Optimal Semiactive Damping Control for a Nonlinear Energy Sink Used to Stabilize Milling

Abstract

Improving product quality of machining components has always met with problems due to the vibration of the milling machine’s spindle, which can be reduced by adding a vibration absorber. The tuned vibration absorber (TVA) has been studied extensively and found to have a narrow bandwidth, but the cutting force possesses wide bandwidth in the process of machining parts. Introducing nonlinearity into the dynamic vibration absorber can effectively increase the bandwidth of vibration suppression and can significantly improve the robustness of the vibration absorber. In addition, a semiactive TVA has proved to be more effective than a passive TVA for many applications, so the main purpose of this study is to find some appropriate semiactive control methods for a nonlinear energy sink (NES), a nonlinear vibration absorber, in structural vibration applications. Two semiactive control methods are considered in this study: continuous groundhook damping control based on velocity and on-off groundhook damping control based on velocity. To fairly compare these vibration absorbers, the optimal parameters of a passive TVA, a passive NES, and two semiactive NESs are designed using numerical optimization techniques to minimize the root-mean-square acceleration. Two cutting forces are introduced in this study, a periodic force and an aperiodic force, and the four vibration absorbers are compared. When the primary structure is excited with aperiodic cutting force, the amplitude of the primary structure decreased by 17.73% with the passive TVA, by 72.29% with the passive NES, by 73.54% with the on-off NES, and by 87.54% with the continuous NES. When the primary structure is excited with periodic cutting force, the amplitude of the primary structure decreased by 49.01% with a passive TVA, by 86.93% with a passive NES, by 96.38% with an on-off NES, and by 99.23% with a continuous NES. The results show that the passive NES is better than the passive TVA; the semiactive NES provides more effective vibration attenuation than the passive NES, and the continuous control is more effective than the on-off control.