Apply Global Fatigue Solution Settings

Apply fatigue solution settings to the entire assembly.

Global default fatigue solution settings are applied automatically when the project is opened, but some adjustments can be made if needed.

  1. In the main toolbar, click Settings > Default fatigue solution settings.
  2. 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
    • Von Mises (random fatigue only)
    Mean Stress Correction
    The following mean stress corrections are available only under uniaxial fatigue method:
    • Goodman
    • Gerber
    • Gerber 2
    • Soderberg
    • FKM
    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
    Random Fatigue Model Settings
    Damage Model
    The following damage models are available:
    • Derlik
    • Lalanne
    • Narrow
    • Steinberg 3-band
    Parameters to Adjust Probability Density Function
    The following parameters are available:
    • Upper stress range factor/upper stress range (MPa)
    • Number of bins/stress range width
    Endurance limit modifying factors
    1. Select Surface condition.

      The following options are available: polish, ground, machine, hotroll, forge.

    2. Select surface treatment.

      The following options are available: Nitrided, shotpeen, coldroll.

    3. Select fatigue strength reduction factor.
    Number of planes Enter the number of critical planes.
  3. 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 ( σ i j MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdm3aaS baaSqaaiaadMgacaWGQbaabeaaaaa@39C3@ ) when thickness correction is applied: (1)
    σ ij = σ ij ( T TREF ) 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

  4. 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 ( σ i j MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdm3aaS baaSqaaiaadMgacaWGQbaabeaaaaa@39C3@ ) when thickness correction is applied: (2)
    σ ij = σ ij ( T TREF ) 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

  5. Click OK.