Tailoring the Dynamic Actuation of 3D-Printed Mechanical Metamaterials through Inherent and Extrinsic Instabilities

The design of smart flexible structures, such as controlled waveguides or soft robotics, has been accentuated, because they can accomplish energy harvesting, precise motion, and high rigidity. Advanced 3D printing techniques are used to improve these designs through the fabrication of complex 3D architected structures encompassing nonlinear elastic behavior. Nevertheless, the materials used for the fabrication process are also highly viscoelastic, obstructing high deformations or the transport of mechanical signals due to high energy dissipation. Herein, how the resonance of 3D-printed structures that require large actuations can be tailored through inherent and extrinsic instabilities is demonstrated. The 3D complex structures are designed such that buckling is evinced, ushering large deformations. In addition, prebuckling of the undeformed samples substantially diminishes the effective viscosity of the structure. Performing vibrational response simulations on both the undeformed and the prebuckled designs and high-speed imaging on fabricated samples, it is observed that the resonant frequency amplitude is enhanced, more resonant frequencies are reinvigorated, and deformation transcends through the whole structure. The results promulgate the utility of the architected design, combined with controlled instabilities, in the modeling of complex smart structures facilitating large deformations, low energy dissipation, and controlled stiffness.