The standards included in WeldFEM are based on the nominal stress concept. Therefore, when extracting the stresses using a strain gauge, a certain distance from the seam transition must be maintained. By that the structure and notch-related increase in stress can be excluded. In a FEA, the results usually do not contain nominal stresses, but local stresses. Depending on the used mesh, these can behave like notch stresses, nominal stresses or something in between. Therefore, for the extraction of stress values, the same principle applies as when determining the required stress values using a strain gauge, an evaluation distance is to be applied. In the standards DVS 1608 and DVS 1612 the evaluation range is specified by a distance to the weld toe. There is no evaluation range based on a distance from the weld root. The DIN EN 13001-3-1 does not contain any recommendations for an evaluation using a FEA. Thus the ones from DVS 1612 are adopted, since both standards are based on the nominal stress concept.


The following equation was defined in WeldFEM to calculate the evaluation range:



The weld assessment of WeldFEM runs on a FE model which is based on two dimensional shell-elements. No three-dimensional properties can be represented with these. The weld orientation and weld geometry cannot be reproduced in detail. For the implementation of the above equation, assumptions had to be made for certain joint types and weld seam shapes in order to determine a reasonable evaluation distance. The term “Standard Specification” can be found in the relevant literature. The “Offset” and the “Weld Leg Length” are values determined by the weld geometry. These are shown in retrospect for the different types of joints and seam shapes.


Tee Joint

Fillet Weld / Z Fillet Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;
  • ;


Note:        The cross section of the weld  is equal to 0,7.

Formula:


Note:        The adapted evaluation range for the flange of the FE-model  is used on both of its sides, since the orientation of the weld is unknown.

Note:        The offset  can either be  or 0. It depends on the way the tee joint is modelled.
The offset is equal to 0 if the connection is modelled with RBE2-elements. In both ways the evaluation distance stays the same with reference to the intersection point of both midsurfaces.


Double Fillet Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;
  • ;


Note:        The cross section of the weld  is equal to 0,5.

Formula:


Note:        The adapted evaluation range for the flange  is used on both of its sides, since the orientation of the weld is unknown.

Note:        The offset  can either be  or 0. It depends on the way the tee joint is modelled.
The offset is equal to 0 if the connection is modelled with RBE2-elements. In both ways the evaluation distance stays the same with reference to the intersection point of both midsurfaces.


HY Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;
  • ;


Note:        The factor of the root face size  is equal to 0,2.
The angle of aperture  is equal to 50°    60°.

Formula:


Note:        The adapted evaluation range for the flange  is used on both of its sides, since the orientation of the weld is unknown.


Note:        For the calculation of  the factor of the root face size  is set to 0,2.
For the calculation of  the angle of aperture  is set to 60°.


Note:        The offset  can either be  or 0. It depends on the way the tee joint is modelled.
The offset is equal to 0 if the connection is modelled with RBE2-elements. In both ways the evaluation distance stays the same with reference to the intersection point of both midsurfaces.


HV Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;
  • ;


Note:        The size of the root face size  is equal to 0 mm    2 mm.
The size of the root opening  is equal to 1 mm    3 mm.
The angle of aperture  is equal to 50°    60°.

Formula:


Note:        The adapted evaluation range for the flange  is used on both of its sides, since the orientation of the weld is unknown.


Note:        For the calculation of  the factor of the root face size  is set to 0.
For the calculation of  the size of the root opening  is set to 3 mm.
For the calculation of  the angle of aperture  is set to 60°.


Note:        The offset  can either be  or 0. It depends on the way the tee joint is modelled.
The offset is equal to 0 if the connection is modelled with RBE2-elements. In both ways the evaluation distance stays the same with reference to the intersection point of both midsurfaces.


Corner Joint

Fillet Weld / Z Fillet Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;
  • ;

Formula:


Note:        The offset  can be either be  or 0. It depends on the way the tee joint is modelled. The same goes for the offset .
The offset is equal to 0 if the connection is modelled with RBE2-elements. In both ways the evaluation distance stays the same with reference to the intersection point of both midsurfaces.


Z Fillet Weld with sealing run

Weld geometry:

FE-adaptation:

Formula:

  • ;
  • ;

Formula:


Note:        The offset  can be either be  or 0. It depends on the way the tee joint is modelled. The same goes for the offset .
The offset is equal to 0 if the connection is modelled with RBE2-elements. In both ways the evaluation distance stays the same with reference to the intersection point of both midsurfaces.


Note:         is the effective cross section of the weld.


Butt Joint

HY Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The factor of the root face size  is equal to 0,2.
The angle of aperture  is equal to 50°    60°.

Formula:


Note:        For the calculation of  the factor of the root face size  is set to 0,2.
For the calculation of  the angle of aperture  is set to 45°. The explanation for that will be given in the formula section of the Y-Weld.


Note:        The weld leg length will be added to both evaluation ranges,  and , since the orientation of the weld is unknown.


HV Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The size of the root face size  is equal to 1 mm    2 mm.
The size of the root opening  is equal to 1 mm    3 mm.
The angle of aperture  is equal to 50°    60°.

Formula:


Note:        For the calculation of  the factor of the root face size  is set to 1,5 mm.
For the calculation of  the size of the root opening  is set to 1,5 mm.
For the calculation of  the angle of aperture  is set to 45°.The explanation for that will be given in the formula section of the Y-Weld.


Note:        The weld leg length will be added to both evaluation ranges,  and , since the orientation of the weld is unknown.


Y Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The factor of the root face size  is equal to 0,2.
The angle of aperture  is equal to 50°    60°.

Formula:


Note:        For the calculation of  the factor of the root face size  is set to 0,2.
For the calculation of  the angle of aperture  is set to 90°.


Note:        The asymmetry of the HY weld would lead to a evaluation range with a larger value than the one from the Y weld, since the orientation of the weld is unknown and therefore the weld leg length is added on both sides. This could potentially lead to better results with the HY weld, because elements farther away from the weld would have been taken into account when assessing the weld. In order to treat the HY and the Y weld in terms of the evaluation range equally, the angle of aperture  is 90° for the symmetrical weld and 45° for the asymmetrical ones.


V Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The size of the root face size  is equal to 0 mm    2 mm.
The size of the root opening  is equal to 0 mm    3 mm.
The angle of aperture  is equal to 50°    60°.

Formula:


Note:        For the calculation of  the factor of the root face size  is set to 0.
For the calculation of  the size of the root opening  is set to 3 mm.
For the calculation of  the angle of aperture  is set to 90°.


Note:        The asymmetry of the HY weld would lead to a evaluation range with a larger value than the one from the Y weld, since the orientation of the weld is unknown and therefore the weld leg length is added on both sides. This could potentially lead to better results with the HY weld, because elements farther away from the weld would have been taken into account when assessing the weld. In order to treat the HY and the Y weld in terms of the evaluation range equally, the angle of aperture  is 90° for the symmetrical weld and 45° for the asymmetrical ones.


I Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The size of the root opening  is equal to 0 mm    3 mm.

Formula:


Note:        For the calculation of  the size of the root opening  is set to 3 mm.


Overlap Joint

Z Fillet Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The cross section of the weld  is equal to 0,7.

Formula:


Note:        The evaluation range  is implemented for the base plate.


Skew Joint

HY Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The angle of aperture  is equal to 50°    60°.

Formula:


Note:        The adapted evaluation range for the flange of the FE-model  is used on both of its sides.


Note:        The weld leg length  will be simplified for skew joints. It is equal to the effective cross section of the weld.


Note:        The calculation of the offsets for the FE-adaptation will be simplified as followed for skew joints.
;


HV Weld

Weld geometry:

FE-adaptation:

Formula:

  • ;


Note:        The angle of aperture  is equal to 50°    60°.

Formula:


Note:        The adapted evaluation range for the flange of the FE-model  is used on both of its sides.


Note:        The weld leg length  will be simplified for skew joints. It is equal to the effective cross section of the weld.


Note:        The calculation of the offsets for the FE-adaptation will be simplified as followed for skew joints.
;