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MODFEM BDF
File conversion

Convert MODFEM to BDF

Verified by Adam B.· reviewed by FE Editorial ·updated Jul 10, 2026
QUICK ANSWER
Is it possible to convert MODFEM to BDF?
Yes - MODFEM converts to BDF.

Open the .modfem model in Femap and use File > Export > Analysis Model, choosing a Nastran analysis type, to write a .bdf (Nastran bulk data) file. The export contains the FE data - nodes, elements, properties, materials, loads and constraints - but not the underlying CAD geometry, groups or postprocessing results.

Also to BDF: FNT · EDF

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Tested on macOS, Windows & Linux
Last verified Oct 2026

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Why convert MODFEM to BDF?

A .modfem is Femap's binary model database, which solvers cannot read. Exporting to a Nastran .bdf bulk data deck lets the mesh and boundary conditions be solved by Nastran-family solvers (Simcenter Nastran, MSC Nastran, NX Nastran and others) that expect this standard text format.

How to convert MODFEM to BDF

Simcenter Femap - Export Analysis Model

Open the .modfem, then run File > Export > Analysis Model and pick a Nastran solver. Femap writes the deck as a .bdf (equivalent to .dat) in ANSI bulk-data format.

Femap analysis set / analysis manager

Define an Analysis Set for a Nastran solver and export it; this generates the same .bdf bulk data and lets you control small- vs large-field formatting.

About these formats

.MODFEM Femap Model File

A .modfem file is the native model file saved by Femap (now Simcenter Femap), the finite element analysis pre- and post-processor from Siemens. It stores a complete FE model in one binary…

Open .MODFEM details →
.BDF Glyph Bitmap Distribution Format

A BDF file is a bitmap font in the Glyph Bitmap Distribution Format, defined by Adobe and widely used in the X Window System on Linux and Unix. The file is plain ASCII text, so any text…

Open .BDF details →

Quality & what to watch

  • The .bdf export includes only FEM data - nodes, elements, properties, materials, loads and constraints - and drops the CAD geometry stored in the .modfem.
  • Groups, views and any solved results are not written into the bulk data file.
  • Small-field format truncates precision; switch to large-field output if your model needs more significant digits.

Frequently asked questions

Is a .bdf the same as a .dat file?
Yes - Femap writes Nastran bulk data with the same content whether the extension is .bdf or .dat.
Does the geometry come across?
No. Only the finite-element mesh and boundary conditions are exported; the Parasolid geometry stays in the .modfem.
Which Nastran flavors can read it?
Pick the matching analysis type in Femap; the deck targets Simcenter/NX/MSC Nastran, and minor card differences exist between flavors.
Can I re-import the .bdf into Femap?
Yes, via File > Import > Analysis Model, which rebuilds the mesh but not the original geometry.