Sensitivity analysis of an open TBM gripping-thrusting-regripping mechanism based on the natural characteristics

Abstract The gripping-thrusting-regripping mechanism, as the core transmission components of the open TBMs, is always subjected to the strong and low frequency distributed impacts in tunneling operations, causing the severe vibration and unexpected damage of the key components. It is therefore crucial to gain deep insight into the basic vibration characteristics. With the consideration of the stiffness of the actuating hydraulic cylinders, coupling of the generalized coordinates and elasticity of main beam, etc., the dynamic model is established by Lagrangian method to analyze the lower order natural frequencies and relevant vibration modes, and it is validated by the finite element model developed in SAMCEF software. The effects of the stiffness, inertial and dimensional parameters on natural frequencies as well as their sensitivity are investigated in detail. The results indicate that the 1st mode shape is the rotation around z -axis of cutter-head, main beam and carrier, and the 2-4th mode shapes are the translations at y, x and z directions; the parameters of cutter-head support unit and propel cylinder are the main factors affecting the natural characteristics. These findings can provide some references to design the mechanical structure and to select the duty parameters in engineering applications.