Architected Energy Dissipation Structures with Tunable Rigid-flexible Behaviors

The DoW requires lightweight protection materials for a variety of applications, including personal protection, vehicle safety, and shielding sensitive electronics. Most protection structures are either a) rigid materials – e.g. metals, ceramics, composites - designed to carry significant mechanical loads and/or blunt kinetic threats, or b) flexible materials – e.g. elastomers, foam structures, structures based on polymeric fibers – intended to compress and/or stretch, are conformable, and effective at reducing peak accelerations [1]. However, most protection solutions cannot provide both rigid material response and conformability which limits applications for the Warfighter. Recently, a new family of energy dissipating structures known as “polycatenated architected materials” have been introduced that may display both solid- and fluid-like behaviors [2]. These structures, essentially “3D chainmail” and realized through additive manufacturing, derive their mechanical behaviors not through intrinsic material properties, but rather through geometric arrangement of internal solid elements, e.g. rings or cage-like particles interconnected into 3D networks (note that these materials consist entirely of solid linkages, collectively displaying “fluid-like” behaviors in response to small deformations). In response to severe loading, rigid elements may align and develop complex force chains that exhibit high strength and offer significant protection mechanisms not possible through conventional flexible options [2,3]. However, elements may also reorganize, slide, and/or rotate, which offers novel design mechanisms for dissipating energy, and new ways to enable comfort for applications related to personal protection. The goal of this topic is to create architected structures with tunable mechanical energy dissipating behaviors that can vary spatially throughout the material. Teams will investigate element and linkage materials, geometries, and nearest neighbor spacings to design architected structures that perform optimally for various static and dynamic loading conditions, e.g. via tensile, compression, impact, and rheology characterization. Teams will then design, process, characterize, and simulate energy dissipating behaviors of materials in multiple geometrical configurations, e.g. through comparisons to legacy impact attenuating materials like foams that are used for impact protection (knee pads, elbow pads, helmet pads). Teams will be expected to work alongside Army scientists and engineers to guide the design, manufacturing, and testing of materials. If successful, this effort would enable new materials design tools for the DoW to create customized protection structures for the expeditionary Soldier.