Finding internal volume of vessels in Inventor

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Finding the mass and volume of a solid part is relatively easy in Inventor, as it is in any parametric modeler.  However, it is not as intuitive to find the volume or mass of an internal volume as one would need to do when designing enclosures or preparing models for CFD analysis.  In this blog post, I will discuss one method to extrapolate the said physical properties of an internal volume as defined by solid part geometry.

Overall, this workflow is dependent on using surfaces and surfacing tools, specifically Patch and Sculpt, so much of our effort will go towards defining useful surfaces.

Finding Internal Volume in Inventor Professional

Step 1 – Prepare your Model

To start, you will use the Copy Object command to make a duplicate of our solid part as a surface object.  The Copy Object command is found in the expanded Modify panel:

From there, set the Input Geometry selection to “solids” and the output to “surface” (“composite” is fine too though) as shown in this picture:


After clicking Okay, the screen should look like the following picture. Notice there is a new folder for surfaces under the normal bodies folder. Feel free to rename the solid bodies and surfaces as needed:

Step 2 – Patch the Holes

From here, surfaces will be used to define the boundaries of the internal volume. Start by turning off visibility of our solid body by right clicking on the solid body under the solid bodies folder in the model browser:

From here, use the Sculpt command to fill in the open faces.  Select the edges which will define the boundary loop of the desired surface. Colors of the surface objects can be changed for convenience as well.

Step 3 – Sculpt the Internal Volume

Initiate the Sculpt command and select the new body option. Clicking the double arrows will expand the dialog box to show more information about your selections as shown:

Select the surfaces either in the workspace or from the model browser.  Note that after you select your surfaces, these green glyphs show up indicating the direction that the resulting solid should build towards. It is not always intuitive to use these glyphs or set the correct directions, but you can also use the details section to select the directions as well.

Click OK and you should now have a solid body:

Step 4 – Checking the Physical Properties

Two solid bodies should now be showing under your solid bodies folder. Note that the materials have been adjusted for the below pictures for visibility, but material choice will of course affect your density and mass properties.

Checking the iProperties of the overall part and looking under the physical properties, the combined results of the two bodies will be displayed:

Right-clicking on the individual bodies allows you to check the physical properties specific to that body:

And that’s it, we’re done. There are multiple ways to derive this information within Inventor.  This method is particularly useful in that it keeps all information within a single file. You can turn off the extra body and surface objects, as necessary.