Metamaterials are a cla b of materials with extraordinary capabilities derived from their engineered structure. In 2017, Frenzel et al. (Science 358, 2017) conceptualized "three-dimensional mechanical metamaterials with a twist,"which convert linear deformation into rotational motion - a mechanical response that surpa bes the bounds of Cauchy continuum mechanics. However, the lack of suitable manufacturing technologies for producing metallic twist metamaterials has precluded their experimental validation and potential applications to date. Herein, 316L-stainle b-steel twist metamaterials are fabricated at various scales using an emerging sintering-based technology - lithography metal manufacturing (LMM) - and their mechanical responses are tested using stereo digital image correlation. Results provide the first empirical evidence of compre bion-induced rotation in steel twist metamaterials and highlight their sensitivity to manufacturing defects.

Interfaces play a critical role in modern structures, where integrating multiple materials and components is essential to achieve specific functions. Enhancing the mechanical performance of these interfaces, particularly their resistance to delamination, is essential to enable extremely lightweight designs and improve energy efficiency. Improving toughness (or increasing energy dissipation during delamination) has traditionally involved modifying materials to navigate the well-known strength-toughness trade-off. However, a more effective strategy involves promoting non-local or extrinsic energy dissipation. This approach encompasses complex degradation phenomena that extend beyond the crack tip, such as long-range bridging, crack fragmentation, and ligament formation. This work explores this innovative strategy within the arena of laminated structures, with a particular focus on fiber-reinforced polymers. This review highlights the substantial potential for improvement by presenting various strategies, from basic principles to proof-of-concept applications. This approach represents a significant design direction for integrating materials and structures, especially relevant in the emerging era of additive manufacturing. However, it also comes with new challenges in predictive modeling of such mechanisms at the structural scale, and here the latest development in this direction is highlighted. Through this perspective, greater durability and performance in advanced structural applications can be achieved.

Metamaterials possess properties not found in nature and are expected to revolutionise the design of structural components. However large-scale production of metallic metamaterials remains locked due to the compromise between print size and resolution in existing metal 3D printing methods. We unlock the possibility of 3D printing of stainless steel metamaterials across scales using lithography metal manufacturing, a vat photopolymerisation technology that uses digital light processing (DLP) on metal-filled resin to 3D print a green body for further debinding and sintering in a furnace. Here in, were explore the effects of energy dose on overpolymerisation, minimal feature size, and print resolution as well as the effects of sintering temperature on microstructure, shape stability, and mechanical properties of 3D printed metamaterials. It has become possible to 3D print steel metamaterials with a twist and auxetic metamaterials with micro-scaled structures on a decimetre scale. Our benchmarking experiments demonstrate that lithography metal manufacturing competes with laser powder bed fusion regarding print accuracy, surface roughness, and design freedom and provides a viable solution for translating metallic metamaterials from laboratories to markets.