Branch-type dynamic vibration absorbers for enhanced and frequency-robust vibration suppression

Abstract

Minimizing vibration transmission from mounted machinery remains an important challenge in vibration engineering. Although isolation mounts reduce vibration transmission, residual vibrations can remain significant when excitation forces are large. Moreover, practical machines such as pumps and compressors generate fundamental and harmonic components, requiring vibration suppression at multiple frequencies. This study utilizes branch-type dynamic vibration absorbers (DVAs) for expanded-bandwidth and enhanced vibration suppression in mount-supported systems. A simplified model with dominant excitation at 60 Hz and harmonics at 120 and 180 Hz is considered. First, a branch-type DVA tuned to 60 Hz is designed such that the acceleration response of the cantilever-tip masses is nearly in phase with the excitation force, thereby generating inertial forces that collectively counteract the transmitted dynamic force. Consequently, the DVA achieves an additional reduction of approximately 97.2% beyond that provided by the isolation mounts alone. Furthermore, incorporating DVAs tuned to 59, 60, and 61 Hz on a single rod broadens the suppression bandwidth around the target frequency, improving robustness against practical operating-frequency variations. The approach is also extended to harmonic excitations by combining DVAs tuned to 60, 120, and 180 Hz, enabling suppression exceeding 90%, 80%, and 70% at the respective frequencies.