We discuss a vibration measurement and control system developed to investigate the complex dynamics of boring-bar chatter. A fundamental question is how best to integrate the sensors and actuators for effective control. Is it sufficient to control only motions normal to the machined surface? We consider a smart structure that consists of two actuator/sensor pairs oriented orthogonally to control the motions of a boring tool in directions normal and tangential to the machined surface. Actuation is achieved with Terfenol-D struts that sting the tool near its base. We develop a control strategy by considering a single-degree- of-freedom chatter model for tool motions normal to the machined surface, showing that enhanced structural damping is an effective chatter control. We adapt a second-order feedback compensation scheme from the literature and point out the special design considerations engendered by the use of Terfenol-D actuation. We consider chatter signatures obtained using the system with and without feedback control and show that the system is very effective at chatter suppression. Because we may control each of the dominant structural modes independently, we examine the validity of a single-mode approximation by considering chatter signatures obtained with only tangential control active. We find that so-called mode coupling effects persist; hence, we expand our modeling efforts to include a coupling due to the cutting forces. We see that a variety of chatter modes exist, depending on the operating parameter, and that, to achieve the most robust performance from the controlled system, it is advisable to have control of both directions.

Date Published: 27 July 1998
PDF: 12 pages
Proc. SPIE 3329, Smart Structures and Materials 1998: Smart Structures and Integrated Systems, (27 July 1998); doi: 10.1117/12.316890

Published in SPIE Proceedings Vol. 3329:
Smart Structures and Materials 1998: Smart Structures and Integrated Systems
Mark E. Regelbrugge, Editor(s)