Special Issue: Selected Papers from DSTA 2019 Conference

Abstract

This special issue would not have been possible with the terrific support of the ASME Journal of Computational and Nonlinear Dynamics, in particular, that of Ms. Amy Suski. Many thanks to her, for making this issue possible.The investigations presented in “Breathing Crack Model Effect on Rotor's Postresonance Backward Whirl,” by Alzarooni, Al-Shudeifat, Shiryayev, Nataraj are focused on the appearance of postresonance backward whirl in a rotor model with a breathing crack. This phenomenon could be employed as an indicator of crack and bearing damage in rotor systems that undergo recurrent passage through critical forward whirl rotational speed during startup and coast down operations. A finite element model is used to develop the linear-time-varying equations of motion of the considered accelerated cracked rotor. The whirl response is obtained through direct numerical integration, since in addition, the effect of bearing anisotropy on the postresonance backward whirl excitation is investigated. The authors found that the appearance of the postresonance backward whirl zones is significantly affected by the depth of the crack, angular acceleration rate, anisotropy of bearings, and the orientation of the unbalance force vector with respect to the crack opening direction.