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 GASK1D            

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. 5

Default = 0.0 (Real ≥ 0.0)

 
VOID Initial void of the gasket. 5

Default = 0.0 (Real ≥ 0.0)

 
LEAKP Leakage pressure. 6

Default = 1.0e-8 (Real > 0.0 or blank)

 
STABMT Membrane and transverse shear stabilization flag. 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)

 
STABSP Stabilization for gasket element that is not supported on all its nodes. 8
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)

 
GASK1D Specifies the option for 1D Gasket (thickness-direction behavior only). 9, 10, 11
0 (Default)
Gasket behavior is activated along all 3 directions (3D Gasket).
1
Gasket behavior is activated only along the thickness direction (1D Gasket).

(Integer)

 

Comments

  1. All gasket element property entries must have unique identification numbers.
  2. 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).

  3. 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.
  4. The initial thickness includes initial open gap and initial void of the gasket.
  5. 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 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa aaleaacaWG0bGaam4BaiaadshacaWGHbGaamiBaaqabaGccqGH9aqp caWGdbWaaSbaaSqaaiaad2gacaWGLbGaam4yaiaadIgaaeqaaOGaey 4kaSIaam4qamaaBaaaleaacaWG0bGaamiAaiaadwgacaWGYbGaamyB aiaadggacaWGSbaabeaaaaa@49CC@
    The thermal closure, C t h e r m a l MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa aaleaacaWG0bGaamiAaiaadwgacaWGYbGaamyBaiaadggacaWGSbaa beaaaaa@3D7A@ , 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 ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa aaleaacaWG0bGaamiAaiaadwgacaWGYbGaamyBaiaadggacaWGSbaa beaakiabg2da9iaadgeacaWGmbGaamiuaiaadIeacaWGbbGaaiOkam aabmaabaGaamivamaaBaaaleaacaWGYbGaamyzaiaadAgaaeqaaOGa eyOeI0IaamivaaGaayjkaiaawMcaaiaacQcadaqadaqaaiaadIeaca aIWaGaeyOeI0Iaam4raiaadgeacaWGqbGaeyOeI0IaamOvaiaad+ea caWGjbGaamiraaGaayjkaiaawMcaaaaa@55A6@
    The effective closure, C MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qaaaa@36BE@ , 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 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qaiabg2 da9iaadoeadaWgaaWcbaGaamyBaiaadwgacaWGJbGaamiAaaqabaGc cqGHsislcaWGhbGaamyqaiaadcfaaaa@3FC7@

    If there is no initial open gap (GAP=0), C MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qaaaa@36BE@ and C m e c h MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa aaleaacaWGTbGaamyzaiaadogacaWGObaabeaaaaa@3A9B@ are identical.

  6. 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.
  7. 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.
  8. 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.
  9. For gasket elements with thickness-direction behavior only (GASK1D=1):
    • The structural properties defined for transverse shear and membrane behaviors are ignored, including STABMT, STABSP and relevant moduli and coefficients defined in MIDG and MID1 fields.
    • A local coordinate system, with local 3rd direction along the thickness direction overwrites the displacement coordinate system of each gasket grid (the CD field on GRID). For the enforcement of single-point constraints (for example, with SPC entry), the component ‘3’ always represents the thickness direction, regardless of the original CD field assigned on the GRID entry.
  10. Gasket elements with thickness-direction behavior only (GASK1D=1), cannot have shared nodes with other type of elements, including full-behavior gasket elements (3D Gasket). Contact is required for the connection to the rest of the structure. Some rules and restrictions are:
    • Gasket elements with thickness-direction behavior only must act as the secondary side.
    • Only small-sliding Node-to-Surface (N2S) contact is supported.
    • Frictional coefficients are invalid; for type STICK or FREEZE the tangential stiffness will be ineffective.
  11. The continuation entry is optional.
  12. This card is represented as a property in HyperMesh.