Analysis on the nonlinear response of cracked rotor in hover flight

The motion equations for a Jeffcott rotor in hover flight are derived. A periodically sampled peak-to-peak value diagram is used for characterizing and distinguishing different types of nonlinear responses in hovering state. The nonlinear responses become more apparent when the rotor is running above the critical speed in flat flight. There are three ways for rotor responses going to chaos, namely through quasi-periodic, intermittence, or period-3 bifurcation to chaos. The hover flight might suppress some nonlinear responses. However, the position of axis center might obviously deflect, leading to either nonlinear response or peak-to-peak value jump near the fraction frequency of swing critical speed.