Nonlinear Inertia and Its Effect Within an X-shaped Mechanism

This paper presents a new understanding and development related to nonlinear inertia and its effect in coupling with an X-shaped anti-vibration mechanism, which is validated by prototyping and experiments. The new inertial unit integrated in a well-designed X-shaped mechanism allows larger excitation displacements and more adjustable inertia ratios, resulting in significantly lower vibration transmissibility and resonance peak, and produces three different typical nonlinear inertia forms. A key parameter indicator (Ratio of Inertia) is proposed to identify and indicate the different types of nonlinearities, and the resulting beneficial effects are explored. The performance improvement in dynamics with respect to the linear counterpart is evaluated for different nonlinear inertia forms. The results show that: (a) The U-shaped symmetrical nonlinear inertia coupling with X-shaped mechanisms can provide better vibration isolation performance at low frequency; (b) High-frequency transmissibility can be tuned to different level, indicating a tunable band-suppress property, which is a unique property discovered in this study; (c) the nonlinear inertia contributes significantly to tune the interactive force between vibration source and object in the low frequency range (<10 Hz in our prototype) and obviously helpful and robust to stronger excitations. This study provides new insights into the application of nonlinear inertia in various engineering systems to achieve better passive vibration suppression or isolation.