Export FEM Mesh

The Export FEM Mesh dialog provides tools for exporting volume meshes to finite element analysis (FEA) solver formats. This includes defining materials, creating node sets and element sets for boundary conditions, configuring solver-specific options, and generating properly formatted output files.

Accessing the Dialog

The Export FEM Mesh dialog can be accessed in two ways:

1. Navigate to the Volume Mesh ribbon tab and click Export FEM Mesh in the FEM section
2. From the Configure FEM Model tool, click the Export... button

Supported Export Formats

Format	Extension	Description
Abaqus	.inp	Abaqus/Standard and Abaqus/Explicit input files
Nastran	.nas, .dat, .bdf	MSC Nastran and NX Nastran bulk data files
LS-DYNA	.k, .dyn, .key	LS-DYNA keyword input files for explicit dynamics
OpenFOAM	polyMesh	OpenFOAM mesh directory structure for CFD
Fluent	.msh	ANSYS Fluent mesh format
Gmsh	.msh	Gmsh mesh format for general meshing workflows

Dialog Tabs

The export dialog is organized into five configuration tabs:

Format & Output

Export Format

Select the target FEA solver format from the dropdown. The format determines:

• Output file syntax and structure
• Available format-specific options
• Required definitions (materials, sets, boundary types)

Output File

Specify the export file path. Click Browse... to select a destination folder and filename. The file extension is automatically suggested based on the selected format.

Format Options

Each format has specific configuration options:

Abaqus Options

Option	Description
Analysis Type	Static, Dynamic Explicit, Frequency, or Heat Transfer analysis
Write assembly structure	Include *ASSEMBLY and *INSTANCE definitions for assembly models
Include history output requests	Add *OUTPUT, HISTORY for time-based tracking

Nastran Options

Option	Description
Field Format	Small Field (8 char), Large Field (16 char), or Free Field
Write executive control section	Include SOL and CEND cards for standalone analysis
Export node sets as SPC constraints	Convert node sets to SPC1 boundary condition cards

LS-DYNA Options

Option	Description
Solid Formulation	ELFORM parameter: Constant Stress (1), Fully Integrated (2), or 1-Point Tetrahedron (10)
Write control cards	Include *CONTROL_TERMINATION and *CONTROL_ENERGY
Termination Time	Simulation end time in seconds

OpenFOAM Options

Option	Description
Case Name	Name of the OpenFOAM case directory
Create full case structure	Generate 0/, constant/, and system/ directories with templates
Write cell zones	Include cellZones for multi-region definitions

Fluent Options

Option	Description
Default Boundary Type	Wall, Pressure Inlet/Outlet, Velocity Inlet, or Symmetry
Default Cell Zone Type	Fluid, Solid, or Porous
Write comments	Include descriptive comments in output

Gmsh Options

Option	Description
Format Version	Version 2.2 (legacy) or Version 4.1 (current)
Write physical groups	Include $PhysicalNames for named regions

Export Preview

The preview area shows a sample of the output file structure, allowing verification before export.

Materials

Define material properties for the FEM model.

Auto-Assignment

Enable Auto-assign materials from grayscale values to automatically map CT image grayscale values to material properties. This is useful for bone modeling where density correlates with Hounsfield Units.

Select a Material preset as the base for grayscale mapping:

• Steel
• Aluminum
• Titanium
• Cortical Bone
• Trabecular Bone
• Soft Tissue

Materials Table

The materials table displays all defined materials with properties:

Column	Description
ID	Unique material identifier
Name	Material name (editable)
E (MPa)	Young's modulus (elastic modulus)
ν	Poisson's ratio
Density	Material density

Use Add Material to create new materials with default properties. Select a material and click Remove to delete it.

Sets & Surfaces

Define node sets, element sets, and surfaces for boundary conditions and output requests.

Node Sets

Collections of nodes for applying:

• Displacement constraints (fixed supports)
• Point loads and moments
• Prescribed temperatures
• Contact definitions

The table shows each node set's ID, name, and node count. Click Add Empty... to create a new node set.

Element Sets

Groups of elements for:

• Material assignment
• Output variable requests
• Initial conditions
• Load distribution

The table shows each element set's ID, name, and element count. Click Add Empty... to create a new element set.

Surfaces

Boundary face collections for:

• Pressure loads
• Contact definitions
• Surface-to-surface constraints
• Heat flux boundaries

Click Detect Boundaries to automatically identify and create surfaces from mesh boundary faces.

Click Remove Selected to delete the selected set or surface.

ROI-Based Set Creation

Create sets from Region of Interest (ROI) primitives:

1. Create ROI primitives (spheres, boxes, etc.) to define regions
2. Specify names for the new node set and element set
3. Click Create Sets and Surfaces from Visible ROIs

This creates:

• Node sets containing all nodes inside the ROI volumes
• Element sets containing elements with centroids inside the ROI
• Boundary surfaces of each element set

Parts

Parts group elements with assigned materials and section properties.

Parts Table

Column	Description
Name	Part name (editable by double-clicking)
Elements	Number of elements in the part
Material	Assigned material name
Section Type	Section definition type

Creating Parts from Element Sets

To create a part from an existing element set:

1. Select the element set from the dropdown
2. Select the material to assign
3. Click Create Part

This converts the element set into a part with the specified material assignment.

Use Add Part to create an empty part or Remove Part to delete the selected part.

Options

General Options

Option	Description	Default
Numeric precision	Decimal places for coordinate output	8
Include comments in output	Add descriptive comments to output file	Enabled

Mesh Statistics

Displays overview of the mesh being exported:

• Total node count
• Total element count
• Number of defined parts

Export Workflow

Basic Export

1. Open the Export FEM Mesh dialog
2. Select the target format
3. Configure format-specific options
4. Specify the output file path
5. Click Preview to verify output structure
6. Click Export to generate the file

Complete FEM Model Export

For a fully defined FEM model:

1. Materials Tab: Define material properties for each region
2. Sets & Surfaces Tab:
   • Create node sets for boundary conditions
   • Create element sets for material regions
   • Define surfaces for contact or loads
3. Parts Tab: Create parts from element sets with material assignments
4. Format & Output Tab: Configure export options
5. Export the complete model

Export for Structural Analysis (Abaqus Example)

1. Select Abaqus (.inp) format
2. Set Analysis Type to Static
3. Go to Materials and define material properties
4. Go to Sets & Surfaces:
   • Create node sets for fixed supports
   • Create element sets for different material regions
5. Go to Parts and assign materials to element sets
6. Set output path and click Export

Export for CFD (OpenFOAM Example)

1. Select OpenFOAM (polyMesh) format
2. Enable Create full case structure
3. Set the Case Name
4. Enable Write cell zones for multi-region setup
5. Go to Sets & Surfaces:
   • Detect boundary surfaces
   • Rename surfaces to match boundary conditions (inlet, outlet, wall)
6. Set output path and click Export

Scripting API

FEM export operations can be automated using Python scripting. See the FEM Operations API for available functions.

Related Tools

• Configure FEM Model - Visualize and manage FEM components
• Surface to Volume Mesh - Create volume meshes for FEM
• Render Properties - Visualize volume mesh before export
• Transform - Position mesh correctly before export