PFATSPW

Bulk Data Entry

PFATSPW – Fatigue Properties for Spot Weld Fatigue Analysis

Description

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
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. Default = SHEET (SHEET, NUGGET, ALL, or AUTO) SHEET – 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: assess nugget damage at the spot weld location assess sheet damage at the spot weld location Where, D is the diameter of the weld connector, is set using the ALPHA field, and T is the thickness of the shell.
ALPHA	The value of 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 (Comment 2). Default = 1.0 (Real > 0.0)
TREF_N	Exponent for the thickness effect consideration (Comment 2). Default = 0.2 (Real ≥ 0.0)
SF	Stress scale factor (Comment 3). Default = 1.0 (Real > 0.0)

Comments

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 CHEXA-based Spot weld in the User's 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 (

) based on the following calculation:

3.	The stress () can also be scaled directly using the Scale Factor field (SF) as follows: