Rotation of a plane in Radioss

Hello everyone!

I have a two dimensional component - a surface meshed with 2D elements, which needs to rotate around a certain point in the system. The point is not the global system's origin, rather, it is defined by a set of known coordinates.

I want the component to imitate a perfectly rigid body and to have a uniform displacement, which is why I have connected all of its nodes with one rigid body element.

The next step would be to give the plane a set of boundary conditions:

1. Constrain all DOF except the rotation around the desired axis (constrained at the main rigid body node)

2. Define an IMPVEL for the rotation around the desired axis (defined at the main rigid body node)

3. Define a coordinate system in the point of rotation (coordinates already known) and reference it to the boundary conditions.

My question here is, is this approach correct? And what kind of coordinate system makes sense in this situation? SKEW/MOV, SKEW/FIX, FRAME/MOV, FRAME/FIX...

I have tried multiple configurations, but for now, I cannot make the plane component rotate about the pre-defined point. It just seems to be rotating around its own center (the main rigid body node).

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Radioss

v2022.3

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Polyvios Romanidis

Hi Martina,

Based on what you described you should also see some changes in your rigid body, when you insert your results to HyperView.

In order to keep the imposed velocity load to the node you have applied you have to go to /RBODY element card and set ICOG = 3 or 4.

You can see the different ICOG formulations available in the following image:

As it has to do with the coordinate systems you can refer to the following links in order to get more info:

https://help.altair.com/hwsolvers/rad/topics/solvers/rad/frames_overview_starter_r.htm

https://help.altair.com/hwsolvers/rad/topics/solvers/rad/skews_overview_starter_r.htm

In general Skew (/SKEW) systems are located in (0,0,0) point, while frames (/FRAME) are located in a specific point. The moving systems (/MOV) are moving with the nodes, while the fixed ones (/FIX) are not.

If you are more interesting in comparing /SKEW and /FRAME you should visit the following link:

https://help.altair.com/hwsolvers/rad/topics/solvers/rad/modeling_tools_c.htm#skew_and_frame_modeling_tools_r

Polyvios

Martina Blazheska

Hi Martina,

Based on what you described you should also see some changes in your rigid body, when you insert your results to HyperView.

In order to keep the imposed velocity load to the node you have applied you have to go to /RBODY element card and set ICOG = 3 or 4.

You can see the different ICOG formulations available in the following image:

As it has to do with the coordinate systems you can refer to the following links in order to get more info:

https://help.altair.com/hwsolvers/rad/topics/solvers/rad/frames_overview_starter_r.htm

https://help.altair.com/hwsolvers/rad/topics/solvers/rad/skews_overview_starter_r.htm

In general Skew (/SKEW) systems are located in (0,0,0) point, while frames (/FRAME) are located in a specific point. The moving systems (/MOV) are moving with the nodes, while the fixed ones (/FIX) are not.

If you are more interesting in comparing /SKEW and /FRAME you should visit the following link:

https://help.altair.com/hwsolvers/rad/topics/solvers/rad/modeling_tools_c.htm#skew_and_frame_modeling_tools_r

Polyvios

Hello Polyvios,

Thank you for your answer! I did not know about the ICoG option for RBody.

I tried to set the, but it unfortunately resulted with the same behavior in the plane on which the rigid body is attached. The plane is just rotating around the rigid body's main node, instead of around the origin of the coordinate system I assigned.

Do you maybe have another idea how to solve this?

Thanks for your time,

Martina

Polyvios Romanidis

Hello Polyvios,

Thank you for your answer! I did not know about the ICoG option for RBody.

I tried to set the, but it unfortunately resulted with the same behavior in the plane on which the rigid body is attached. The plane is just rotating around the rigid body's main node, instead of around the origin of the coordinate system I assigned.

Do you maybe have another idea how to solve this?

Thanks for your time,

Martina

Based on what you described I have created a model to showcase the effect of ICOG parameter. I attach this file, so you can see the set up! This object is rotating in a node different from the center of mass!

If the point of rotation is outside of your surface body you can insert a free node at the axis of rotation and make this node the master node of the body even if it is not located in your original geometry!

Polyvios

first_trial_0000.rad

first_trial_0001.rad

Martina Blazheska

Based on what you described I have created a model to showcase the effect of ICOG parameter. I attach this file, so you can see the set up! This object is rotating in a node different from the center of mass!

If the point of rotation is outside of your surface body you can insert a free node at the axis of rotation and make this node the master node of the body even if it is not located in your original geometry!

Polyvios

Hello Polyvios!

I did indeed set the main node in the desired center of rotation and now the plane is moving the way I intended it to.

Thanks!