A rotary metadamper with magnetically assisted snap-back induced energy dissipation

A novel fluid-free noncontact rotary metadamper is developed that dissipates the input energy through repeating snap-back instabilities. The developed metadamper consists of two main components: a system of rotational magnet pairs with incremental negative torsional stiffness and a torsion spring composed of viscoelastic arms. The former is realized by positioning permanent magnets in a circular arrangement and exhibits a snap-through behavior with periodic stable equilibrium states in rotation. Adding the torsion spring in series with the rotational magnet pairs can lead to repeating snap-back instabilities in the overall system response, during which a portion of the potential energy stored in the system is released. The periodically released energy can be exploited to perform specific functionalities or left to be dissipated through vibrations of the viscoelastic arms and their internal damping mechanisms; herein, the latter strategy is employed. The amount of snap-back induced energy dissipation can be readily tuned by changing the air gap between the magnets in rotational magnet pairs, which is feasible in situ and even at the post-fabrication stage. The developed metadamper is subject to no leakage and minimum wear and, therefore, is a viable choice for use in clean and confined environments. Furthermore, it offers a tunable energy dissipation rate owing to the high tailorability of magnetic interactions.