Analyze a surface model, create surfaces using the Midsurface and Patch tools, then
optimize the surfaces.
In this lesson you will learn how to:
Import surfaces from CAD
Assign a thickness to a surface using the Property Editor
Midsurface simple and complex thin solids
Create surfaces from solids using the Patch tool
Analyze and optimize surfaces
Overview
Surface or "shell" models are a way of representing thin-walled 3D structures in a
numerically accurate and efficient way. They are often used when the thickness of a
part is significantly thinner (approximately 1/10th or less) than its other standard
dimensions. Using surface models in these cases can produce much shorter analysis
and optimization run times.
Surfaces are typically created in one of the following ways:
Importing surfaces from CAD.
Using the sketching tools in Inspire.
Applying the Midsurface tool to a thin solid generated from CAD or in
Inspire.
Applying the Patch tool to a thin solid generated from CAD or in
Inspire.
Note: All surfaces must be assigned a thickness to run properly. For surfaces,
the geometry is always defined as being at the midsurface.
Analyze a Surface Model
Let's start by exploring the benefits of using surfaces.
Press F7 to open the Demo Browser.
Double-click the rhs_01.stmod file to load it in the
modeling window.
Make sure the display units in the Unit System Selector are set to
MMKS (mm kg N s).
Select the part.
The model is represented by a single part with multiple surfaces.
The rhs (right hand side) beam is restrained at one end and loaded at
the other, with forces and supports applied to the part edges.
Press F3 to open the Property Editor. A thickness of 10
mm has been assigned to the part under the Mass Properties.
Click the button on the Analyze icon to set up an analysis
using the following options.
Set the Element size to 4 mm and the
Speed/Accuracy to Faster.
Click Run and note the speed of execution. If this was
modeled as a solid, the run time would increase by an order of magnitude or more
to achieve similar accuracy in the results.
Double-click the run name to open the Analysis Explorer
and examine the Displacement and other results.
Import CAD and Assign a Thickness
One way to obtain a surface is to import a CAD model into
Inspire.
Note that all surfaces must be assigned a thickness in the Property Editor. Failure
to assign a thickness will prevent contacts from being detected and result in failed
runs.
Double-click the sheet_metal_bracket.x_t file in the Demo
Browser to import the CAD model into Inspire.
Select the Tray part and enter a Thickness of
5 mm under Mass Properties in the Property
Editor.
Assign a Thickness of 5 mm to the
Bosses part as well.
Select the Contacts tool on the Structure ribbon to
search for contacts, and orbit the model.
One contact is found and indicated by the thick blue lines on the shared part
boundaries.
Inspire uses a part-to-part contact definition with the
boss regions and the main structure in separate parts, so this is the expected
behavior.
Create Surfaces Using the Midsurface Tool
Surfaces can also be created directly in Inspire by applying
the Midsurface tool, which automatically detects thin solids and allows you to replace them
with a surface.
There are some restrictions on the types of parts that can be midsurfaced.
Note: The
Midsurface tool can only be applied to non-manifold (non-branching) parts with
constant thickness. X, Y, T and other similar types of sections are not
supported.
This restricts the target parts to those that can be formed or bent from
a flat initial sheet.
Slots, holes, and cut-outs are allowable.
Constant section non-manifold parts such as extrusions are
supported.
Partitioning of parts prior to midsurfacing and subsequent connection
with other parts can often be performed.
Double-click the midsurface_examples.stmod file in the
Demo Browser.
This model contains a number of thin solids that meet the requirements for
midsurfacing.
Select the Midsurface tool on the Geometry ribbon.
Select the L part in the modeling window to replace it
with a midsurface.
A preview of the midsurface is shown. The thickness is automatically
calculated and displayed in the microdialog, but cannot be edited.
Click the Extract button on the guide bar to extract the
midsurface.
Double-right-click to exit the tool, then select the newly created
midsurface.
Check the Property Editor and note that a thickness has been assigned to the
midsurface.
Note: The Midsurface tool automatically calculates thickness and assigns it to
the part. Surfaces created using another method must have a thickness
assigned manually in the Property Editor.
Select the Midsurface tool again and use box selection
to select the remaining parts.
Click Extract on the guide bar to extract the
midsurfaces.
Note: Note that while the parts in the fabricated bracket assembly are correctly
midsurfaced, they are not necessarily aligned.
Now open the plate.x_t file located in the Demo
Browser.
This is a more complex model.
Select the Midsurface tool on the Geometry ribbon.
Select the part in the modeling window. A preview of the midsurface is
shown.
Note: Even though the part has holes and curvature, it is a constant section and
satisfies the criteria for a valid thin solid.
Click Extract to create the midsurface and
double-right-click to exit the tool.
Create Surfaces Using the Patch Tool
Another way to create a surface is by applying the Patch tool to a solid.
More often used to close and repair geometry, the Patch tool can also be used to
delete surface patches on the solid. This is very powerful because as soon as any
solid has a patch deleted it becomes a surface. For example, the RHS model at the
beginning of the tutorial was created by deleting the ends of a solid rectangular
box.
Open the x-tubes.stmod file in the Demo Browser.
This model is a simple 3D structure created in Inspire,
but could also have been imported from CAD.
Click the face on the end of one of the tubes to select it.
You may need to zoom in to select the face.
Click again to delete the face.
As soon as it is deleted, the solid part becomes a surface, and an area
rather than a volume is shown in the Property Editor.
Use the same process to remove the remaining three faces from the ends of the
tubes, as well as all of the interior surfaces.
The model should look as shown below:
Double-right-click to exit the Patch tool.
Select the part and enter a Thickness of 5
mm in the Property Editor.
Note: The Mass is automatically calculated.
The model is now ready to have loads and supports applied for an analysis or
optimization. Open the x-tubes_RUN.stmod file in the Demo
Browser to load and view the model with analysis results.
Optimize a 2D Surface Model
Note that surfaces can be designated a design space, just as with solid
parts.
Press F7 to open the Demo Browser.
Open the 2dtopology_and_contact.stmod file from the Demo
Browser.
This model contains both geometry and loads.
Select the Tray part and enter a
Thickness of 3 mm under Mass
Properties in the Property Editor.
Assign a Thickness of 3 mm to
Part 1 and Part 2 as well.
Right-click on the Tray part to open the part context
menu and designate it as a Design Space.
button on the Analyze icon to set up an analysis
using the following options.
Tip: To find and open a tool, press Ctrl+F. For more information, see Find and Search for Tools.
