Self-excited vibrations of rotating discs and shafts with applications to sawing and milling

This thesis investigates a number of major self-excited vibrations and instabilities that are involved in the interactions between moving flexible components, such as rotating discs or rotating shafts, and stationary systems, such as work-pieces or constrained systems. These investigations are applicable to a broad range of problems involved in the rotor-stator interactions. As an application, an undesirable lateral self-excited vibration in wood cutting called washboarding is studied theoretically and experimentally. A thorough investigation in selfexcited instabilities due to multiple moving interactions between the saw blade and work-piece such as regenerative cutting force, non-conservative following cutting forces and in-plane asymmetric stress fields are simulated and presented based on a number of new developments in modelling and algorithms. A new theoretical approach for the prediction of chatter in rnilling is also proposed based on a dynamic rnilling model including a rotating spindle. The stability characteristics of this imlling system are investigated by using the generalized Fourier series Method presented in this thesis. A comprehensive experimental study on the self-excited lateral vibration in the wood cutting and washboarding phenomenon was conducted to verify the simulations. A side-cut experiment using the pendulum cutting rig was also conducted in order to support the modelling of regenerative cutting force. To detect the self-excited vibration modes during cutting experimentally, several efficient methods and algorithms of identifying travelling modes, such as the Artificial Damping Method, are also proposed and presented in this thesis.Applied Science, Faculty ofMechanical Engineering, Department ofGraduat