Rainflow Cycle Counting

This calculation generates the rainflow cycle count for a stress history. A suitable stress history can be generated from the relevant loads using the Channel combination calculation.

Click the Select... button to select stress channels to be processed. If you have selected multiple channels you will be able to specify a number of load cases and variables to be processed in a single calculation, and the results for each load case will then be stored as additional outputs of that load case, and/or accumulated over the turbine lifetime.

For each variable to be processed, enter the following data:

• Minimum value: the start of the stress distribution (should be less than the minimum stress).

• Maximum value: the end of the stress distribution (should be greater than the maximum stress).

• Number of bins: suggest 20. A higher number (maximum 128) will give finer resolution, provided there is sufficient data.

• Minimum range: the smallest signal range to be counted as a cycle. A non-zero value may be useful to remove the effect of any spurious noise on the signal.

If you select Calculate Equivalent Loads, enter up to 10 inverse S-N slopes to use for the calculation of equivalent loads. These are the sinusoidal loads which would produce the same fatigue damage at the specified S-N slope if the frequency of the sinusoid is as specified.

Last updated 30-08-2024