model (“Porous metal plasticity,”
Section 20.2.9).
See “Combining material behaviors,” Section 18.1.3, for more details.
Elements
Porous elasticity cannot be used with hybrid elements or plane stress elements (including shells and
membranes), but it can be used with any other pure stress/displacement element in Abaqus/Standard.
If used with reduced-integration elements with total-stiffness hourglass control, Abaqus/Standard
cannot calculate a default value for the hourglass stiffness of the element if the shear behavior is defined
through Poisson’s ratio. Hence, you must specify the hourglass stiffness. See “Section controls,”
Section 24.1.4, for details.
If fluid pore pressure is important (such as in undrained soils), stress/displacement elements that
include pore pressure can be used.
19.3.1–3
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