New design of magnetic nonlinear energy sink for shock mitigation in dynamic structures

Targeted energy transfer is of significant concern in the nonlinear energy sinks (NESs) used for shock (blasts, earthquakes) mitigation in small and large scale dynamic structures which saves human and equipment. The NES is a light-weighted device (<10% of the whole structure mass) which passively absorbs and rapidly dissipates a considerable portion of the initial shock energy induced to the linear dynamic structure. The proposed new design is based on utilizing the permanent magnets that generate a nonlinear repulsive magnetic force which is nearly equivalent to the required stiffness-based NES force. Using magnets instead of stiffness-based elastic materials yields a flexible and compact design of comparable efficiency with the stiffness-based existing NESs. This proposed design is expected to have wide range of applications for either small systems (Aircraft wings) or large scale dynamic structures (large scale buildings or towers). Hence, symmetric and asymmetric designs of magnetbased NESs are considered here to achieve the aimed optimum performance for shock mitigation. The results of the numerical simulation of the symmetric magnet-based NES are found to be comparable to the stiffness-based NES. However the asymmetric magnet-based design has shown better performance than the stiffness-based NES which is promising for the real life applications.