Nonlinear responses of two-span rotor-bearing system with coupling faults of crack and pedestal looseness

A dynamic model was set up for the two-span rotor-bearing system with coupling faults of crack and pedestal looseness supported on three plain journal bearings.The nonlinear dynamics behaviors that induced by crack,pedestal looseness and coupling faults are numerically studied.In the case of crack faults,quasi-periodic motion appears within the range of sub-and super-critical speed range.When the pedestal looseness fault occurs,the quasi-periodic motion appears in the sub-critical speed range,but chaotic motion takes place within the super-critical speed range.The pedestal looseness fault is the main influence on the coupling fault system,and there is period-3 motion appearing in the system.The influence of crack fault increases along with the depth of crack.The results may provide theoretical references for fault diagnosis,dynamic design,and safe operation of rotor-bearing system.