/RBE2

Block Format Keyword

/RBE2 - Rigid Element

Description

Defines a rigid body whose independent degrees of freedom are specified at a single master node and whose dependent degrees of freedom are specified at an arbitrary number of slave nodes.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/RBE2/rbe2_ID
rbe2_title
node_ID	Trarotref	skew_ID	grnd_ID	Iflag

Field	Contents
rbe2_ID	Rigid element identifier (Integer, maximum 10 digits)
rbe2_title	Rigid element title (Character, maximum 100 characters)
node_ID	Master node identifier (Integer)
Trarotref	Code of DOF used for the dependent components (6 Booleans) =0: free DOF =1: fixed DOF Default (blank or 6 zeros) set on all DOF
skew_ID	Local skew identifier of element (Integer)
grnd_ID	Slave nodes group identifier (Integer)
Iflag	Dependent relation formulation flag (Comment 1) (Integer) = 0: Rigid body formulation (OptiStruct) (default) = 1: Rigid link formulation

(1)-1	(1)-2	(1)-3	(1)-4	(1)-5	(1)-6	(1)-7	(1)-8	(1)-9	(1)-10
			TX	TY	TZ		X	Y	Z

Field	Contents
TX	Code for translation TX =0: free DOF =1: fixed DOF (Boolean)
TY	Code for translation TY =0: free DOF =1: fixed DOF (Boolean)
TZ	Code for translation TZ =0: free DOF =1: fixed DOF (Boolean)
X	Code for rotation X =0: free DOF =1: fixed DOF (Boolean)
Y	Code for rotation Y =0: free DOF =1: fixed DOF (Boolean)
Z	Code for rotation Z =0: free DOF =1: fixed DOF (Boolean)

1.	Two formulations of dependent motion are available in Iflag:

rbe2_Iflag_eq

The default formulation Iflag =0 corresponds to OptiStruct’s RBE2, in which the motion of a group of slave nodes depends on the motion of one master node which always has 6 DOF. The input Trarotref is applied on the slave nodes and the element behaves like a rigid body.

The second formulation is similar to Rigid Link; but takes into account the equilibrium between translations and rotations. The input Trarotref is applied on master node, this formulation is used prior to version 10.0.5.

2.	A master node can be defined in different RBE2 as master node and/or slave node, but the slave node cannot have the incompatible kinematic conditions (depends on different independent nodes in the same component directions).

It is not recommended to define a hierarchy involving RBE2, with other constraint equation (kinematic conditions), However, this is permitted if the hierarchy rule has been respected: RBE2 should have a higher level than Interface type 2 (master nodes of Interface type 2 can be slave node of RBE2); but a lower level than RBE3 and RBODY. The hierarchy between different RBE2s is allowed, re-ordering will be done automatically to determine the hierarchy by RADIOSS Starter, if hierarchy levels between RBE2 are too high, error will be printed out.

4.	Hierarchy rule involving /INTER/TYPE2, /RBE2, /RBE3 and /RBODY is the following:

RBODY > RBE3 > RBE2 > INTERFACE TYPE2

5.	More output messages could be obtained using Ipri of /IOFLAG: Ipri > 3 will printout new mass and inertia of the master nodes; Ipri > 5 will printout the new RBE2 identifier and hierarchy level after re-ordering.