Linear Elastic Material

The built in is selected by default. The list contains any additional boundary coordinate systems that the model includes. The coordinate system is used for interpreting directions of orthotropic and anisotropic material data and when stresses or strains are presented in a local system. Many of the possible subnodes inherit the coordinate system settings.

Define the and the linear elastic material properties.

Solid Model

Select a linear elastic — (the default), , or . Select:

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for a linear elastic material that has the same properties in all directions.

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for a linear elastic material that has different material properties in orthogonal directions, so that its stiffness depends on the properties Ei, νij, and Gij.

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for a linear elastic material that has different material properties in different directions, and the stiffness comes from the symmetric elasticity matrix, D.

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Material Models

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Linear Elastic Material

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Orthotropic and Anisotropic Materials

Density

The default ρ uses values . For enter another value or expression.


	The density is needed for dynamic analysis or when the elastic data is given in terms of wave speed. It is also used when computing mass forces for gravitational or rotating frame loads, and when computing mass properties (Computing Mass Properties).

Specification of Elastic Properties for Isotropic Materials

For an , from the list select a pair of elastic properties for an isotropic material — , , , , or . For each pair of properties, select from the applicable list to use the value or enter a value or expression.


	Each of these pairs define the elastic properties and it is possible to convert from one set of properties to another (see Table 3-1 in the theory chapter).

The individual property parameters are:

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(elastic modulus) E.

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ν.

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λ and μ.

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(longitudinal wave speed) cp.

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(transverse wave speed) cs. This is the wave speed for a solid continuum. In plane stress, for example, the actual speed with which a longitudinal wave travels is lower than the value given.

Specification of Elastic Properties for Orthotropic Materials

When is selected from the list, the material properties vary in orthogonal directions only. The can be specified in either or notation. When is selected in 3D, enter three values in the fields for E, ν, and the G. This defines the relationship between engineering shear strain and shear stress. It is applicable only to an orthotropic material and follows the equation


	νij is defined differently depending on the application field. It is easy to transform among definitions, but check which one the material uses.

Specification of Elastic Properties for Anisotropic Materials

When is selected from the list, the material properties vary in all directions, and the stiffness comes from the symmetric , D. The can be specified in either or notation. When is selected, a 6-by-6 symmetric matrix is displayed.

Mixed Formulation

For a material with a very low compressibility, using only displacements as degrees of freedom may lead to a numerically ill-posed problem. You can then use a mixed formulation, which add an extra dependent variable for either the pressure or for the volumetric strain. For details, see the Mixed Formulation section in the Structural Mechanics Theory chapter.

From the list, select , , or .

Geometric Nonlinearity

If a study step is geometrically nonlinear, the default behavior is to use a large strain formulation in all boundaries. There are, however, some rare cases when the use of a small strain formulation for a certain boundary is needed.

In such cases, select the check box. When selected, a small strain formulation is always used, independently of the setting in the study step.

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Modeling Geometric Nonlinearity

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Studies and Solvers in the COMSOL Multiphysics Reference Manual

Energy Dissipation

The section is available when you also have the Nonlinear Structural Materials Module. To display the section, click the button (

) and select in the dialog box.

Select the check box as needed to compute the energy dissipated by , , or .

Discretization

If is used, select the discretization for the — , , , or . If is used, select the discretization for the — , , , or .


	The Discretization section is available when Pressure formulation or Strain formulation is selected from the Use mixed formulation list. To display the section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box.

Quadrature Settings

Select the check box to reduce the integration points for the weak contribution of the feature. Select a method for — , , or to use in combination with the reduced integration scheme. The default stabilization technique is based on the shape function and shape order of the displacement field.

Control the hourglass stabilization scheme by using the option. Select (default) or .

When is selected, enter a stabilization shear modulus, Gstb. The value should be in the order of magnitude of the equivalent shear modulus.

When is selected, enter a stabilization bulk modulus, Kstb. The value should be in the order of magnitude of the equivalent bulk modulus.

Location in User Interface

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