Transpiration cooling is crucial for the performance of aerospace engine components,relying heavily on the processing quality and accuracy of microchannels.Laser powder bed fusion(LPBF)offers the potential for integra...Transpiration cooling is crucial for the performance of aerospace engine components,relying heavily on the processing quality and accuracy of microchannels.Laser powder bed fusion(LPBF)offers the potential for integrated manufacturing of complex parts and precise microchannel fabrication,essential for engine cooling applications.However,optimizing LPBF’s extensive process parameters to control processing quality and microchannel accuracy effectively remains a significant challenge,especially given the time-consuming and labor-intensive nature of handling numerous variables and the need for thorough data analysis and correlation discovery.This study introduced a combined methodology of high-throughput experiments and Gaussian process algorithms to optimize the processing quality and accuracy of nickel-based high-temperature alloy with microchannel structures.250 parameter combinations,including laser power,scanning speed,channel diameter,and spot compensation,were designed across ten high-throughput specimens.This setup allowed for rapid and efficient evaluation of processing quality and microchannel accuracy.Employing Bayesian optimization,the Gaussian process model accurately predicted processing outcomes over a broad parameter range.The correlation between various processing parameters,processing quality and accuracy was revealed,and various optimized process combinations were summarized.Verification through computed Tomography testing of the specimens confirmed the effectiveness and precision of this approach.The approach introduced in this research provides a way for quickly and efficiently optimizing the process parameters and establishing process-property relationships for LPBF,which has broad application value.展开更多
High cracking susceptibility of Al-Li alloys with Ti/Ce B6addition is thoroughly suppressed in laser powder bed fusion(LPBF)processing of Ti/Ce co-modified 2195 alloys at relatively high scan speeds,while the cracking...High cracking susceptibility of Al-Li alloys with Ti/Ce B6addition is thoroughly suppressed in laser powder bed fusion(LPBF)processing of Ti/Ce co-modified 2195 alloys at relatively high scan speeds,while the cracking suppression mechanism and phase formation in these composites are not clarified.In this work,microstructure evolution and mechanical performance of the LPBF-fabricated Ti/Ce co-modified 2195 are investigated to reveal their cracking suppression and strengthening mechanisms.The results show that apparent grain refinement of the composites is ascribed to high supercooling from rapid formation of constitutional supercooling zone in front of solid–liquid interfaces by high-Q-value Ti solute,and heterogeneous nucleation of in situ formed Al3Ti and Al11Ce3precipitates.Their synergistic interactions promote formation of fine equiaxed grains and thus inhibit crack initiation.The composites exhibit high microhardness of 100±5HV0.2,nano-hardness of 1.6±0.1 GPa and elastic modulus of 97±3 GPa,where the elastic modulus increases by 27%and 31%compared to those of LPBF-processed and conventionally manufactured 2195 alloys,respectively.A tensile strength of 336 MPa and an elongation of 3%are obtained from in-situ synchrotron X-ray diffraction measurement.The improved properties are derived from grain refinement and Orowan strengthening.Based on the optimal processing parameter and composition,a bracket component filled with lattice structures is designed and manufactured with good manufacturing quality and processing accuracy.展开更多
The addition of ceramic reinforcements provides a promising approach to achieving high-performance magnesium matrix composites.In this work,AZ91D magnesium alloys and 2 wt.%TiC/AZ91D composites have been manufactured ...The addition of ceramic reinforcements provides a promising approach to achieving high-performance magnesium matrix composites.In this work,AZ91D magnesium alloys and 2 wt.%TiC/AZ91D composites have been manufactured by laser powder bed fusion(LPBF)with variations of laser processing parameters.The effect of TiC reinforcement addition on the laser absorption behaviors,forming quality,microstructure evolution and mechanical properties of the magnesium alloys is investigated.The TiC addition improves the interactions of laser with alloy powder and laser absorption rate of alloy powder,and decreases powder spatter of powder bed.The results show that high relative density of~99.4%and good surface roughness of~12μm are obtained for the LPBF-fabricated composites.The TiC addition promotes the precipitation of β-Mg_(17)Al_(12)in the alloys and the transformation of coarse columnar to fine equiaxed grains,where the grains are refined to~3.1μm.The TiC/AZ91D composites exhibit high microhardness of 114.6±2.5 HV_(0.2),high tensile strength of~345.0 MPa and a uniform elongation~4.1%.The improvement of tensile strength for the composites is ascribed to the combination of grain refinement strengthening and Orowan strengthening fromβ-Mg_(17)Al_(12)precipitates and Al_8Mn_5 nanoparticles.In the composites,the unmelted TiC particles can act as an anchor for the network structure of β-Mg_(17)Al_(12)precipitates,effectively impeding crack propagation and enhancing their performance.This work offers an insight to fabricating high-performance magnesium matrix composites by laser additive manufacturing.展开更多
Electrically conductive carbide ceramics with high hardness and fracture toughness are promising for advanced applications.However,enhancing both electrical conductivity and fracture toughness simultaneous is challeng...Electrically conductive carbide ceramics with high hardness and fracture toughness are promising for advanced applications.However,enhancing both electrical conductivity and fracture toughness simultaneous is challenging.This study reports the synthesis of(Ti_(0.2)W_(0.2)Ta_(0.2)Hf_(0.2)Mo_(0.2))C-diamond composites with varying densities using high-pressure and high-temperature(HPHT)method.The carbides are uniformly dispersed in a titanium carbide matrix,forming conductive channels that reduce resistivity to 4.6×10^(-7)W·m.These composite materials exhibit metallic conductivity with a superconducting transition at 8.5 K.Superconducting behavior may result from d-p orbital hybridization and electron-phonon coupling in transition metal carbides,such as TaC,Mo_(2)C,and MoC.Optimizing intergranular bonding improves the fracture toughness without compromising hardness.The highest indentation toughness value is 10.1±0.4 MPa·m^(1/2),a 130%increase compare to pure TiC.Enhanced toughness arises from transgranular and intergranular fracture modes,multiple crack bridging,and large-angle crack deflection,which dissipate fracture energy and inhibit crack propagation.This study introduces a novel microstructure engineering strategy for carbide ceramics to achieve superior mechanical and electrical properties.展开更多
Lightweight porous materials with high load-bearing,damage tolerance and energy absorption(EA)as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications,e.g....Lightweight porous materials with high load-bearing,damage tolerance and energy absorption(EA)as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications,e.g.aerospace,automobiles,electronics,etc.Cuttlebone produced in the cuttlefish has evolved vertical walls with the optimal corrugation gradient,enabling stress homogenization,significant load bearing,and damage tolerance to protect the organism from high external pressures in the deep sea.This work illustrated that the complex hybrid wave shape in cuttlebone walls,becoming more tortuous from bottom to top,creates a lightweight,load-bearing structure with progressive failure.By mimicking the cuttlebone,a novel bionic hybrid structure(BHS)was proposed,and as a comparison,a regular corrugated structure and a straight wall structure were designed.Three types of designed structures have been successfully manufactured by laser powder bed fusion(LPBF)with NiTi powder.The LPBF-processed BHS exhibited a total porosity of 0.042% and a good dimensional accuracy with a peak deviation of 17.4μm.Microstructural analysis indicated that the LPBF-processed BHS had a strong(001)crystallographic orientation and an average size of 9.85μm.Mechanical analysis revealed the LPBF-processed BHS could withstand over 25000 times its weight without significant deformation and had the highest specific EA value(5.32 J·g^(−1))due to the absence of stress concentration and progressive wall failure during compression.Cyclic compression testing showed that LPBF-processed BHS possessed superior viscoelastic and elasticity energy dissipation capacity.Importantly,the uniform reversible phase transition from martensite to austenite in the walls enables the structure to largely recover its pre-deformation shape when heated(over 99% recovery rate).These design strategies can serve as valuable references for the development of intelligent components that possess high mechanical efficiency and shape memory capabilities.展开更多
Significant contributions have been made to understanding the processing of various metal materials using laser powder bed fusion (LPBF) for the design and fabrication of high-performance metal components in many fiel...Significant contributions have been made to understanding the processing of various metal materials using laser powder bed fusion (LPBF) for the design and fabrication of high-performance metal components in many fields. For laser additive manufacturing, aluminum-based materials are regarded as difficult-to-fabricate materials be- cause of their special physical properties, including low density, low laser absorption, high thermal conductivity, and ease of oxidation. Currently, LPBF-formed structural materials require high densification, fine grains, high specific strength, high ductility, and optimized physical or chemical properties. Therefore, comprehensive un- derstanding of the fabrication and performance of Al-based materials processed by LPBF is of significant value. This paper covers emerging research on aluminum-based materials using LPBF, providing an overall view of the basic scientific mechanisms behind manufacturing. The state-of-the-art researches of aluminum-based materials for LPBF formability as well as the microstructures, properties and corresponding metallurgical mechanisms are reviewed. The mechanisms of some of the main defects (pores, cracks, balling, and oxide inclusions) and control measures are also discussed. A summary and outlook for the further development of Al-based materials for LPBF are addressed.展开更多
The bipolar plate(BPP)is a crucial component of proton exchange membrane fuel cells(PEMFC).However,the weight of BPPs can account for around 80%of a PEMFC stack,posing a hindrance to the commercialization of PEMFCs.Th...The bipolar plate(BPP)is a crucial component of proton exchange membrane fuel cells(PEMFC).However,the weight of BPPs can account for around 80%of a PEMFC stack,posing a hindrance to the commercialization of PEMFCs.Therefore,the lightweight design of BPPs should be considered as a priority.Honeycomb sandwich structures meet some requirements for bipolar plates,such as high mechanical strength and lightweight.Animals and plants in nature provide many excellent structures with characteristics such as low density and high energy absorption capacity.In this work,inspired by the microstructures of the Cybister elytra,a novel bio-inspired vertical honeycomb sandwich(BVHS)structure was designed and manufactured by laser powder bed fusion(LPBF)for the application of lightweight BPPs.Compared with the conventional vertical honeycomb sandwich(CVHS)structure formed by LPBF under the same process parameters setting,the introduction of fractal thin walls enabled self-supporting and thus improved LPBF formability.In addition,the BVHS structure exhibited superior energy absorption(EA)capability and bending properties.It is worth noting that,compared with the CVHS structure,the specific energy absorption(SEA)and specific bending strength of the BVHS structure increased by 56.99%and 46.91%,respectively.Finite element analysis(FEA)was employed to study stress distributions in structures during bending and analyze the influence mechanism of the fractal feature on the mechanical properties of BVHS structures.The electrical conductivity of structures were also studied in this work,the BVHS structures were slightly lower than the CVHS structure.FEA was also conducted to analyze the current flow direction and current density distribution of BVHS structures under a constant voltage,illustrating the influence mechanism of fractal angles on electrical conductivity properties.Finally,in order to solve the problem of trapped powder inside the enclosed unit cells,a droplet-shaped powder outlet was designed for LPBF-processed components.The number of powder outlets was optimized based on bending properties.Results of this work could provide guidelines for the design of lightweight BPPs with high mechanical strength and high electrical conductivity.展开更多
The stringent requirements for functional protective materials are driving innovation in flexible mechanical metamaterials.In this study,we proposed a bionic layered interwoven structure(BLI)based on the doubly period...The stringent requirements for functional protective materials are driving innovation in flexible mechanical metamaterials.In this study,we proposed a bionic layered interwoven structure(BLI)based on the doubly periodic continuous surfaces(DPCSs)inspired by the microstructure of the hermit crab chela and developed three gradient design strategies,including thickness gradient(TG),elastic modulus gradient(EG),and hybrid gradient(HG).NiTi-based samples were fabricated using laser powder bed fusion(LPBF)technology,and the manufacturability,phase,compression response,and superelasticity(SE)were investigated.The results indicated that the LPBF process ensured the geometrical fidelity of BLIs,but the manufacturability was challenged by high residual stresses.The mechanical responses of BLIs depended on the properties of the sublayers and their affected zones,and the hybrid gradient exhibited the highest ultimate strength of~1.51 MPa and ultimate strain of~0.375.Notably,BLIs showed superior mechanical flexibility with an ultra-low modulus of~13.9 MPa approaching that of rubber-based triply periodic minimal surface(TPMS),which can be attributed to the combination effect of wavelike deformations,high deformation degree of freedom,and effective stress transfer.The strategic sacrifice of weak sublayers induced a reduction of the actual strain in other regions,leading to the enhancement in the durability of gradient structures.The designs could serve as a reference for the development of metal flexible metamaterials.展开更多
基金project supported by the National Natural Science Foundation of China(Grant Nos.52225503 and 52405380)National Key Research and Development Program(Grant Nos.2023YFB4603303 and 2023YFB4603304)+4 种基金Key Research and Development Program of Jiangsu Province(Grant Nos.BE2022069 and BE2022069-3)National Natural Science Foundation of China for Creative Research Groups(Grant No.51921003)The 15th Batch of“Six Talents Peaks”Innovative Talents Team Program of Jiangsu province(Grant Nos.TD-GDZB-001)Shanghai Aerospace Science and Technology Innovation Fund Project(Grant No.SAST2023-066)The Fundamental Research Funds for the Central Universities(Grant Nos.NS2023035 and NP2024128)。
文摘Transpiration cooling is crucial for the performance of aerospace engine components,relying heavily on the processing quality and accuracy of microchannels.Laser powder bed fusion(LPBF)offers the potential for integrated manufacturing of complex parts and precise microchannel fabrication,essential for engine cooling applications.However,optimizing LPBF’s extensive process parameters to control processing quality and microchannel accuracy effectively remains a significant challenge,especially given the time-consuming and labor-intensive nature of handling numerous variables and the need for thorough data analysis and correlation discovery.This study introduced a combined methodology of high-throughput experiments and Gaussian process algorithms to optimize the processing quality and accuracy of nickel-based high-temperature alloy with microchannel structures.250 parameter combinations,including laser power,scanning speed,channel diameter,and spot compensation,were designed across ten high-throughput specimens.This setup allowed for rapid and efficient evaluation of processing quality and microchannel accuracy.Employing Bayesian optimization,the Gaussian process model accurately predicted processing outcomes over a broad parameter range.The correlation between various processing parameters,processing quality and accuracy was revealed,and various optimized process combinations were summarized.Verification through computed Tomography testing of the specimens confirmed the effectiveness and precision of this approach.The approach introduced in this research provides a way for quickly and efficiently optimizing the process parameters and establishing process-property relationships for LPBF,which has broad application value.
基金supported by the National Natural Science Foundation of China(Nos.52205382,52225503)National Key Research and Development Program(No.2023YFB4603300)+3 种基金Key Research and Development Program of Jiangsu Province(Nos.BE2022069,BZ2024019)National Natural Science Foundation of China for Creative Research Groups(No.51921003)International Joint Laboratory of Sustainable Manufacturing,Ministry of Education and the Fundamental Research Funds for the Central Universities(NG2024014)Postgraduate Research&Practice Innovation Program of NUAA(xcxjh20230616)。
文摘High cracking susceptibility of Al-Li alloys with Ti/Ce B6addition is thoroughly suppressed in laser powder bed fusion(LPBF)processing of Ti/Ce co-modified 2195 alloys at relatively high scan speeds,while the cracking suppression mechanism and phase formation in these composites are not clarified.In this work,microstructure evolution and mechanical performance of the LPBF-fabricated Ti/Ce co-modified 2195 are investigated to reveal their cracking suppression and strengthening mechanisms.The results show that apparent grain refinement of the composites is ascribed to high supercooling from rapid formation of constitutional supercooling zone in front of solid–liquid interfaces by high-Q-value Ti solute,and heterogeneous nucleation of in situ formed Al3Ti and Al11Ce3precipitates.Their synergistic interactions promote formation of fine equiaxed grains and thus inhibit crack initiation.The composites exhibit high microhardness of 100±5HV0.2,nano-hardness of 1.6±0.1 GPa and elastic modulus of 97±3 GPa,where the elastic modulus increases by 27%and 31%compared to those of LPBF-processed and conventionally manufactured 2195 alloys,respectively.A tensile strength of 336 MPa and an elongation of 3%are obtained from in-situ synchrotron X-ray diffraction measurement.The improved properties are derived from grain refinement and Orowan strengthening.Based on the optimal processing parameter and composition,a bracket component filled with lattice structures is designed and manufactured with good manufacturing quality and processing accuracy.
基金supported by the National Natural Science Foundation of China(52205382,52225503)National Key Research and Development Program(2023YFB4603300)+1 种基金Key Research and Development Program of Jiangsu Province(BZ2024019,BE2022069)International Joint Laboratory of Sustainable Manufacturing,Ministry of Education and the Fundamental Research Funds for the Central Universities(NG2024014,XCA2300501)。
文摘The addition of ceramic reinforcements provides a promising approach to achieving high-performance magnesium matrix composites.In this work,AZ91D magnesium alloys and 2 wt.%TiC/AZ91D composites have been manufactured by laser powder bed fusion(LPBF)with variations of laser processing parameters.The effect of TiC reinforcement addition on the laser absorption behaviors,forming quality,microstructure evolution and mechanical properties of the magnesium alloys is investigated.The TiC addition improves the interactions of laser with alloy powder and laser absorption rate of alloy powder,and decreases powder spatter of powder bed.The results show that high relative density of~99.4%and good surface roughness of~12μm are obtained for the LPBF-fabricated composites.The TiC addition promotes the precipitation of β-Mg_(17)Al_(12)in the alloys and the transformation of coarse columnar to fine equiaxed grains,where the grains are refined to~3.1μm.The TiC/AZ91D composites exhibit high microhardness of 114.6±2.5 HV_(0.2),high tensile strength of~345.0 MPa and a uniform elongation~4.1%.The improvement of tensile strength for the composites is ascribed to the combination of grain refinement strengthening and Orowan strengthening fromβ-Mg_(17)Al_(12)precipitates and Al_8Mn_5 nanoparticles.In the composites,the unmelted TiC particles can act as an anchor for the network structure of β-Mg_(17)Al_(12)precipitates,effectively impeding crack propagation and enhancing their performance.This work offers an insight to fabricating high-performance magnesium matrix composites by laser additive manufacturing.
基金support from the Science and Technology Development Project of Jilin Province(Grant No.SKL202402004)the Program for the Development of Science and Technology of Jilin Province(Grant No.YDZJ202201ZYTS308)the Open Research Fund of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry(Jilin University,Grant Nos.2022-16 and 2022-23).
文摘Electrically conductive carbide ceramics with high hardness and fracture toughness are promising for advanced applications.However,enhancing both electrical conductivity and fracture toughness simultaneous is challenging.This study reports the synthesis of(Ti_(0.2)W_(0.2)Ta_(0.2)Hf_(0.2)Mo_(0.2))C-diamond composites with varying densities using high-pressure and high-temperature(HPHT)method.The carbides are uniformly dispersed in a titanium carbide matrix,forming conductive channels that reduce resistivity to 4.6×10^(-7)W·m.These composite materials exhibit metallic conductivity with a superconducting transition at 8.5 K.Superconducting behavior may result from d-p orbital hybridization and electron-phonon coupling in transition metal carbides,such as TaC,Mo_(2)C,and MoC.Optimizing intergranular bonding improves the fracture toughness without compromising hardness.The highest indentation toughness value is 10.1±0.4 MPa·m^(1/2),a 130%increase compare to pure TiC.Enhanced toughness arises from transgranular and intergranular fracture modes,multiple crack bridging,and large-angle crack deflection,which dissipate fracture energy and inhibit crack propagation.This study introduces a novel microstructure engineering strategy for carbide ceramics to achieve superior mechanical and electrical properties.
基金supported by the National Natural Science Foundation of China(Grant No.52225503)National Key Research and Development Program of China(Grant No.2022YFB3805701)+1 种基金Development Program of Jiangsu Province(Grant Nos.BE2022069 and BE2022069-1)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX21-0207).
文摘Lightweight porous materials with high load-bearing,damage tolerance and energy absorption(EA)as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications,e.g.aerospace,automobiles,electronics,etc.Cuttlebone produced in the cuttlefish has evolved vertical walls with the optimal corrugation gradient,enabling stress homogenization,significant load bearing,and damage tolerance to protect the organism from high external pressures in the deep sea.This work illustrated that the complex hybrid wave shape in cuttlebone walls,becoming more tortuous from bottom to top,creates a lightweight,load-bearing structure with progressive failure.By mimicking the cuttlebone,a novel bionic hybrid structure(BHS)was proposed,and as a comparison,a regular corrugated structure and a straight wall structure were designed.Three types of designed structures have been successfully manufactured by laser powder bed fusion(LPBF)with NiTi powder.The LPBF-processed BHS exhibited a total porosity of 0.042% and a good dimensional accuracy with a peak deviation of 17.4μm.Microstructural analysis indicated that the LPBF-processed BHS had a strong(001)crystallographic orientation and an average size of 9.85μm.Mechanical analysis revealed the LPBF-processed BHS could withstand over 25000 times its weight without significant deformation and had the highest specific EA value(5.32 J·g^(−1))due to the absence of stress concentration and progressive wall failure during compression.Cyclic compression testing showed that LPBF-processed BHS possessed superior viscoelastic and elasticity energy dissipation capacity.Importantly,the uniform reversible phase transition from martensite to austenite in the walls enables the structure to largely recover its pre-deformation shape when heated(over 99% recovery rate).These design strategies can serve as valuable references for the development of intelligent components that possess high mechanical efficiency and shape memory capabilities.
基金supported by National Natural Science Foundation of China(Grant No.52225503)Key Research and Development Pro-gram of Jiangsu Province(Grant Nos.BE2022069 and BE2022069-1)+2 种基金The Pre-research Project of Civil Aerospace Technology(Grant No.D020302)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23_0366)State Key Laboratory of Mechanics and Control for Aerospace Structures(Grant No.MCAS-S-0423G01).
文摘Significant contributions have been made to understanding the processing of various metal materials using laser powder bed fusion (LPBF) for the design and fabrication of high-performance metal components in many fields. For laser additive manufacturing, aluminum-based materials are regarded as difficult-to-fabricate materials be- cause of their special physical properties, including low density, low laser absorption, high thermal conductivity, and ease of oxidation. Currently, LPBF-formed structural materials require high densification, fine grains, high specific strength, high ductility, and optimized physical or chemical properties. Therefore, comprehensive un- derstanding of the fabrication and performance of Al-based materials processed by LPBF is of significant value. This paper covers emerging research on aluminum-based materials using LPBF, providing an overall view of the basic scientific mechanisms behind manufacturing. The state-of-the-art researches of aluminum-based materials for LPBF formability as well as the microstructures, properties and corresponding metallurgical mechanisms are reviewed. The mechanisms of some of the main defects (pores, cracks, balling, and oxide inclusions) and control measures are also discussed. A summary and outlook for the further development of Al-based materials for LPBF are addressed.
基金Supported by Defense Industrial Technology Development Program of China(Grant No.JCKY2020605C007)Key Research and Development Program of Jiangsu Province of China(Grant Nos.BE2022069,BE2022069-1,BE2022069-3)Aeronautical Science Foundation of China(Grant No.2020Z049052001).
文摘The bipolar plate(BPP)is a crucial component of proton exchange membrane fuel cells(PEMFC).However,the weight of BPPs can account for around 80%of a PEMFC stack,posing a hindrance to the commercialization of PEMFCs.Therefore,the lightweight design of BPPs should be considered as a priority.Honeycomb sandwich structures meet some requirements for bipolar plates,such as high mechanical strength and lightweight.Animals and plants in nature provide many excellent structures with characteristics such as low density and high energy absorption capacity.In this work,inspired by the microstructures of the Cybister elytra,a novel bio-inspired vertical honeycomb sandwich(BVHS)structure was designed and manufactured by laser powder bed fusion(LPBF)for the application of lightweight BPPs.Compared with the conventional vertical honeycomb sandwich(CVHS)structure formed by LPBF under the same process parameters setting,the introduction of fractal thin walls enabled self-supporting and thus improved LPBF formability.In addition,the BVHS structure exhibited superior energy absorption(EA)capability and bending properties.It is worth noting that,compared with the CVHS structure,the specific energy absorption(SEA)and specific bending strength of the BVHS structure increased by 56.99%and 46.91%,respectively.Finite element analysis(FEA)was employed to study stress distributions in structures during bending and analyze the influence mechanism of the fractal feature on the mechanical properties of BVHS structures.The electrical conductivity of structures were also studied in this work,the BVHS structures were slightly lower than the CVHS structure.FEA was also conducted to analyze the current flow direction and current density distribution of BVHS structures under a constant voltage,illustrating the influence mechanism of fractal angles on electrical conductivity properties.Finally,in order to solve the problem of trapped powder inside the enclosed unit cells,a droplet-shaped powder outlet was designed for LPBF-processed components.The number of powder outlets was optimized based on bending properties.Results of this work could provide guidelines for the design of lightweight BPPs with high mechanical strength and high electrical conductivity.
基金supported by the National Natural Science Foundation of China(Grant No.52225503)the Key Research and Development Program of Jiangsu Province(Grant Nos.BE2022069,BE2022069-1)+1 种基金the National Natural Science Foundation of China for Creative Research Groups(Grant No.51921003)the Fundamental Research Funds for the Central Universities(Grant No.NI2024003)。
文摘The stringent requirements for functional protective materials are driving innovation in flexible mechanical metamaterials.In this study,we proposed a bionic layered interwoven structure(BLI)based on the doubly periodic continuous surfaces(DPCSs)inspired by the microstructure of the hermit crab chela and developed three gradient design strategies,including thickness gradient(TG),elastic modulus gradient(EG),and hybrid gradient(HG).NiTi-based samples were fabricated using laser powder bed fusion(LPBF)technology,and the manufacturability,phase,compression response,and superelasticity(SE)were investigated.The results indicated that the LPBF process ensured the geometrical fidelity of BLIs,but the manufacturability was challenged by high residual stresses.The mechanical responses of BLIs depended on the properties of the sublayers and their affected zones,and the hybrid gradient exhibited the highest ultimate strength of~1.51 MPa and ultimate strain of~0.375.Notably,BLIs showed superior mechanical flexibility with an ultra-low modulus of~13.9 MPa approaching that of rubber-based triply periodic minimal surface(TPMS),which can be attributed to the combination effect of wavelike deformations,high deformation degree of freedom,and effective stress transfer.The strategic sacrifice of weak sublayers induced a reduction of the actual strain in other regions,leading to the enhancement in the durability of gradient structures.The designs could serve as a reference for the development of metal flexible metamaterials.
