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`


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: $D < α \sqrt{T}$ assess nugget damage at the spot weld location $D \geq α \sqrt{T}$ assess sheet damage at the spot weld location Where, $D$ 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)

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.
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 ( $σ_{i j}$ ) based on:
$σ_{ij} = σ_{ij} {(\frac{T}{TREF})}^{TREF_N}$
The stress ( $σ_{i j}$ ) can also be scaled directly using the Scale Factor field (SF) as:
$σ_{ij} = σ_{ij} (SF)$