No abstract

Numerical investigation is conducted into the nonlinear dynamic responses to fluid-structure interaction in deep-hole drilling shaft system. Based on the theories of pipes and tubes conveying fluid, the governing equation of the drilling shaft system is obtained taking into account of the fluid-structure interaction and the effect of the motion constraints. The nonlinear partial differential governing equation of motion is discretized in modal space using the Galerkin method and then transformed into a set of ordinary different equations. Numerical solutions of these equations are then obtained using the fourth order Runge-Kutta method. The influence of the forcing frequency and the support constraints on the dynamic behaviors of the drilling shaft is examined. The nonlinear dynamic behaviors of the drilling shaft system are presented by the bifurcation diagram and phase diagram. It has been found that the magnitude of support stiffness and the number and position of support constraints have a significant influence on dynamic behaviors of the drilling shaft system. The study in the paper provides an effective guidance to maintain the stability of the BTA deep-hole drilling shaft system through selecting the favorable operation parameters in deep hole drilling process.

Abstract. Numerical investigation was conducted into dynamics of deep-hole drilling shaft system. The rotating drilling shaft was modeled as a Rayleigh beam conveying the fluid and subjected to torque, compressive axial force and support constraints. From the viewpoint of rotor dynamics and fluid-structure interaction, the governing equation of the drilling shaft system for lateral vibration was obtained taking into account of the fluid-structure interaction, the rotational inertia, the gyroscopic effect, the effect of the motion constraints and frictional damping generated by the surrounding fluid. The influence of the cutting fluid flow velocity, rotational angular velocity, torque, compressive axial force, and the support constraints on natural frequency and stability of the drilling shaft system was examined. It has been found that the cutting fluid flow velocity, compressive axial force and torque decreases natural frequencies of the drilling shaft system, whereas rotational angular velocity and support constraints can improve the stability of the drilling shaft system.

Abstract. Dynamics of deep-hole drilling shaft system is closely related to hole processing quality. From the viewpoint of rotor dynamics and fluid-structure interaction, the governing equation of the drilling shaft system for lateral vibration is obtained taking into account of fluid-structure interaction, rotational inertia, gyroscopic effect, the effect of motion constraints and frictional damping generated by surrounding fluid. The influence of rotational angular velocity and compressive axial force on transient vibration of drilling shaft is mainly examined. It has been found that rotational angular velocity has an obvious effect on the lateral vibration of drilling shaft, whereas the lateral vibration of drilling shaft does not change significantly with the increase of compressive axial force.