Damage-tolerant architected materials inspired by crystal microstructure

Abstract

Architectured materials comprised of periodic arrangements of nodes and struts are 11 lightweight materials that can exhibit combinations of properties which are inaccessible to 12 conventional solids. However, with regards to their mechanical performance, they have an 13Achilles heel in that these materials can exhibit a catastrophic post-yielding collapse, causing 14 substantial drops in strength and energy absorption during plastic deformation. This post-15 yielding collapse is the result of the activity of single shear bands, and originates from the single 16 orientation of macro-lattices. We observe that this behaviour is analogous to deformation by slip 17 in metallic single crystals. In this study we propose that, by mimicking the microstructure 18 observed in crystalline materials, we may be able to employ hardening mechanisms found in 19 crystalline materials to help us to develop robust and damage-tolerant architected materials. This 20 study demonstrates that crystal-inspired meso-structures can play as an important role in the 21 mechanical properties of architectured materials as do crystallographic microstructures in the 22 case of metallic alloys. Consequently, designing meso-structures that mimic crystallographic 23 microstructure in crystalline metals enables the fusion of metallurgy and architectured materials 24 to transform the way of designing a new type of materials with desired properties. 25 26 Main text references 363

Ultrahigh Energy Absorption Multifunctional Spinodal Nanoarchitectures

“…The high specific strength of nanoscale glassy carbon compared to most bulk materials may explain the superior energy absorption capability of our nanospinodals compared to larger-scale periodic shellbased structures with gyroid, p-Schwarz or other triply minimal surface topologies. [38,39] However, stochastic spinodal topologies where shown remarkably imperfection insensitive compared Small 2019, 15,1903834 to perfect shells, like thin walled cylinders, [18] and lack of periodicity has been shown to increase the damage tolerance of beam-based architectures; [40] this suggests that stochastic spinodals may also have topological advantages over periodic shell-based designs for crack deflection and progressive failure.…”

Design, Fabrication, and Mechanics of 3D Micro‐/Nanolattices

“…Analogs to hardening mechanisms found in crystalline materials, including grain boundary, precipitation, and multiphase strengthening, are integrated with the design of architected materials and have been demonstrated to significantly enhance the mechanical properties and performances of micro‐/nanolattices . For example, inserting vertical twin boundaries or randomly distributed hard precipitates into single crystalline‐like lattices prevents the occurrence of localized deformation (such as the nucleation and propagation of shear bands or cracks and the local buckling of beams), leading to significant improvements in the compressive strength and excellent damage tolerance …”

Enhancement of the Damping Behavior of Ti6Al4V Alloy through the Use of Trabecular Structure Produced by Selective Laser Melting

“…Apart from internal friction and dislocation motion, the bending and buckling of the struts further increase the material damping ability. In recent years, the rapid development of additive manufacturing (AM) technologies has spread the possibility of realizing cellular materials with regular structure, commonly named trabecular or lattice structures …”