Perform rainflow counting on the stress-time history of each element along the contact wire. Store these stress-time histories in a two-dimensional array, where each row represents the stress of all elements at a specific instant, and each column represents the stress-time history of a single element. The implementation process is as follows:
(1) Compression of consecutive identical values: For each column in the 2D array, examine consecutive elements in the stress-time history; if they are identical, retain only one.
(2) Extraction of peaks and valleys: For each column in the compressed 2D array, check the product of the differences between adjacent values. If the product is greater than zero, identify and extract the peak (or valley) value.
(3) Adjustment of peaks and valleys: For each column in the 2D array, determine whether the total number of peaks and valleys is odd or even. If odd, leave the stress-time history (as processed in the previous two steps) unchanged. If even, remove the last point. Examine the first and last points: if they are peaks, set both to the larger of the two values; if they are valleys, set both to the smaller of the two values.
(4) Reconfiguration (Joining): Identify the highest peak (or lowest valley) in each column of the adjusted 2D array. Split the stress-time history at this point and join the start of the left segment to the end of the right segment, ensuring that the new stress-time history begins and ends with the highest peak (or lowest valley).
(5) Initial rainflow counting: Apply the "four-point" rainflow counting method. Select the four points sequentially in a cyclic manner to extract the stress amplitude and mean stress for each cycle, and record the corresponding number of stress cycles.
(6) Iterative rainflow counting: Establish a loop to process the remaining points after the initial rainflow counting. Continue extracting stress cycles until only three points remain (representing a complete cycle formed by the extreme values within the array). The extracted stress cycles, the points remaining after each rainflow counting iteration, and the arrays used to track points for removal are stored in separate two-dimensional arrays. One-dimensional arrays are employed to store the points remaining after rainflow counting and the number of entries in each column of the stress cycles; these are updated following each rainflow counting iteration. The arrays used for tracking points to be removed and those storing the remaining points are initialized with the stress time-history data-processed through the preceding four steps-and are subsequently updated after each rainflow counting iteration.
(7) Removal of insignificant amplitudes: A range-threshold formula is applied to filter out stress cycles with negligible, very small amplitudes.
(8) Statistical analysis of stress cycles: The number of stress cycles is tallied according to stress-amplitude intervals, with a bin size of 1 MPa. Through the aforementioned rainflow counting process, the sets of stress amplitudes, mean stress values, and their corresponding cycle counts for the contact wire elements are obtained.
