Geometric Nonlinearity
The Geometric Nonlinearity node () is a subnode to the Auxiliary Settings node (see Auxiliary Settings (Feature Nodes) and contains a setting for indicating whether the parent physics feature adds geometric nonlinearity to the problem.
Geometric Nonlinearity
Select an option:
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Never (the default). This option is the same as not adding the Geometric nonlinearity node at all; that is, the feature does not make the model geometrically nonlinear.
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On request. Adding the physics feature to a model enables the geometric nonlinearity option in the study steps so that the user can choose if the model should be regarded as geometrically nonlinear. The feature must always generate linear or nonlinear equations depending on the current study step setting. Note that other features with the geometric nonlinearity setting set to Always can take control over the setting, enforcing geometric nonlinearity.
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Always. Adding the physics feature to a model makes the geometric nonlinearity option in the study steps visible but selected and disabled so that the model is always regarded as geometrically nonlinear.
There are two parts that need to be implemented when making a physics interface compatible with geometric nonlinearity. The physics features must indicate if they listen to the geometric nonlinearity setting in the study steps, which then must be visible, or if they always add geometric nonlinearity to the problem, thus taking control of the study step setting. This part is done by using the Geometric Nonlinearity node.
The other part is to make physics features generate linear or nonlinear equations depending on the geometric nonlinearity setting in the current study step. This is done by placing the relevant variables and equations under a Usage Condition node. Typically the features that need support for both linear and nonlinear equations are the ones that have Geometric nonlinearity set to On request.
To set up a usage condition that is true when the geometric nonlinearity option is selected in the current study step, configure it in the following way: Select the User input check box, set Specify user input to By name, set From to User input from Study step, type geometricNonlinearity in the User input field, and finally add “on” as the activating value.