MASS PROPERTIES

[dawn836]

Hi all
I have an object drawn in 3d using lines and 3d face object i want to find the mass properties of this shape like center of gravity and volume etc...

How can i do this?!

 

[CADSTUDENT]

Dawn836
The MASSPROP command allows you to analyze a solid model for its physical properties. The data obtained from MASSPROP command can be retained for reference by saving it a ASCII text file with an .mpr extension (mass properties). The analysis can be used for third party applications to produce finite element analysis, material lists, or other testing studies. Selecting the MASSPROP command by selecting inquiry in the Tools pull-down menu and then picking Region/Mass Properties, picking the Mass Properties button in the inquiry toolbar, or typing MASSPROP at the command: prompt. Hope this helps - John

 

[dawn836]

well thanks for answer but i already know that this work good in 2d
is there a way to do massprop is 3d?

 

[cadcoke5]

This command does work in 3d. But, like many AutoCAD commands, only works on a subset of 3d objects... specifically ACIS solids (which list as 3DSOLID if you list them).

If the object isn't already an ACIS object, there might be ways to convert them, but not within AutoCAD.

 

[structuresguy]

Hi

The above post is correct, sort of. If you can create the 3D element by extruding a polyling or region, the mass properties command will work. So for relatively simple shapes, you can easily create the 3D element inside autocad. More complex shapes would be tedious to create in CAD, but could still be done.

Not knowing what your object looks like, but going on "lines and 3d face object", it should be possible to assemble the 3d solid by extruding the faces and combining them to form the product you want.

Hopes this helps.

One further tip I have found using mass properties. If you move the item so that its centroid is located at 0,0,0 you will find that the principle moments equal the moment of inertia about the centroid. This makes it a little easier to know for sure which is the correct moment to use. At least I think so, but I may not know exactly what all the various properties mean. Usually I want the moment of inertia bent about the neutral axis for structural purposes. But others may want other moments about a reference axis for other reasons.