PFBODY

Bulk Data Entry Defines a flexible body out of a list of finite element properties, elements, and grid points.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PFBODY BID BODY_NAME
  TYPE1 ID1 ID2 ID3 ID4 ID5 ID6 ID7  
    ID8 etc            
  TYPE2 ID9 ID10 etc          
  TYPE# etc              
  etc                
  CMS CTYPE UB_FREQ NMODES          
  FLXNODE NOAUTO/

C

 G1 G2 G3 G4 G5 G6  
  FLXNODE C G8 G9 etc        
  etc                
  DAMPING DTYPE DVAL            

Example 1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PFBODY 3 Control_arm
  PSHELL 23 21            
  PBEAM 9 59 48          
  CONM2 2345              
  GRID 400 401 402          
  CMS CB   50          
  FLXNODE 123 400 499          
  FLXNODE 123456 402 300          

Example 2

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PFBODY 3 Linkage
  PSOLID 13 15            
  CMS CB 2000.0            
  FLXNODE NOAUTO              
  FLXNODE 123 900 901 902 903 1000 1001  
  FLXNODE 123456 11 12 13        
  DAMPING CRATIO 0.8            

Definitions

Field Contents SI Unit Example
BID Unique body identification number.

No default (Integer > 0)

  
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)

  
TYPE# Indicates 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, PCOMPP, PCOMPG, PDAMP, PELAS, PGAP, PROD, PSHEAR, PSHELL, PSOLID, PVISC, PWELD, CELAS2, CONM2, PLOTEL, RBE2, RBE3, RBAR, RROD, or GRID)

  
ID# Identification numbers of entities of the preceding TYPE flag.

No default (Integer > 0)

  
CMS Indicates that information on the method used for reducing the flexible body is to follow.  
CTYPE Component Mode Synthesis method to be employed.
CB (Default)
Craig-Bampton
CC
Craig-Chang
  
UB_FREQ Upper bound frequency for the eigenvalue analysis.
0.0 or blank
No upper bound is used. 8 9

Default = blank (Real > 0.0, or blank)

  
NMODES Number of modes to be extracted from eigenvalue analysis.
-1 or blank
Number of modes is limitless. 8 9

Default = blank (Integer > -1, or blank)

  
FLXNODE Indicates that flexible body interface node information is to follow. 11  
NOAUTO Flag to not automatically determine the interface nodes for the flexible body.  
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)

  
G# Grid identification numbers.

(Integer > 0)

  
DAMPING Indicates the flexible body modal damping.  
DTYPE Damping option.
DEFAULT (Default)
CRATIO
  
DVAL Damping ratio value, if DTYPE is specified as CRATIO.

(Real ≥ 0.0)

  

Comments

  1. A maximum of 56 characters may be given for BODY_NAME.
  2. Flex H3D file name will be <BODY_NAME>.h3d or OUTFILE_body_<BID>.h3d in the outfile directory.
  3. Any number of property definitions; CELAS2, CONM2, PLOTEL, RBAR, RBE2, RBE3 or RROD elements or grid points can be given.
  4. At least one property definition, element, or grid point must be given.
  5. A property definition; CELAS2, CONM2, PLOTEL, RBAR, RBE2, RBE3 or RROD element or grid point can only belong to one body (flexible or rigid).
  6. All property definitions, elements and grid points defined on a PFBODY Bulk Data Entry form one flexible body.
  7. CMS definition defines the component mode synthesis method to reduce the flexible body for the multibody analysis. Exactly one must be defined for each PFBODY.
  8. UB_FREQ and NMODES cannot both be blank.
  9. When UB_FREQ = 0.0 and NMODES = 0, this is a special case where no eigen modes will be included in CMS mode generation.
  10. 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.
  11. 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.
  12. ASSIGN can be used in two ways, to identify flex body for result recovery or in further OS-MBD analysis in the PFBODY Bulk Data Entry.
    • Identifies an external nodal flexh3d file which contains the analysis recovery information for displacements, velocities, accelerations, stresses and strains. Provides a Flex Body ID for the information therein, and the path to the name of the flexh3d file.
    • The identified flexh3d file can also be used as a flex body in OS-MBD analysis. This can be activated by referencing the Flex Body ID on the BID field of the PFBODY Bulk Data Entry. In such cases, the included flex body (ASSIGN, H3DMBD, Flex Body ID) is used in the analysis and the PFBODY information for flex body generation is not used.
  13. This card is represented as a group in HyperMesh.