Irrational Nonlinearity Enhances the Targeted Energy Transfer in a Rotary Nonlinear Energy Sink

Efficient passive vibration absorption can prevent the failure of systems without requiring sensors or energy sources. Nonlinear energy sinks (NES) have gained popularity as passive vibration absorbers due to their targeted energy transfer (TET) mechanisms that extract and dissipate vibrational energy over broad frequency ranges. In this work, the vibration suppression performance of a novel bistable rotary nonlinear energy sink (BRNES) is studied numerically in the cases of impulse and harmonic excitation. The BRNES consists of a secondary mass that connects to the primary system by a rigid arm and spring that pivot at each connection point. The spring produces an irrational nonlinear restoring force that introduces bistability and favorable oscillatory TET mechanisms. The BRNES outperforms the traditional rotary NES and, in some cases, even the bistable NES. Moreover, unlike most NESs restricted to rectilinear motion, the BRNES is efficient at multiple orientations, thus demonstrating its potential to passively suppress vibrations in any in-plane direction over broad excitation magnitude and frequency ranges.