Activation

Use the subnode to activate or deactivate parts of a domain according to an that you define. The subnode uses a scale factor that reduces the elastic stiffness and density of the material, to emulate that material is not present. When the is satisfied, the material is activated in a state of zero stress.

When the material is not active, the following is done to emulate that the material is not present:

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The elasticity matrix is multiplied by the .

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The density is multiplied by the square of the .

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If viscoelasticity is present, shear and bulk moduli, as well as relaxation times, are scaled using the .

When the material is activated, the following is done to ensure that the activation is stress free:

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At the instant of activation, that is when the is first satisfied, the elastic strains corresponding to the previous time or parameter step are removed from the total strains.

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Initial stresses are always removed, regardless of the .

External stresses are never removed, regardless of the .

The subnode can be used in combination with , and in the Wire interface with .

Activation

Enter the . This is the expression that will determine whether material is active or inactive.

Enter the . The default value is 10−5.

The subnode is only available with some COMSOL products (see https://www.comsol.com/products/specifications/)


	See also Activating and Deactivating Material in the Structural Mechanics Modeling chapter.

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