Pre-Run Analyses |
 
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Pre-Run Analyses |
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In the case of the Stress Spectra mode, you provide a list of Pre-Run Analyses, and LifeFrequency reads the stress spectra from each of these Flexcom runs in order to perform the fatigue life estimation.
In the case of the RAOs mode, you provide a list of Pre-Run Analyses, consisting of the Flexcom analyses corresponding to the scatter diagram reference seastates. There are a couple of important points to note regarding this data.
(i)You first identify a combination of Hs and Tz or Tp, which must correspond to a reference seastate in the wave scatter diagram. Then you identify an associated direction, which must correspond to one of the directions with non-zero percentage occurrence you specified as part of long-term directionality data. You also specify the name of the Flexcom analysis you ran for this combination of seastate and direction.
(ii)Note that you must specify a data combination (i.e. a combination of Hs and Tz or Tp, an associated direction, and a Flexcom analysis) for every reference seastate for every direction with non-zero percentage occurrence. So, for example, if you have five reference seastates and four directions, you must have 20 data combinations in the Pre-run Analyses specification. When you come to actually run the LifeFrequency analysis, the program does check this for you, and if there is a combination in the environmental data without a Flexcom file name, the program prints an error message to that effect and the fatigue analysis does not run.
•*SEASTATE FILES is used to specify all of the Flexcom random sea analyses on which the LifeFrequency calculations are to be based, and to tabulate the percentage occurrences of the corresponding seastates.
•*BLOCK is used to input the fatigue analysis wave scatter diagram, including the definition of blocks and/or reference seastates as appropriate.
•*DIRECTION is used to specify long-term directionality data.
•*SPECTRUM is used to specify the wave spectrum type to use for fatigue life calculations.