Using the Damping subnode, you can add several types of damping to the material model. Damping can be used in Time Dependent, Eigenfrequency, and Frequency Domain studies; for other study types the settings in the
Damping subnode are ignored.
Select a Damping type, and enter settings depending on the type.
In this damping model, the damping parameter ξ is expressed in terms of the mass
m and the stiffness
k as
Select Input parameters —
Alpha and beta — to enter the damping parameters explicitly, or
Damping ratios to derive the damping parameters from the relative damping at two frequencies.
When Damping ratios is selected, enter two pairs of frequencies,
f1 and
f2, and the corresponding damping ratios
ζ1 and
ζ2 at these frequencies. The Rayleigh damping parameters are computed as
The isotropic loss factor damping is described by the single isotropic loss factor ηs, which acts on all entries in the elastic constitutive matrix. It can be used for isotropic, orthotropic, and anisotropic materials.
When Isotropic loss factor is selected, use the
Isotropic structural loss factor list to select the way to enter
ηs. The default is to take the value
From material. For
User defined, enter another value or expression.
An elastic material is in general described by a symmetric 6-by-6 elasticity matrix D. The loss can be isotropic or anisotropic, and is described by either the isotropic loss factor
ηs or by a symmetric anisotropic 6-by-6 loss factor matrix
ηD or
ηDVo. The orientations are the same as in the parent node.
When Anisotropic loss factor is selected, use the
Loss factor for elasticity matrix D list to select the way to enter
ηD or
ηDVo. The default is to take the values
From material. For
User defined enter the components of
ηD or
ηDVo in the upper-triangular part of a symmetric 6-by-6 matrix.
An orthotropic material is described by three Young’s modulus components (Ex,
Ey, and
Ez) and three shear modulus components (
Gxy,
Gyz, and
Gxz). For an orthotropic material, loss factors can be specified in three different ways:
When Orthotropic loss factor is selected, use the
Loss factor for orthotropic Young’s modulus list to select the way to enter
ηE. The default is to take the values
From material. For
User defined enter other values or expressions.
Use the Loss factor for orthotropic shear modulus list to select the way to enter
ηG or
ηGVo. The default is to take the values
From material. For
User defined enter other values or expressions.
With viscous damping, the material will get additional stresses proportional to the strain rate. Enter Bulk viscosity ηb and
Shear viscosity ηv to model damping.caused by volume change and deformation respectively.
Physics tab with Linear Elastic Material,
Hyperelastic Material, or
Nonlinear Elastic Material node selected in the model tree:
Attributes>Damping
