Analysis of Crunch .rcc files

Wind & Water Computer-Aided Engineering Software Tools
1

Hi,

I wish to analyze the performance of two different control methods based on their ability to minimize fatigue damage.

I’m using Crunch to analyze the output data from FAST_v8. I’ve generated RCC files for certain channels. The RCC files contain two columns X and Y for each channel, as stated:

The -values are the peak-to-peak magnitudes of the rainflow cycles.
The [Y]-values are the rainflow cycles per second for those peak-to-peak magnitudes.

However, the - values don’t seem to match for the two files I wish to compare. So I can’t directly compare which control led to fewer cycles.

What would be a good method to compare the two? Can I use “summation XY” for each channel and then use that for comparision?

Sarat

2

Dear Sarat,

I have not used Crunch recently (in favor of MCrunch, MExtremes, and MLife), but I recall that there is an option in Crunch for the user to specify the bin width (or the bin range) instead of having Crunch calculate it automatically.

Alternatively, often the influence of control methods are compared in terms of aggregated damage-equivalent loads (DELs). While DELs cannot be computed by the old Crunch tool, you can calculate them using MCrunch (nwtc.nrel.gov/MLife). MCrunch and MLife also support different options for rainflow-cycle counting.

Best regards,