CAD-Line | Mass Properties tab

See also : CAD-Line dialog-box


MechDesigner has three sources of Mass-Properties:

Mass-Properties that are user-defined on the CAD-Line.
Mass Properties imported with a SolidWorks document.
Mass Properties that are derived from Profile/Extrusions on a Part.

CAD-Line dialog-box

Mass Properties tab

Dialog-13.2-CADLine-Masstab


tog_minus User Mass Properties 

Dialog-13.2-CADLine-Mass-User

Mass : (kg)

Centre-of-Mass: X–axis (mm)

The X-axis is along the CAD-Line, with (0mm) at the start-Point of the Part.

Centre-of-Mass: Y–axis (mm)

The Y-axis is at +90º from the CAD-Line, with (0mm) at the start-Point of the Part.


Inertia

If you define the mass on its position, then the mass will be a Point-Mass.

Its mass distribution is defined its

Radius-of-Gyration (mm)

or

Moment-of-Inertia (kg.m2)

Note: Units: kilogram.metres2 NOT kilogram.millimeter2

If you enter Moment-of-Inertia, then with the Mass, MechDesigner calculates the equivalent Radius-of-Gyration

Radius of Gyratio3

If you enter Radius-of-Gyration, then with the Mass, MechDesigner calculates the equivalent Moment-of-Inertia

Radius of Gyratio4


Parallel Axis Theorem

MechDesigner uses the Parallel Axis Theorem to calculate the Moment-of-Inertia, Io , about the Part's rotational axis:

I0 = IG +M.h2 where h is the distance from the Centre-of-Mass to the rotational axis

tog_minus SolidWorks Mass Properties 

When you import a SolidWorks document onto a CAD-Line, you can also import the SolidWorks Mass-Properties

Dialog-13.2-CADLine-Mass-SW

Button Red-14-1b IMPORT / UPDATE Mass Properties FROM THE ACTIVE SolidWorks DOCUMENT

Note: Before you click this button, make sure that the  active SolidWorks document is the model on the CAD-Line.

Mass : (kg)

The Mass of the active SolidWorks document SolidWorks

Centre-of-Mass : X-axis: (mm)

The distance along the X-axis from the CAD-Line start-Point to the Centre-of-Mass.

Centre-of-Mass Y-axis (mm)

The distance along the Y-axis, from the CAD-Line start-Point to the Centre-of-Mass.

Moment-of-Inertia (C.o.G) (kg.m2)

The Inertia with respect to the Centre-of-Mass

Button Red-14-2 Remove SolidWorks Mass Properties

tog_minus Total Mass Properties 

Total Mass Properties:

The Total Mass Properties for ALL CAD-Lines in one Part.

EXPLICITLY: the Total Mass Properties include, for each Part, ALL of those:

Mass and Mass-Properties as calculated for ALL Profile/Extrusions in the Part
User Mass-Properties as defined for ALL CAD-Lines in the Part
SolidWorks Mass-Properties as defined for ALL CAD-Lines in the Part

Dialog-13.2-CADLine-Mass-Total

NOTES:

Parallel-Axis Theorem

Inertia about Part's Rotational-Axis = Total Inertia about Centre-of-Mass + Mass × (Distance to Part's Rotational-Axis)2


Relationship between Moment-of-Inertia and Radius of Gyration

Total Inertia (about Center-of-Mass) = Total Mass × (Radius-of-Gyration)2


Total Mass of Part =

Mass of all Extrusions + Total mass of other CAD-Lines in the same Part


Total Inertia about the Part's Centre-of-Gravity =

Inertia of all Extrusions + Total Inertia of other CAD-Lines in the same Part

Tutorials and Reference Help Files for MechDesigner and MotionDesigner 14.2 + © Machine, Cam, Mechanism, and Motion Design Software by PSMotion Ltd