Abstract: Aiming at the semi-active control of the machining chatter in boring, a new type boring bar is designed, which contains an electrorheological(ER) fluid and is with a controllable vibration characteristic. An investigation to the nonlinear dynamics of the ER fluid in the bar is given, which is dependent on applied electrical field strength and vibration amplitude. The experimental and theoretical analysis is presented to prove that the ER fluid in the bar serves as friction damper with on-line adjustable parameters under some certain conditions. At last, an experimental result about on-line chatter controlling based on the nonlinear dynamics of ER fluids is given.

Key words: Boring bar, Chatter, Electrorheological fluid, Friction damper, Nonlinear dynamic characteristics