The Rainflow DataMode stores multiple channels of rainflow cycle histograms in the output data file. The CX23-R acquires peaks and valleys from triggered or un-triggered time history data streams using the user-specified hysteresis value and the peak valley processing algorithm. The resulting peak valley stream runs through the rainflow cycle counting algorithm to yield the set of closed cycles. The closed cycles are histogrammed using the user-defined options for the type and size of histogram.
After initializing, the peak valley processing algorithm alternates searching for peaks and valleys based on the user-defined hysteresis. There are three states of the algorithm - initialize, peak search and valley search.
Rainflow counted cycles are typically used in low cycle fatigue damage analyses. The rainflow counting algorithm is based on the "one-pass" algorithm described in the paper Simple Rainflow Counting Algorithms, International Journal of Fatigue, January 1982, by D. Socie and S. Downing. The algorithm described in this paper generates the set of closed cycles for the input peak valley sequence, assuming that the sequence repeats itself.
However, to support proper "rainflow histogram addition" (that is, generating a composite rainflow histogram from multiple rainflow histograms defined in a specific sequence), the system stores both the sequence of unclosed reversals and the histogrammed set of closed cycles in the Rainflow DataMode.