Kirigami-inspired multifunctional re-entrant metamaterials for vibration isolation and multistage response

The conventional re-entrant structure has gained extensive application in energy absorption because of its lightweight characteristics and auxetic properties. However, its multifunctional application potential remains underdeveloped. This research introduces a kirigami-inspired multifunctional re-entrant metamaterial (KMRM) by innovatively applying cutting operations to a 2D re-entrant configuration and converting it into a 3D form. The multi-dimensional mechanical characteristics of the multifunctional metamaterial were explored through both experimental and numerical methods. In 1D arrays, KMRM can achieve broadband vibration isolation in two modes and can tune bandgaps with respect to their ranges and branches. The above features are attributed to the multistable behavior introduced by the kirigami-inspired cut-based design. In 3D arrays, KMRM exhibits dual load plateaus and a 3D auxetic effect under in-plane crushing. The features are due to the KMRM's multistage deformation response. The multistable stage contributes to buffering, preventing the protected object from experiencing high peak stress, while the auxetic stage contributes to enhanced energy absorption and load-bearing capacity. The influence of functionally graded design and hierarchical design on the mechanical properties was further studied. Through reasonable design, 1D KMRM has achieved an ultra-wide elastic bandgap of 155–1233 Hz and a low-frequency bandgap as low as 47–137 Hz; 3D KMRM has achieved programmability in the number and performance of zigzag plateaus. This study provides a novel design paradigm for developing multifunctional lightweight metamaterials.