Apply Local Fatigue Solution Settings

Apply fatigue solution settings to a group of parts in the assembly.

1. In the Project Tree for the fatigue subcase, right-click Solution settings and choose Edit.
2. Click New.
   A new group appears in the group list.
3. In the modeling window, select one or more parts/spot welds for the group.
   Tip: You can also select parts/spot welds from the Project Tree.
4. Optional: You can choose Exclude all to exclude all parts/spot welds in the assembly.
5. Optional: You can select the Include all seam welds check box to include all seam welds in the assembly.
6. Under the General tab in the dialog, choose from the following options:

   Option	Procedure
   Fatigue Method	The following methods are available: Uniaxial Multiaxial
   SN Model Settings	Stress Combination The following stress combination models are available only under uniaxial fatigue method: Critical plane Absolute max principal Maximum principal Signed von Mises Signed max shear Tension Damage Model The following tension damage models are available: Goodman FKM - mean stress sensitivity input is required Shear Damage Model The Findley model is available for shear damage model under multiaxial fatigue method only. Findley constant and shear fatigue strength coefficient are required.
   EN Model Settings	Stress Combination The following stress combinations are available only under uniaxial fatigue method: Critical plane Absolute max principal Maximum principal Signed von Mises Signed max shear Tension Damage Model The following tension damage models are available: Smith, Watson, and Topper Morrow Shear Damage Model The following shear damage models are available only under multiaxial fatigue method: Fatemi-Socie Brown-Miller
   Endurance limit modifying factors	Select Surface condition. The following options are available: polish, ground, machine, hotroll, forge. Select surface treatment. The following options are available: Nitrided, shotpeen, coldroll. Select fatigue strength reduction factor.
   Number of planes	Enter the number of critical planes.

7. Under the Spot weld tab in the dialog, choose from the following options:

   Option	Procedure
   Model method	The following methods are available: Rupp Modified Rupp
   Mean stress correction	FKM model is available. Mean stress sensitivity input is required.
   Thickness correction	Thickness effect consideration. Thickness reference and thickness reference exponent inputs are required. 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), the thickness effect is included by increasing the stress ( ${\sigma }_{ij}$ ) when thickness correction is applied: (1) $${\sigma }_{\mathit{ij}}={\sigma }_{\mathit{ij}}{\left(\frac{T}{\mathit{TREF}}\right)}^{\mathit{TREF}\_N}$$ Default thickness reference = 25mm Default reference exponent = 0.2
   Endurance limit modifying factors	Certainty of survival. Enter a value based on the scatter of the SN curve. Default = 0.5
   Number of angles	Specify the number of angles to examine on sheet and nugget. Default = 20

8. Under the Seam weld tab in the dialog, choose from the following options:

   Option	Procedure
   Model method	Volvo fatigue analysis method is available. This method calculates the bending and membrane stresses by using stress linearization approach at specific data points at the weld toe. The number of data points are determined by the weld length. Damage is linearly interpolated between these points.
   Stress combination	The following options are available: Normal Critical plane Absolute max principle
   Mean stress correction	FKM model is available. Mean stress sensitivity input is required.
   Bending ratio threshold	Specify the threshold for bending ratio. If the calculated bending ratio is higher than the threshold, an SN curve that is interpolated between membrane stress-life SN curve and bending stress-life SN curve is used. Seam weld membrane stress-life SN curve is used if the calculated value is lower than the threshold. Default = 0.5
   Maximum weld depth	Specify the maximum weld depth. The specified value sets the maximum depth for which stress linearization through the thickness of the connected part from the weld toe is performed. Default = 5mm
   Thickness correction	Thickness effect consideration. Thickness reference and thickness reference exponent inputs are required. 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), the thickness effect is included by increasing the stress ( ${\sigma }_{ij}$ ) when thickness correction is applied: (2) $${\sigma }_{\mathit{ij}}={\sigma }_{\mathit{ij}}{\left(\frac{T}{\mathit{TREF}}\right)}^{\mathit{TREF}\_N}$$ Default thickness reference = 25mm Default reference exponent = 0.2
   Endurance limit modifying factors	Certainty of survival. Enter a value based on the scatter of the SN curve. Default = 0.5

9. Click OK.