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Fatigue Analysis Setup

You may create a new fatigue analysis either by pressing the New fatigue analysis button placed in the tool bar, or by selecting the New fatigue analysis item from the pop-up menu that displays as you click the Fatigue folder in the model browser.

Before launching any fatigue analysis, you must have run at least one dynamic analysis.

Once a new fatigue analysis is created, you may edit the analysis parameters either of the following ways:

  • Double click the fatigue analysis name from the model browser

  • Right click the fatigue analysis name from the model browser and select Edit in the pop-up menu that displays.

The Edit fatigue window is composed of two main parts. The upper part includes an Edit box used to specify the name of the fatigue analysis and five action buttons, whereas the lower part consists in 4 tab sheets.

The action buttons located in the upper-right corner of the window are associated with the following actions:

  • OK: Save and close the edit panel
  • Save: Used to confirm the current state of the parameters set through the window and save all data input to the Fatigue Analysis Edition window.
  • Close : Close the edit panel in the last saved state.
  • Calculate: Used to generate the *.DSF file and run the fatigue analysis processing in interactive mode.
  • Generate DSF file: Used to generate the *DSF file associated with the current set of parameters and input data.

The 4 tab-sheets serves to define all fatigue analysis parameters and shall be named as follows:

  • General: This tab is used to set-up the most general parameters for the fatigue analysis, including the type of analysis, the damage calculation method in case the complete fatigue analysis type is selected, the type of line to be selected between steel riser, anchor leg and bounded flexible hose, and general results storage options. The type of line to be studied directly impacts the tab-sheets "Stress components" and "Line sections".

  • Load cases: The content of this tab changes automatically depending on the type of calculation method for the damage (either spectral or Rain-flow). This tab is used to define the load cases, i.e. the series of fatigue sea-states and selection of dynamic analyses used to derive the stress or the tension.

  • Stress component: This tab is used to define the stress components when the line type is steel riser only. This tab is not visible if the type of line is different from Steel riser. The stress could be either computed on the external or internal diameter of the steel section, considering a user-defined number of calculation points along the pipe circumference.

  • Lines sections: This tab is used to define the lines sections along which the fatigue post-processing must be carried out.