On the probability density function of rainflow stress range for sine on random processes

Sine on Random (SoR) vibration environment is largely employed to recreate behaviour of machines with rotating parts (i.e. rocket, propeller aircraft, turbine engine). However, despite being widely used, this process remains poorly characterized in statistical terms. This lack of knowledge closes the doors to the use of stochastic durability assessment in frequency domain. This study investigates the statistics of a Sine on Random (SoR) process, defining the probability density function of the rainflow-range counting. The starting point of the study is the well-known Dirlik probability density functions (PdF), Rainflow Range occurrences for a Gaussian wideband random process. The study propose a modification of Dirlik PdF to assess the Rainflow-Range occurrences for a Sine on Random process, the resulding PdF was validated by the mean of numerical test finding a comllete agreement.