Harnessing fractal cuts to design lattice metamaterials for energy dissipation

This study explores a new group of lattice metamaterials with fractal cuts, demonstrating a noticeable energy dissipation capability via sliding friction and viscoelastic damping. Here, lattice metamaterials with three types of cuts were designed and manufactured by 3D Polyjet printing technology. Experimental results show that the structural ductility can be enhanced sharply by increasing fractal levels while keeping their shape recoverability. Though energy absorption and dissipation obtained from bending tests are significantly different, their loss factors are very close, which could be attributed to the hybrid effect of friction and viscoelasticity. Guided by finite element simulations, we further demonstrate that the sliding friction plays a critical role. Results suggest that bending depth has neglectable effect on the bending stiffness and loss factors while there exists a linear scaling law between bending stiffness and sample thickness. Our study opens a new avenue to create mechanical metamaterials with exceptional energy dissipation, finding applications in many industrial sectors such as defense, energy and transportation.