PFBODY – Flexible Body Definition for Multi-body Simulation
Defines a flexible body out of a list of finite element properties, elements, and grid points.
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PFBODY |
BID |
BODY_NAME |
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TYPE1 |
ID1 |
ID2 |
ID3 |
ID4 |
ID5 |
ID6 |
ID7 |
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ID8 |
… |
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TYPE2 |
ID9 |
ID10 |
… |
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TYPE# |
… |
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… |
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CMS |
CTYPE |
UB_FREQ |
NMODES |
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FLXNODE |
NOAUTO/C1 |
G1 |
G2 |
G3 |
G4 |
G5 |
G6 |
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FLXNODE |
C2 |
G8 |
G9 |
… |
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… |
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DAMPING |
DTYPE |
DVAL |
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PFBODY |
3 |
Control_arm |
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PSHELL |
23 |
21 |
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PBEAM |
9 |
59 |
48 |
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CONM2 |
2345 |
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GRID |
400 |
401 |
402 |
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CMS |
CB |
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50 |
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FLXNODE |
123 |
400 |
499 |
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FLXNODE |
123456 |
402 |
300 |
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PFBODY |
3 |
Linkage |
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PSOLID |
13 |
15 |
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CMS |
CB |
2000.0 |
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FLXNODE |
NOAUTO |
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FLXNODE |
123 |
900 |
901 |
902 |
903 |
1000 |
1001 |
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FLXNODE |
123456 |
11 |
12 |
13 |
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DAMPING |
CRATIO |
0.8 |
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Field |
Contents |
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BID |
Unique body identification number. No default (Integer > 0) |
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BODY_NAME |
Unique body name. This name is used as the Flex H3D file name to which the reduced flexible body information will be written out for the PFBODY. Default = OUTFILE_body_<BID>.h3d (character string) |
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TYPE# |
Flag indicating that the following list of IDs refer to entities of this type. All property definitions; CELAS2, CONM2, PLOTEL, RBE2, RBE3, RBAR, RROD, and GRID are valid types for this field. No default (PBAR, PBARL, PBEAM, PBEAML, PBUSH, PCOMP, PDAMP, PELAS, PGAP, PROD, PSHEAR, PSHELL, PSOLID, PVISC, PWELD, CELAS2, CONM2, PLOTEL, RBE2, RBE3, RBAR, RROD, or GRID) |
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ID# |
Identification numbers of entities of the preceding TYPE flag. No default (Integer > 0) |
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CMS |
CMS flag indicating that information on the method used for reducing the flexible body is to follow. |
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CTYPE |
Component Mode Synthesis method to be employed. See comment 8. Default = CB (CB or CC) |
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UB_FREQ |
Upper bound frequency for the eigenvalue analysis. If 0.0 or blank, no upper bound is used. See comments 9 and 10. Default = blank (Real > 0.0, or blank) |
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NMODES |
Number of modes to be extracted from eigenvalue analysis. If set to -1 or blank, number of modes is limitless. See comments 9 and 10. Default = blank (Integer > -1, or blank) |
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FLXNODE |
FLXNODE flag indicating that flexible body interface node information is to follow. See comment 12. |
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NOAUTO |
NOAUTO flag indicating that OptiStruct will not automatically determine the interface nodes for the flexible body. |
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C# |
Component number indicating the interface degrees of freedom for the following list of grids. No default (up to 6 unique digits (0 < digit < 6) may be placed in the field with no embedded blanks) |
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G# |
Grid identification numbers. (Integer > 0) |
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DAMPING |
DAMPING flag indicating the flexible body modal damping. |
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DTYPE |
Damping option. Default = DEFAULT (DEFAULT or CRATIO) |
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DVAL |
Damping ratio value if DTYPE is specified as CRATIO. (Real > 0.0) |
A maximum of 56 characters may be given for BODY_NAME.
Flex H3d file name will be <BODY_NAME>.h3d or OUTFILE_body_<BID>.h3d in the outfile directory.
Any number of property definitions; CELAS2, CONM2, PLOTEL, RBAR, RBE2, RBE3 or RROD elements or grid points can be given.
At least one property definition, element, or grid point must be given.
A property definition; CELAS2, CONM2, PLOTEL, RBE2, RBE3, RBAR or RROD element or grid point can only belong to one body (flexible or rigid).
All property definitions, elements and grid points defined on a PFBODY bulk data entry form one flexible body.
CMS definition defines the component mode synthesis method to reduce the flexible body for the multi-body analysis. Exactly one must be defined for each PFBODY.
Two methods are available for Component Mode Synthesis:
a) CB - Craig-Bampton
b) CC - Craig-Chang
UB_FREQ and NMODES cannot both be blank.
When UB_FREQ = 0.0 and NMODES = 0, this is a special case where no eigen modes will be included in CMS mode generation.
If FLXNODE is not defined, a default set of interface nodes and degrees of freedom. will be generated based on the actual interface nodes and degrees of freedom of the flexible body.
One FLXNODE line can have up to six interface grid IDs. No continuation lines are allowed. Add multiple FLXNODE lines to add more than six interface nodes.
Go To
Guidelines for Bulk Data Entries
Alphabetical List of Bulk Data Entries