Dynamic modeling and analysis of the rotor system with cracked double diaphragm coupling

HE Shuting; ZHU Rupeng; WANG Duanhuang; ZHU Yajie

doi:10.16579/j.issn.1001.9669.2026.03.014

Abstract：[Objective]Aiming at the insufficient research on the dynamic characteristics of the rotor system with cracked double diaphragm coupling,the cross-coupling term of coupling stiffness was considered,and the time-varying stiffness matrix of the cracked diaphragm was derived to provide a reference for the crack fault diagnosis and safe operation of such systems.[Methods]Firstly,a dynamic equation of the rotor system including the cross-coupling stiffness term was established to provide model support for the analysis of crack effects.Secondly,the critical speed of the system was solved based on the finite element method,and compared with the simulation results of Ansys software to verify the correctness of the model.Then,the dynamic responses with and without cracks were solved by the Newmark-β method to obtain speed-amplitude diagrams,frequency response-speed waterfall diagrams and axis trajectories.Finally,the influence laws of crack length(5-30 mm)and position(inner and outer diameters)on the system response were systematically analyzed.[Results]The results show that cracks introduce 2 harmonic rotational frequency components,and the inner ring of the axis trajectory rotates about 180° when the speed crosses ω1/2(630 r/min).When the crack length at the output end increases to 20 mm,the first-order critical speed decreases from 1 270 r/min to 1 260 r/min,and the 2 harmonic component is significantly enhanced.The influence of cracks at the outer diameter is more obvious in the initial stage,and the influence at the inner diameter dominated with the increase of crack length,verifying the effectiveness of the model and analysis method.