HyperMesh (and OptiStruct) mesh export workflow

Introduction

This section presents the steps to follow in HyperMesh (V14.0) to export the mesh in a Nastran file.

Preliminary

Before detailing the workflow to follow, here are some useful information for a first HyperMesh using :

  • To displace the geometry in the graphic area, the Ctrl key must be always pressed. To move by translation, use the right click. To move by rotation, make one left click to define the rotation center, then move the mouse with the left click
  • To select objects (faces, solids, etc.), make a left click on each object. To unselect objects, make a right click on each object.
  • The transparency of geometry and mesh is managed by the following icons:

To open the help, press the key « F1 ». The help will be opened on the page concerning the active command.

Workflow

In the following table, the steps to follow in HyperMesh for a nominal scenario are presented (geometry imported from CAD file, air box creation, etc.).

Note: This workflow request some competences with HyperMesh.
Stage Description Illustration
1 Open HyperMesh > HyperMesh Desktop
2 In the « user Profiles » window choose the «Nastran» or «OptiStruct» format and validate the box
3

Import the geometry CAD file

→ After the import, the components are visible in the « Model » tab.

It is possible to manage the visibility of each component (geometry and mesh)
4

Make the assembly of the objects in contact to have a conform mesh:

Geometry > Edit > Solids > Boolean

  • Choose the operation A+B (keep all parts), in the category « advanced »
  • Choose to combine through « none »
  • Select a solid in « A », then the other solid (in contact) in « B »
  • Click on « calculate »
  • Click on « return »

→ The faces in contact become yellow.
5

Create the surface mesh :

Mesh > Create > 2D Automesh

  • Select all the surfaces to mesh (click on « surfs », then on « all » to mesh all)
  • Define the « element size » (measure the distance between 2 points of the geometry if necessary)
  • Choose the elements shape (triangle/quadrangle/…)
  • Choose the mesh order (1 st or 2 nd )
  • Etc… (define other parameters if necessary)
  • Mesh by clicking on « mesh »
  • Click on « return »
6

It is possible to create the air box in HyperMesh or in Flux.

If user wants to create the air box in HyperMesh :

  • Create a new component for the air box (click right on « component » in the « model » tab, then make « create » or « duplicate »)
  • Create the box:

    Geometry > Create > Solids > Block

  • Click on « base node »
  • Enter the coordinates of the 3 vertex
  • Click on « return »
  • Click on « create »

→ The box is automatically assigned to the component created before.
7

If user has created the air box in HyperMesh (previous step):

To manage correctly the air box volume mesh, a Boolean operation of separation has to be applied:

Geometry > Edit > Solids > Boolean

  • Choose the operation {A-B,B} which is in « simple (combine all) »
  • Select in A the box, and in B the device geometry
  • Click on « calculate »
  • Click on « return »
8

Mesh in volume :

Mesh > Create > Tetra Mesh

  • Select all the solids
  • Choose the elements type in 2D and 3D
  • Choose the option « Elems to Surf/Solid Comp » to assign a component mesh to the component
  • Define the element size value
  • Click on « mesh »
  • Click on « return »
9

Create the properties and assign to each component :

Properties > Create > Properties

  • Click on the command « properties » to create a property. Repeat the operation to create one property per component
  • Assign to each component a property: for that, select a component in the data tree and choose the property in the window below.

→ This operation allows identifying the volumes at the import in Flux.
10

Export the mesh in a Nastran (.bdf,…) or OptiStruct (.fem) file :

File > Export > Solver deck