/RBODY

Engine Keyword

/RBODY - Activate/Deactivate Rigid Bodies

Description

Listed rigid bodies will be activated or deactivated.

Format

/RBODY/Keyword2

node_ID1... node_IDN

Data

Description

Keyword2

Activation flag:

ON: some part of the previous kinetic energy is accounted for as rotation energy of the rigid body.

OFF: most of the rotation energy of the rigid body becomes translational kinetic energy.

node_ID1 ...

node_IDN

List of master node numbers of rigid bodies.

Comments

1.	This option can lead to the deactivation of shells and solids entirely connected to a given rigid body, as shown below:

Activation flag	Effect on elements	Effect on rigid bodies
ON	deactivated	activated
OFF	activated	deactivated
Default (first run)	deactivated	activated
Default (subsequent runs)	as previous run	as previous run

2.	A limitation with /RBODY/OFF occurs on the solid or thick shell formulation in case a rigid body is set to OFF, and next set ON.

The stresses in solid elements included into the rigid body are non-zero, but do not turn with the rigid body rotations while the rigid body is set ON.

Consequently, there will be an error if the rigid body is next set OFF for:

•	8 node bricks and Isolid =1, 2, or 12

•	4 node tetrahedra

•	10 node tetrahedra

•	16 node thick shells and 20 nodes bricks

3.	The limitation does not apply to:

•	8 node bricks Isolid = 1, 2 and 12 with Iframe =2

•	8 node bricks and thick shells type HA8, HEPH and HSEPH

•	6 node pentahedra PA6

4.	If a rigid body is activated with /RBODY/ON, the center of gravity computation (ICoG) flag is then ignored; the rigid body is activated with respect to ICoG =2 characteristics (see /RBODY).