Review and application of Rainflow residue processing techniques for accurate fatigue damage estimation

Most fatigue loaded structural components are subjected to variable amplitude loads which must be processed into a form that is compatible with design life calculations. Rainflow counting allows individual stress cycles to be identified where they form a closed stress-strain hysteresis loop within a random signal, but inevitably leaves a residue of open data points which must be post-processed. Comparison is made between conventional methods of processing the residue data points, which may be non-conservative, and a more versatile method, presented by Amzallag et al [Amzallag C, Gerey JP, Robert JL, Bahuaud J. Standardization of the rainflow counting method for fatigue analysis. Int. J. Fatigue 1994; 16:287–293], which allows transition cycles to be processed accurately. This paper presents an analytical proof of the method presented by Amzallag et all. We also demonstrate the impact of residue processing on fatigue calculations through the application and comparison of the different techniques in two case studies using long term, high resolution data sets.