In this review,we propose a comprehensive overview of additive manufacturing(AM)technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field,of which many are i...In this review,we propose a comprehensive overview of additive manufacturing(AM)technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field,of which many are inspired by nature itself.It describes how new AM technologies(e.g.continuous liquid interface production and multiphoton polymerization,etc)and recent developments in more mature AM technologies(e.g.powder bed fusion,stereolithography,and extrusion-based bioprinting(EBB),etc)lead to more precise,efficient,and personalized biomedical components.EBB is a revolutionary topic creating intricate models with remarkable mechanical compatibility of metamaterials,for instance,stress elimination for tissue engineering and regenerative medicine,negative or zero Poisson’s ratio.By exploiting the designs of porous structures(e.g.truss,triply periodic minimal surface,plant/animal-inspired,and functionally graded lattices,etc),AM-made bioactive bone implants,artificial tissues,and organs are made for tissue replacement.The material palette of the AM metamaterials has high diversity nowadays,ranging from alloys and metals(e.g.cobalt-chromium alloys and titanium,etc)to polymers(e.g.biodegradable polycaprolactone and polymethyl methacrylate,etc),which could be even integrated within bioactive ceramics.These advancements are driving the progress of the biomedical field,improving human health and quality of life.展开更多
Herein,cure characteristics,morphology,and mechanical properties of natural rubber filled with activated carbon-based materials were investigated.Carbon-based materials were prepared from bagasse,coffee grounds and pi...Herein,cure characteristics,morphology,and mechanical properties of natural rubber filled with activated carbon-based materials were investigated.Carbon-based materials were prepared from bagasse,coffee grounds and pineapple crowns by the pyrolysis method at temperatures in the range of 300℃.As-synthesized carbon materials were characterized by optical microscopy(OM),scanning electron microscopy(SEM),and Fourier-transform infrared spectroscopy(FTIR)to analyze size distribution,morphology,and functional groups,respectively.OM and SEM analysis revealed that particles,flakes,and a small quantity of fiber-like carbon were obtained using bagasse and pineapple crown as raw materials,while honeycomb-like carbon materials can be derived from coffee grounds.To investigate the mechanical properties,natural rubber was filled with carbon black and as-synthesized carbon materials by the internal mixing and compression molding process.Transmission electron microscopy(TEM)was utilized to characterize the dispersion of carbon materials in the rubber matrix.The results of tensile testing showed that the natural rubber mixed with as-synthesized carbon materials from pineapple crowns exhibited 54%and 74%improvement in the ultimate tensile strength and Young’s modulus,respectively,compared with natural rubber without filled carbon materials.The enhancement in mechanical properties by activated carbon materials derived from pineapple crowns can be attributed to the flake-and fiber-like structures and good dispersion of carbon materials in the rubber matrix.In addition,it is higher than that of rubber mixed with carbon black.The results demonstrated that as-synthesized carbon materials from pineapple crowns have the potential materials to substitute carbon black in the rubber compound industry.展开更多
This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential ther...This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.展开更多
Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machin...Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.展开更多
Two sets of alloys,Mg-Zn-Ca-xNi(0≤x≤5),have been developed with tunable corrosion and mechanical properties,optimized for fracturing materials.High-zinc artificial aged(T6)Mg-12Zn-0.5Ca-x Ni(0≤x≤5)series,featuring...Two sets of alloys,Mg-Zn-Ca-xNi(0≤x≤5),have been developed with tunable corrosion and mechanical properties,optimized for fracturing materials.High-zinc artificial aged(T6)Mg-12Zn-0.5Ca-x Ni(0≤x≤5)series,featuring a straightforward preparation method and the potential for manufacturing large-scale components,exhibit notable corrosion rates up to 29 mg cm^(-2)h^(-1)at 25℃ and 643 mg cm^(-2)h^(-1)at 93℃.The high corrosion rate is primary due to the Ni–containing second phases,which intensify the galvanic corrosion that overwhelms their corrosion barrier effect.Low-zinc rolled Mg-1.5Zn-0.2Ca-x Ni(0≤x≤5)series,characterizing excellent deformability with an elongation to failure of~26%,present accelerated corrosion rates up to 34 mg cm^(-2)h^(-1)at 25℃ and 942 mg cm^(-2)h^(-1)at 93℃.The elimination of corrosion barrier effect via deformation contributes to the further increase of corrosion rate compared to the T6 series.Additionally,Mg-Zn-Ca-xNi(0≤x≤5)alloys exhibit tunable ultimate tensile strengths ranging from~190 to~237 MPa,depending on their specific composition.The adjustable corrosion rate and mechanical properties render the Mg-Zn-Ca-x Ni(0≤x≤5)alloys suitable for fracturing materials.展开更多
Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages,ultimately impairing its normal physiological function.A...Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages,ultimately impairing its normal physiological function.Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration,promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions.The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties.However,a comprehensive understanding of the underlying mechanisms remains somewhat elusive,limiting the broader application of these innovations.In this review,we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin.The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration.The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity,facilitating efficient cellular reprogramming and,consequently,promoting the regeneration of skin appendages.In summary,the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing,coupled with the restoration of multiple skin appendage functions.展开更多
In order to address the limited mechanical properties of silicon-based materials,this study designed 12 B-site mixed-valence perovskites with s^(0)+s^(2)electronic configurations.Five machine learning models were used...In order to address the limited mechanical properties of silicon-based materials,this study designed 12 B-site mixed-valence perovskites with s^(0)+s^(2)electronic configurations.Five machine learning models were used to predict the bandgap values of candidate materials,and Cs_(2)AgSbCl_(6)was selected as the optimal light absorbing material.By using first principles calculations under stress and strain,it has been determined that micro-strains can achieve the goals of reducing material strength,enhancing flexible characteristics,directionally adjusting the anisotropy of stress concentration areas,improving thermodynamic properties,and enhancing sound insulation ability without significantly affecting photoelectric properties.According to device simulations,tensile strain can effectively increase the theoretical efficiency of solar cells.This work elucidates the mechanism of mechanical property changes under stress and strain,offering insights into new materials for solar energy conversion and accelerating the development of high-performance photovoltaic devices.展开更多
Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising a...Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising as SIBs cathodes due to their high theoretical capacities and facile synthesis.However,their practical applications are hindered by the limitations in energy density and cycling stability.The comprehensive understanding of failure mechanisms within bulk structure and at the cathode/electrolyte interface of cathodes is still lacking.In this review,the issues related to bulk phase degradation and surface degradation,such as irreversible phase transitions,cation migration,transition metal dissolution,air/moisture instability,intergranular cracking,interfacial reactions,and reactive oxygen loss,are discussed.The latest advances and strategies to improve the stability of layered oxide cathodes and full cells are provided,as well as our perspectives on the future development of SIBs.展开更多
Smart materials,especially shape memory composites and 4D printing materials,are widely used in aerospace.Deflectors are essential equipment in wind tunnel construction.Classical deflectors are made of metal materials...Smart materials,especially shape memory composites and 4D printing materials,are widely used in aerospace.Deflectors are essential equipment in wind tunnel construction.Classical deflectors are made of metal materials and have a relatively high structural weight.The deflector made of smart material has the advantage of being lighter in weight compared to classical structure,and it could change the bending angle of the deflector structure under external excitation.In this study,the corresponding mechanical property test and finite element simulation of the smart material are carried out,and the deflector made of smart material is further studied and analyzed.Maxwell viscoelasticity model for the material is established,and relevant parameters are obtained through stress relaxation test fitting.According to relevant parameters and literature,finite element simulation of intelligent deflector structure is carried out.The pressure loss coefficient,airflow deflection angle,and velocity uniformity are studied.The numerical model of the minimum pressure loss coefficient is established with reference to the relevant data,and the formula for calculating the optimal upwind radius of the deflector is obtained.Combined with the numerical simulation results of the flow deflection angle and velocity uniformity of the flow field,it provides a reference for the selection of the size of the deflector.展开更多
The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,h...The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.展开更多
The bulge test is a widely utilized method for assessing the mechanical properties of thin films,including metals,polymers,and semiconductors.However,as film thickness diminishes to nanometer scales,boundary condition...The bulge test is a widely utilized method for assessing the mechanical properties of thin films,including metals,polymers,and semiconductors.However,as film thickness diminishes to nanometer scales,boundary conditions dominated by weak van der Waals forces significantly impact mechanical responses.Instead of sample fracture,interfacial shear deformation and delamination become the primary deformation modes,thereby challenging the applicability of conventional bulge models.To accommodate the interfacial effect,a modified mechanical model based on the bulge test has been proposed.This review summarizes recent advancements in the bulge test to highlight the potential challenges and opportunities for future research.展开更多
Additive manufacturing(AM)is an innovative technique that enables the flexible design and construction of three-dimensional objects.In the nuclear industry,AM enables the use of advanced materials and high-performance...Additive manufacturing(AM)is an innovative technique that enables the flexible design and construction of three-dimensional objects.In the nuclear industry,AM enables the use of advanced materials and high-performance components.Although AM processing has been extensively investigated,the corresponding mechanical properties and structural integrity issues of AM parts have received less attention.This study reviews the mechanical behavior and key challenges of typical AM materials,fuel components,compact heat exchangers with complex geometries,and additive repair of damaged reactor components.The findings of this review will guide the efficient and reliable implementation of AM techniques in nuclear reactors.展开更多
Road construction in Africa is faced with a shortage of quality materials, leading to delays and increased costs. Traditional materials, such as clay soils of the bar soil type, have inadequate properties for pavement...Road construction in Africa is faced with a shortage of quality materials, leading to delays and increased costs. Traditional materials, such as clay soils of the bar soil type, have inadequate properties for pavement sub-base layers, particularly in terms of bearing capacity. This study explores a composite material combining bar soil and bamboo fibers to improve the mechanical performance of bar soil, offering a sustainable and cost-effective solution. The Tori-Bossito bar soil was characterised by particle size analysis, Atterberg limits, Proctor compaction tests and the California Bearing Ratio (CBR). The results show that this material is a class A2 sandy-clay soil with a CBR of 18, which is insufficient for foundation layers requiring a CBR of over 30. To improve its performance, Sèmè-Kpodji bamboo fibers, 30 to 100 microns in diameter and 3 to 5 cm long, were incorporated at rates of 0.9% to 2.7%. The optimum mix, with 2.4% fiber, has a CBR of 35, a dry density of 1.92 t/m3 and a moisture content of 12.4%. This reinforced material is suitable as a base course for low-traffic roadways.展开更多
Bio-based thermoplastic film from flax fiber and fatty acid(FA)was obtained using trifluoroacetic anhydride(TFAA)as an impelling agent.Different quantities of TFAA/FA,size of flax fiber,and fatty acids were applied to...Bio-based thermoplastic film from flax fiber and fatty acid(FA)was obtained using trifluoroacetic anhydride(TFAA)as an impelling agent.Different quantities of TFAA/FA,size of flax fiber,and fatty acids were applied to investigate chemical structure in relation to the mechanical properties.Decreasing the quantity of TFAA/FA by almost half from 1:4 to 1:2.5(flax to TFAA/FA)only reduces by 22%the weight percent gain(WPG)and ester content and reducing flax fiber size slightly increases the WPG and ester content.All the treatments showed sig-nificant chemical structure modification,observed by FTIR and solid CP/MAS^(13)C NMR,confirming the presence of carbonyl ester groups and alkyl chains,in relatively similar intensities.The crystallinity index(CrI)of esterified flax was evaluated by comparing the signal of solid CP/MAS^(13)C NMR in crystalline and amorphous regions and CrI was higher in esterified flax using a lower quantity of reagent and longer fatty acid.Esterified flax in a high quantity of reagent showed ductile or flexible behavior.Decreasing the reagent to 1:2.5 significantly increases the tensile strength and Young’s modulus,and decreases the elongation at break,presenting more brittle and stiff material.Using flax fiber in the original size results in slightly higher tensile strength and Young’s modulus and slightly lower elongation than milled flax.The tensile strength and Young’s modulus of stearic acid esterified flax obtained in this research were higher than myristic acid and comparable to the polyethylene plastics-LDPE and HDPE.展开更多
This study is devoted to a novel fractional friction-damage model for quasi-brittle rock materials subjected to cyclic loadings in the framework of micromechanics.The total damage of material describing the microstruc...This study is devoted to a novel fractional friction-damage model for quasi-brittle rock materials subjected to cyclic loadings in the framework of micromechanics.The total damage of material describing the microstructural degradation is decomposed into two parts:an instantaneous part arising from monotonic loading and a fatigue-related one induced by cyclic loading,relating to the initiation and propagation of microcracks.The inelastic deformation arises directly from frictional sliding along microcracks,inherently coupled with the damage effect.A fractional plastic flow rule is introduced using stress-fractional plasticity operations and covariant transformation approach,instead of classical plastic flow function.Additionally,the progression of fatigue damage is intricately tied to subcracks and can be calculated through application of a convolution law.The number of loading cycles serves as an integration variable,establishing a connection between inelastic deformation and the evolution of fatigue damage.In order to verify the accuracy of the proposed model,comparison between analytical solutions and experimental data are carried out on three different rocks subjected to conventional triaxial compression and cyclic loading tests.The evolution of damage variables is also investigated along with the cumulative deformation and fatigue lifetime.The improvement of the fractional model is finally discussed by comparing with an existing associated fatigue model in literature.展开更多
Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable...Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable and stable mechanical properties can be constructed. This study investigates the mechanical performance of randomly stacked open thin-shell mechanical metamaterials using a combined experimental and numerical simulation approach. Results indicate that under compressive loading, shell unit cells primarily dissipate energy through large deformation, snap-fit behavior, friction, and shell relocation. Different combinations of randomly stacked mechanical metamaterials demonstrate nearly identical energy dissipation ratios during the first compressionunloading cycle, indicating that the energy dissipation efficiency exhibits robust stability independent of contact and geometric randomness. However, under limit cycle conditions, increasing the proportion of Type Ⅱ shells enhances the maximum relative displacement, energy dissipation capacity, and energy dissipation ratio by up to fivefold. Notably, under compressive loading, Type Ⅰ shells engaged through snap-fit behavior exhibit irreversible deformation after unloading, while Type Ⅱ shells maintain their configuration without active engagement. The proportion of Type Ⅱ shells directly determines the mechanical performance of the structure.This research provides new references for the development of lightweight mechanical metamaterials, disordered mechanical metamaterials, and adjustable mechanical metamaterials.展开更多
A highly thermally conductive magnesium borate/boron nitride(A-MBN)composite whisker was developed which was surface functionalized by(3-Aminopropyl)triethoxysilane.Its growth mechanism was proposed.Then,A-MBN/epoxy c...A highly thermally conductive magnesium borate/boron nitride(A-MBN)composite whisker was developed which was surface functionalized by(3-Aminopropyl)triethoxysilane.Its growth mechanism was proposed.Then,A-MBN/epoxy composites were prepared.When the A-MBN content is 8wt%,the thermal conductivity of the A-MBN/EP composite is 0.61 W·m^(-1)·K^(-1),which is 230%higher than that of pure EP.At the same time,the tensile strength of the composite material is 85.4%higher than that of the pure EP,and it also maintains excellent electrical insulation property.Finally,the infrared imaging test verifies the excellent heat dissipation performance of the composite material,indicating that the composite material has broad application prospects in the field of thermal conductive materials.展开更多
Microstructure uniformity of the Al-Nd target materials with Al11 Nd_(3) significantly affects the performance of the fabricated Al-Nd film,which is widely used as wiring material in large-size thin-film transistor li...Microstructure uniformity of the Al-Nd target materials with Al11 Nd_(3) significantly affects the performance of the fabricated Al-Nd film,which is widely used as wiring material in large-size thin-film transistor liquid crystal display(TFT-LCD)panels.Understanding the inherent mechanical properties and chemical bonds of Al11 Nd_(3) is crucial for homogenizing the Al-Nd target.Here,by a combined experimental and ab-initio theoretical study,the microstructure and deformability of the Al-3wt%Nd alloy and the inherent mechanical properties and chemical bonds of Al11 Nd_(3) were investigated comprehensively.The Al-3wt%Nd alloy is composed of the pre-eutecticα-Al matrix and the eutecticα-Al and a high stableα-Al11 Nd_(3) phase.During the plastic deformation,the eutectic microstructure transforms from a cellular to a lamel-lar shape,while the morphology and dimension ofα-Al11 Nd_(3) are not changed significantly.By examin-ing ideal tensile strength,elastic moduli,hardness and brittleness-ductility,the hardness-brittleness ofα-Al11 Nd_(3) is quantitatively evaluated,accounting for its difficulties of plastic deformation and fragmen-tation.Combining band structure,population analysis,topological analysis and crystal orbital Hamilton population,we found thatα-Al11 Nd_(3) possesses two types of chemical bonds:the Nd-Al and Al-Al bonds.The former is a typical ionic bond with electron transfer from Nd to Al,while the latter,dominated by both 3 s-3 p and 3 p-3 p interactions,is a weak covalent bond.The mixed chemical bond is responsible for the high hardness-brittleness ofα-Al11 Nd_(3).This work is expected to lay a foundation for Al-Nd alloy and catalyze the fabrication of high-quality Al-Nd target materials.展开更多
Chiral metamaterials are manmade structures with extraordinary mechanical properties derived from their special geometric design instead of chemical composition.To make the mechanical deformation programmable,the non-...Chiral metamaterials are manmade structures with extraordinary mechanical properties derived from their special geometric design instead of chemical composition.To make the mechanical deformation programmable,the non-uniform rational B-spline(NURBS)curves are taken to replace the traditional ligament boundaries of the chiral structure.The Neural networks are innovatively inserted into the calculation of mechanical properties of the chiral structure instead of finite element methods to improve computational efficiency.For the problem of finding structure configuration with specified mechanical properties,such as Young’s modulus,Poisson’s ratio or deformation,an inverse design method using the Neural network-based proxy model is proposed to build the relationship between mechanical properties and geometric configuration.To satisfy some more complex deformation requirements,a non-homogeneous inverse design method is proposed and verified through simulation and experiments.Numerical and test results reveal the high computational efficiency and accuracy of the proposed method in the design of chiral metamaterials.展开更多
Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,me...Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,mechanical metamaterials can realize a range of counterintuitive properties on a larger scale.In this work,a type of mechanical metamaterial unit cell is proposed,exhibiting both compression-twist coupling behavior and bistability that can be programmed.The design involves linking two cylindrical frames with topology-designed inclined beams.Under uniaxial loading,the structure undergoes a compression-twist deformation,along with buckling at two joints of the inclined beams.Through a rational design of the unit's geometric parameters,the structure can retain its deformed state once the applied displacement surpasses a specified threshold,showing a programmed bistable characteristic.We investigated the influence of the involved parameters on the mechanical response of the unit cells numerically,which agrees well with our experimental results.Since the inclined beams dominate the elastic deformation of unit cells,the two cylindrical frames are almost independent of the bistable response and can therefore be designed in any shape for various arrangements of unit cells in multi-dimensional space.展开更多
基金sponsored by the Science and Technology Program of Hubei Province,China(2022EHB020,2023BBB096)support provided by Centre of the Excellence in Production Research(XPRES)at KTH。
文摘In this review,we propose a comprehensive overview of additive manufacturing(AM)technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field,of which many are inspired by nature itself.It describes how new AM technologies(e.g.continuous liquid interface production and multiphoton polymerization,etc)and recent developments in more mature AM technologies(e.g.powder bed fusion,stereolithography,and extrusion-based bioprinting(EBB),etc)lead to more precise,efficient,and personalized biomedical components.EBB is a revolutionary topic creating intricate models with remarkable mechanical compatibility of metamaterials,for instance,stress elimination for tissue engineering and regenerative medicine,negative or zero Poisson’s ratio.By exploiting the designs of porous structures(e.g.truss,triply periodic minimal surface,plant/animal-inspired,and functionally graded lattices,etc),AM-made bioactive bone implants,artificial tissues,and organs are made for tissue replacement.The material palette of the AM metamaterials has high diversity nowadays,ranging from alloys and metals(e.g.cobalt-chromium alloys and titanium,etc)to polymers(e.g.biodegradable polycaprolactone and polymethyl methacrylate,etc),which could be even integrated within bioactive ceramics.These advancements are driving the progress of the biomedical field,improving human health and quality of life.
基金funded by Faculty of Engineering,Burapha University,grant number 003/2567.
文摘Herein,cure characteristics,morphology,and mechanical properties of natural rubber filled with activated carbon-based materials were investigated.Carbon-based materials were prepared from bagasse,coffee grounds and pineapple crowns by the pyrolysis method at temperatures in the range of 300℃.As-synthesized carbon materials were characterized by optical microscopy(OM),scanning electron microscopy(SEM),and Fourier-transform infrared spectroscopy(FTIR)to analyze size distribution,morphology,and functional groups,respectively.OM and SEM analysis revealed that particles,flakes,and a small quantity of fiber-like carbon were obtained using bagasse and pineapple crown as raw materials,while honeycomb-like carbon materials can be derived from coffee grounds.To investigate the mechanical properties,natural rubber was filled with carbon black and as-synthesized carbon materials by the internal mixing and compression molding process.Transmission electron microscopy(TEM)was utilized to characterize the dispersion of carbon materials in the rubber matrix.The results of tensile testing showed that the natural rubber mixed with as-synthesized carbon materials from pineapple crowns exhibited 54%and 74%improvement in the ultimate tensile strength and Young’s modulus,respectively,compared with natural rubber without filled carbon materials.The enhancement in mechanical properties by activated carbon materials derived from pineapple crowns can be attributed to the flake-and fiber-like structures and good dispersion of carbon materials in the rubber matrix.In addition,it is higher than that of rubber mixed with carbon black.The results demonstrated that as-synthesized carbon materials from pineapple crowns have the potential materials to substitute carbon black in the rubber compound industry.
基金the support from Jinhua Sanhuan Welding Materials Company LimitedSchool of Materials Science and Engineering,Nanjing University of Science and Technology.
文摘This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.
基金financial support from the National Key Research and Development Program of China(2018YFA0703400)the Fundamental Research Funds for the Provincial Universities of Zhejiang(GK239909299001021)+1 种基金the Ninth China Association for Science and Technology Youth Talent Lift Project Support Plan(KYZ015324002)the Changjiang Scholars Program of Chinese Ministry of Education。
文摘Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.
基金supported by the National Key Research and Development Program(No.2022YFE0122000)National Natural Science Foundation of China under Grant Nos.52234009,52274383,52222409,and 52201113。
文摘Two sets of alloys,Mg-Zn-Ca-xNi(0≤x≤5),have been developed with tunable corrosion and mechanical properties,optimized for fracturing materials.High-zinc artificial aged(T6)Mg-12Zn-0.5Ca-x Ni(0≤x≤5)series,featuring a straightforward preparation method and the potential for manufacturing large-scale components,exhibit notable corrosion rates up to 29 mg cm^(-2)h^(-1)at 25℃ and 643 mg cm^(-2)h^(-1)at 93℃.The high corrosion rate is primary due to the Ni–containing second phases,which intensify the galvanic corrosion that overwhelms their corrosion barrier effect.Low-zinc rolled Mg-1.5Zn-0.2Ca-x Ni(0≤x≤5)series,characterizing excellent deformability with an elongation to failure of~26%,present accelerated corrosion rates up to 34 mg cm^(-2)h^(-1)at 25℃ and 942 mg cm^(-2)h^(-1)at 93℃.The elimination of corrosion barrier effect via deformation contributes to the further increase of corrosion rate compared to the T6 series.Additionally,Mg-Zn-Ca-xNi(0≤x≤5)alloys exhibit tunable ultimate tensile strengths ranging from~190 to~237 MPa,depending on their specific composition.The adjustable corrosion rate and mechanical properties render the Mg-Zn-Ca-x Ni(0≤x≤5)alloys suitable for fracturing materials.
基金supported in part by the National Nature Science Foundation of China(92268206,81830064)the CAMS Innovation Fund for Medical Sciences(CIFMS,2019-I2M-5-059)+4 种基金the Military Medical Research Projects(145AKJ260015000X,2022-JCJQ-ZB-09600)the Military Key Basic Research of Foundational Strengthening Program(2020-JCJQ-ZD-256-021)the Science Foundation of National Defense Science and Technology for Excellent Young(2022-JCJQ-ZQ-017)the Military Medical Research and Development Projects(AWS17J005,2019-126)the Specific Research Fund of The Innovation Platform for Academicians of Hainan Province(YSPTZX202317).
文摘Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages,ultimately impairing its normal physiological function.Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration,promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions.The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties.However,a comprehensive understanding of the underlying mechanisms remains somewhat elusive,limiting the broader application of these innovations.In this review,we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin.The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration.The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity,facilitating efficient cellular reprogramming and,consequently,promoting the regeneration of skin appendages.In summary,the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing,coupled with the restoration of multiple skin appendage functions.
基金financially supported by the National Key Research and Development Program Projects of China(No.2023YFB3608901)the Xi'an University of Architecture and Technology Branch of Xi'an Computing Center.
文摘In order to address the limited mechanical properties of silicon-based materials,this study designed 12 B-site mixed-valence perovskites with s^(0)+s^(2)electronic configurations.Five machine learning models were used to predict the bandgap values of candidate materials,and Cs_(2)AgSbCl_(6)was selected as the optimal light absorbing material.By using first principles calculations under stress and strain,it has been determined that micro-strains can achieve the goals of reducing material strength,enhancing flexible characteristics,directionally adjusting the anisotropy of stress concentration areas,improving thermodynamic properties,and enhancing sound insulation ability without significantly affecting photoelectric properties.According to device simulations,tensile strain can effectively increase the theoretical efficiency of solar cells.This work elucidates the mechanism of mechanical property changes under stress and strain,offering insights into new materials for solar energy conversion and accelerating the development of high-performance photovoltaic devices.
基金supported by the National Natural Science Foundation of China(Grant No.W2412060,22325902 and 52171215)the State Key Laboratory of Clean Energy Utilization(Open Fund Project No.ZJUCEU2023002)。
文摘Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising as SIBs cathodes due to their high theoretical capacities and facile synthesis.However,their practical applications are hindered by the limitations in energy density and cycling stability.The comprehensive understanding of failure mechanisms within bulk structure and at the cathode/electrolyte interface of cathodes is still lacking.In this review,the issues related to bulk phase degradation and surface degradation,such as irreversible phase transitions,cation migration,transition metal dissolution,air/moisture instability,intergranular cracking,interfacial reactions,and reactive oxygen loss,are discussed.The latest advances and strategies to improve the stability of layered oxide cathodes and full cells are provided,as well as our perspectives on the future development of SIBs.
文摘Smart materials,especially shape memory composites and 4D printing materials,are widely used in aerospace.Deflectors are essential equipment in wind tunnel construction.Classical deflectors are made of metal materials and have a relatively high structural weight.The deflector made of smart material has the advantage of being lighter in weight compared to classical structure,and it could change the bending angle of the deflector structure under external excitation.In this study,the corresponding mechanical property test and finite element simulation of the smart material are carried out,and the deflector made of smart material is further studied and analyzed.Maxwell viscoelasticity model for the material is established,and relevant parameters are obtained through stress relaxation test fitting.According to relevant parameters and literature,finite element simulation of intelligent deflector structure is carried out.The pressure loss coefficient,airflow deflection angle,and velocity uniformity are studied.The numerical model of the minimum pressure loss coefficient is established with reference to the relevant data,and the formula for calculating the optimal upwind radius of the deflector is obtained.Combined with the numerical simulation results of the flow deflection angle and velocity uniformity of the flow field,it provides a reference for the selection of the size of the deflector.
基金supported by the National Natural Science Foundation of China,Grant Nos.42477185,41602308the Zhejiang Provincial Natural Science Foundation of China,Grant No.LY20E080005+2 种基金the Zhejiang Province University Students Science and Technology Innovation Program,Grant No.0201310P28the PostGraduate Course Construction Project of Zhejiang University of Science and Technology,Grant No.2021yjskj05the Zhejiang University of Science and Technology Graduate Research and Innovation Fund,Grant No.2023yjskc10.
文摘The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.22072031,12372107,11832010,and 11890682)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB36000000).
文摘The bulge test is a widely utilized method for assessing the mechanical properties of thin films,including metals,polymers,and semiconductors.However,as film thickness diminishes to nanometer scales,boundary conditions dominated by weak van der Waals forces significantly impact mechanical responses.Instead of sample fracture,interfacial shear deformation and delamination become the primary deformation modes,thereby challenging the applicability of conventional bulge models.To accommodate the interfacial effect,a modified mechanical model based on the bulge test has been proposed.This review summarizes recent advancements in the bulge test to highlight the potential challenges and opportunities for future research.
基金supported by Stable Support Initiative of the State Key Laboratory of Advanced Nuclear Energy Technology(Grant No.YNSW-0124-0101-03)the author Cheng Zhang would like to thank the support by Stable Support Program for Scientific Research of China(Grant No.WDZC-2023-02-02-05).
文摘Additive manufacturing(AM)is an innovative technique that enables the flexible design and construction of three-dimensional objects.In the nuclear industry,AM enables the use of advanced materials and high-performance components.Although AM processing has been extensively investigated,the corresponding mechanical properties and structural integrity issues of AM parts have received less attention.This study reviews the mechanical behavior and key challenges of typical AM materials,fuel components,compact heat exchangers with complex geometries,and additive repair of damaged reactor components.The findings of this review will guide the efficient and reliable implementation of AM techniques in nuclear reactors.
文摘Road construction in Africa is faced with a shortage of quality materials, leading to delays and increased costs. Traditional materials, such as clay soils of the bar soil type, have inadequate properties for pavement sub-base layers, particularly in terms of bearing capacity. This study explores a composite material combining bar soil and bamboo fibers to improve the mechanical performance of bar soil, offering a sustainable and cost-effective solution. The Tori-Bossito bar soil was characterised by particle size analysis, Atterberg limits, Proctor compaction tests and the California Bearing Ratio (CBR). The results show that this material is a class A2 sandy-clay soil with a CBR of 18, which is insufficient for foundation layers requiring a CBR of over 30. To improve its performance, Sèmè-Kpodji bamboo fibers, 30 to 100 microns in diameter and 3 to 5 cm long, were incorporated at rates of 0.9% to 2.7%. The optimum mix, with 2.4% fiber, has a CBR of 35, a dry density of 1.92 t/m3 and a moisture content of 12.4%. This reinforced material is suitable as a base course for low-traffic roadways.
基金UR 4370 LERMAB is supported by a grant overseen by the French National Research Agency(ANR)as part of the“Investissements d’Avenir”program(ANR-11-LABX-0002-01,Lab of Excellence ARBRE)in the frame of the project“Woodstic”ICEEL for the financial in the frame of the project“BoisPlast”(CARN 001301).
文摘Bio-based thermoplastic film from flax fiber and fatty acid(FA)was obtained using trifluoroacetic anhydride(TFAA)as an impelling agent.Different quantities of TFAA/FA,size of flax fiber,and fatty acids were applied to investigate chemical structure in relation to the mechanical properties.Decreasing the quantity of TFAA/FA by almost half from 1:4 to 1:2.5(flax to TFAA/FA)only reduces by 22%the weight percent gain(WPG)and ester content and reducing flax fiber size slightly increases the WPG and ester content.All the treatments showed sig-nificant chemical structure modification,observed by FTIR and solid CP/MAS^(13)C NMR,confirming the presence of carbonyl ester groups and alkyl chains,in relatively similar intensities.The crystallinity index(CrI)of esterified flax was evaluated by comparing the signal of solid CP/MAS^(13)C NMR in crystalline and amorphous regions and CrI was higher in esterified flax using a lower quantity of reagent and longer fatty acid.Esterified flax in a high quantity of reagent showed ductile or flexible behavior.Decreasing the reagent to 1:2.5 significantly increases the tensile strength and Young’s modulus,and decreases the elongation at break,presenting more brittle and stiff material.Using flax fiber in the original size results in slightly higher tensile strength and Young’s modulus and slightly lower elongation than milled flax.The tensile strength and Young’s modulus of stearic acid esterified flax obtained in this research were higher than myristic acid and comparable to the polyethylene plastics-LDPE and HDPE.
基金Fundamental Research Funds for the Central Universities(Grant No.B230201059)for the support.
文摘This study is devoted to a novel fractional friction-damage model for quasi-brittle rock materials subjected to cyclic loadings in the framework of micromechanics.The total damage of material describing the microstructural degradation is decomposed into two parts:an instantaneous part arising from monotonic loading and a fatigue-related one induced by cyclic loading,relating to the initiation and propagation of microcracks.The inelastic deformation arises directly from frictional sliding along microcracks,inherently coupled with the damage effect.A fractional plastic flow rule is introduced using stress-fractional plasticity operations and covariant transformation approach,instead of classical plastic flow function.Additionally,the progression of fatigue damage is intricately tied to subcracks and can be calculated through application of a convolution law.The number of loading cycles serves as an integration variable,establishing a connection between inelastic deformation and the evolution of fatigue damage.In order to verify the accuracy of the proposed model,comparison between analytical solutions and experimental data are carried out on three different rocks subjected to conventional triaxial compression and cyclic loading tests.The evolution of damage variables is also investigated along with the cumulative deformation and fatigue lifetime.The improvement of the fractional model is finally discussed by comparing with an existing associated fatigue model in literature.
文摘Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable and stable mechanical properties can be constructed. This study investigates the mechanical performance of randomly stacked open thin-shell mechanical metamaterials using a combined experimental and numerical simulation approach. Results indicate that under compressive loading, shell unit cells primarily dissipate energy through large deformation, snap-fit behavior, friction, and shell relocation. Different combinations of randomly stacked mechanical metamaterials demonstrate nearly identical energy dissipation ratios during the first compressionunloading cycle, indicating that the energy dissipation efficiency exhibits robust stability independent of contact and geometric randomness. However, under limit cycle conditions, increasing the proportion of Type Ⅱ shells enhances the maximum relative displacement, energy dissipation capacity, and energy dissipation ratio by up to fivefold. Notably, under compressive loading, Type Ⅰ shells engaged through snap-fit behavior exhibit irreversible deformation after unloading, while Type Ⅱ shells maintain their configuration without active engagement. The proportion of Type Ⅱ shells directly determines the mechanical performance of the structure.This research provides new references for the development of lightweight mechanical metamaterials, disordered mechanical metamaterials, and adjustable mechanical metamaterials.
基金Funded by the Guangxi Natural Science Foundation(No.2024GXNSFBA010338)。
文摘A highly thermally conductive magnesium borate/boron nitride(A-MBN)composite whisker was developed which was surface functionalized by(3-Aminopropyl)triethoxysilane.Its growth mechanism was proposed.Then,A-MBN/epoxy composites were prepared.When the A-MBN content is 8wt%,the thermal conductivity of the A-MBN/EP composite is 0.61 W·m^(-1)·K^(-1),which is 230%higher than that of pure EP.At the same time,the tensile strength of the composite material is 85.4%higher than that of the pure EP,and it also maintains excellent electrical insulation property.Finally,the infrared imaging test verifies the excellent heat dissipation performance of the composite material,indicating that the composite material has broad application prospects in the field of thermal conductive materials.
基金supported by the National Key R&D Program of China(No.2022YFB3504401).
文摘Microstructure uniformity of the Al-Nd target materials with Al11 Nd_(3) significantly affects the performance of the fabricated Al-Nd film,which is widely used as wiring material in large-size thin-film transistor liquid crystal display(TFT-LCD)panels.Understanding the inherent mechanical properties and chemical bonds of Al11 Nd_(3) is crucial for homogenizing the Al-Nd target.Here,by a combined experimental and ab-initio theoretical study,the microstructure and deformability of the Al-3wt%Nd alloy and the inherent mechanical properties and chemical bonds of Al11 Nd_(3) were investigated comprehensively.The Al-3wt%Nd alloy is composed of the pre-eutecticα-Al matrix and the eutecticα-Al and a high stableα-Al11 Nd_(3) phase.During the plastic deformation,the eutectic microstructure transforms from a cellular to a lamel-lar shape,while the morphology and dimension ofα-Al11 Nd_(3) are not changed significantly.By examin-ing ideal tensile strength,elastic moduli,hardness and brittleness-ductility,the hardness-brittleness ofα-Al11 Nd_(3) is quantitatively evaluated,accounting for its difficulties of plastic deformation and fragmen-tation.Combining band structure,population analysis,topological analysis and crystal orbital Hamilton population,we found thatα-Al11 Nd_(3) possesses two types of chemical bonds:the Nd-Al and Al-Al bonds.The former is a typical ionic bond with electron transfer from Nd to Al,while the latter,dominated by both 3 s-3 p and 3 p-3 p interactions,is a weak covalent bond.The mixed chemical bond is responsible for the high hardness-brittleness ofα-Al11 Nd_(3).This work is expected to lay a foundation for Al-Nd alloy and catalyze the fabrication of high-quality Al-Nd target materials.
基金supported by the National Natural Science Foundation of China(grant numbers 11972287 and 12072266)the State Key Laboratory of Structural Analysis,Optimization and CAE Software for Industrial Equipment(GZ23106)+1 种基金the National Key Laboratory of Aircraft Configuration Design(No.2023-JCJQ-LB-070)the Fundamental Research Funds for the Central Universities.
文摘Chiral metamaterials are manmade structures with extraordinary mechanical properties derived from their special geometric design instead of chemical composition.To make the mechanical deformation programmable,the non-uniform rational B-spline(NURBS)curves are taken to replace the traditional ligament boundaries of the chiral structure.The Neural networks are innovatively inserted into the calculation of mechanical properties of the chiral structure instead of finite element methods to improve computational efficiency.For the problem of finding structure configuration with specified mechanical properties,such as Young’s modulus,Poisson’s ratio or deformation,an inverse design method using the Neural network-based proxy model is proposed to build the relationship between mechanical properties and geometric configuration.To satisfy some more complex deformation requirements,a non-homogeneous inverse design method is proposed and verified through simulation and experiments.Numerical and test results reveal the high computational efficiency and accuracy of the proposed method in the design of chiral metamaterials.
基金supported by the National Natural Science Foundation of China(Grant Numbers:12125205,12321002,12072316,12132014)the Zhejiang Provincial Natural Science Foundation of China(LD22A020001).
文摘Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,mechanical metamaterials can realize a range of counterintuitive properties on a larger scale.In this work,a type of mechanical metamaterial unit cell is proposed,exhibiting both compression-twist coupling behavior and bistability that can be programmed.The design involves linking two cylindrical frames with topology-designed inclined beams.Under uniaxial loading,the structure undergoes a compression-twist deformation,along with buckling at two joints of the inclined beams.Through a rational design of the unit's geometric parameters,the structure can retain its deformed state once the applied displacement surpasses a specified threshold,showing a programmed bistable characteristic.We investigated the influence of the involved parameters on the mechanical response of the unit cells numerically,which agrees well with our experimental results.Since the inclined beams dominate the elastic deformation of unit cells,the two cylindrical frames are almost independent of the bistable response and can therefore be designed in any shape for various arrangements of unit cells in multi-dimensional space.
