The Nonlinear Elastic Material feature is used to model stress-strain relationships which are nonlinear even at infinitesimal strains. It is available in the Solid Mechanics and Membrane interfaces. This material model requires either the Nonlinear Structural Materials Module or the Geomechanics Module.
By adding the following subnodes to the Nonlinear Elastic Material node you can incorporate many other effects:
The Global coordinate system is selected by default. The
Coordinate system list contains any additional coordinate systems that the model includes (except boundary coordinate systems). The coordinate system is used when stresses or strains are presented in a local system. The coordinate system must have orthonormal coordinate axes, and be defined in the material frame. Many of the possible subnodes inherit the coordinate system settings.
All nonlinear elastic material models have density as an input. The default Density ρ uses values
From material. For
User defined enter another value or expression.
If any material in the model has a temperature dependent mass density, and From material is selected, the
Volume reference temperature list will appear in the
Model Input section. As a default, the value of
Tref is obtained from a
Common model input. You can also select
User defined to enter a value or expression for the reference temperature locally.
From the Specify list select a pair of elastic properties for an isotropic material —
Young’s modulus and Poisson’s ratio (the default for Ramberg–Osgood, Power law, Duncan–Chang, and Duncan–Selig) or
Bulk modulus and shear modulus (the default for Hyperbolic law and Hardin–Drnevich).
For Uniaxial data the
Uniaxial stress function σax uses the value
From material (if it exists) or
User defined. If
User defined is selected from the list, the default expression for
σax is the linear function
210[GPa]*<physics>.eax, which corresponds to a linear elastic material with a Young’s modulus of 210 GPa. The variable
<physics>.eax corresponds to the elastic uniaxial strain in pure axial loading, and is named using the scheme
<physics>.eax, for example,
solid.eax.
From the Specify list select how to specify the second elastic property for the material —
Bulk modulus or
Poisson’s ratio. Then, depending on the selection, enter a value or select from the applicable list to use the value
From material or enter a
User defined value or expression:
When you select Bulk modulus, the Young’s modulus is computed from the tensile part of the
Uniaxial stress function σax. When you select
Poisson’s ratio, you can either use the tensile part (default), or use the full tensile-compressive function by selecting the check box
Use nonsymmetric stress-strain data.
For Shear data the
Shear stress function τ uses the value
From material (if it exists) or
User defined. If
User defined is selected from the list, the default expression for
τ is the linear function
80[GPa]*<physics>.esh, which corresponds to a linear elastic material with a shear modulus of 80 GPa. The variable
<physics>.esh corresponds to the elastic shear strain in pure shear loading, and it is named using the scheme
<physics>.esh, for example,
solid.esh.
The default Bulk modulus K uses values
From material. For
User defined enter another value or expression.
For Bilinear elastic enter a value or select from the applicable list to use the value
From material or enter a
User defined value or expression.
In the User defined material model, you specify the bulk modulus implicitly by entering the relation between pressure and volumetric elastic strain. Enter a value or select from the applicable list to use the value
From material or enter a
User defined value or expression.
Select the Calculate dissipated energy check box as needed to compute the energy dissipated by
Creep,
Plasticity,
Viscoplasticity, or
Viscoelasticity.
) and select Advanced Physics Options in the Show More Options dialog box.