Working with nodal coordinate systems

Each node in your model has two types of nodal coordinate systems:

• ReferenceThe nodal reference coordinate system determines the locations of the node coordinates (grid positions) that are written to the solver input deck. This coordinate system lets you easily move nodes (and their attached elements) in a particular direction, which is especially useful when working with appended meshes.

• DisplacementThe nodal displacement coordinate system provides a frame of reference for the structural degrees of freedom with regard to both displacement and rotation.

By default, both of these nodal coordinate systems are the same as the absolute coordinate system (also called the global coordinate system). However, under some circumstances, you might want to assign a different coordinate system to selected nodes. For example, if you are working with a large assembly, it might be helpful to assign a nodal reference coordinate system to each component to facilitate work on the individual parts.

You can identify the assigned nodal reference or displacement coordinate systems, as well as display a coordinate system triad for each node in the graphics window.

Assigning a nodal coordinate system

You can assign a nodal reference coordinate system only when the FEM file is the work part. You can assign a nodal displacement coordinate system when either the Simulation or FEM file is the work part.

If you assign a nodal coordinate system when the FEM file is the work part, that coordinate system assignment is saved with the FEM file and is inherited by all simulations that use that FEM file.

If you assign a nodal displacement coordinate system when the Simulation file is the work part, that coordinate system assignment overrides the nodal displacement coordinate system defined for the FEM file and is saved with the Simulation file.

Note:

When you define a constraint, the software might automatically assign a nodal displacement coordinate system to the affected nodes. If you subsequently assign a nodal displacement coordinate system to the same nodes manually, the manually assigned coordinate system overrides the programmatically assigned one.

Identifying nodal coordinate systems

Identifying the assigned nodal reference or displacement coordinate systems can help you distinguish them from other coordinate systems that might exist in the model.

You can highlight only one type of coordinate system at a time (such as only the displacement coordinate systems). You can also optionally limit the highlighted coordinate systems to those associated with a specific node or geometry.

When the Simulation file is the work part, you can highlight the reference coordinate systems associated with the FEM file. However, you can highlight only the displacement coordinate systems associated with the Simulation file. When the FEM file is the work part, you can highlight all of the reference or displacement coordinate systems associated with the FEM file.

Identifying the nodal reference or displacement coordinate system highlights both the coordinate system object in the graphics window (if it is visible) and the corresponding coordinate system under CSYS in the Simulation Navigator.

Displaying nodal coordinate systems

Displaying nodal coordinate systems enables you to see whether they are defined as expected. For example, you can confirm that the nodes along a curved face use a cylindrical coordinate system.

You can display only one type of coordinate system at a time (such as only the displacement coordinate systems). You can optionally limit the displayed coordinate systems to those associated with a specific node or geometry. You can also specify the color for each direction of the coordinate system triad.

By default, the displayed coordinate systems remain visible in the graphics window until you hide them by clearing the Retain Label Visibility After Dialog Closes check box in the Display Nodal CSYS dialog box or use the Refresh or Fit commands.

Nodal reference coordinate systems with default colors

Nodal displacement coordinate systems with defined colors

Where do I find it?

Application	Pre/Post
Prerequisite	A Simulation file or FEM file as the work part and displayed part
Command Finder	Assign Nodal Coordinate System Nodal Coordinate System Display Nodal Coordinate System

How do I

Assign nodal coordinate systems

Identify nodal coordinate systems

Display nodal coordinate systems

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Command reference

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Working with nodal coordinate systems, Simcenter 3D 2021.1 Series

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