Rainflow Cycle Counting

The drop can fall on another roof and to continue to slip according to rules a) and b). If the fall begins from a valley it continues till it arrests for one of the following reasons 

The drop can fall on another roof and continue according to rules c) and d). The above mentioned rules are schematized in Fig. 8.13. As it can be seen, the original time history, Fig. 8.13a, has been rearranged as to start from the largest peak. Fig. 8.13b. All peaks preceding peak A have been reintroduces at the end of the spectrum. Then, the time axis has been rotated by 90° and the load history becomes a series of roofs and valleys with peaks on the left and valley on the right. The rain fall may start from peaks or valleys as well. The result shall be the same. 

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Assuming rainflow cycle counting, it can be shown that the expected fatigue damage is given by Rychlik (1993)... 

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