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RBADD |
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RBADD |
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»Click here to display Table of Contents«
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RBADD |
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RBADD |
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Bulk Data Entry
RBADD – Rigid Body Addition
Description
Defines a rigid body as a combination of Rigid Bodies (RBODY).
Format
(1) |
(2) |
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(4) |
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(6) |
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(10) |
RBADD |
ID |
REFG |
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RBODY |
BID1 |
BID2 |
... |
... |
... |
... |
BID7 |
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MASS |
M |
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INERTIA |
IXX |
IXY |
IYY |
IXZ |
IYZ |
IZZ |
CID |
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COG |
X |
Y |
Z |
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Field |
Contents |
BID |
Unique body identification number. RBADD and RBODY bulk data entries cannot have the same BID. No default (Integer > 0) |
REFG |
Reference Grid. See Comment 6. Default = <COG> (Integer > 0). |
RBODY |
Flag indicating that the following list of IDs refer to Rigid Bodies defined using RBODY or RBADD. No default |
BID# |
Identification numbers of RBODY or RBADD entities for the preceding RBODY flag. No default (Integer > 0) |
MASS |
Flag to overwrite the finite element mass of the body. Indicates that a mass value is to follow. |
M |
Mass. (Real > 0.0) |
INERTIA |
Flag to overwrite the finite element inertia of the body. Indicates that the inertia properties are to follow. |
IXX,IYY,IZZ, |
Moments of inertia. For IXX, IYY, IZZ Real > 0.0 For IXY, IXZ, IYZ Real |
CID |
Coordinate system identification number to define the orientation of the inertia tensor. A CID of zero or blank references the basic coordinate system. (Integer > 0 or blank) |
COG |
Flag to overwrite the finite element center of gravity of the body. Indicates that the center of gravity information is to follow. |
X, Y, Z |
Location of the center of gravity. (Real) |
| 1. | A minimum of one Rigid Body (RBODY) or RBADD should be referenced on any RBADD entry. |
| 2. | An RBADD entry cannot reference itself recursively (with the same BID). |
| 3. | The mass and inertia properties are defined by the finite element and mass properties specified in the corresponding RBODY’s, unless they are overwritten by the mass (MASS) and inertia (INERTIA) properties specified on the continuation lines on the RBADD entry. |
| 4. | The mass, inertia and center of gravity input are optional, if element/grid/surface information are provided in the RBODY definitions. |
| 5. | If just the principal inertia is specified, IXX, IYY, and IZZ must be positive non-zero values and they must satisfy the condition: the sum of two inertia values must be greater than the third (IXX + IYY > IZZ, IYY+IZZ > IXX, IZZ+IXX > IYY). |
| 6. | If MASS continuation line is specified, then either REFG or COG should be present. If MASS continuation line is not input, and both REFG and COG are not specified, the respective center of gravity of the element/grid/surface selections is used. |
