1. Fatigue calculation in SIMA and RIFLEX

This describes the stress and calculation done in SIMA and Riflex for fatigue calculations.

2. Stress time series

\[\sigma(t) = (SCFA * F(i) / AST) - (SCFMY * MY(t) / WST * ZCOR) - (SCFMZ * MZ(t) / WST * YCOR)\]

  • Time series of the element forces:

    • F(i) are effective axial tension

    • MY(i) bending moment around the local Y axis

    • MZ(i) bending moment around the local Z axis

  • Stress concentration factors and cross-section stress calculation factors:

    • SCFA are the stress concentration factors for axial stress

    • SCFY are the stress concentration factors bending stress from the moment around the local Y-axis

    • SCFZ are the stress concentration factors for bending stress from the moment around the local Z-axis

  • Cross-section stress calculation factors:

    • AST and WST are the cross-section stress calculation factors for axial and bending stresses

    • YCOR and ZCOR are the cosine and sine of the angle of the point on the outer radius that stresses are calculated for.

      • For 8 points around the circumference, stresses will be calculated for 0, 45, 90, 135, 180, 225, 270 and 315 degrees from the local Y-axis.