Constraints can also be formulated as a Weak Form Equation using an extra degree of freedom.

To add the Weak Constraint node (), first add a Component, Feature, Property, or usage condition then:

The Settings window has the following sections:

The content of the Expression field adds up as a weak-form contribution to the system of equations that you later solve for in the Model Builder.

The options in the Selection list and Output entities list define the selection where this contribution definition is valid. See Specifying Selections for more information.

Clear the Use volume factor in axial symmetry or for non-orthonormal systems check box if you want to skip any volume factors in the weak contribution. In axial symmetry this means that you do not get the factor 2πr. It is also possible to select the Assume constant volume factor check box in this section.

If you want to use a different base vector system than the parent feature or property, you can choose a different system in the Base vector system list. You can also specify the integration order from the Integration order list: Automatic (the default, which picks an integration order that is consistent with the shape function order) or Customized; if you choose Customized, enter an integration order (a positive integer; default value: 2) in the Order field.