An improved rainflow counting method for multiaxial stress states using the minimum circumscribed circle method to identify shear stress ranges

Most of the rainflow counting methods are developed for uniaxial stress states. In this paper, a new method for rainflow counting of multiaxial stress states has been proposed. The proposed method is a two-step procedure based on a modified three-point ASTM uniaxial rainflow counting algorithm where normal stress ranges are identified along with start and end indexes of each range. For each identified cycle, shear stress ranges are evaluated based on cycle start and end points using the minimum circumscribed circle method. The proposed algorithm is compared to two commonly applied multiaxial cycle counting methods on simulated and experimental data.