Coordinate systems in post-processing

The solver writes out results as a set of component values at nodes and/or elements with respect to a coordinate system determined by the solver and element formulation. When you load results into this software, this unprocessed data is transformed into a consistent coordinate system, and derived results are calculated.

When you define the results display for a post view, you can specify the coordinate system into which component results are transformed.

When boundary conditions are defined with respect to local coordinate systems, transforming results into those coordinate systems can produce cleaner and more meaningful results displays.

You can post-process results with respect to the following coordinate systems:

• Absolute The software transforms results with respect to the absolute coordinate system origin and orientation. Although the absolute coordinate system is always Cartesian, you can specify Absolute Rectangular, Absolute Cylindrical, or Absolute Spherical for post-processing.

• WorkThe software transforms results with respect to the current work coordinate system (WCS) origin and orientation. As with the absolute coordinate system, you can specify rectangular, cylindrical, or spherical coordinates.

• MaterialIf any meshes or elements in your model have a defined material orientation (as for orthotropic or anisotropic materials or composite laminates), you can view tensor component results in the material coordinate system. Optionally, when Material is selected for the coordinate system on the Result dialog box, you can click Display Material Orientation to temporarily display the material orientation vectors.

• SelectedYou can select any coordinate system that is visible and selectable in the graphics region, or listed in the Simulation Navigator, to arbitrarily transform results. Choose from Selected Rectangular, Selected Cylindrical, or Selected Spherical.

• NativeFor post-processing, the native coordinate system is the untransformed coordinate system in which results are written to the solver output file. Typically, this is the element coordinate system, but may be some other coordinate system based on the solver, analysis type, or element formulation. This coordinate system is useful for viewing element resultants for structural elements, such as beams and shells.

The coordinate system you select when you define the results display applies to all other post-processing operations as well. For example, if you display results using the Work Cylindrical coordinate system, and then use Identify to output results values at selected nodes, the result components at those nodes will be defined in the work coordinate system using cylindrical components. Likewise, deformation are defined with respect to the specified coordinate system.

The following images compare contour plots of stress components transformed into different coordinate systems.

XY shear stress, absolute rectangular CSYS	XY shear stress, untransformed native results (element CSYS)
12 shear stress, material CSYS	rθ shear stress, selected cylindrical CSYS

Selected coordinate system support

You can select any coordinate system that is visible and selectable in the graphics region, or listed in the Simulation Navigator, to arbitrarily transform results. You can select:

• Coordinate systems listed in the solver output file, such as nodal coordinate systems and local coordinate systems used to define component force loads or user-defined constraints.Coordinate systems in the solver output file are listed under the Post View node in the Post Processing Navigator. Result coordinate systems are hidden by default. Expand the Post View node and select the visibility check box for the Result CSYS node to display result coordinate systems and make them selectable.

• Coordinate systems in the displayed part file (typically, the Simulation file).You must ensure that the displayed part coordinate systems are visible in the graphics region. To do this, you can create a multiple viewport layout, or you can control the visibility of layers containing coordinate systems.

• Coordinate systems listed in the Simulation Navigator.By default, all local coordinate systems defined in the currently displayed Simulation or FEM file are listed in the Simulation Navigator. You can click to highlight the CSYS node in the Simulation Navigator to select a coordinate system when setting the result display in a post view.

The following figure compares arrow plots for a model undergoing twisting. The first plot displays the XYZ displacement in the absolute rectangular coordinate system and the second plot displays the θ displacement in a selected cylindrical coordinate system. The selectable result coordinate system is just visible at the bottom center of each image.

XYZ displacement in the absolute rectangular coordinate system	θ displacement in a selected cylindrical coordinate system

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Coordinate systems in post-processing, Simcenter 3D 2021.1 Series

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