Rainflow Algorithm for converting variable amplitude loading spectrum to constant amplitude loading and its application in aerospace technology

As we know in real condition، most components are subjected to variable amplitude loading and their amplitude، average value and loading frequency varies with time But fatigue relations are obtained from constant amplitude loading. For this reason for fatigue calculation، it is necessary we convert variable amplitude loading to constant amplitude loading for a component which is subjected to variable amplitude loading. In this paper first we discuss about the property of variable amplitude loading and then the simplest form of this loading which contains a complex blocks of constant amplitude loading and Miner and Madiag’s methods are introduced. After this stage، we demonstrate how a arbitrary variable amplitude loading is conerted to constant amplitude loading. the method used here is Rainflow and its algorithm and flowchart are discussed here. Because in this method، hand calculation specially in complex loading is difficult to do، a MATLAB program is written and with using this program، the calculation will be don simply. At the end of this article، application of converting variable amplitude loading to constant amplitude loading in aerospace technology will be demonstrated.