Design of a smart material-based damper for vibration supression

High-speed machining is of significant interest to the aerospace industry as it is the enabling technology for machining lightweight and thin-walled parts. A problem that is frequently encountered in machining these kinds of components is the chatter phenomenon, the occurrence of which is undesirable in machining for reasons such as shorter tool life, damage to the machine, and poor surface finish. In this study, a smart damper was developed to introduce additional damping into the system that would allow one to increase the axial depths of cut in an end milling process without inducing chatter. A variety of smart fluids were considered for application and magnetorheological (MR) fluids were selected as the medium for the smart damper because of their low power requirements, higher force capability and greater stability. A MR fluid-based smart damper was designed and fabricated. An experimental setup was also designed to test the device both as a conventional damper and as a vibration absorber. Experiments were conducted to test the efficiency of the damper and good results were obtained. As a conventional damper, a 22% - 66% reduction in the vibration amplitude was obtained. The results were lower when the damper was used as an absorber; only a 7%-26% reduction was obtained. A clipped optimal controller was designed to control the dynamic response of the inherently nonlinear smart damper and simulated results are presented. These simulations showed good response of the damper in minimizing the structural vibrations and proved to be an effective control strategy --Abstract, page iii