On the Distribution of Rainflow Range for Gaussian Random Processes with Bimodal PSD

The distribution of rainflow range is investigated for the Gaussian random process using bimodal PSD. The new method evaluates the distribution of range by taking the sum of two Rayleigh distributions which correspond to two dominant frequencies in bimodal PSD. Representative distribution data have been obtained from rainflow analysis for simulated time histories. The applicability of the proposed method is examined for the range distribution generated by the simulation. It is shown that the method estimates the distribution of range with high accuracy even, in the case of a random wave with a large irregularity factor. Since range data for unimodal PSD can be evaluated by Rayleigh approximation, the new method for bimodal PSD greatly extends the region of analytical treatment.