PLOAD4

Bulk Data Entry

PLOAD4 – Pressure Loads on Face of Structural Elements

Description

Defines a load on a face of a HEXA, PENTA, TETRA, PYRA, TRIA3, TRIA6, QUAD4, or QUAD8 element. It can also be used to define the EXCITEID field (Amplitude “A”) of dynamic loads in RLOAD1, RLOAD2, TLOAD1 and TLOAD2 bulk data entries. Additionally, the PLOAD4 entry can be defined as Follower Loads in Large Displacement Nonlinear Analysis.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PLOAD4	SID	EID	P1	P2	P3	P4	G1	G3 or G4
	CID	N1	N2	N3

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PLOAD4	2	1106	10.0	8.0	5.0	1.0	1	48
	6	0.0	1.0	0.0

Alternate Format and Example

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PLOAD4	SID	EID1	P1	P2	P3	P4	“THRU”	EID2
	CID	N1	N2	N3
PLOAD4	2	1106	10.0	8.0	5.0		THRU	1143
	6	0.0	1.0	0.0

Field	Contents
SID	Load set identification number. (Integer > 0)
EID1, EID2	Element identification number. (Integer > 0, EID1 < EID2)
P1, P2, P3, P4	Load per unit surface area (pressure) at the corners of the face of the element (real or blank). (P1 is the default for P2, P3, and P4). If P2, P3 (and P4) are blank, the load intensity is uniform and equal to P1. P4 has no meaning for a triangular face and may be left blank.
G1	Identification number of a grid point connected to a corner of the face. Required data for solid elements only (Integer or blank). For PYRA elements, this grid must be on an edge of the quadrilateral face. G1 is ignored for TRIA3, TRIA6, QUAD4, and QUAD8 elements.
G3	Identification number of a grid point connected to a corner diagonally opposite to G1 on the same face of a HEXA or PENTA element. Required data for quadrilateral faces of HEXA and PENTA elements only (Integer or blank). G3 must be omitted for a triangular surface on a PENTA element and the quadrilateral face on a PYRA element. For triangular faces of PYRA elements, this grid must be on the edge next to the quadrilateral face. G1 and G3 must define a positive direction into the element using the right hand rule. G3 is ignored for TRIA3, TRIA6, QUAD4, and QUAD8 elements.
G4	TETRA grid point identification number located at the corner not on the face being loaded. This is required data and is used for TETRA elements only.
CID	Coordinate system identification number. (Integer > 0)
N1, N2, N3	Components of vector measured in coordinate system defined by CID (Real). Used to define the direction (but not the magnitude) of the load intensity. N1, N2, and N3 are not supported in NLGEOM subcases.

Comments

The continuation is optional. If fields 2, 3, 4, and 5 of the continuation are blank, the load is assumed to be a pressure acting normal to the face. If these fields are not blank, the load acts in the direction defined in these fields. Note that, if CID is a curvilinear coordinate system, the direction of load may vary over the surface of the element. The load intensity is the load per unit of surface area, not the load per unit of area normal to the direction of loading.

2.	For solid elements the direction of positive pressure (defaulted continuation card) is inward. The load intensity P1 acts at grid point G1 and load intensities P2, P3 (and P4) act at the other corners in a sequence determined by applying the right hand rule to the outward normal.

For plate elements the direction of positive pressure (defaulted continuation) is in the direction of positive normal, determined by applying the right hand rule to the sequence of connected grid points. The load intensities PI, P2, P3 (and P4) act respectively at corner points G1, G2, G3 (and G4). (See plate connection).

4.	Equivalent grid point loads are computed by linear (or bilinear) interpolation of load intensity, followed by numerical integration using isoperimetric shape functions. Note that uniform load intensity does not necessarily result in equal equivalent grid point loads.

5.	The alternate form is available only for TRIA3, TRIA6, QUAD4, and QUAD8 elements. The continuation card may be used in the alternate form.

For triangular faces of PENTA elements, G1 is an identification number of a corner grid point that is on the face being loaded and the G3 or G4 field is left blank. For faces of TETRA elements, G1 is an identification number of a corner grid point that is on the face being loaded and G4 is an identification number of the corner grid point that is not on the face being loaded. Since a TETRA has only four corner points, this point, G4, is unique and different for each of the four faces of a TETRA element.

For the quadrilateral face of the PYRA element, G1 is an identification number of a corner grid point on the face and the G3 or G4 field is left blank. For the triangular faces, G1 and G3 must specify the grids on the edge of the face that borders the quadrilateral face and the grids must be ordered so that they define an inward normal using the right hand rule.

8.	This card is represented as a pressure load in HyperMesh.