This package contains an implementation of the ASTM E1049-85 rainflow-counting algorithem and it can be used to asses fatigue properties of a structure by reducing a stress spectrum down to simple stress reversals that can be handeled by Palmgren-Miner linear damage rule.
The package can be installed by:
Pkg.add("Rainflow")And a plotting package to visualize the results:
Pkg.add("Plots")The use of the package can be seen in the following example:
using Rainflow
using Plots
signal = 10*randn(100); # Gennerates some random data
extremum, t = sort_peaks(signal) # Sorts the signal to local extrema's, could optional take a time vector
plot(signal)
scatter!(t,extremum) # plots extrema's
cycles = count_cycles(extremum, t) # find all the cycles in the data
bins = sum_cycles(cycles, 10, 1) # Sums the cycles together dependant on intervals, here there is 10 range interval and one mean interval
bar(bins)
range_intervals = [0, 40, 45, 50, 55, 60, 100.] # There can also be specified user defined intervals
mean_intervals = [0.,100.] # The intevals needs to go from 0-100
bins = sum_cycles(cycles, range_intervals, mean_intervals) # Sums the cycles in the given intervals
# Plotting the results with the user defined intervals
boundaries = find_boundary_vals(cycles); # Find the min max values to scale or interpolate the calculated values
range_values = range_intervals/100*boundaries.max_range # Scale the range values
# The bar plot in julia only takes integer array as tick marks
range_values = collect(Iterators.drop(range_values,1)) # Drop the interval with 0 amplitude
range_values = map(x->round.(x), range_values) # round off the values so they can be converted to Int
range_values = convert(Array{Int64,1},range_values); # Convert the array to Int
bar(range_values, bins, xticks = range_values)The algorithem and functions has been tested on data set of 1e8 numbers, and the sorting and sum the cycles into bins can be performed in less than 20s on a laptop.
Don't hesitate to file an issue or pull-request to improve the package.