PGASK

Bulk Data Entry Defining the properties for solid gasket elements.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PGASK	`PID`	`MIDG`	`MID1`	`CORDM`	`H0`	`GAP`	`VOID`	`LEAKP`
	`STABMT`	`STABSP`

Example

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PGASK	1	2	1	1		0.5

Definitions

Field	Contents	SI Unit Example
`PID`	Unique gasket element property identification number. No default (Integer > 0)
`MIDG`	A `MGASK` entry identification number that defines thickness-direction and transverse shear behaviors of the gasket. No default (Integer > 0)
`MID1`	A `MAT1` entry identification number that defines membrane properties and mass density of the gasket. Blank means zero membrane stiffness, zero membrane thermal expansion coefficient, and zero mass density. Default = blank (Integer > 0 or blank)
`CORDM`	Material coordinate system identification number. 3 -1 (Default) Means the element local coordinate system. 0 Means the basic coordinate system. (Integer ≥ -1)
`H0`	Initial thickness of the gasket. Includes initial open gap and initial void of the gasket. 0.0 or blank means using initial thickness of the gasket element. Default = 0.0 (Real ≥ 0.0)
`GAP`	Initial open gap of the gasket. 4 Default = 0.0 (Real ≥ 0.0)
`VOID`	Initial void of the gasket. 4 Default = 0.0 (Real ≥ 0.0)
`LEAKP`	Leakage pressure. 5 Default = 1.0e-8 (Real > 0.0 or blank)
`STABMT`	Membrane and transverse shear stabilization flag. 6 0 (Default) No stabilization. 1 Automatic stabilization stiffness. Real > 0.0: directly prescribed stabilization stiffness with the unit of stress. Real < 0.0: stabilization stiffness selected as \|Real\|*(initial compressive stiffness of the thickness behavior). (Integer)
`STABSP`	Stabilization for gasket element that is not supported on all its nodes. 7 0 (Default) No stabilization. 1 Automatic stabilization stiffness. Real > 0.0: directly prescribed stabilization stiffness with the unit of stress. Real < 0.0: stabilization stiffness selected as \|Real\|*(initial compressive stiffness of the thickness behavior). (Integer)

Comments

All gasket element property entries must have unique identification numbers.
PGASK refers to two material entries, MGASK and MAT1. MGASK defines the thickness-direction and transverse shear behaviors of the gasket material, and MAT1 defines the membrane behavior of the gasket material.
The thickness-direction stiffness is defined with the unit of stress per unit displacement (the pressure-closure distance relationship for the thickness compression), the transverse shear stiffness is defined with either the unit of stress per unit displacement or the unit of force per unit area, and the membrane stiffness is defined with the unit of force per unit area (the stress-strain relationship).
The gasket material coordinate system can be defined as the element local coordinate system (CORDM = -1) or a prescribed system (CORDM = Integer ≥ 0). The material local 3-direction is taken as the gasket thickness direction, and the material local 1-direction and 2-direction are taken as the gasket membrane principle directions. If the angle between the thickness direction (the material local 3-direction) and the default one (the element local 3-direction) is larger than 20 degrees, a warning will be provided.
The total closure of a gasket element consists of the mechanical closure and the thermal closure:(1)
$C_{t o t a l} = C_{m e c h} + C_{t h e r m a l}$

The thermal closure, $C_{t h e r m a l}$ , is calculated as:(2)
$C_{t h e r m a l} = A L P H A * (T_{r e f} - T) * (H 0 - G A P - V O I D)$

The effective closure, $C$ , which is used to determine pressure with the loading/unloading of tables defined in the MGASK card, is calculated as:(3)
$C = C_{m e c h} - G A P$

If there is no initial open gap (GAP=0), $C$ and $C_{m e c h}$ are identical.
The sealing status of gasket is detected with the leakage pressure. If the gasket pressure is larger than the leakage pressure, it is detected to be sealed - the output status index value is 1; otherwise, it is leaking - the output status index value is 0.
STABMT is recommended to be 1 or a non-zero Real number if the gasket membrane or transverse shear stiffness is zero. STABMT=1 has the same effect as STABMT=-0.001, i.e., this type of automatic stabilization stiffness is 0.1% of the initial compressive stiffness of the thickness behavior.
STABSP is recommended to be 1 or a non-zero Real number if some of the gasket nodes are not supported, for example, some extend outside of contact projection zone. STABSP=1 has the same effect as STABSP=-0.05, i.e., this type of automatic stabilization stiffness is 5% of the initial compressive stiffness of the thickness behavior.
The continuation entry is optional.
This card is represented as a property in HyperMesh.