Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices,making them simultaneously strong and tough.Herein,we describe our investigations of the mechanical propertie...Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices,making them simultaneously strong and tough.Herein,we describe our investigations of the mechanical properties and the underlying mechanisms of additively manufactured nickel–chromium superalloy(IN625)microlattices after surface mechanical attrition treatment(SMAT).Our results demonstrated that SMAT increased the yielding strength of these microlattices by more than 64.71%and also triggered a transition in their mechanical behaviour.Two primary failure modes were distinguished:weak global deformation,and layer-by-layer collapse,with the latter enhanced by SMAT.The significantly improved mechanical performance was attributable to the ultrafine and hard graded-nanograin layer induced by SMAT,which effectively leveraged the material and structural effects.These results were further validated by finite element analysis.This work provides insight into collapse behaviour and should facilitate the design of ultralight yet buckling-resistant cellular materials.展开更多
Modern additive manufacturing processes enable fabricating architected cellular materials of complex shape,which can be used for different purposes.Among them,lattice structures are increasingly used in applications r...Modern additive manufacturing processes enable fabricating architected cellular materials of complex shape,which can be used for different purposes.Among them,lattice structures are increasingly used in applications requiring a compromise among lightness and suited mechanical properties,like improved energy absorption capacity and specific stiffness-to-weight and strength-to-weight ratios.A dedicated modeling strategy to assess the energy absorption capacity of lattice structures under uni-axial compression loading is presented in this work.The numerical model is developed in a non-linear framework accounting for the strain rate effect on the mechanical responses of the lattice structure.Four geometries,i.e.,cubic body centered cell,octet cell,rhombic-dodecahedron and truncated cuboctahedron 2+,are investigated.Specifically,the influence of the relative density of the representative volume element of each geometry,the strain-rate dependency of the bulk material and of the presence of the manufacturing process-induced geometrical imperfections on the energy absorption capacity of the lattice structure is investigated.The main outcome of this study points out the importance of correctly integrating geometrical imperfections into the modeling strategy when shock absorption applications are aimed for.展开更多
Lithium metal anode holds an important position in fast-charging batteries.But lithium dendrite issues tend to exacerbate at high currents.Li F can be considered as an effective way to improve the Li metal surface ele...Lithium metal anode holds an important position in fast-charging batteries.But lithium dendrite issues tend to exacerbate at high currents.Li F can be considered as an effective way to improve the Li metal surface electrochemical stability to achieve high power and high energy.However,most of reported work are relying on in situ formation of a 2D Li F on Li metal in liquid electrolyte,which limits the scalability and plated Li quantity.Here,we address this challenge and report a scalable synthesis of Li F-rich 3D architected Li metal anode via a direct pyrolysis of molten lithium and fluoropolymer to enable fast Li charging with high current density(20 mA cm-2)and high areal capacity(20 m Ah cm-2).The 3D structure is synthesized by the pyrolysis of fluoropolymer with Li metal and results show high similarity to the pristine electrolyte-derived solid-electrolyte-interphase(SEI).This concept using pyrolysis of fluoropolymer with Li-containing active materials could be also extended to modify Li metal oxide cathode(e.g.,Li Ni0.5Mn1.5O4)for mixed conductive interphase and engineer Li solid ion conductors(e.g.,Li garnet-type oxides)for interface stabilization andframework design.展开更多
The impact region of the dactyl club of mantis shrimp features a rare sinusoidally helicoidal architecture,contributing to its efficient impact-resistant characteristics.This study aims to attain bioinspired sinusoida...The impact region of the dactyl club of mantis shrimp features a rare sinusoidally helicoidal architecture,contributing to its efficient impact-resistant characteristics.This study aims to attain bioinspired sinusoidally architected composites from a practical engineering way.Morphological features of plain-woven fabric were characterized,which demonstrated that the interweaving warp and weft yarns exhibited a sinusoidal architecture.Interconnected woven composites were thus employed and helicoidally stacked to achieve the desired structure.Quasi-static three-point bending and low-velocity impact tests were subsequently performed to evaluate their mechanical performance.Under three-point bending condi-tion,the dominant failure mode gradually changed from fiber breakage to delamination with the increase in the pitch angle.Failure displacement and energy absorption of the heli-coidal woven composites were,respectively,43.89%and 141.90%greater than the unidirectional ones.Under low-velo-city impact condition,the damage area of the helicoidal woven composites decreased by 49.66%while the residual strength increased by 10.10%compared with those of the unidirectional ones,exhibiting better damage resistance and tolerance.Also,effects of fiber architecture on mechanical properties were examined.This work will shed light on future design of the next-generation impact-resistant architected composites.展开更多
Architected stretchable materials with well-organized microarchitectures evolve very rapidly due to their potential in customizing mechanical properties and achieving exotic functions.In many applications,the architec...Architected stretchable materials with well-organized microarchitectures evolve very rapidly due to their potential in customizing mechanical properties and achieving exotic functions.In many applications,the architected stretchable materials are required to sustain large deformation,and their fracture is size-dependent.However,the size effect on the fracture of architected stretchable materials is still elusive.Here,we study this issue by experiment and finite element calculation.It is found that the fracture energy of architected stretchable materials increases with the specimen size ratio,H/h,within a range.When H/h reaches a transition ratio,Rt,the fracture energy approaches a plateau.This transition ratio differentiates the size-dependent and size-independent fracture behavior of architected stretchable materials.The mechanical properties of constituent material only have a minor effect on the transition ratio.The degree of constraint and stress concentration at the node,which are affected by the geometry of the unit-cell,dominate the specimen size effect.The result gives a practical guidance in choosing the specimen size to measure the steady state fracture energy of this class of materials.This work provides insights into the fracture of architected stretchable materials and design for fractureresistant architected stretchable devices.展开更多
In the last decade,micro-architected structures have gained significant attention in academia and industry for their lightweight,strong,and thermally efficient properties.Inspired by biomimicry design,this paper prese...In the last decade,micro-architected structures have gained significant attention in academia and industry for their lightweight,strong,and thermally efficient properties.Inspired by biomimicry design,this paper presents a novel ribbed family of additively manufactured Micro-Architected Domes(MAD).The design incorporates tetrapod pyramid unit cells,golden ratio-based fractal patterns,Schoen’s Minimal Gyroid,and spherical geometry.The study focuses on dome radius,height,and azimuth/elevation partitioning as input variables,with the main output being ribbed micro-cell diameter.The relationships between unit-cells’diameter and input variables were established through problem-solving and numerical computations:linear dependency with the dome radius and hyperbolic dependency with the azimuth and elevation partitioning.The proposed design successfully adhered to the Surface-to-Volume ratio of Schoen’s Minimal Gyroid,achieving an average volume relative density of 2.5%,confirming its lightweight nature.The feasibility of the design was further supported by fabricating three specimens using Filament Fused Fabrication.This research showcases the potential of biomimicry-inspired micro-architected structures,paving the way for innovative applications in various fields.展开更多
基金support provided by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030the Hong Kong General Research Fund(GRF)Scheme(Ref:CityU 11216219)+2 种基金the Research Grants Council of Hong Kong(Project No:AoE/M-402/20)Shenzhen Science and Technology Program:JCYJ20220818101204010the Hong Kong Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center.
文摘Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices,making them simultaneously strong and tough.Herein,we describe our investigations of the mechanical properties and the underlying mechanisms of additively manufactured nickel–chromium superalloy(IN625)microlattices after surface mechanical attrition treatment(SMAT).Our results demonstrated that SMAT increased the yielding strength of these microlattices by more than 64.71%and also triggered a transition in their mechanical behaviour.Two primary failure modes were distinguished:weak global deformation,and layer-by-layer collapse,with the latter enhanced by SMAT.The significantly improved mechanical performance was attributable to the ultrafine and hard graded-nanograin layer induced by SMAT,which effectively leveraged the material and structural effects.These results were further validated by finite element analysis.This work provides insight into collapse behaviour and should facilitate the design of ultralight yet buckling-resistant cellular materials.
文摘Modern additive manufacturing processes enable fabricating architected cellular materials of complex shape,which can be used for different purposes.Among them,lattice structures are increasingly used in applications requiring a compromise among lightness and suited mechanical properties,like improved energy absorption capacity and specific stiffness-to-weight and strength-to-weight ratios.A dedicated modeling strategy to assess the energy absorption capacity of lattice structures under uni-axial compression loading is presented in this work.The numerical model is developed in a non-linear framework accounting for the strain rate effect on the mechanical responses of the lattice structure.Four geometries,i.e.,cubic body centered cell,octet cell,rhombic-dodecahedron and truncated cuboctahedron 2+,are investigated.Specifically,the influence of the relative density of the representative volume element of each geometry,the strain-rate dependency of the bulk material and of the presence of the manufacturing process-induced geometrical imperfections on the energy absorption capacity of the lattice structure is investigated.The main outcome of this study points out the importance of correctly integrating geometrical imperfections into the modeling strategy when shock absorption applications are aimed for.
基金supported by the startup funding at University of Delaware
文摘Lithium metal anode holds an important position in fast-charging batteries.But lithium dendrite issues tend to exacerbate at high currents.Li F can be considered as an effective way to improve the Li metal surface electrochemical stability to achieve high power and high energy.However,most of reported work are relying on in situ formation of a 2D Li F on Li metal in liquid electrolyte,which limits the scalability and plated Li quantity.Here,we address this challenge and report a scalable synthesis of Li F-rich 3D architected Li metal anode via a direct pyrolysis of molten lithium and fluoropolymer to enable fast Li charging with high current density(20 mA cm-2)and high areal capacity(20 m Ah cm-2).The 3D structure is synthesized by the pyrolysis of fluoropolymer with Li metal and results show high similarity to the pristine electrolyte-derived solid-electrolyte-interphase(SEI).This concept using pyrolysis of fluoropolymer with Li-containing active materials could be also extended to modify Li metal oxide cathode(e.g.,Li Ni0.5Mn1.5O4)for mixed conductive interphase and engineer Li solid ion conductors(e.g.,Li garnet-type oxides)for interface stabilization andframework design.
基金National Natural Science Foundation of China[No.12172025]Science Foundation of National Key Laboratory of Science and Technology on Advanced Composites in Special Environments[No.6142905222707].
文摘The impact region of the dactyl club of mantis shrimp features a rare sinusoidally helicoidal architecture,contributing to its efficient impact-resistant characteristics.This study aims to attain bioinspired sinusoidally architected composites from a practical engineering way.Morphological features of plain-woven fabric were characterized,which demonstrated that the interweaving warp and weft yarns exhibited a sinusoidal architecture.Interconnected woven composites were thus employed and helicoidally stacked to achieve the desired structure.Quasi-static three-point bending and low-velocity impact tests were subsequently performed to evaluate their mechanical performance.Under three-point bending condi-tion,the dominant failure mode gradually changed from fiber breakage to delamination with the increase in the pitch angle.Failure displacement and energy absorption of the heli-coidal woven composites were,respectively,43.89%and 141.90%greater than the unidirectional ones.Under low-velo-city impact condition,the damage area of the helicoidal woven composites decreased by 49.66%while the residual strength increased by 10.10%compared with those of the unidirectional ones,exhibiting better damage resistance and tolerance.Also,effects of fiber architecture on mechanical properties were examined.This work will shed light on future design of the next-generation impact-resistant architected composites.
基金supported by the National Natural Science Foundation of China[12002255]National Key R&D Program of China[2021YFB3201700].
文摘Architected stretchable materials with well-organized microarchitectures evolve very rapidly due to their potential in customizing mechanical properties and achieving exotic functions.In many applications,the architected stretchable materials are required to sustain large deformation,and their fracture is size-dependent.However,the size effect on the fracture of architected stretchable materials is still elusive.Here,we study this issue by experiment and finite element calculation.It is found that the fracture energy of architected stretchable materials increases with the specimen size ratio,H/h,within a range.When H/h reaches a transition ratio,Rt,the fracture energy approaches a plateau.This transition ratio differentiates the size-dependent and size-independent fracture behavior of architected stretchable materials.The mechanical properties of constituent material only have a minor effect on the transition ratio.The degree of constraint and stress concentration at the node,which are affected by the geometry of the unit-cell,dominate the specimen size effect.The result gives a practical guidance in choosing the specimen size to measure the steady state fracture energy of this class of materials.This work provides insights into the fracture of architected stretchable materials and design for fractureresistant architected stretchable devices.
基金The authors would like to thank Ecole Nationale Superieure d’Arts&Metiers de Meknes,Moulay Ismail University,Morocco for providing Ansys SpaceClaim R21.Many thanks also to Euromed Center of Research,Euromed University of Fes,Morocco for the availability of Matlab(2022)that allowed performing all the numerical computations,as well as the access to the VOLUMIC Stream 30 Ultra 3D printer for MAD prototyping.
文摘In the last decade,micro-architected structures have gained significant attention in academia and industry for their lightweight,strong,and thermally efficient properties.Inspired by biomimicry design,this paper presents a novel ribbed family of additively manufactured Micro-Architected Domes(MAD).The design incorporates tetrapod pyramid unit cells,golden ratio-based fractal patterns,Schoen’s Minimal Gyroid,and spherical geometry.The study focuses on dome radius,height,and azimuth/elevation partitioning as input variables,with the main output being ribbed micro-cell diameter.The relationships between unit-cells’diameter and input variables were established through problem-solving and numerical computations:linear dependency with the dome radius and hyperbolic dependency with the azimuth and elevation partitioning.The proposed design successfully adhered to the Surface-to-Volume ratio of Schoen’s Minimal Gyroid,achieving an average volume relative density of 2.5%,confirming its lightweight nature.The feasibility of the design was further supported by fabricating three specimens using Filament Fused Fabrication.This research showcases the potential of biomimicry-inspired micro-architected structures,paving the way for innovative applications in various fields.
