Nonlinear dynamic response and chaos of a cracked rotor with two disks

In this paper, the nonlinear response and chaos of a cracked rotor with two disks are studied. Considering the breadth of crack in one rotor revolution, the motion equations of the system are derived and then solved. The results show that the rotor response is sensitive to the crack depth, rotating speed, damping ratio and imbalance. When a crack occurs, the frequency of swing vibration is a multiple of rotating speed (NΩ, N = 2, 3,...). There are three main routes for response to chaos, that is from quasi-periodic to chaos, from quasi-periodic to quasi-periodic bifurcation and then to chaos and the intermittence to chaos. The intermittence chaos occurs even for a small crack. With the intermittence chaos range there exists the periodic-doubling bifurcation with time. Larger imbalance parameter and damping ratio can suppress chaos. The diagram of time-phase is a useful way to analyze the nonlinear response.