PFBODY

Bulk Data Entry

PFBODY – Flexible Body Definition for Multi-body Simulation

Description

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	…
	TYPE2	ID9	ID10	…
	TYPE#	…
	…
	CMS	CTYPE	UB_FREQ	NMODES
	FLXNODE	NOAUTO/C1	G1	G2	G3	G4	G5	G6
	FLXNODE	C2	G8	G9	…
	…
	DAMPING	DTYPE	DVAL

(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

(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

Field	Contents
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 - Craig-Bampton CC - Craig-Chang Default = CB (CB or CC)
UB_FREQ	Upper bound frequency for the eigenvalue analysis. If 0.0 or blank, no upper bound is used. See comments 8 and 9. Default = blank (Real > 0.0, or blank)
NMODES	Number of modes to be extracted from eigenvalue analysis. If set to -1 or blank, number of modes is limitless. See comments 8 and 9. Default = blank (Integer > -1, or blank)
FLXNODE	Indicates that flexible body interface node information is to follow. See comment 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 (DEFAULT or 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, RBE2, RBE3, RBAR 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 multi-body 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, H3DMBD 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.