The dynamic model for a dual-disc cantilever rotor system with imbalance-fixed point rubbing coupling faults was established. In the coupling model

the rubbing force of fixed point rubbing was characterized by nonlinear hysteretic force model. In the process of numerical simulation

the moment of rubbing happening was estimated by linear interpolation method. The results of numerical simulation were used to analyze the influences of degree of hardness

softness and convexity of casing convex point on the rubbing response of rotor. Results showed that when the material of the casing convex point was comparatively hard

quasi-periodic motion of rotor could appear at lower speed. For a sharp convex point

the system response turned out to generate phenomenons of nonlinearities including periodic and quasi-periodic motions. When the clearance between rotor and stator was smaller

nonlinear vibration of the system would come into being in a region of high rotating speed.