A displacement equipartition structure assisted self-friction metamaterial for energy dissipation

To address the issues of low energy dissipation efficiency and significant force fluctuation in traditional series-connected negative stiffness metamaterials (NSMs), this study proposes a displacement equalization structure (DES) assisted self-friction metamaterial (DES-SFM). The DES-SFM employs an external bow-shaped frame to provide monostable restoring force. Its core energy dissipation mechanism, inspired by backpack buckles, consists of a friction system formed by vertical clamping beams with trapezoidal protrusions and horizontal cantilever beams, which synchronously exhibit negative stiffness behavior during snap-through events. The DES enables multi-level displacement equalization through geometric constraints provided by a rhombus linkage mechanism. The performance of the DES-SFM is validated via theoretical modeling, numerical simulations, and experimental tests. Results demonstrate that the energy dissipation efficiency of DES-SFM reaches 65.5%, and it exhibits excellent reusability. Adjusting the geometric parameters can further enhance the energy dissipation capacity. Moreover, it effectively reduces impact response time, achieving a maximum peak acceleration reduction of up to 95.8%. In the six-stage series configuration, the DES demonstrates a fluctuation suppression rate of 90%. The proposed DES-SFM provides a new solution for reusable buffering applications, while its DES design offers insights into load balancing in series-connected metamaterial systems.