Gunnstein
commented
1 year ago Hey,
The four-point cycle counting algorithm only counts full cycles, any half-cycles are left in the so called residual that remain after rainflow cycle counting. According to the cited ISO standard, the half cycles may be accounted for by concatenating the residual with itself (residual after one pass of rainflow cycle counting of the original signal) and then the full-cycles contained within the concatenated residual signal is included in the final count by performing rainflow cycle counting on the concatenated signal one time.
There are edge cases (in particular for short signals), where there may be a significant difference between the 4-point algorithm in fatpack (and the way of handling the residual/half cycles mentioned above) and the 3-point algorithm that includes half cycles, but for the majority of practical cases the result is the same.
The rainflow package implements the 3-point algorithm, it is easy to use and perhaps what you are looking for. You could also use it together with fatpack and get an understanding of the differences between the two rainflow cycle counting algorithms or just check it for your particular use case.
Best regards, Gunnstein
kmacolini
Hi there! This is not an issue--can you please explain how half cycles are accounted for in your rainflow script? I have read through some of the cited articles, but I only have a beginner level understanding of rainflow counting. Does it have to do with reversal concatenation?
The only place I see it mentioned explicitly in the code is in find_range_count using the optional "weight" argument.
Thank you!