A Weak Differential Response 3D Printing Approach for Strain Rate-Dependent Mechanical Metamaterials
3D printable strain rate-dependent machine-matter
Recently, we proposed a new class of strain rate-dependent mechanical metamaterials that are made from viscoelastic bilayer beams (i.e., bi-beams).The buckling direction of such bi-beams can be controlled with the applied strain rate.The proposed approach, however, suffers from a major limitation : 3d printing of such bi-beams with such a'strong'differential strain rate-dependent response is very challenging.Here, we propose an alternative approach that only requires a'weak'differential response and a rationally designed geometric artifact to control the buckling direction of bi-beams.We present an analytical model that describes the landscape of all possible combinations of geometric designs and hyperelastic as well as viscoelastic properties that lead to the desired strain rate-dependent switching of the buckling direction.We also demonstrate how multi-and single-material 3d printing techniques can be used to fabricate the proposed bi-beams with microscale and submicron resolutions.Finally, we use the same 3d printing techniques to produce strain rate-dependent gripper
mechanisms as showcases of potential applications.
