Creo Simulate > Modeling Structure and Thermal Problems > Connections > Rigid Link > About Rigid Links
About Rigid Links
A rigid link is a type of connection that connects geometric entities such as surfaces, curves, and points so that they remain rigidly connected during an analysis. Rigid links can be used to effectively replace a component whose rigidity is far greater than the others, and whose only contribution is to maintain set displacements between attached components. Components so connected are free to move in any manner, but will maintain their relative positions.
Click Refine Model > Rigid Link open the Rigid Link Definition dialog box to create rigid links in your model. Rigid links are available in native as well as FEM mode.
When you connect entities using rigid links, be aware of the following:
The entities move together as if part of a single rigid body.
The entities do not deform, but the rigid body can move as a whole.
Because Creo Simulate uses linear constraint equations to enforce the rigid rotations, rather than equations with sines and cosines, you should use rigid links only for small rotation angles of rigidly connected entities. Use rigid links in this way, even if you intend to use them in a large deformation analysis.
The following apply to 3D and 2D models:
You can create, edit, and delete rigid links.
You can turn rigid link visibility on and off by selecting or clearing Rigid Links check box on the Simulation Display dialog box.
Additionally, you can use rigid links to connect two or more parts at selected surfaces, or to help idealize complex models. For example, you can use a rigid link to connect a point mass representing an engine to the engine mount bolt holes.
You can create a rigid link from one point to a second point. If you are working with a 3D model, at least one of the points must meet one of these two conditions:
The point must lie on a spring, beam, or shell.
The point must act as the reference for a point constraint with at least one free rotation, a point load with a moment, or a point mass with a nonzero moment of inertia.
You can create a rigid link from one or more curves or surfaces on your model to a free point that is not otherwise associated with the model geometry. Use a rigid link from a surface to a free point with a constraint, for example, to model a pin support. If you create a rigid link from one edge, to a free point, and then to a second edge, the two edges will move together when you apply a load.
When you create a rigid link to a free point, be aware of the following:
You can create a displacement measure on a free point with a rigid link, but the point will not be visible when you view results.
You cannot query displacements or rotations at rigidly connected free points. However, Creo Simulate will include loads or constraints on a rigidly connected point when calculating measures over the entire model, such as maximum displacement.
You can also control the selection of independent degrees of freedom (DOFs) by creating an advanced rigid link. To create an advanced rigid link select Advanced in the Type list in the Rigid Link Definition dialog box. Advanced rigid links allow you to connect elements with unmatched DOFs. For example, it is common to connect shell elements, which have rotational DOFs, to solids, which do not. In this case, rigid links can minimize perturbation of the elements' stress and strain at the interface boundary. The following applies to advanced rigid links:
You can select a point for the independent set, and a set of single points, feature of points, pattern of points, curves or surfaces for the dependent set.
You can use a rigid link to define the relative translational or rotational motion or both between the independent and dependent sides. Creo Simulate defines the DOFs with respect to the WCS or any other UCS to control the relative motion.
When you create an advanced rigid link, be aware of the following:
You cannot create an advanced rigid link in 2D models.
On the independent side, you cannot select a surface or curve
If the dependent sides of two links refer to the same Cartesian coordinate system -
they cannot have a common DOF.
neither link can have all translational DOFs constrained if the other link has one or more translational DOFs constrained.
neither link can have all rotational DOFs constrained if the other link has one or more rotational DOFs constrained.