Rainflow count
As a rainflow-counting algorithm , or Rainflowzählverfahren , a special zweiparametriges is counting process within the operating strength , respectively. The process is used, for example, in the automotive industry for the operationally stable design of road-excited components.
The English name Rainflow is derived from a clear explanation of the counting method with rainwater flows over pagoda roofs .
The process is characterized by the conversion of a stress-time sequence into a sequence of classified reversal points and the subsequent counting of closed hystereses as a defined fundamental damage event. The closed hystereses arise from plastic deformations in the material and can also be illustrated in the stress-strain diagram . Since the procedure has two parameters, it allows a clear inverse transformation of mean values and amplitudes.
Half-loop or half-hysteresis is called the area where the “rainwater” from one pagoda roof meets the next pagoda roof.
Rules of the rainflow count when evaluating the cycles
Overall, there are three main rules for visually evaluating a rainflow count using a cycle diagram.
- Half loop or half hysteresis ends at the end of the time series
- Half-loop, or half-hysteresis, ends when it meets another half-loop that started at an earlier point in time.
- Half-loop or half-hysteresis ends when the opposite peak value is greater than the start value of the half-loop under consideration.
literature
- Clormann, UH, Seeger, T .: Rainflow-HCM: A hysteresis loop counting algorithm based on material mechanics . In: FF-22, Department of Mechanics of Materials, TH Darmstadt . 1985.