A hybrid soft-structure interaction metastructure combining bio-inspired sandwich structure with shear stiffening gel for advanced dynamic crushing performance

Inspired by the structural feature and viscoelastic mechanism found in Cybister elytra, this study proposes a hybrid bio-inspired mechanism synergistic strategy to design the composite bio-inspired sandwich structure embedded with shear stiffening gel (CBSS-SSG). Dynamic impact tests are conducted to investigate the dynamic response of the CBSS-SSG. Meanwhile, the non-linear explicit finite element method is utilized to further explore the rate-dependent characteristics and crushing mechanisms of the CBSS-SSG. The proposed CBSS-SSG under various impact loadings simultaneously possesses a stable and high crushing force level, no obvious peak force, and high energy absorption capacity through the synergistic integration of bio-inspired structural features and viscoelastic protection mechanisms. Comparative analysis with the empty (CBSS-Empty), polymethacrylimide foam-filled (CBSS-Foam), and shear thickening fluid-filled (CBSS-STF) counterparts reveals that the CBSS-SSG exhibits good energy absorption characteristics under different crushing loadings by yielding a superior rate-sensitivity in crushing force efficiency (CFE) and specific energy absorption (SEA). The CBSS-SSG achieves a synchronous boost in CFE and SEA across the studied velocity range, with the enhancement reaching 28.28 %–365.14 % and 7.69 %–528.57 %, respectively, compared with the CBSS-Empty. Additionally, the influences of the SSG's viscoelastic material parameters and the arc-shaped core's configuration parameters on the dynamic performance of CBSS-SSG are further investigated to pinpoint the most efficient CBSS-SSG and achieve the performance-driven customization. The hybrid bio-inspired mechanism synergistic strategy provides a viable pathway toward improvable and allowable for tailoring the dynamic behavior of the protective structure.