/RBE2
Block Format Keyword Defines a rigid body whose independent degrees of freedom are specified at a single independent node and whose dependent degrees of freedom are specified at an arbitrary number of dependent 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 |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
rbe2_ID | Rigid element
identifier (Integer, maximum 10 digits) |
|
rbe2_title | Rigid element
title (Character, maximum 100 characters) |
|
node_ID | Independent node
identifier (Integer) |
|
Trarotref | Code of DOF used for the
dependent components.
(6 Booleans) Default (blank or 6 zeros) set on all DOF |
|
Skew_ID | Local skew identifier of
element. (Integer) |
|
grnd_ID | Dependent nodes group
identifier. (Integer) |
|
Iflag | Dependent relation
formulation flag. 1
(Integer) |
Codes for Translation and Rotation: Trarot
(1)-1 | (1)-2 | (1)-3 | (1)-4 | (1)-5 | (1)-6 | (1)-7 | (1)-8 | (1)-9 | (1)-10 |
---|---|---|---|---|---|---|---|---|---|
TX | TY | TZ |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
TX | Code for translation
TX
(Boolean) |
|
TY | Code for translation
TY
(Boolean) |
|
TZ | Code for translation
TZ
(Boolean) |
|
Code for rotation
(Boolean) |
||
Code for rotation
(Boolean) |
||
Code for rotation
(Boolean) |
Comments
- Two formulations of dependent motion are available in
Iflag:If Iflag=0
(1) (2) If Iflag=1(3) (4) (5) With , , =0,1
The default formulation Iflag =0 corresponds to OptiStruct's RBE2, in which the motion of a group of dependent nodes depends on the motion of one independent node which always has 6 DOF. The input Trarotref is applied on the dependent nodes and the element behaves like a rigid body.
The second formulation is similar to /RLINK; but takes into account the equilibrium between translations and rotations. The input Trarotref is applied on independent node, this formulation is used prior to version 10.0.5.
- A independent node can be attached to a finite element. The independent node can also be defined in a different RBE2 as independent node and/or dependent node, but the dependent node cannot have the incompatible kinematic conditions.
- It is not recommended for dependent or independent nodes of an /RBE2 to also be dependent or independent nodes in another constraint equation (kinematic conditions). However, this is permitted if the hierarchy rule has been respected: RBE2 should have a higher level than Interface TYPE2 (independent nodes of Interface TYPE2 can be dependent 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.
- Hierarchy rule involving
/INTER/TYPE2, /RBE2,
/RBE3 and /RBODY
is:
RBODY > RBE3 > RBE2 > INTERFACE TYPE2
- More output messages could be obtained using Ipri of /IOFLAG: Ipri > 3 will printout new mass and inertia of the independent nodes; Ipri > 5 will printout the new RBE2 identifier and hierarchy level after re-ordering.
- The RBE2 uses a scalar inertia calculation similar to using /RBODY with Ispher=1.