Dynamic modeling and simulation analysis of inter-shaft bearing fault of a dual-rotor system

•A Lagrangian energy equation containing kinetic energy, potential energy, Rayleigh dissipation energy and generalized force virtual work is derived from the dynamics universal equation, based on which a fault dynamics model of an 8-degree-of-freedom dual-rotor inter-shaft bearing system is developed.•Validate the model to be accurate in simulating local defects.•Accurately simulated the time-frequency characteristics of the dual-rotor inter-shaft bearing system when failures occur.•Based on the discrete characteristics of Lagrange's equation, the analysis of different structural vibration characteristics in the same system increases the efficiency of work.•It is found that the rotor vibration signal is accompanied by high harmonic vibration signal when there is a fault in the system, and this conclusion provides theoretical support for aero-engine fault vibration analysis.