Three-Point Cycle Counting

Similar to the three-point cycle counting method, the four-point cycle counting rule uses four consecutive points to extract a cycle. Figure 8.11 illustrates the principles for two possible cycles counted in a most generic time history. The four... 

Finally, from point 1 there will be the last unloading to the origin. Let s count the applied cycles by using the rain flow rule (see Sect. 8.2.4). The procedure outlined in Fig. 8.13 is shown in Fig. 6.40. In the loading time history of Fig. 6.37 three independent cycles can be identified and separated, namely cycle (a), cycle (b) and cycle (c). These three cycles correspond to hysteresis loop 2-3-2, 1—4-5 and 0-1-0 of Fig. 6.39. The same cycles can be identified and separated using the rain flow procedure, as schematized in Fig. 6.41. Let s apply the SWT method to evaluate the allowable number N of cycles using Eq. (6.22) and the damage... 

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