Selecting physical property tables to create CFAST and CWELD connections (Nastran)

If you select Patch by Property Label from the Patch Selection list, you can use physical property tables or PIDs (physical property table IDs) to define the 2D element patches to connect with CFAST or CWELD connections. This option corresponds to the PROP and PARTPAT fields on the CFAST and CWELD bulk data entries, respectively.

Note:

You cannot use the CFAST/CWELD Connection command to connect 2D meshes that use the same physical property table.

To define a connection by selecting physical property tables, you must:

• Specify the diameter of the fastener or the weld in the PFAST or PWELD physical property table dialog box. See Defining properties and parameters for CFAST/CWELD connections for more information.Note: Because the diameter of the CWELD or CFAST connection affects the locations at which you can define those connections, you should always define the diameter in the PFAST or PWELD dialog box before you create the connection itself.

• Select the Location Type option to specify how to define the end points for the connection.

• Define the physical property tables to connect.If you select Target 1 (GA)/Target 2 (GB), use the Side A and Side B options to specify the type and name of the two different physical property tables to connect.If you select Projection Point (GS), the software searches within a Search Distance that you specify for appropriate physical property tables to connect.

Selecting the location type for the connection

You can use the Location Type options to control how you specify the location of the connection on the 2D element patches.

• Select Target 1 (GA)/Target 2 (GB) to explicitly select the end points on side A and side B for the connection. The software creates a new node at each location you select.

• Select Projection Point (GS) to select define a location and have the software project that location along a normal onto the elements that comprise side A and side B of the connection. You can use options in the Select By list to control whether you define the location by:Selecting existing nodes or points or by creating new points or nodes. If you create a new point, the software automatically generates a node at that location.Reading in a CSV file that contains the list of point locations. The software automatically generates nodes at those locations.Selecting a curve and specifying the number of nodes for the software to create along that curve.

Defining a single connection location on an edge or curve

Use the Point on Curve/Edge option to create a series of CFAST or CWELD connections along an edge or curve and replicate spot weld or fastener point patterns from the manufacturing process in your CAE model. You can create connections:

• That are located along an edge or curve or that are offset from a selected edge or curve.

• In a specified pattern that repeats along the length of the edge or curve. You enter the distances along the curve at which you want to create the connections in either a comma or space delimited list.The software uses the Distance from Start value to create the first point. To create the next points, the software adds the distances you specified in the Pattern of Points box. The software repeats the pattern until it reaches the specified Distance from End value.For example, if you specify a Distance from Start value of 2 and a Pattern of 2, 1, 2, the software creates the first point 2 inches from the start of the curve, the second point 4 inches from the start of the curve, the third point 5 inches from the start of the curve, and the fourth point 7 inches from the start of the curve.

CFAST and CWELD connection requirements for defining patches by physical property tables using a projection point

For the software to create a CFAST or CWELD connection at a selected location when the Patch Selection list is set to Patch by Property Label and the Type is set to Projection Point (GS), the following conditions must be met:

• The fastener or weld diameter that you specify in the PFAST or PWELD physical property table dialog boxes must be appropriate for the geometry you are connecting.The distance between a selected point and the free edge closest to that point cannot be less than the specified weld or fastener diameter. This means that you cannot create a CFAST or CWELD connection along an edge.The distance between individual CFAST or CWELD connections cannot be less than the specified weld or fastener diameter.

• The meshes you connect must be nearly parallel. To ensure this, the software projects two normals onto two meshes within the search distance. If the angle between the normals is greater than 20°, the software does not create the connection.

• The elements around the circumference of the weld diameter must be relatively flat and not highly curved.

If the software is unable to create a CFAST or CWELD connection at a selected point, the software places the point in an output group in the Groups node in the Simulation Navigator.

Example: Creating connections in a pattern

The model in the graphic below is comprised of several individual sheet bodies that will be welded together during the manufacturing process. (A) shows the locations of the CWELD connections that are offset from one edge on the top body. Notice that the CWELD connections were created in a pattern, with one inch between each individual connection and three inches between each group of connections.

(A) Locations of the CWELD connections that are offset from an edge of the top sheet body

Where do I find it?

Application	Pre/Post
Prerequisite	An active FEM file with Nastran as the specified solver.
Command Finder	CFAST/CWELD Connection

Learn more

CFAST and CWELD Connections (Nastran)

Selecting elements to create CFAST and CWELD connections (Nastran)

Defining properties and parameters for CFAST/CWELD connections

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Bulk Entry Descriptions

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Selecting physical property tables to create CFAST and CWELD connections (Nastran), Simcenter 3D 2021.1 Series

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