Rainflow-counting algorithm

The rainflow-counting algorithm is used in calculating the <a href="/facts/Fatigue_(material)/zmJY8hMt">fatigue</a> life of a component in order to convert a loading sequence of varying <a href="/facts/Stress_(physics)/ErAXDbbd">stress</a> into a set of constant amplitude stress reversals with equivalent fatigue damage. The method successively extracts the smaller interruption cycles from a sequence, which models the material memory effect seen with stress-strain <a href="/facts/Hysteresis/9M2pwR62">hysteresis</a> cycles. This simplification allows the number of cycles until failure of a component to be determined for each rainflow cycle using either <a href="/facts/Fatigue_(material)/zmJY8hMt">Miner's rule</a> to calculate the fatigue damage, or in a <a href="/facts/Crack_growth_equation/6n78f8Pw">crack growth equation</a> to calculate the crack increments. Both methods give an estimate of the fatigue life of a component. In cases of multiaxial loading, <a href="/facts/Critical_plane_analysis/af518bHx">critical plane analysis</a> can be used together with rainflow counting to identify the uniaxial history associated with the plane that maximizes damage. The <a href="/facts/Algorithm/fnl5NmRt">algorithm</a> was developed by <a href="/facts/Tatsuo_Endo_(engineer)/ryH0vvDe">Tatsuo Endo</a> and M. Matsuishi in 1968.
The rainflow method is compatible with the cycles obtained from examination of the stress-strain hysteresis cycles. When a material is cyclically strained, a plot of stress against strain shows loops forming from the smaller interruption cycles. At the end of the smaller cycle, the material resumes the stress-strain path of the original cycle, as if the interruption had not occurred. The closed loops represent the energy dissipated by the material.

Rainflow-counting algorithm open-in-new

Rainflow-counting algorithm