Activation
Use the Activation subnode to activate or de-activate parts of a domain according to an Activation expression that you define. The Activation subnode uses a scale factor that reduces the elastic stiffness and density of the material, to emulate that material is not present. When the Activation expression 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 Activation scale factor.
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The density is multiplied by the square of the Activation scale factor.
When the material is activated, the following is done to ensure that the activation is stress-free:
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Elastic strains at the instant of activation are removed from the total strains.
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Initial stresses are removed.
The Activation subnode can be used in combination with Linear Elastic Material.
Activation
Enter the Activation expression. This is the expression that will determine whether material is active or inactive.
Enter the Activation scale factor. The default value is 10−5.
The Activation subnode is only available with some COMSOL products (see http://www.comsol.com/products/specifications/)
See also Activating and Deactivating Material in the Structural Mechanics Modeling chapter.
Location in User Interface
Context Menus
 Solid Mechanics>Linear Elastic Material>Activation
Ribbon
Physics tab with Linear Elastic Material, node selected in the model tree:
Attributes>Activation