FEM and Blender

Introduction

• Blender
  • 3D print add-on (Check all)
  • BFEX - Blender FEA Exporter https://github.com/MiguelDLM/BFEX
  • Blendmsh https://github.com/senthurayyappan/blendmsh
  • quad remesher https://www.youtube.com/watch?v=kfQfU_cDRWE
  • Fix meshes https://github.com/evaherbst/Blender_remeshing_guide
• Elmer https://www.elmerfem.org/blog/
• FreeCAD
• Gmsh https://gmsh.info/
• Netgen https://ngsolve.org/
• OpenFOAM https://www.openfoam.com/
• Paraview https://www.paraview.org/
• Salome
• TetGen

Blender and CAD

• TinyCAD https://docs.blender.org/manual/en/4.1//addons/mesh/tinycad.html
• CadSketcher https://www.cadsketcher.com/
• Parts list
  • Using a script: Selected parts only, and don't apply rotations! https://github.com/kittengue-dot/Blender-Script-Export-Part-list https://www.youtube.com/watch?v=C1RZszKlojQ

import bpy
import csv

def export_selected_mesh_dimensions_to_csv(filepath):
    """Export Parts
    Args:
        filepath (str): Le chemin du fichier CSV de sortie.
    """

    with open(filepath, 'w', newline='', encoding='utf-8') as csvfile:
        fieldnames = ['Part', 'Section X (mm)', 'Section Y (mm)', 'Length Z (mm)']
        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)

        writer.writeheader()
        for obj in bpy.context.selected_objects:
            if obj.type == 'MESH':
                
                dimensions = obj.dimensions
                x = [0,0,0]
                x[0] = round(dimensions.x * 1000, 3)
                x[1] = round(dimensions.y * 1000, 3)
                x[2] = round(dimensions.z * 1000, 3)
                x.sort()

                writer.writerow({'Part': obj.name, 'X (mm)': x[0], 'Y (mm)': x[1], 'Z (mm)': x[2]})

filepath = "/home/user/Downloads/part_list.csv"  # Replace destination path

export_selected_mesh_dimensions_to_csv(filepath)

FreeCAD import

Steps:

• Export in Blender
  • Use Boolean
  • Eliminate the bolts and some holes
• Part -> Create shape from mesh
• Part -> MakeSolid

Some problems (see a Part check Geometry)

• Geometry is a shell -- not a solid: a shell mesh on meshing
  • Check this by right clicking on the mesh and printing mesh informations (Tasks: Node count vs Triangle count vs Tetrahedron count)
• Self intersections
  • Use Boolean
  • Self intersecting meshes are considered dirty
  • eg Netfabb cleans

Theory

Frame formulas: https://structx.com/frames.html