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Why the Main Node of a RBody moves automatically to a beam component.

I am defining a Node and using it as the main node of a Rbody. This Rbody is supposed to connect shell elements with a beam element. The Main node position is important as there is a Spring element that needs to have this node as one of it own. When I define this in Hypermesh, it looks like this:

Red element: RBody

Dark Grey: Beam to be connected with the shells

Green: Shells or Sh3ns

Light Grey: Spring

When I run Radioss with this model, there is no errors. I have Warnings due to the Main Node of some RBodies being connected to an element, but that has not been an issue in the past with other similar configurations. However, when I open Hyperview to see results, I get this:

I am afraid this would change the direction of the Spring force, as it is changing nodes locations.

Does anybody know why I am getting this effect?

Thanks in advance

Diego

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English

Radioss

v2022.1

Accepted answers

PaulAltair

The main node of an RBODY will (by default) be moved to CoG of the (main and) secondary nodes, for this reason standard, recommended practice is that you should not normally connect anything to it (it should be a free node), you should connect your spring to a secondary node instead probably, you may change the behaviour of the main node by setting icog flag differently (e.g. icog = 3) but I would recommend leaving it as icog =0/1 and connecting spring to secondary instead

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PaulAltair

Diego CARO MARTIN

The main node of an RBODY will (by default) be moved to CoG of the (main and) secondary nodes, for this reason standard, recommended practice is that you should not normally connect anything to it (it should be a free node), you should connect your spring to a secondary node instead probably, you may change the behaviour of the main node by setting icog flag differently (e.g. icog = 3) but I would recommend leaving it as icog =0/1 and connecting spring to secondary instead

Thanks a million, it helped me to identify a bigger issue, the CoG is in the Beam element because the mass is so much hihger than it should be hahah Anyways, thanks as always Paul, this has been super useful.