PFATSPW

Bulk Data Entry Defines properties for spot weld fatigue analysis.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PFATSPW ID SPTFAIL ALPHA HEXA_D TREF TREF_N SF    

Definitions

Field Contents SI Unit Example
ID Each PFATSPW card must have a unique ID. This ID may be referenced from a FATDEF definition.

No default (Integer > 0)

  
SPTFAIL Damage assessment option type.
SHEET (Default)
Only assess sheet damage at the spot weld location.
NUGGET
Only assess nugget damage at the spot weld location.
ALL
Assess both sheet and nugget damage at the spot weld location.
AUTO
Automatically assess damage based on the following condition, if:
D < α T
assess nugget damage at the spot weld location
D ≥ α T
assess sheet damage at the spot weld location

Where, D MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraaaa@36C0@ is the diameter of the weld connector, α is set using the ALPHA field, and T is the thickness of the shell.

  
ALPHA The value of α used to determine the AUTO option on the SPTFAIL field.

Default = 3.5 (Real > 0.0)

  
HEXA_D Effective diameter of the spot weld that is generated using Hexahedron (CHEXA) elements.

Default = See Comment 1 (Real ≥ 0.0)

  
TREF Reference thickness for thickness effect consideration. 2

Default = 25.0 (Real > 0.0)

  
TREF_N Exponent for the thickness effect consideration. 2

Default = 0.2 (Real ≥ 0.0)

  
SF Stress scale factor. 3

Default = 1.0 (Real > 0.0)

  

Comments

  1. For spot weld that is generated using Hexahedron (CHEXA) elements, grid point forces and moments are internally calculated and resolved to the centroids of both faces of the CHEXA weld element in contact with the sheets. The CHEXA element is then internally considered to be equivalent to a 1D CBAR element.
    The effective diameter can be calculated in two ways:
    • You can directly input the effective diameter of the CHEXA-based spot weld element on the CHEXA_D field.
    • If the CHEXA_D field is blank, then the effective diameter is set equal to two times the smallest distance from the face centroid to an edge in the end A. For more information, refer to Sheet Location (1 or 2) in the User Guide.
  2. TREF is used to define the reference thickness for thickness effect consideration. If the thickness of a shell (T) is greater than the specified value (TREF), and the THCKCORR field on the FATPARM entry is set to YES, then the thickness effect is included by increasing the stress ( σ i j MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdm3aaS baaSqaaiaadMgacaWGQbaabeaaaaa@39C3@ ) based on: (1)
    σ ij = σ ij ( T TREF ) TREF _ N
  3. The stress ( σ i j MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdm3aaS baaSqaaiaadMgacaWGQbaabeaaaaa@39C3@ ) can also be scaled directly using the Scale Factor field (SF) as: (2)
    σ ij = σ ij ( SF )