OrcaFlex Manual - Orcina

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Save
Saves the data to the currently selected file name (shown in title bar of the window).
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Fatigue Analysis, Data
� If results have been calculated then these are also saved to the file. This allows you to view results at a later date
without having to perform the calculation again. Note that results can only be saved to the binary format file
(.ftg).
� If results have not been calculated then the file will contain input data only.
Save As
This is the same as Save, but allows you to specify the file name to save to.
Open Data
If the file contains results and there are a large number of load cases then the file can take a long time to load. If you
want to work with just the input data then this command loads just the input data which is a much quicker process.
Most Recent Files List
A list of the most recently used files. Selecting an item on the list causes the file to be loaded. The size of the list can
be adjusted from the Preferences form.
Analysis Menu
Estimate Calculation Time
Gives an estimate of how long it will take to do the fatigue analysis and present the results. This is useful for long
analyses, e.g. rainflow analyses involving a lot of cases or long simulations.
Check
The Check command performs a preliminary check of the fatigue analysis data. For example it checks that all the
specified load case simulation files exist and that the named line and the specified arc length intervals exist in each
load case.
The Check command is generally much quicker that the fatigue analysis itself, so we recommend that the Check
command is used before the Fatigue Analysis is run, since the check can often detect data errors that would
otherwise only be found part way through what may be quite a long fatigue analysis. It is particularly important to
use the Check command when a new fatigue analysis has been first set up or when significant changes have been
made to the data.
Calculate
The Calculate command starts the Fatigue Analysis. The fatigue analysis can take a long time if there are many load
cases, or if there are many log samples in the load case simulations, or finally if there are a lot of segments in the arc
length intervals specified. A progress window is displayed and you can cancel the analysis if desired.
When the calculation is complete the results are displayed in a spreadsheet window.
8.3 DATA
Title
Used to label all output of the fatigue analysis.
Damage calculation
A variety of methods are available for calculating damage:
� Homogeneous pipe stress which assumes a pipe made of a straight, uniform, homogeneous, linear material.
The damage calculation is based on ZZ Stress. This option is appropriate for metal risers.
� An approach based on stress factors. Here the stress is assumed to comprise a tensile contribution
(proportional to either wall tension or effective tension) and a bending contribution (proportional to
curvature). This approach is commonly used for umbilicals but could also be used for unbonded flexibles.
� The mooring fatigue option calculates damage from effective tension ranges using T-N curves.