How to Pre-Process Tire Model: Option 1 (Automated)
The PM FlexTire™ pre-processor (STPtoOBJ.exe) is a Python-based executable that:
- Converts STEP files to BDF mesh files.
- Converts BDF files to Wavefront OBJ files for use in EDEM.
For a full list and description of available flags, refer to Appendix D of the PM FlexTire™ User Manual. For quick reference, see the image below summarizing the pre-processor flags.
Example Automated Workflow: Tractor Tire
Below is a batch file example demonstrating the automated conversion of Tractor_Tire.stp to an OBJ file while generating the required .off files for simulation:
Key details in this example:
- STEP file converted:
Tractor_Tire.stp - Meshing tool: Altair HyperMesh
- Bead tolerance: 5% of meshed elements
- Element size: Max = 50 mm, Min = 25 mm
- Belt threshold: 84% of nodes
- Offset: 1260 mm in the Z direction
- Rotation: -90° about the Y-axis
Batch File Command:
"C:\Program Files\Altair\2024\EDEM\bin\STPtoOBJ.exe" -c mesher_config.yml -i Tractor_Tire.stp -hm -tol 5.0E-02 -max 50.0 -min 25.0 -dbelt 0.84 -x 0.0 -y 0.0 -z 1260.0 -b313 0.0 -90.0 0.0
About mesher_config.yml
The mesher_config.yml file was introduced to eliminate the need to set environment variables manually. Below is an example of its structure for reference:
Output Files Generated
Running STPtoOBJ.exe produces the following outputs:
tire.obj – Wavefront OBJ file used in EDEM for tire geometry.tire.bdf – Nastran BDF file for reference/debugging (not used in the solver).tire_bead.off – Surface elements in contact with the rim.tire_inside.off – Surface elements subjected to applied air pressure.tire_belt.off – Surface elements comprising the belt.tire_sidewall.off – Surface elements comprising the sidewalls.
These outputs prepare your tire model for direct use in PM FlexTire™ simulations within EDEM.
How to Video
The Step-by-step video can be access here: Altair How-to-Video
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