GRAV

Bulk Data Entry 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`

Example

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
GRAV	47	3	32.2	0.0	0.0	-1.0

Definitions

Field	Contents	SI Unit Example
`SID`	Set identification number. No default (Integer > 0)
`CID`	Coordinate system identification number. A `CID` of zero references the basic coordinate system. 0 (Default) References the basic coordinate system. (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

The gravity vector is defined by:
$\vec{g} = G * ({\vec{N}}_{1}, {\vec{N}}_{2}, {\vec{N}}_{3})$

The direction of $\vec{g}$ is the direction of free fall. ${\vec{N}}_{1}$ , ${\vec{N}}_{2}$ , and ${\vec{N}}_{3}$ are defined in the coordinate system CID.
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.
For mass penalization information when GRAV is used in a Topology optimization, refer to Design Variables in the User Guide.
This card is represented as a load collector in HyperMesh.