RADIOSS, MotionSolve, and OptiStruct

RBE3

RBE3

Previous topic Next topic No expanding text in this topic  

RBE3

Previous topic Next topic JavaScript is required for expanding text JavaScript is required for the print function  

Bulk Data Entry

RBE3 – Interpolation Constraint Element

Description

Defines the motion at a "reference" grid point as the weighted average of the motions at a set of other grid points.

Format

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

RBE3

EID

blank

REFGRID

REFC

WT1

C1

G1,1

G1,2

 

 

G1,3

WT2

C2

G2,1

G2,2

etc.

WT3

C3

 

 

G3,1

G3,2

etc.

WT4

C4

G4,1

G4,2

etc.

 

 

"UM"

GM1

CM1

GM2

CM2

GM3

CM3

blank

 

 

blank

GM4

CM4

GM5

CM5

etc.

 

blank

 

Example

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

RBE3

14

 

100

1234

1.0

123

1

3

 

 

5

4.7

1

2

4

6

5.2

2

 

 

7

8

9

5.1

1

15

16

 

 

 

UM

100

14

5

3

7

2

 

 

 

Field

Contents

EID

Unique element identification number.

REFGRID

Reference grid point.  This is the dependent GRID.  Some, or all, of the dependent degrees-of-freedom of this grid can be made independent by redefining all of the dependent degrees-of-freedom following the UM flag.

(Integer > 0)

REFC

Global components of motion whose values will be computed at the reference grid point.  Any of the digits 1, 2, ..., 6 with no embedded blanks.

(Integer > 0)

WTi

Weighting factor for components of motion on the following entry at grid points Gi,j.

(Real)

Ci

Global components of motion that have weighting factor WT, at grid points Gi,j.  Any of the digits 1, 2, ..., 6, with no embedded blanks.

(Integer > 0)

Gi,j

Grid point whose components Ci have weighting factor WTi in the averaging equations.

(Integer > 0)

UM

Optional flag indicating that a data set redefining the entire dependent degree-of-freedom set is to follow.  The default is that all of the components in REFC at the reference grid point form the dependent degree-of-freedom set. See comments 4, 5 and 6.

GMi

Grid points with components in the redefined dependent degree-of-freedom set.

(Integer > 0)

CMi

Components of motion at GMi in the redefined dependent degree-of-freedom set.  Any of the digits 1 through 6, with no embedded blanks.

(Integer > 0)

Comments

1.It is recommended that for most applications only the translation components 123 be used for Ci.  An exception is the case where the Gij are collinear.  A rotation component may then be added to one grid point, to stabilize its associated rigid body mode for the element.
2.Blank spaces may be left at the end of a Gij sequence.
3.The default for the dependent degree-of-freedom set should be used except in cases where you want to redefine some or all REFC components as the dependent degree-of-freedom set.  If the default is not used for the dependent degree-of-freedom set:
The total number of components therein (i.e., the total number of dependent degrees-of-freedom defined by the element) must be equal to the number of components in REFC (four components in the example).
The components therein must be a subset of the components mentioned in REFC and Gij_Ci.
The coefficient matrix [Rm] in the constraints equation [RM] {um} + [Rn] {un} = 0 must be nonsingular, where um denotes the dependent degree-of-freedom set and un denotes the independent degree-of-freedom set.
4.When the AMSES eigenvalue solver is used, the UM data should be used when loaded RBE3 have more than 500 DOF.  Large loaded RBE3 will dramatically increase the run times for AMSES because the residual vectors will contain many DOF, unless the UM data is used to make the loaded center GRID independent.
5.UM data should not be used on large unloaded RBE3, as this will lead to an increase in the run time.
6.Dependent degrees-of-freedom assigned by one rigid element may not also be assigned dependent by another rigid element or by a multi-point constraint, and may not be specified on SPC data.
7.In version 5.0, the RBE3 element calculation was modified in order to make the results independent of the units used in the model.  For this purpose, the weights of the rotational degrees-of-freedom have been scaled by the square of the average distance between the independent grid points and the reference point.  This change will only affect the results if independent grid points with rotational degrees-of-freedom exist in the RBE3 element.  The previous RBE3 formulation can be enforced with the debug statement debug,OLDRBE3,1.0.
8.Rigid elements are ignored in heat transfer analysis.
9.This card is represented as an rbe3 element in HyperMesh.

Go To

Bulk Data Section

Guidelines for Bulk Data Entries

Bulk Data Entries by Function

The Input File