FreeCAD: Stress Analysis (2/3)

Condition settings

1. Creating analysis case

   Switch workbench to FEM workbench and create new analysis.

2. Material setteings

   We will set a material for analysis in this section. At first, select material setting tool. Then select "ABS-Generic" as "Material card" and click OK to close the dialog. ABS is a kind of resin and one of the most common material used in 3D printings.

   

   In addition to ABS, you can use Aluminum alloy, steel, concrete, glass, PLA or wood etc. as material. It is also possible to set any Young's modulus, Poisson's ratio, density, etc. values for material.

3. Fixed condition settings

   Select fixed condition. Select the face of the screw hole at the lower Y coordinate in the 3D view and click Add on the dialog to set fixed condition. Red pins will be shown on the face with fixed condition. After settings, click OK to close the dialog.

   

   

4. Force condition settings

   Select force condition. Select the face of the screw hole at the upper Y coordinate in the 3D view and click Add on the dialog to set force condition. Red arrows will be shown on the face with force condition.

   Enter "500" at "Load". The force unit is N (Newton).

   

   

   If you want to change the direction of the force, click Direction and then select the edge in the 3D view that you want to specify. You can also check "Reverse direction" to reverse the direction of the force.

   When all settings is done, click OK to close the dialog.

5. Creating meshes

   Select the shape (Body) to be analyzed on model tree and run creating mesh with Netgen.

   At first, set "Max. Size" to "5" on task tab. Then confirm that "Second order" has been checked. By this option, second-order elements with high computational accuracy (but costs more computational time) will be used.

   

   

   Confirm the mesh fineness has been set to "Moderate" and click Apply. If there is no problem with the mesh shown in the 3D view, click OK to close the dialog.

   

   

   The parameters are as follows:

   Parameters

   Max. Size	Maximum size of an element
   Second order	Generate 2nd-order elements or not
   Fineness	Mesh fineness. Possible settings are "Very Coarse", "Coarse", "Moderate", "Fine", "Very Fine" or "User Defined".
   Growth Rate	Growth rate for neighbor mesh
   Nbr Segs per Edge	Number of segments per edge
   Nbr Segs per Radius	Number of segments per radius
   Optimize	Do optimization or not

6. The model tree after these settings

   The material and conditions are added under "Analysis" in the model tree. If you want to change these conditions, double-click the item in model tree and change parameters. If you want to delete these conditions, select the item in model tree and press Delete key.

   

Running calculation

Double-clcik "SolverCcxTools" in model tree to show a dialog for running calculation.

Confirm that "Static" has been selected as analysis type.

Click "Write .inp file" to write input file and click "Run CalculiX" to start calculation. When the calculation is finished successfully, messages as "CalculiX done without error!" and "Loading result sets..." will be displayed in the text area at the bottom of the dialog, so click Close to close the dialog.

After calculation, "CCX_Results" and "ccx_dat_file" items will be added to model tree as analysis result.

The next step is to view analysis result and to improve the shape.