Learning Forum

[vinnakbm]

Hi

In CFX, can a rigid body motion be defined about an axis not passing through the center of mass? In my simulation the lever center of mass is different from its pivot point. Any help is appreciated!! Thank you

[Surya Deb]

Hello, 

Yes. You can create your own coordinate system and then use that as your "Coordinate Frame" for the Immersed Solid/Rigid Body Solution. You can then specify the moment of inertias about this system.

Regards,

SD

[vinnakbm]

Thank you for your response Surya. In the documentation, I found that the rigid body coordinate frame must be placed at the center of mass. I created my global coordinate frame at the pivot (same orientaion as the rigid body coordinate frame but Y axis translated by a certain amount). So, should I specify the mass moment of intertia about global axes instead of center of mass? Also, in the "Dynamics tab", the documentation states that the rotational degrees of freedom have to specified w.r.t. a coordinate frame

• Has the same initial orientation as the rigid body coordinate frame
• Has its origin at the rigid body center of mass
• Moves rigidly with the rigid body

How can these conditions be satisfied even I specify the mass moment of inertia about the global axis? 

Thank you!