Inspect Displacement Vectors in FreeCAD FEM Results

This guide explains how to inspect displacement vectors in FreeCAD's Finite Element Method (FEM) workbench to understand structural deformation. You will learn how to activate the VTK-based post-processing pipeline, generate 3D vector arrows (glyphs) indicating direction and magnitude, configure display scaling, and inspect localized nodal displacement values.

1. Run the Solver and Generate Results

Before visualizing displacement vectors, ensure your analysis has finished solving.

  1. In the tree view, double-click your solver object (e.g., CalculiX).
  2. Click Write .inp file, followed by Run CalculiX.
  3. Once completed successfully, close the solver task panel. A result object (typically named CCX_Results) will appear inside your Analysis container.

2. Create a Post-Processing Pipeline

FreeCAD utilizes a VTK-based pipeline for advanced field and vector visualizations.

  1. Select the CCX_Results object in the model tree.
  2. Navigate to the FEM workbench toolbar or the FEM menu > Post Processing.
  3. Click on Post Pipeline from Result. This creates a Pipeline object under your analysis container.

3. Add a Vector Filter (Glyphs)

To transform the scalar displacement field into directional 3D vector arrows:

  1. Select the newly created Pipeline object in the tree.
  2. In the FEM toolbar, click Post Create Vector Filter (represented by directional vector arrows). A VectorFilter or GlyphFilter sub-object will be created under the pipeline.
  3. Hide the original mesh or result object by selecting it and pressing the Spacebar to prevent visual clutter.

4. Configure Vector Display Properties

With the vector filter active, adjust its parameters in the Property View (Data tab) to make vectors readable:

  • Vector Field: Ensure this property is set to Displacement.
  • Scale Factor: Real-world displacements are often microscopic compared to part dimensions. Increase the Scale Factor (e.g., from 1.0 to 100.0 or higher) until arrows are clearly visible.
  • Glyph Type: Choose between representations such as Arrow, Cone, or Line. Arrow is the standard for displacement visualization.
  • Max Points / Density: Adjust this to control how many arrows are drawn across the mesh surface. Lowering density helps avoid overlapping arrows on dense meshes.

5. Inspect Exact Component Values

To read exact displacement numbers (magnitude, X, Y, and Z components) at specific regions:

  1. Select the Post Create Data at Point Filter tool while the pipeline is highlighted.
  2. Click on a point on the deformed geometry to display a numeric readout of the displacement vector components at that coordinate.
  3. Alternatively, double-click the original CCX_Results object to open the task panel, switch the display field to Displacement, and select individual directional components (X-Displacement, Y-Displacement, or Z-Displacement) to view scalar contour plots of each vector axis.