This study pioneers the integrated fabrication of magnesium corrugated-core sandwich structures using wire-arc directed energy deposition(WA-DED).Two sandwich structures—V-type and X-type—were designed with optimize...This study pioneers the integrated fabrication of magnesium corrugated-core sandwich structures using wire-arc directed energy deposition(WA-DED).Two sandwich structures—V-type and X-type—were designed with optimized deposition paths to achieve comparable grain morphology while enhancing strength.The compression properties and failure modes of the two corrugated-core sandwich structures were examined through quasi-static compression tests.Results showed that the V-type structure exhibited a higher specific compressive strength(93 MPa∙cm^(3)/g)than the X-type structure(72 MPa∙cm^(3)/g).Both finite element analysis and experimental compression tests indicated that failure occurred at the midsection of the corrugated core.This work offers valuable insights for the efficient fabrication of high-strength corrugated-core sandwich structures.展开更多
Over the past several decades,the integration of IONs into EP emerged as an effective method for enhancing its mechanical properties.Nevertheless,challenges remain,especially with u-IONs,where the interfacial strength...Over the past several decades,the integration of IONs into EP emerged as an effective method for enhancing its mechanical properties.Nevertheless,challenges remain,especially with u-IONs,where the interfacial strength with EP is suboptimal,resulting in aggregation within the EP matrix and a subsequent deterioration in the mechanical performance of u-ION/EP nanocomposites.In this comprehensive review,we explored advanced chemical modification techniques tailored for IONs incorporated into EP,providing a detailed examination of the mechanical characteristics of surface cm-ION/EP nanocomposites.This review investigates various chemical modification methods and their distinct impacts on the mechanical attributes of the resulting EP nanocomposites.Special emphasis is given to addressing the persistent challenges of inadequate interfacial strength and aggregation.Furthermore,this article examines prospective surface modification approaches for inorganic oxide nanoparticles,offering a visionary outlook on methods to improve the mechanical performance of EP in future.展开更多
The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coat...The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coating’s resistance to CMAS corrosion.The results indicate a phase transformation over time,transitioning from Ca_(2)Lu_(8)(SiO_(4))6O_(2) apatite and Lu_(2)Si_(2)O_(7) to solely Lu_(2)Si_(2)O_(7).The interaction of the Lu_(2)Si_(2)O_(7) coating with the CMAS melts was divided into three stages based on the corrosion reaction behavior.The delamination cracks were distributed throughout the interface between the Si bond layer and Lu_(2)Si_(2)O_(7) layer after corroded at 1400℃ for 50 h,signifying coating failure.In addition,the influence of monosilicates,disilicates,and corrosion duration on the recession layer thickness was analyzed by comparing previous reports on RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7) coatings(RE=Gd,Yb,Lu,Er).Furthermore,the variation in the thermally grown oxide layer thickness in CMAS-corroded Lu_(2)Si_(2)O_(7) coatings was systematically investigated.展开更多
The curing behavior of composites significantly influences their performance,making it crucial to understand the curing process.This study experimentally measured specific heat capacity,thermal conductivity,glass tran...The curing behavior of composites significantly influences their performance,making it crucial to understand the curing process.This study experimentally measured specific heat capacity,thermal conductivity,glass transition temperature,coefficient of thermal expansion,and cure shrinkage of materials.A simulation model of its curing deformation was established and validated against strain data obtained from fiber Bragg grating experiments.The effects of thickness,heating rate,and cooling rate on the curing temperature field and residual stress field during the molding of thick-section composite plates were analyzed.展开更多
This paper presents a combination of experimental and numerical investigations on the dynamic response of scaling cabin structures under internal blast loading.The purpose of this study is to modify the similar relati...This paper presents a combination of experimental and numerical investigations on the dynamic response of scaling cabin structures under internal blast loading.The purpose of this study is to modify the similar relationship between the scaled-down model and the prototype of the cabin structures under internal blast loading.According to the Hopkinson’s scaling law,three sets of cabin structure models with different scaling factors combined with different explosive masses were designed for the experimental study.The dynamic deformation process of the models was recorded by a three-dimensional digital imaging correlation(DIC)method and a 3D scanning technology was used to reconstruct the deformation modes of the specimen.In addition,a finite element model was developed for the modification of the scaling law.The experimental results showed that the final deflection-to-thickness ratio was increased with the increase of the model size despite of the similar trend of their deformation processes.The reason for this inconsistency was discussed based on the traditional scaling law and a modified formula considering of the effects of size and strain-rate was provided.展开更多
Inspired by the gradient structure of the nature,two gradient lattice structures,i.e.,unidirectional gradient lattice(UGL)and bidirectional gradient lattice(BGL),are proposed based on the body-centered cubic(BCC)latti...Inspired by the gradient structure of the nature,two gradient lattice structures,i.e.,unidirectional gradient lattice(UGL)and bidirectional gradient lattice(BGL),are proposed based on the body-centered cubic(BCC)lattice to obtain specially designed mechanical behaviors,such as load-bearing and energy absorption capacities.First,a theoretical model is proposed to predict the initial stiffness of the gradient lattice structure under compressive loading,and validated against quasi-static compression tests and finite element models(FEMs).The deformation and failure mechanisms of the two structures are further studied based on experiments and simulations.The UGL structure exhibits a layer-by-layer failure mode,which avoids structure-wise shear failure in uniform structures.The BGL structure presents a symmetry deformation pattern,and the failure initiates at the weakest part.Finally,the energy absorption behaviors are also discussed.This study demonstrates the potential application of gradient lattice structures in load-transfer-path modification and energy absorption by topology design.展开更多
High-entropy diborides(HEBs)have attracted extensive research due to their potential ultra-high hardness.In the present work,the effects of transition metals(TM)on lattice parameters,electron work function(EWF),bondin...High-entropy diborides(HEBs)have attracted extensive research due to their potential ultra-high hardness.In the present work,the effects of transition metals(TM)on lattice parameters,electron work function(EWF),bonding charge density,and hardness of HEBs are comprehensively investigated by the first-principles calculations,including(TiZrHfNbTa)B_(2),(TiZrHfNbMo)B_(2),(TiZrHfTaMo)B_(2),(TiZrNbTaMo)B_(2),and(TiHfNbTaMo)B_(2).It is revealed that the disordered TM atoms result in a severe local lattice distortion and the formation of weak spots.In view of bonding charge density,it is understood that the degree of electron contribution of TM atoms directly affects the bonding strength of the metallic layer,contributing to the optimized hardness of HEBs.Moreover,the proposed power-law-scaled relationship integrating the EWF and the grain size yields an excellent agreement between our predicted results and those reported experimental ones.It is found that the HEBs exhibit relatively high hardness which is higher than those of single transition metal diborides.In particular,the hardness of(TiZrNbTaMo)B_(2)and(TiHfNbTaMo)B_(2)can be as high as29.15 and 28.02 GPa,respectively.This work provides a rapid strategy to discover/design advanced HEBs efficiently,supported by the coupling hardening mechanisms of solid solution and grain refinement based on the atomic and electronic interactions.展开更多
Increasing attention has been focused on potassium ion batteries(KIBs) as promising energy-sto rage system(ESS) owing to the abundance and low-cost of potassium resources.Here,SnS2/SnO2 hete rostructures were successf...Increasing attention has been focused on potassium ion batteries(KIBs) as promising energy-sto rage system(ESS) owing to the abundance and low-cost of potassium resources.Here,SnS2/SnO2 hete rostructures were successfully fixed onto stainless steel mesh(SnS2/SnO2/SSM) through a facile two-step hydrothermal method and used as anodes for KIBs.Due to the advantages of SnS2/SnO2 heterostructures and good conductivity of SSM substrate,the SnS2/SnO2/SSM anodes display enhanced electrochemical performance.The SnS2/SnO2/SSM anodes deliver specific capacity of 394 mA h g^-1 at 50 mA g^-1 over 100 cycles,better than SnO2/SSM.Even at 500 mA g^-1 after 250 cycles,high capacity of 155 mA h g^-1 can still be obtained.展开更多
Benefiting from excellent mechanical properties and low density,cellular ceramic structures(CCSs)are competitive candidates as structural components.However,inherent brittleness from strong chemical bonds among atoms ...Benefiting from excellent mechanical properties and low density,cellular ceramic structures(CCSs)are competitive candidates as structural components.However,inherent brittleness from strong chemical bonds among atoms extremely impeded CCSs'application.Natural materials occupied outstanding strength and toughness simultaneously due to the dual-phase interpenetrated structure.Inspired by natural materials,it was proposed to fabricate coating covered and fulfilled polyurea/CCS interpenetrated composites(C/CCSs and B/CCSs)to circumvent the brittleness of 3D-printed Al_(2)O_(3)CCSs.It was demonstrated that polyurea coating had less effect on the compressive strength of C/CCSs but tremendously improved their energy-absorbing ability.The energy-absorbing ability of C/CCSs was improved from26.48-52.57 kJ·m^(-3)of CCSs to 1.04-1.89 MJ·m^(-3)because of the extended plateau stage.Furthermore,compressive strength and energy-absorbing ability of B/CCSs were strengthened to 1.33-1.36 and 2.84-4.61 times of C/CCSs,respectively.Besides,failure mode of C/CCSs changed from localized deformation to fracturing entirely with the increase in relative density of CCSs inside,which was the same as that of CCSs.However,with the help of polyurea coating,C/CCSs were still intact at strains up to60%,which would neve r fail catastrophically as CCSs at low strains.B/CCSs tended to fracture as a whole,which was not influenced by relative density of pristine CCSs.It was believed that this work provided a creative way to circumvent the brittleness of CCSs and improve their mechanical performances.展开更多
In this paper,a liquid-solid origami composite design is proposed for the improvement of impact resistance.Employing this design strategy,Kresling origami composite structures with different fillings were designed and...In this paper,a liquid-solid origami composite design is proposed for the improvement of impact resistance.Employing this design strategy,Kresling origami composite structures with different fillings were designed and fabricated,namely air,water,and shear thickening fluid(STF).Quasi-static compression and drop-weight impact experiments were carried out to compare and reveal the static and dynamic mechanical behavior of these structures.The results from drop-weight impact experiments demonstrated that the solid-liquid Kresling origami composite structures exhibited superior yield strength and reduced peak force when compared to their empty counterparts.Notably,the Kresling origami structures filled with STF exhibited significantly heightened yield strength and reduced peak force.For example,at an impact velocity of 3 m/s,the yield strength of single-layer STF-filled Kresling origami structures increased by 772.7%and the peak force decreased by 68.6%.This liquid-solid origami composite design holds the potential to advance the application of origami structures in critical areas such as aerospace,intelligent protection and other important fields.The demonstrated improvements in impact resistance underscore the practical viability of this approach in enhancing structural performance for a range of applications.展开更多
Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety a...Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.展开更多
Electrochemical metallurgy at low temperature(<473 K)shows promise for the extraction and refinement of metals and alloys in a green and sustainable manner.However,the kinetics of the electrodeposition process is g...Electrochemical metallurgy at low temperature(<473 K)shows promise for the extraction and refinement of metals and alloys in a green and sustainable manner.However,the kinetics of the electrodeposition process is generally slow at low temperature,resulting in large overpotential and low current efficiency.Thus,the application of external physical fields has emerged as an effective strategy for improving the mass and charge transfer processes during electrochemical reactions.This review highlights the challenges associated with low-temperature electrochemical processes and briefly discusses recent achievements in optimizing electrodeposition processes through the use of external physical fields.The regulating effects on the optimization of the electrodeposition process and the strategies for select-ing various external physical fields,including magnetic,supergravity,and ultrasonic fields are summarized from the perspectives of equipment and mechanisms.Finally,advanced methods for in-situ characterization of external physical field-assisted electrodeposition processes are reviewed to gain a deeper understanding of metallic electrodeposition.An in-depth exploration of the mechanism by which external physical fields affect the electrode process is essential for enhancing the efficiency of metal extraction at low temperatures.展开更多
Vat photopolymerization additive manufacturing produces lightweight load-bearing ceramic lattice structures that have flexibility,time-efficiency,and high precision,compared to conventional technology.However,understa...Vat photopolymerization additive manufacturing produces lightweight load-bearing ceramic lattice structures that have flexibility,time-efficiency,and high precision,compared to conventional technology.However,understanding the compression behavior and failure mechanism of such structures under loading remains a challenge.In this study,considering the correlation between the strut angle and bearing capacity,body-centered tetragonal(BCT)lattice structures with varying angles are designed based on a body-centered cubic(BCC)structure.BCT Al_(2)O_(3) ceramic lattice structures with varying angles are fabricated by vat photopolymerization.The mechanical properties,deformation process,and failure mechanism of the Al_(2)O_(3) ceramic lattice structures are characterized through a combination of ex-and in-situ X-ray computed tomography(X-CT)compression testing and analyzed using a finite element method(FEM)at macro-and micro-levels.The results demonstrate that as the angle increases,the stress concentration gradually expands from the node to the strut,resulting in an increased loadbearing capacity.Additionally,the failure mode of the Al_(2)O_(3) ceramic lattice structures is identified as diagonal slip shear failure.These findings provide a greater understanding of ceramic lattice structure failures and design optimization approaches.展开更多
The complex ceramic core used for hollow turbine blades requires a high porosity and a high fiexural strength. For a better balance between porosity and fiexural strength, ceramic materials with porous structures are ...The complex ceramic core used for hollow turbine blades requires a high porosity and a high fiexural strength. For a better balance between porosity and fiexural strength, ceramic materials with porous structures are preferred. In order to achieve the transition from disordered pore formation to ordered pore formation, Al_(2)O_(3) ceramic cores with triply periodic minimal surface(TPMS) micro lattice structures with different structural configurations(gyroid, diamond, and neovius) and different volume fractions of lattice structures(30, 40, and 50, vol.%) were designed and prepared by vat photopolymerization 3D printing. The effects of structural configuration and volume fraction of the lattice structure on the following structural shrinkage, microstructure, and flexural strength were investigated. The shrinkage relationship of the three lattice configurations is: neovius>diamond>gyroid. Besides, it is found that with an increase in the volume fraction of the 3D printed Al_(2)O_(3) ceramic micro lattice structures, their fiexural strength correspondingly increases ranging from 54.95 MPa to 139.1 MPa. The maximum average fiexural strength of the 3D printed Al_(2)O_(3) ceramic micro lattice structures is obtained when the structural configuration is diamond and with a volume fraction of 50vol.%, which is 139.1 MPa. Even when the volume fraction of the lattice structure is 30vol.%, that is to say the porosity is 70%, the fiexural strength is as high as 50-70 MPa, which can still be maintained at a high level. In addition, when the volume fraction of the lattice structure is a certain value, the sample with diamond configuration has a higher strength. The internal pore morphology, pore size, and porosity of the cores are precisely controlled, achieving both a high porosity and a high strength. Therefore, this study maintains high porosity and high strength simultaneously, providing a new lattice structure design idea for 3D printed ceramic cores.展开更多
The development of machine learning has provided a new perspective for the design of electromagnetic metastructures,particularly in the rapid design of key performance metrics such as effective absorption bandwidth.Tr...The development of machine learning has provided a new perspective for the design of electromagnetic metastructures,particularly in the rapid design of key performance metrics such as effective absorption bandwidth.Traditional methods,grounded in electromagnetic theory and empirical approaches,often lacked sufficient flexibility and adaptability.In this work,three types of machine learning models were developed to establish the relationship between effective absorption bandwidth and structural parameters.The results indicated that the random forest model achieved the most accurate and efficient design for this task.Then,the additive manufacturing optimal metastructure obtained using this approach outperformed existing designs in terms of both effective absorption bandwidth and reflectivity,while also exhibiting superior radar stealth performance and mechanical load-bearing capacity.Furthermore,through interpretable machine learning and data analysis,the intrinsic mechanisms underlying the relationship between effective absorption bandwidth and structural parameters were revealed.Overall,this work introduced a novel approach to metastructure design and enhanced the understanding of the relationship between structural parameters and electromagnetic properties,providing a key foundation for future design.展开更多
The development of low-energy consumption and environmentally friendly electrodeposition of metal/alloy films or coatings is presently one of the primary topics for the research community.For this purpose,deep eutecti...The development of low-energy consumption and environmentally friendly electrodeposition of metal/alloy films or coatings is presently one of the primary topics for the research community.For this purpose,deep eutectic solvents(DESs)are valued as electrolytes for their advantages of low operating temperature and wide electrochemical windows.At present,there is large amount of literature on this emerging field,but there are no specialized reviews of these studies.Here,after a brief introduction of DESs’concept and history,we comprehensively reviewed the lastest progress on the metal/alloy electrodeposition in DESs.Additionally,we discussed the key influence factors of the electrodeposition process and analyzed the corresponding mechanisms.Based on these,we emphasized the importance of the establishment of predictive models for dealing with the challenges in large-scale applications.展开更多
In thermal protection structures,controlling and optimizing the surface roughness of carbon/phenolic(C/Ph)composites can effectively improve thermal protection performance and ensure the safe operation of carriers in ...In thermal protection structures,controlling and optimizing the surface roughness of carbon/phenolic(C/Ph)composites can effectively improve thermal protection performance and ensure the safe operation of carriers in high-temperature environments.This paper introduces a machine learning(ML)framework to forecast the surface roughness of carbon-phenolic composites under various thermal conditions by employing an ML algorithm derived from historical experimental datasets.Firstly,ablation experiments and collection of surface roughness height data of C/Ph composites under different thermal environments were conducted in an electric arc wind tunnel.Then,an ML model based on Ridge regression is developed for surface roughness prediction.The model involves incorporating feature engineering to choose the most concise and pertinent features,as well as developing an ML model.The ML model considers thermal environment parameters and feature screened by feature engineering as inputs,and predicts the surface height as the output.The results demonstrate that the suggested ML framework effectively anticipates the surface shape and associated surface roughness parameters in various heat flow conditions.Compared with the conventional 3D confocal microscope scanning,the method can obtain the surface topography information of the same area in a much shorter time,thus significantly saving time and cost.展开更多
Layered materials,such as graphite and molybdenum disulfide,are promising for electrode materials and microelectronic devices due to their excellent ion-intercalating properties.However,the intercalation and de-interc...Layered materials,such as graphite and molybdenum disulfide,are promising for electrode materials and microelectronic devices due to their excellent ion-intercalating properties.However,the intercalation and de-intercalation of ions,causing structural deformation and material property variations,would affect battery performance and alter external field responses.The complex problem coupling multiphysics is significant for study and poses a crucial research challenge.This paper reviews the coupling between mechanics,electrochemistry,and electrics during the reaction process,including in situ experimental characterization,theoretical modeling,and design considerations at various scales.Current research has focused on experimental observations beyond the nanoscale and continuum phenomenological models.Further advancements in characterizing layered structural evolution,electron cloud interactions at the atomic level,and developing physics-based multi-field models are essential.展开更多
It is known that tailoring the transformation behavior and functionalities of NiTi alloys is extremely difficult through conventional metallurgical methods,since they are too sensitive to the microstructural and compo...It is known that tailoring the transformation behavior and functionalities of NiTi alloys is extremely difficult through conventional metallurgical methods,since they are too sensitive to the microstructural and compositional changes,especially the Ni content.Laser powder bed fusion(L-PBF)is a promising metallurgical approach to address this challenge through in-situ alloying using powder mixture as feedstock.In this work,pre-alloyed Ni_(50.6)Ti_(49.4)(at%)and elemental Ni powders were used to in-situ alloy the NiTi alloys with different Ni content.The results indicate that a wide L-PBF process window exists to produce dense and defect-free Ni_(50.6)Ti_(49.4)+xNi(x=0at%,0.15 at%,0.30 at%)alloys.Ni is homogeneously distributed in the matrix,and no Ni-rich phase or segregation of Ni is detected in the as-built samples.The combination of adding Ni and varying laser scanning speed provides a feasible approach to tailoring the transformation temperatures over a wide range(e.g.,austenite transformation finish temperature,A_(f),from 278 to 336 K).The plateau stress ranging from 172 to 556 MPa could be obtained at room temperature.Moreover,a transition from shape memory to superelastic recovery is achieved in the Ni_(50.6)Ti_(49.4)+0.15Ni alloy by solely regulating the laser scanning speed.The results of this work indicate that L-PBF in-situ alloying is a promising method to tailor precisely the Ni content,and thus the transformation behavior and functionalities of NiTi alloys.展开更多
Auxetic metamaterials have attracted much attention due to their outstanding advantages over traditional materials in terms of shear capacity,fracture resistance,and energy absorption.However,there are lack of design ...Auxetic metamaterials have attracted much attention due to their outstanding advantages over traditional materials in terms of shear capacity,fracture resistance,and energy absorption.However,there are lack of design inspirations for novel auxetic structures.According to the materials databases of atomic lattice,some natural crystals possess negative Poisson’s ratio(NPR).In this paper,the mechanism of auxeticity in microscale Ti crystal is investigated through density functional theory simulation.Then we propose a macroscopic auxetic metamaterial by mimicking the microscopic atomic lattice structure of the bodycentered cubic Ti crystal.The NPR property of the macroscopic metamaterial is verified by theoretical,numerical and experimental methods.The auxeticity keeps effective when scaling up to macroscopic Ti crystal-mimic structure,with the similar deformation mechanism.Furthermore,from the geometric parameter investigation,the geometric parameters have great influence on the Poisson’s ratio and Young’s modulus of the macroscopic metamaterial.Importantly,an optimized structure is obtained,which exhibits 2 times enhancement in auxeticity and 25 times enhancement in normalized Young’s modulus,compared to the original architecture.This work establishes a link between the physical properties at micro-nanoscale and macroscale structures,which provides inspirations for high load-bearing auxetic metamaterials.展开更多
基金supported by JCKY Project(Grant No.JCKY2023602B012).
文摘This study pioneers the integrated fabrication of magnesium corrugated-core sandwich structures using wire-arc directed energy deposition(WA-DED).Two sandwich structures—V-type and X-type—were designed with optimized deposition paths to achieve comparable grain morphology while enhancing strength.The compression properties and failure modes of the two corrugated-core sandwich structures were examined through quasi-static compression tests.Results showed that the V-type structure exhibited a higher specific compressive strength(93 MPa∙cm^(3)/g)than the X-type structure(72 MPa∙cm^(3)/g).Both finite element analysis and experimental compression tests indicated that failure occurred at the midsection of the corrugated core.This work offers valuable insights for the efficient fabrication of high-strength corrugated-core sandwich structures.
基金supported by the National Key Research and Development of China(No.2018YFA0702804).
文摘Over the past several decades,the integration of IONs into EP emerged as an effective method for enhancing its mechanical properties.Nevertheless,challenges remain,especially with u-IONs,where the interfacial strength with EP is suboptimal,resulting in aggregation within the EP matrix and a subsequent deterioration in the mechanical performance of u-ION/EP nanocomposites.In this comprehensive review,we explored advanced chemical modification techniques tailored for IONs incorporated into EP,providing a detailed examination of the mechanical characteristics of surface cm-ION/EP nanocomposites.This review investigates various chemical modification methods and their distinct impacts on the mechanical attributes of the resulting EP nanocomposites.Special emphasis is given to addressing the persistent challenges of inadequate interfacial strength and aggregation.Furthermore,this article examines prospective surface modification approaches for inorganic oxide nanoparticles,offering a visionary outlook on methods to improve the mechanical performance of EP in future.
基金supported by the National Science and Technology Major Project of China(No.2017-VI-0020-0093).
文摘The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coating’s resistance to CMAS corrosion.The results indicate a phase transformation over time,transitioning from Ca_(2)Lu_(8)(SiO_(4))6O_(2) apatite and Lu_(2)Si_(2)O_(7) to solely Lu_(2)Si_(2)O_(7).The interaction of the Lu_(2)Si_(2)O_(7) coating with the CMAS melts was divided into three stages based on the corrosion reaction behavior.The delamination cracks were distributed throughout the interface between the Si bond layer and Lu_(2)Si_(2)O_(7) layer after corroded at 1400℃ for 50 h,signifying coating failure.In addition,the influence of monosilicates,disilicates,and corrosion duration on the recession layer thickness was analyzed by comparing previous reports on RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7) coatings(RE=Gd,Yb,Lu,Er).Furthermore,the variation in the thermally grown oxide layer thickness in CMAS-corroded Lu_(2)Si_(2)O_(7) coatings was systematically investigated.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172045,U2241240,and 12221002)the National Program on Key Basic Research Project,China(Grant No.2019-JCJQ-ZD-308-00).
文摘The curing behavior of composites significantly influences their performance,making it crucial to understand the curing process.This study experimentally measured specific heat capacity,thermal conductivity,glass transition temperature,coefficient of thermal expansion,and cure shrinkage of materials.A simulation model of its curing deformation was established and validated against strain data obtained from fiber Bragg grating experiments.The effects of thickness,heating rate,and cooling rate on the curing temperature field and residual stress field during the molding of thick-section composite plates were analyzed.
基金the support from the National Natural Science Foundation of China under Grant No. 11902031,No. 11802030 , No. 11802031Beijing Municipal Science and Technology Project Management Approach under No. Z181100004118002
文摘This paper presents a combination of experimental and numerical investigations on the dynamic response of scaling cabin structures under internal blast loading.The purpose of this study is to modify the similar relationship between the scaled-down model and the prototype of the cabin structures under internal blast loading.According to the Hopkinson’s scaling law,three sets of cabin structure models with different scaling factors combined with different explosive masses were designed for the experimental study.The dynamic deformation process of the models was recorded by a three-dimensional digital imaging correlation(DIC)method and a 3D scanning technology was used to reconstruct the deformation modes of the specimen.In addition,a finite element model was developed for the modification of the scaling law.The experimental results showed that the final deflection-to-thickness ratio was increased with the increase of the model size despite of the similar trend of their deformation processes.The reason for this inconsistency was discussed based on the traditional scaling law and a modified formula considering of the effects of size and strain-rate was provided.
基金the National Natural Science Foundation of China(Grant Nos.11972049 and 12002050)National Key Laboratory Foundation of Science and Technology on Materials under Shock and Im-pact(Grant No.6142902200401)Opening Fund of State Key Laboratory of Nonlinear Mechanics.
文摘Inspired by the gradient structure of the nature,two gradient lattice structures,i.e.,unidirectional gradient lattice(UGL)and bidirectional gradient lattice(BGL),are proposed based on the body-centered cubic(BCC)lattice to obtain specially designed mechanical behaviors,such as load-bearing and energy absorption capacities.First,a theoretical model is proposed to predict the initial stiffness of the gradient lattice structure under compressive loading,and validated against quasi-static compression tests and finite element models(FEMs).The deformation and failure mechanisms of the two structures are further studied based on experiments and simulations.The UGL structure exhibits a layer-by-layer failure mode,which avoids structure-wise shear failure in uniform structures.The BGL structure presents a symmetry deformation pattern,and the failure initiates at the weakest part.Finally,the energy absorption behaviors are also discussed.This study demonstrates the potential application of gradient lattice structures in load-transfer-path modification and energy absorption by topology design.
基金financially supported by the Science Challenge Project(No.TZ 2018002)。
文摘High-entropy diborides(HEBs)have attracted extensive research due to their potential ultra-high hardness.In the present work,the effects of transition metals(TM)on lattice parameters,electron work function(EWF),bonding charge density,and hardness of HEBs are comprehensively investigated by the first-principles calculations,including(TiZrHfNbTa)B_(2),(TiZrHfNbMo)B_(2),(TiZrHfTaMo)B_(2),(TiZrNbTaMo)B_(2),and(TiHfNbTaMo)B_(2).It is revealed that the disordered TM atoms result in a severe local lattice distortion and the formation of weak spots.In view of bonding charge density,it is understood that the degree of electron contribution of TM atoms directly affects the bonding strength of the metallic layer,contributing to the optimized hardness of HEBs.Moreover,the proposed power-law-scaled relationship integrating the EWF and the grain size yields an excellent agreement between our predicted results and those reported experimental ones.It is found that the HEBs exhibit relatively high hardness which is higher than those of single transition metal diborides.In particular,the hardness of(TiZrNbTaMo)B_(2)and(TiHfNbTaMo)B_(2)can be as high as29.15 and 28.02 GPa,respectively.This work provides a rapid strategy to discover/design advanced HEBs efficiently,supported by the coupling hardening mechanisms of solid solution and grain refinement based on the atomic and electronic interactions.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51704188,51464020,5170219961705125 and 51802181)the research starting foundation from Shaanxi University of Science and Technology(No.2018GBJ-04)。
文摘Increasing attention has been focused on potassium ion batteries(KIBs) as promising energy-sto rage system(ESS) owing to the abundance and low-cost of potassium resources.Here,SnS2/SnO2 hete rostructures were successfully fixed onto stainless steel mesh(SnS2/SnO2/SSM) through a facile two-step hydrothermal method and used as anodes for KIBs.Due to the advantages of SnS2/SnO2 heterostructures and good conductivity of SSM substrate,the SnS2/SnO2/SSM anodes display enhanced electrochemical performance.The SnS2/SnO2/SSM anodes deliver specific capacity of 394 mA h g^-1 at 50 mA g^-1 over 100 cycles,better than SnO2/SSM.Even at 500 mA g^-1 after 250 cycles,high capacity of 155 mA h g^-1 can still be obtained.
基金financially supported by the National Natural Science Foundation of China(No.52275310)the Open Project of State Key Laboratory of Explosion Science and Technology(No.QNKT22-15)the BIT Research and Innovation Promoting Project(No.2022YCX020)。
文摘Benefiting from excellent mechanical properties and low density,cellular ceramic structures(CCSs)are competitive candidates as structural components.However,inherent brittleness from strong chemical bonds among atoms extremely impeded CCSs'application.Natural materials occupied outstanding strength and toughness simultaneously due to the dual-phase interpenetrated structure.Inspired by natural materials,it was proposed to fabricate coating covered and fulfilled polyurea/CCS interpenetrated composites(C/CCSs and B/CCSs)to circumvent the brittleness of 3D-printed Al_(2)O_(3)CCSs.It was demonstrated that polyurea coating had less effect on the compressive strength of C/CCSs but tremendously improved their energy-absorbing ability.The energy-absorbing ability of C/CCSs was improved from26.48-52.57 kJ·m^(-3)of CCSs to 1.04-1.89 MJ·m^(-3)because of the extended plateau stage.Furthermore,compressive strength and energy-absorbing ability of B/CCSs were strengthened to 1.33-1.36 and 2.84-4.61 times of C/CCSs,respectively.Besides,failure mode of C/CCSs changed from localized deformation to fracturing entirely with the increase in relative density of CCSs inside,which was the same as that of CCSs.However,with the help of polyurea coating,C/CCSs were still intact at strains up to60%,which would neve r fail catastrophically as CCSs at low strains.B/CCSs tended to fracture as a whole,which was not influenced by relative density of pristine CCSs.It was believed that this work provided a creative way to circumvent the brittleness of CCSs and improve their mechanical performances.
基金supported by the National Natural Science Foundation of China(Grant Nos.12302151 and 52105575)the BIT Research and Innovation Promoting Project(Grant No.2023YCXY049)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.QTZX23063)the Aeronautical Science Foundation of China(Grant No.2022Z073081001)the Open Research Funds of State Key Laboratory of Intelligent Manufacturing Equipment and Technology(Grant No.IMETKF2024008).
文摘In this paper,a liquid-solid origami composite design is proposed for the improvement of impact resistance.Employing this design strategy,Kresling origami composite structures with different fillings were designed and fabricated,namely air,water,and shear thickening fluid(STF).Quasi-static compression and drop-weight impact experiments were carried out to compare and reveal the static and dynamic mechanical behavior of these structures.The results from drop-weight impact experiments demonstrated that the solid-liquid Kresling origami composite structures exhibited superior yield strength and reduced peak force when compared to their empty counterparts.Notably,the Kresling origami structures filled with STF exhibited significantly heightened yield strength and reduced peak force.For example,at an impact velocity of 3 m/s,the yield strength of single-layer STF-filled Kresling origami structures increased by 772.7%and the peak force decreased by 68.6%.This liquid-solid origami composite design holds the potential to advance the application of origami structures in critical areas such as aerospace,intelligent protection and other important fields.The demonstrated improvements in impact resistance underscore the practical viability of this approach in enhancing structural performance for a range of applications.
基金supported by the National Natural Science Foundation of China(Nos.U2241240,12172045 and 12221002)the Opening Fund of State Key Laboratory of Explosion Science and Technology of Beijing Institute of Technology,China(No.ZDKT23-02)。
文摘Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.
基金supported by Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2023SP243)the National Key Research and Development Program of China(No.2022YFC2906100)the National Natural Science Foundation of China(No.92475202)are acknowledged.
文摘Electrochemical metallurgy at low temperature(<473 K)shows promise for the extraction and refinement of metals and alloys in a green and sustainable manner.However,the kinetics of the electrodeposition process is generally slow at low temperature,resulting in large overpotential and low current efficiency.Thus,the application of external physical fields has emerged as an effective strategy for improving the mass and charge transfer processes during electrochemical reactions.This review highlights the challenges associated with low-temperature electrochemical processes and briefly discusses recent achievements in optimizing electrodeposition processes through the use of external physical fields.The regulating effects on the optimization of the electrodeposition process and the strategies for select-ing various external physical fields,including magnetic,supergravity,and ultrasonic fields are summarized from the perspectives of equipment and mechanisms.Finally,advanced methods for in-situ characterization of external physical field-assisted electrodeposition processes are reviewed to gain a deeper understanding of metallic electrodeposition.An in-depth exploration of the mechanism by which external physical fields affect the electrode process is essential for enhancing the efficiency of metal extraction at low temperatures.
基金supported by National Natural Science Foundation of China(Grant Nos.52275310,52402084)the China Postdoctoral Science Foundation(Grant No.2024M751646).
文摘Vat photopolymerization additive manufacturing produces lightweight load-bearing ceramic lattice structures that have flexibility,time-efficiency,and high precision,compared to conventional technology.However,understanding the compression behavior and failure mechanism of such structures under loading remains a challenge.In this study,considering the correlation between the strut angle and bearing capacity,body-centered tetragonal(BCT)lattice structures with varying angles are designed based on a body-centered cubic(BCC)structure.BCT Al_(2)O_(3) ceramic lattice structures with varying angles are fabricated by vat photopolymerization.The mechanical properties,deformation process,and failure mechanism of the Al_(2)O_(3) ceramic lattice structures are characterized through a combination of ex-and in-situ X-ray computed tomography(X-CT)compression testing and analyzed using a finite element method(FEM)at macro-and micro-levels.The results demonstrate that as the angle increases,the stress concentration gradually expands from the node to the strut,resulting in an increased loadbearing capacity.Additionally,the failure mode of the Al_(2)O_(3) ceramic lattice structures is identified as diagonal slip shear failure.These findings provide a greater understanding of ceramic lattice structure failures and design optimization approaches.
基金supported by the National Natural Science Foundation of China (Grant No. 52275310)。
文摘The complex ceramic core used for hollow turbine blades requires a high porosity and a high fiexural strength. For a better balance between porosity and fiexural strength, ceramic materials with porous structures are preferred. In order to achieve the transition from disordered pore formation to ordered pore formation, Al_(2)O_(3) ceramic cores with triply periodic minimal surface(TPMS) micro lattice structures with different structural configurations(gyroid, diamond, and neovius) and different volume fractions of lattice structures(30, 40, and 50, vol.%) were designed and prepared by vat photopolymerization 3D printing. The effects of structural configuration and volume fraction of the lattice structure on the following structural shrinkage, microstructure, and flexural strength were investigated. The shrinkage relationship of the three lattice configurations is: neovius>diamond>gyroid. Besides, it is found that with an increase in the volume fraction of the 3D printed Al_(2)O_(3) ceramic micro lattice structures, their fiexural strength correspondingly increases ranging from 54.95 MPa to 139.1 MPa. The maximum average fiexural strength of the 3D printed Al_(2)O_(3) ceramic micro lattice structures is obtained when the structural configuration is diamond and with a volume fraction of 50vol.%, which is 139.1 MPa. Even when the volume fraction of the lattice structure is 30vol.%, that is to say the porosity is 70%, the fiexural strength is as high as 50-70 MPa, which can still be maintained at a high level. In addition, when the volume fraction of the lattice structure is a certain value, the sample with diamond configuration has a higher strength. The internal pore morphology, pore size, and porosity of the cores are precisely controlled, achieving both a high porosity and a high strength. Therefore, this study maintains high porosity and high strength simultaneously, providing a new lattice structure design idea for 3D printed ceramic cores.
基金financially supported by the Key Research and Development Program of the Ministry of Science and Technology under No.2022YFB3806104.
文摘The development of machine learning has provided a new perspective for the design of electromagnetic metastructures,particularly in the rapid design of key performance metrics such as effective absorption bandwidth.Traditional methods,grounded in electromagnetic theory and empirical approaches,often lacked sufficient flexibility and adaptability.In this work,three types of machine learning models were developed to establish the relationship between effective absorption bandwidth and structural parameters.The results indicated that the random forest model achieved the most accurate and efficient design for this task.Then,the additive manufacturing optimal metastructure obtained using this approach outperformed existing designs in terms of both effective absorption bandwidth and reflectivity,while also exhibiting superior radar stealth performance and mechanical load-bearing capacity.Furthermore,through interpretable machine learning and data analysis,the intrinsic mechanisms underlying the relationship between effective absorption bandwidth and structural parameters were revealed.Overall,this work introduced a novel approach to metastructure design and enhanced the understanding of the relationship between structural parameters and electromagnetic properties,providing a key foundation for future design.
基金financially supported from the National Natural Science Foundation of China(Nos.52274291,52204305)Beijing Institute of Technology Research Fund Program for Young Scholars,China(No.1740011182102).
文摘The development of low-energy consumption and environmentally friendly electrodeposition of metal/alloy films or coatings is presently one of the primary topics for the research community.For this purpose,deep eutectic solvents(DESs)are valued as electrolytes for their advantages of low operating temperature and wide electrochemical windows.At present,there is large amount of literature on this emerging field,but there are no specialized reviews of these studies.Here,after a brief introduction of DESs’concept and history,we comprehensively reviewed the lastest progress on the metal/alloy electrodeposition in DESs.Additionally,we discussed the key influence factors of the electrodeposition process and analyzed the corresponding mechanisms.Based on these,we emphasized the importance of the establishment of predictive models for dealing with the challenges in large-scale applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2241240,12172045,and 12221002).
文摘In thermal protection structures,controlling and optimizing the surface roughness of carbon/phenolic(C/Ph)composites can effectively improve thermal protection performance and ensure the safe operation of carriers in high-temperature environments.This paper introduces a machine learning(ML)framework to forecast the surface roughness of carbon-phenolic composites under various thermal conditions by employing an ML algorithm derived from historical experimental datasets.Firstly,ablation experiments and collection of surface roughness height data of C/Ph composites under different thermal environments were conducted in an electric arc wind tunnel.Then,an ML model based on Ridge regression is developed for surface roughness prediction.The model involves incorporating feature engineering to choose the most concise and pertinent features,as well as developing an ML model.The ML model considers thermal environment parameters and feature screened by feature engineering as inputs,and predicts the surface height as the output.The results demonstrate that the suggested ML framework effectively anticipates the surface shape and associated surface roughness parameters in various heat flow conditions.Compared with the conventional 3D confocal microscope scanning,the method can obtain the surface topography information of the same area in a much shorter time,thus significantly saving time and cost.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2408000).
文摘Layered materials,such as graphite and molybdenum disulfide,are promising for electrode materials and microelectronic devices due to their excellent ion-intercalating properties.However,the intercalation and de-intercalation of ions,causing structural deformation and material property variations,would affect battery performance and alter external field responses.The complex problem coupling multiphysics is significant for study and poses a crucial research challenge.This paper reviews the coupling between mechanics,electrochemistry,and electrics during the reaction process,including in situ experimental characterization,theoretical modeling,and design considerations at various scales.Current research has focused on experimental observations beyond the nanoscale and continuum phenomenological models.Further advancements in characterizing layered structural evolution,electron cloud interactions at the atomic level,and developing physics-based multi-field models are essential.
基金financially supported by the Natural Science Foundation of Shandong Province(No.ZR2022ZD08)the Taishan Scholar Foundation of Shandong Province(No.tsqn202211002)the National Natural Science Foundation of China(No.12272045)
文摘It is known that tailoring the transformation behavior and functionalities of NiTi alloys is extremely difficult through conventional metallurgical methods,since they are too sensitive to the microstructural and compositional changes,especially the Ni content.Laser powder bed fusion(L-PBF)is a promising metallurgical approach to address this challenge through in-situ alloying using powder mixture as feedstock.In this work,pre-alloyed Ni_(50.6)Ti_(49.4)(at%)and elemental Ni powders were used to in-situ alloy the NiTi alloys with different Ni content.The results indicate that a wide L-PBF process window exists to produce dense and defect-free Ni_(50.6)Ti_(49.4)+xNi(x=0at%,0.15 at%,0.30 at%)alloys.Ni is homogeneously distributed in the matrix,and no Ni-rich phase or segregation of Ni is detected in the as-built samples.The combination of adding Ni and varying laser scanning speed provides a feasible approach to tailoring the transformation temperatures over a wide range(e.g.,austenite transformation finish temperature,A_(f),from 278 to 336 K).The plateau stress ranging from 172 to 556 MPa could be obtained at room temperature.Moreover,a transition from shape memory to superelastic recovery is achieved in the Ni_(50.6)Ti_(49.4)+0.15Ni alloy by solely regulating the laser scanning speed.The results of this work indicate that L-PBF in-situ alloying is a promising method to tailor precisely the Ni content,and thus the transformation behavior and functionalities of NiTi alloys.
基金supported by the National Key R&D Program of China(Grant No.2021YFA1400300)the National Natural Science Foundation of China(Grant Nos.12172047,12372177,and 12102007)+1 种基金Beijing Natural Science Foundation(Grant Nos.1244057 and Z190011)Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘Auxetic metamaterials have attracted much attention due to their outstanding advantages over traditional materials in terms of shear capacity,fracture resistance,and energy absorption.However,there are lack of design inspirations for novel auxetic structures.According to the materials databases of atomic lattice,some natural crystals possess negative Poisson’s ratio(NPR).In this paper,the mechanism of auxeticity in microscale Ti crystal is investigated through density functional theory simulation.Then we propose a macroscopic auxetic metamaterial by mimicking the microscopic atomic lattice structure of the bodycentered cubic Ti crystal.The NPR property of the macroscopic metamaterial is verified by theoretical,numerical and experimental methods.The auxeticity keeps effective when scaling up to macroscopic Ti crystal-mimic structure,with the similar deformation mechanism.Furthermore,from the geometric parameter investigation,the geometric parameters have great influence on the Poisson’s ratio and Young’s modulus of the macroscopic metamaterial.Importantly,an optimized structure is obtained,which exhibits 2 times enhancement in auxeticity and 25 times enhancement in normalized Young’s modulus,compared to the original architecture.This work establishes a link between the physical properties at micro-nanoscale and macroscale structures,which provides inspirations for high load-bearing auxetic metamaterials.
