## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Rotational acceleration – Ansys workbench

• simon_pr
Subscriber

Hello,

Currently I am working the harmonic analyse of a canteliver beam with Ansys workbench.

With a point for the load and another for the measurement, I got the FrF of the linear acceleration. However I would like to find how to measure rotational acceleration (or velocity). I can not choose rotational parameter in the tab to draw a frequency reponse fonction, it only offers linear parameters like acceleration or velocity.   I did fine tutorial or topic useful.. If you have any advice, it would be very kindly !

Simon

• sk_cheah
Subscriber

Hi Simon,

If you have solid elements, rotation degrees of freedom is not available. If you are you using shell elements, you could use User Defined Results with RZ being rotation in the Z axis.

Kind regards,
Jason

• peteroznewman
Subscriber

Hi Simon,

Vibration analysis is based on small deflections. When deflections are small, rotations are vanishingly small. I advise not looking at rotational deformations.

For a large deflection nonlinear Transient Structural model, finite rotations are worth looking at and Jason has provided some guidance on how to do that. In addition, on a solid model, there is a Flexible Rotation probe available.

• sk_cheah
Subscriber

Hi Peter,

When I tried that myself on a solid body, I got the error below. Looks like it does the same thing as User Defined Results RZ.

Kind regards,
Jason

• peteroznewman
Subscriber

Hi Jason,

Right click on Model to insert a Remote Point scoped to the face on the solid body of interest. Then scope the Flexible Rotation Probe to that Remote Point.

Kind regards,
Peter

• simon_pr
Subscriber

Hi Peter and Jason,

I agree that deflections could be small, but I am rather looking for angular accelerations which are larger (experimentally I have 30 ° / s², so measurable I think). Also I do not understand why it is possible to measure a normal acceleration that may be smaller than an angular acceleration (on vibration nodes for example).

I will try with the shell elements, in addition it is more suitable for my geometry.  Thanks

Kind regards,

Simon