About Mass Properties

Assign physical properties to components to calculate assembly weight and volume, to locate a center of gravity, and to export data to another application for further analysis.

Analyzing physical properties helps you evaluate how your designed model correlates to its physical counterpart. To verify design intent, you can calculate physical properties for both parts and assemblies.

Analyzing physical properties helps you evaluate how your designed model correlates to its physical counterpart. To verify design intent, you can calculate physical properties for parts.

Mass properties are not automatically updated with model changes. If model changes affect physical properties, the last known values become out of date and display N/A.

BOM expressions and drawing text may display physical properties (mass, volume, area, and density). N/A is displayed in BOM expressions and drawing text whenever model properties are out of date.

Tip: To maintain physical properties up to date when the model is saved, select the Update Physical Properties on Save option in the Application Options dialog box.

Note: Enter a volume and mass for virtual components. When a virtual component has a volume or mass, the moments of inertia, surface area, and center of gravity of an assembly using virtual components may not be accurate. Possible reasons are:

• The location of virtual component cannot be defined other than the origin of the assembly.
• The surface area and moments of inertia of virtual components do not exist.

Why calculate physical properties?

It is useful to assign physical properties to components to calculate assembly weight and volume, to locate a center of gravity (for placement of a handle that is critical for balance, for example), and to export data to another application for further analysis.

It is useful to assign physical properties to components to locate a center of gravity, and to export data to another application for further analysis.

Which properties are calculated?

You can specify different materials for individual components, set analysis tolerances, and calculate values such as:

• Center of gravity
• Mass, volume, and surface area
• Mass moments of inertia
• Principle moments of inertia
• Orientation of principle axes

How are physical property calculations affected by occurrences and cosmetic welds?

Many designers place a single occurrence of a small part such as a rivet or screw in an assembly, knowing that the final assembly requires thousands of the same item. Designers trade the advantage of faster loading and updating of the assembly for accuracy, knowing that they can override the calculated number of occurrences with the correct count in the bill of materials.

The calculation of physical properties includes quantity overrides and cosmetic welds.

Can I override calculated physical properties?

User-defined override values are allowed for both mass and volume. By entering your own values, you can adjust for and accurately represent the true physical mass and volume of selected components that cannot be modeled, such as oil or grease added to a completed assembly. Override values also offer more accurate modeling when working with simplified representations, such as an assembly in which multiple fasteners are represented only as centerlines.

User-defined override values are allowed for both mass and volume. By entering your own values, you can adjust for and accurately represent the true physical mass and volume of selected components that cannot be modeled.