4D printed multi-stable metamaterials with mechanically tunable performance

The function of the metamaterials is determined by the configuration and spatial arrangement of the lattice microstructure. Once manufactured, the geometry and function of the metamaterials are irreversible and cannot be adapted to the environment to be variable and adjustable. This paper studies a shape-reconfigurable, functionally deployable, mechanically adjustable and reusable intelligent multi-stable metamaterial. Based on a 4D printing method that combines digital additive manufacturing technique and thermally induced shape memory polymer exhibiting significant change in modulus of elasticity, this metamaterial is created with reconfigurable, self-expandable and mechanical properties adjustable features. The macroscopic deformation and the morphology change of the lattice microstructure on the metamaterial during the compression test are analyzed using experiment and finite element method. The adjustable, selectable, and controllable for micro-lattice in the metamaterial during deformation and recovery can be achieved by microstructure gradients and composite design methods. The new micro-lattice programmable mechanical metamaterial has excellent versatility and the ability to adapt to environmental changes. This 4D printed multi-stable metamaterial has broad application prospects, such as in soft robots, smart damping interfaces, aerospace adjustable and expandable structures, and tunable function devices.