The Linear Elastic Material node adds the equations for a linear elastic solid and an interface for defining the elastic material properties.

By adding the following subnode to the Linear Elastic Material node you can incorporate damping effects; see Damping.

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 for interpreting directions of orthotropic and anisotropic material data and 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.

Define the Solid model and the linear elastic material properties.

The Solid model is always Isotropic for a linear elastic material that has the same properties in all directions.

The default Density ρ uses values From material. For User defined enter another value or expression.

For an Isotropic Solid model, from the Specify list select a pair of elastic properties for an isotropic material—Young’s modulus and Poisson’s ratio, Young’s modulus and shear modulus, Bulk modulus and shear modulus, Lamé parameters, or Pressure-wave and shear-wave speeds. For each pair of properties, select from the applicable list to use the value From material or enter a User defined value or expression.

Different pairs of elastic moduli can be used, and as long as two moduli are defined. The others can be computed according to Table 15-1.

According to Table 15-1, the elasticity matrix D for isotropic materials is written in terms of Lamé parameters λ and μ,

or in terms of the bulk modulus K and shear modulus G:

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 adds 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 Use mixed formulation list, select None, Pressure formulation, or Strain formulation.

Select the Calculate dissipated energy check box as needed to compute the energy dissipated by damping.

Select the Reduced integration check box to reduce the integration points for the weak contribution of the feature. Select a method for Hourglass stabilization — Automatic, Manual, or None to use in combination with the reduced integration scheme. The default Automatic stabilization technique is based on the shape function and shape order of the displacement field.

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

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

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

Physics Tab with Solid Mechanics selected: