peak and continue to the end and wrapping around to the beginning. Four point method This method evaluates each set of 4 adjacent turning points A-B-C-D in turn: Any pair of points B-C that lies within or equal to A-D is a rainflow cycle. Remove the pair B-C and re-evaluate the sequence from the beginning. Continue until no further pairs can be identified. Pagoda roof method This method considers the flow of water down of a series of pagoda roofs. Regions where the water will not flow identify the rainflow cycles which are seen as an interruption to the main cycle. Reduce the time history to a sequence of (tensile) peaks and (compressive) valleys. Imagine that the time history is a template for a rigid sheet (pagoda roof). Turn the sheet clockwise 90° (earliest time to the top). Each "tensile peak" is imagined as a source of water that "drips" down the pagoda. Count the number of half-cycles by looking for terminations in the flow occurring when either: case (a) It reaches the end of the time history; case (b) It merges with a flow that started at an earlier tensile peak; or case (c) An opposite tensile peak has greater or equal magnitude. Repeat step 5 for compressive valleys. Assign a magnitude to each half-cycle equal to the stress difference between its start and termination. Pair up half-cycles of identical magnitude (but opposite sense) to count the number of complete cycles. Typically, there are some residual half-cycles. Example The stress history in Figure 2 is reduced to tensile peaks in Figure 3 and compressive valleys in Figure 4. From the tensile peaks in Figure 3: The first half-cycle starts at tensile peak 1 and terminates opposite a greater tensile stress, peak 3 (case c); its magnitude is 16 MPa (2 - (-14) = 16). The half-cycle starting at peak 9 terminates where it is interrupted by a flow from earlier peak 8 (case b); its magnitude is 16 MPa (8 - (-8) = 16). The half-cycle starting at peak 11 terminates at the end of the time history (case a); its magnitude is 19 MPa (15 - (-4) = 19). Similar half-cycles are calculated for compressive stresses (Figure 4) and the half-cycles are then matched. References External links StoFlo freeware rainflow cycle counting Excel template Matlab Central rainflow counting method WAFO. Wave Analysis for Fatigue and Oceanography (Matlab) GAC