About Weighted Links (FEM Mode)

A weighted link is an interpolation constraint element that takes masses or loads acting at a single source node and distributes them to a collection of target nodes. Weighted links have the following characteristics:

• Weighted links distribute masses or loads in a balanced manner.

• Weighted links help you to control this distribution through degrees of freedom (DOF) that you assign to a target node group as a whole. Assigning degrees of freedom enables the target nodes to move in specific directions. Creo Simulate uses degrees of freedom to construct linear constraint equations while calculating load or mass distribution.

• Weighted links can have only one source node that follows the average motion of the target node group. Thus, the source node is called dependent and the target nodes—independent. Nodes on the independent side determine the motion of a single node on the dependent side. In other words, any motion of a node on the dependent side reflects the average motion of the nodes on the independent side.

These characteristics make weighted links useful when you need to attach mass idealizations to your model without stiffening the structure.

Click Refine Model > Weighted Link to open the Weighted Link Definition dialog box to create weighted links in your model. After you create a weighted link, you can edit or delete it by selecting the associated icon on the model tree and using the right mouse button to select Edit Definition or Delete as appropriate. If you are deleting a weighted link, Creo Simulate asks you for confirmation first.

While creating, editing, or deleting weighted links, keep in mind the following:

• Use the precedence rules.

• Control visibility of the weighted link icons by using the View > Simulation Display command. Creo Simulate places two icons—one for the link, another for the degrees of freedom—on the model.

• Place the weighted links on layers.

• Use object action to make any changes to the weighted links.

A weighted link defined in the FEM mode is suppressed in the native mode, in the following instances:

• The weighted link has one or more rotational DOFs specified.

• The weighted link has a UCS or Nodal coordinate system specified for the dependent side.

• The weighted link has a Nodal coordinate system specified for the independent side.

Creo Simulate outputs weighted links as RBE3 cards to be used with the NASTRAN and ANSYS solvers. If you try to choose another solver, Creo Simulate ignores the weighted links. Creo Simulate does not output the weighted link whose dependent side has constraints.

You cannot define weighted links for 2D models. |