mesh2cdb

Write MAPDL .cdb archives from any mesh meshio reads.

meshio reads about forty mesh formats and writes thirty. .cdb is not one of them, so a mesh built in gmsh, Abaqus or Nastran has no path into MAPDL. That is the gap this fills.

Installation

pip install mesh2cdb

Usage

mesh2cdb part.msh -o part.cdb
mesh2cdb part.inp                 # .bdf, .vtu, .vtk, ...

part.msh -> part.cdb
  1364 nodes, 650 tetra10
  node component FIXED: 205
  elem component BODY: 650

From Python:

import meshio
from mesh2cdb import from_meshio, write

write(from_meshio(meshio.read("part.msh")), "part.cdb")

Then in MAPDL:

from ansys.mapdl.core import launch_mapdl

mapdl = launch_mapdl()
mapdl.prep7()
mapdl.cdread("DB", "part.cdb")

Elements

Wedges and pyramids are written as degenerate SOLID185/186 with repeated nodes. Unsupported cell types raise rather than being silently dropped.

Named regions

gmsh physical groups and Abaqus *NSET/*ELSET become MAPDL components:

gmsh.model.addPhysicalGroup(2, [face], name="fixed")   # in the mesher

mapdl.cmsel("S", "FIXED")                              # in MAPDL
mapdl.d("ALL", "ALL", 0)

Solid groups become element components; surface groups become node components. Names are uppercased, non-alphanumeric characters become underscores, and the limit is 32 characters. Two names that collide after that are refused rather than merged.

The mesh converts from every format meshio reads. Names do not:

Not supported

Materials, sections, boundary conditions, loads and load steps. .cdb carries all of them; this writes nodes, elements, element types and components only.

Shells and beams.

CAD geometry. MAPDL cannot import STEP; mesh it in gmsh and convert the mesh.

Tests

pip install mesh2cdb[test]

python tests/verify_meshio.py         # reader agreement
python tests/verify_formats.py        # what survives each format
python tests/verify_all_elements.py   # patch test per element type, launches MAPDL
python tests/verify_cmblock.py        # named regions reach MAPDL, launches MAPDL

Each asserts and exits non-zero. tools/ holds interactive helpers for regenerating the node-ordering tables and inspecting a .cdb; they open windows, so they are run by hand.

gmsh and ansys-mapdl-core are test dependencies only. ansys-mapdl-core>=0.73.2 is a hard floor: earlier versions fail to launch MAPDL 2026 R1 with MapdlDidNotStart: No err file generated.

Licence

MIT. Not affiliated with Ansys, Inc. Using the output requires a legal Ansys licence.