4D printing of customizable and reconfigurable mechanical metamaterials

Customizable and reconfigurable mechanical behavior is critical for self-adaptive low-frequency vibration isolators operating in dynamic environments. Herein, the mechanical metamaterials with customizable and configurable geometries, material stiffnesses, cushioning properties, and vibration isolation capabilities are fabricated using a 4D printed multi-material system. The metastructure is characterized by the connection of a flexural beam structure and a collapsible straw structure. At the unit level, the stiffness characteristics are analyzed by geometric and theoretical mechanical models. The effect of geometric parameters and material composition on the stiffness behavior of multi-material metamaterials is investigated. Metamaterials' customizable and configurable characteristics are examined by the quasi-static compression mechanical properties, cushion performances, and vibration isolation capabilities under varying geometric parameters and material compositions. Finally, the reprogrammable stiffness of the metamaterial is demonstrated through the modification of geometric parameters utilizing the shape memory properties in 4D printing. The customizable and configurable metamaterials inspire the next generation of cushioning and vibration isolators, holding significant promise for applications demanding superior vibration isolation performances in dynamic environments.