Fused deposition modeling (FDM) enables simultaneous programming and production of thermo-responsive shape-shifting materials.

No abstract

Rationally designed meta-implants were found to create compression along both of their contact lines with the surrounding bone, thereby decreasing the chance of bone–implant interface failure (Hoffman's criterion) and wear particle-induced osteolysis, and improving bone ingrowth.

Rational programming of the shape-shifting behavior of flat materials (possibly decorated with complex surface features) to create complex three-dimensional structures.

Mechanical metamaterials are usually designed to exhibit novel properties and functionalities that are rare or even unprecedented. What is common among most previous designs is the quasi-static nature of their mechanical behavior. Here, we introduce a previously unidentified class of strain rate-dependent mechanical metamaterials. The principal idea is to laterally attach two beams with very different levels of strain rate-dependencies to make them act as a single bi-beam. We use an analytical model and multiple computational models to explore the instability modes of such a bi-beam construct, demonstrating how different combinations of hyperelastic and viscoelastic properties of both beams, as well as purposefully introduced geometric imperfections, could be used to create robust and highly predictable strain rate-dependent behaviors of bi-beams. We then use the bi-beams to design and experimentally realize lattice structures with unique strain rate-dependent properties including switching between auxetic and conventional behaviors and negative viscoelasticity.