GRAV

Bulk Data Entry

GRAV – Gravity Vector

Description

Defines the gravity vectors for use in determining gravity loading for the static structural model. It can also be used to define the EXCITEID field (Amplitude “A”) of dynamic loads in RLOAD1, RLOAD2, TLOAD1, TLOAD2 and NLOAD1 bulk data entries for dynamic solution sequences.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
GRAV	SID	CID	G	N1	N2	N3

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
GRAV		3	32.2	0.0	0.0	-1.0

Field	Contents
SID	Set identification number. No default (Integer > 0)
CID	Coordinate system identification number. A CID of zero references the basic coordinate system. Default = 0 (Integer > 0)
G	Gravity vector scale factor. (Real ≠ 0.0)
N1,N2, N3	Gravity vector components. No default (Real; at least one non-zero component)

Comments

1.	The gravity vector is defined by . The direction of is the direction of free fall. , , and are defined in the coordinate system CID.

2.	CID =0 references the basic coordinate system.

The LOAD Subcase Information Entry can be used to reference the GRAV Bulk Data Entry in Static subcases. The GRAV Bulk Data Entry can also be associated by the LOADADD Bulk Data Entry, which is in turn referenced by a LOAD Subcase Entry. For Dynamic or Transient solution sequences, the TYPE field on RLOAD1, RLOAD2, TLOAD1, TLOAD2, and NLOAD1 bulk data entries should be set to LOAD, if GRAV is referenced on the EXCITEID field.

4.	For mass penalization information when GRAV is used in a Topology optimization, see Design Variables for Topology Optimization in the User’s Guide.

5.	This card is represented as a loadcollector in HyperMesh.