Point-to-point and node-to-node connections

You use point-to-point (geometry based) and node-to-node (FE-based) connectors to connect nodes or points on one body or component FEM to nodes or points on another body or component FEM. Typical uses for these connection types include:

• Modeling structures such as pins, bolts, or struts.

• Creating spider elements for distributing masses or loads.

• Joining meshes when edge-to-edge or edge-to-face connections are not appropriate. For example, you can use node-to-node connections to join imported meshes with no underlying geometry.

One-to-one connections

When you select a single source node or point and a single target node or point, and click Apply or OK, the software generates a single element of the specified type. This method is usually used with structural 1D elements for modeling structures such as pins, bolts, or struts.

One-to-one, point-to-point beam element.

One-to-many connections

If you select a single source node or point and multiple target nodes or points (or vice versa), and you specify a rigid or constraint element type (such as Nastran RBE2s or RBE3s), the software creates a spider element. The single source node is the core node, and the multiple target nodes are the leg nodes.

One-to-many, node-to-node spider element.

If you create a one-to-many connection using structural 1D elements, the software generates a mesh of multiple elements that share an end node.

For more information, see Spider element connections.

Many-to-many connections

When you select multiple source nodes or points and multiple target nodes or points, the software pairs source and target nodes to create a connection mesh. The following figure shows a node-to-node connection of rigid link elements joining two solid meshes at adjacent faces.

Many-to-many node-to-node connection.

The software creates source-target pairs using the specified Method of Connection:

• If you choose Proximity, the software pairs locations by finding the shortest distance between the source and the target.

• If you choose Order of selection, the software pairs locations according to the order in which you selected them. For example, the first source location that you select is paired with the first target location that you select, the second with the second, and so on.Note: If you use Order of selection together with one of the smart selection methods, the resulting pairs may not be as expected.

• If you choose Mean Vector, the software calculates the mean location of all source points/nodes and target points/nodes and creates a vector between those locations. The software then takes a source node/point and draws a vector that is parallel to the mean vector. The software uses the parallel vector to find the closest node/point on the target and creates the 1D element between those points.

• If you choose X Ordered, Y Ordered, or Z Ordered, the software first sorts all the source nodes or points based on their X, Y, or Z coordinates, depending on the option you select. The software then sorts all the target points based on their X, Y, or Z coordinates. The software uses those sorted lists to create the 1D elements between the source and target nodes or points.

• If you choose Proximity Spider, the software connects every leg node that lies within the search distance of a core node to that core node. With this method, one leg node can connect to multiple core nodes, which means that a single leg node can be used in multiple connection elements if it lies within the Search Distance of those core nodes.

As a general guideline for methods other than Proximity Spider, the source and target selections should contain the same number of nodes or points. This ensures that the software pairs each source node or point with a target node or point. If the source and target selections are unequal, the software pairs source and target locations using the specified Method of connection and ignores the remainder.

If you select multiple source and target nodes using one of the selecting methods, you get the most predictable results if the source and target selections have a similar distribution and pattern of nodes.

Selecting points or mesh points

You can select points or mesh points to define a point-to-point connection.

• To select points, you must include them in the FEM when you create the FEM file. To include points in your FEM, in the New FEM dialog box, click Geometry Options and select Include Points.

• You create mesh points prior to creating a point-to-point connection. Choose Insert→Model Preparation→Mesh Point to create mesh points.

Selecting nodes

When selecting nodes to create a node-to-node connection, you can use the selection methods on the Top Border bar to quickly select multiple related nodes.

• Use the Related Nodes method to select nodes by their relationship to the underlying polygon geometry.

• Use Feature Edge Nodes and Feature Angle Nodes to select nodes by features of the mesh. These methods are especially useful when the FEM contains no associated geometry.

• Use Nodes by Group to select nodes stored in a group.

For more information, see Selection methods.

Number of elements created

The number of elements that the software creates when you click OK or Apply depends upon the type of connection element you select.

• If you select a single source node or point and multiple target nodes or points:For spider-like connection elements that have a single source node and multiple leg nodes, such as RBE2 and RBE3 elements, the software creates one connection element between the source and the targets for each core node.For all other connection element types, the number of connection element that the software creates is equal to the number of target nodes or points.

• If you select multiple source nodes or points and multiple target nodes or points, the number of connection elements that the software creates is the minimum number of either source or target nodes or points. For example, if you select four source nodes and five target nodes, the software creates four connection elements between the nodes.

How do I

Create a node-to-node connection

Create an element edge to element face connection

Create a point-to-point connection

Create a point-to-edge connection

Create a point-to-face connection

Create an edge-to-edge connection

Create an edge-to-face connection

Create a face-to-face connection

Learn more

1D Connection

Edge-face 1D connections

Spider element connections

Working with RBE2 and RBE3 spider elements

1D mesh to face connections

Understanding Samcef RBE and MEAN elements (Simcenter Samcef)

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Point-to-point and node-to-node connections, Simcenter 3D 2021.1 Series

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