Ensuring the consistent mechanical performance of three-dimensional(3D)-printed continuous fiber-reinforced composites is a significant challenge in additive manufacturing.The current reliance on manual monitoring exa...Ensuring the consistent mechanical performance of three-dimensional(3D)-printed continuous fiber-reinforced composites is a significant challenge in additive manufacturing.The current reliance on manual monitoring exacerbates this challenge by rendering the process vulnerable to environmental changes and unexpected factors,resulting in defects and inconsistent product quality,particularly in unmanned long-term operations or printing in extreme environments.To address these issues,we developed a process monitoring and closed-loop feedback control strategy for the 3D printing process.Real-time printing image data were captured and analyzed using a well-trained neural network model,and a real-time control module-enabled closed-loop feedback control of the flow rate was developed.The neural network model,which was based on image processing and artificial intelligence,enabled the recognition of flow rate values with an accuracy of 94.70%.The experimental results showed significant improvements in both the surface performance and mechanical properties of printed composites,with three to six times improvement in tensile strength and elastic modulus,demonstrating the effectiveness of the strategy.This study provides a generalized process monitoring and feedback control method for the 3D printing of continuous fiber-reinforced composites,and offers a potential solution for remote online monitoring and closed-loop adjustment in unmanned or extreme space environments.展开更多
In engineering,the demand for high energy absorption by structures subjected to impact loads is increasing.Balancing the limited space,manufacturing feasibility,and energy absorption capabilities is a key point in the...In engineering,the demand for high energy absorption by structures subjected to impact loads is increasing.Balancing the limited space,manufacturing feasibility,and energy absorption capabilities is a key point in the design of many enclosed structures with energy absorption requirements.To achieve a lightweight design and controllable energy absorption by the structures,within a limited space,this study proposes a bio-inspired double-layer impact-resistant structure that can be manufactured by an additive manufacturing method(powder bed fusion),inspired by the microstructure of a woodpecker’s head.The structure is composed of two basic structural units:a quasi-circular ring and an oblique cylinder.The controllable energy absorption capabilities of the structure were studied through a combination of theoretical analyses,numerical simulations,and physical experiments.The results showed that,for the quasi-circular ring structure,the specific energy absorption range of 13-72 J/g could be effectively regulated by adjusting the structural parameters.The specific energy absorption range of 11-137 J/g could be effectively regulated for oblique cylindrical structures.Finally,the structure was applied to the design of engineering impact-resistant devices,proving the effectiveness of the controllable energy absorption of the structure.Moreover,the design process of the structure was optimized,laying a foundation for the structure to better serve engineering design applications.展开更多
SiC is a wave-absorbing material with good dielectric properties,high-temperature resistance,and corrosion resistance,which has great potential for development in the field of high-temperature wave-absorbing.However,S...SiC is a wave-absorbing material with good dielectric properties,high-temperature resistance,and corrosion resistance,which has great potential for development in the field of high-temperature wave-absorbing.However,SiC is limited by its low impedance-matching performance and single wave-absorbing mechanism.Therefore,compatible metamaterial technologies are required to enhance its wave-absorbing performance further.The electromagnetic wave(EMW)absorbing metamaterials can realize perfect absorption of EMWs in specific frequency bands and precise regulation of EMW phase,propagation mode,and absorption frequency bands through structural changes.However,the traditional molding methods for manufacturing complex geometric shapes require expensive molds,involve process complexity,and have poor molding accuracy and other limitations.Therefore,additive manufacturing(AM)technology,through material layered stacking to achieve the processing of materials,is a comprehensive multidisciplinary advanced manufacturing technology and has become the core technology for manufacturing metamaterials.This review introduces the principles and applications of different AM technologies for SiC and related materials,discusses the current status and development trends of various AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,summarizes the limitations and technological shortcomings of existing AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,and provides an outlook for the future development of related AM technologies.展开更多
3D printing technology can realize the rapid fabrication of complicated structures with short production chain,which just meet the requirements for space manufacturing in the future.This Special Issue features the cut...3D printing technology can realize the rapid fabrication of complicated structures with short production chain,which just meet the requirements for space manufacturing in the future.This Special Issue features the cutting-edge 3D printing technologies considering the space environment,focusing on the experimental validation and simulation on the 3D printing process and structural technologies,including whole process chain from raw materials,structural design,process,equipment,as well as functional verification.展开更多
Additive Manufacturing(AM)has significantly impacted the development of high-performance materials and structures,offering new possibilities for industries ranging from aerospace to biomedicine.This special issue feat...Additive Manufacturing(AM)has significantly impacted the development of high-performance materials and structures,offering new possibilities for industries ranging from aerospace to biomedicine.This special issue features pioneering research that integrates AI-driven methods with AM,enabling the design and fabrication of complex,optimized structures with enhanced properties.展开更多
In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the p...In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the production of parts and larger structures was investigated in detail.With different experimental setups in normal and microgravity,laser spots with diameters from 5 mm to 100 mm were realized to melt the regolith simulant EAC-1A and an 80%/20%mixture of TUBS-T and TUBS-M,which are used as a substitute for the actual lunar soil.In the experiments performed,the critical parameters are the size of the laser spot,the velocity of the laser spot on the surface of the powder bed,the gravity and the wettability of the powder bed by the melt.The stability of the melt pool as a function of these parameters was investigated and it was found that the formation of a stable melt pool is determined by gravity for large melt pool sizes in the range of 50 mm and by surface tension for small melt pool sizes in the range of a few mm.展开更多
Additive manufacturing(AM)technology has revolutionized engineering field by enabling the creation of intricate,high-performance structures that were once difficult or impossible to fabricate.This transformative techn...Additive manufacturing(AM)technology has revolutionized engineering field by enabling the creation of intricate,high-performance structures that were once difficult or impossible to fabricate.This transformative technology has particularly advanced the development of metamaterials-engineered materials whose unique properties arise from their structure rather than composition-unlocking immense potential in fields ranging from aerospace to biomedical engineering.展开更多
Additive manufacturing(AM)is an advanced production method for layer-by-layer fabrication,offering a paradigm shift in manufacturing.However,the sustainability of AM processes is poor,since suppliers recommend reusing...Additive manufacturing(AM)is an advanced production method for layer-by-layer fabrication,offering a paradigm shift in manufacturing.However,the sustainability of AM processes is poor,since suppliers recommend reusing 50%-70%of reprocessed powder,contributing to a significant increase in material disposal.To explore the possibility of fully reusing the polymeric material,we conduct a comprehensive characterisation of the powder particulates,in combination with analysis of the final prints.Utilizing optical and scanning electron microscopes,we statistically evaluate the size,morphology,and shape of the particles.Furthermore,tensile strength and deformation of printed bars is evaluated,showcasing the impact of aging on the print properties.The findings reveal that consecutive reuse of used powder significantly influences dimensional accuracy of the printed parts.We detect a 30.63%relative value of shrinkage after six printing iterations,which corresponds to an absolute shrinkage increase by 0.98%.This is significant considering the standard shrinkage for the material used is already 3.2%.Additionally,parts that are printed with reused material exhibit a small increase in elongation at yield,as well as an unexpected rise in tensile strength.Significant agglomeration of small particles is observed in the aged powder,since there are particles of less than 10μm,which are not found in the virgin powder.These results contribute to a better understanding of the issues related to the reusing of aged material,and offer invaluable insights for mitigating the environmental impact that is associated with material disposal in AM.展开更多
Selective laser melting(SLM)plays a critical role in additive manufacturing,particularly in the fabrication of complex high-precision components.This study selects the AlSi10Mg alloy for its extensive use in the aeros...Selective laser melting(SLM)plays a critical role in additive manufacturing,particularly in the fabrication of complex high-precision components.This study selects the AlSi10Mg alloy for its extensive use in the aerospace and automotive industries,which require lightweight structures with superior thermal and mechanical properties.The thermal load induces residual tensile stress,leading to a decline in the geometric accuracy of the workpiece and causing cracks that reduce the fatigue life of the alloy.The rapid movement of the laser heat source during the material formation creates a localized and inhomogeneous temperature field in the powder bed.Significant temperature gradients are generated,resulting in thermal stresses and distortions within the part,affecting the quality of the molding.Therefore,understanding the effects of processing parameters and scanning strategies on the temperature field in SLM is crucial.To address these issues,this study proposes a multiscale method for predicting the complex transient temperature field during the manufacturing process based on the heat-conduction equation.Considering the influence of temperature on the material properties,a temperature-prediction model for discontinuous scanning paths in SLM and a temperature field-calculation model for irregular scanning paths are developed.The models are validated using finite-element results and are in excellent agreement.The analytical model is then used to investigate the effects of the laser power,scanning speed,and scanning spacing on the temperature distribution.The results reveal that the peak temperature decreases exponentially with increasing scanning speed and increases linearly with increasing laser power.In addition,with increasing scanning spacing,the peak temperature of the adjacent tracks near the observation point decreases linearly.These findings are critical for optimizing the SLM-process parameters and improving the material-forming quality.展开更多
Specially shaped permanent magnet structures can satisfy the requirements of equipment with limited space or unique shapes.Thereby,these optimize the distribution of magnetic fields.However,traditional manufacturing m...Specially shaped permanent magnet structures can satisfy the requirements of equipment with limited space or unique shapes.Thereby,these optimize the distribution of magnetic fields.However,traditional manufacturing methods are limited by the mold design and insufficient material utilization.In this study,a polymer-based Nd_(2)Fe_(14)B(NdFeB)magnetic slurry was developed based on direct ink writing(DIW)3D printing technology.A rapidly volatilizable magnetic slurry was used to achieve 3D oriented controllable layering,thus realizing the direct molding fabrication of NdFeB permanent magnets with complex structures.By exploring and optimizing the 3D printing process parameters,specially shaped bonded NdFeB permanent magnet structures with high precision and shape fidelity were prepared.The test results indicated that the remnant magnetization of the printed magnets was proportional to the NdFeB content in the slurry,the coercivity closely matched that of the original powder,and the mechanical properties of the printed magnets were favorable.Building on this,a magnetically driven helical-structure robot was designed and printed to achieve stable motion in low-Reynolds-number fluids.This paper presents a new,low-cost solution for the room-temperature preparation of shape-bonded NdFeB permanent magnets.展开更多
Additive manufacturing(AM),particularly fused deposition modeling(FDM),has emerged as a transformative technology in modern manufacturing processes.The dimensional accuracy of FDM-printed parts is crucial for ensuring...Additive manufacturing(AM),particularly fused deposition modeling(FDM),has emerged as a transformative technology in modern manufacturing processes.The dimensional accuracy of FDM-printed parts is crucial for ensuring their functional integrity and performance.To achieve sustainable manufacturing in FDM,it is necessary to optimize the print quality and time efficiency concurrently.However,owing to the complex interactions of printing parameters,achieving a balanced optimization of both remains challenging.This study examines four key factors affecting dimensional accuracy and print time:printing speed,layer thickness,nozzle temperature,and bed temperature.Fifty parameter sets were generated using enhanced Latin hypercube sampling.A whale optimization algorithm(WOA)-enhanced support vector regression(SVR)model was developed to predict dimen-sional errors and print time effectively,with non-dominated sorting genetic algorithm Ⅲ(NSGA-Ⅲ)utilized for multi-objective optimization.The technique for Order Preference by Similarity to Ideal Solution(TOPSIS)was applied to select a balanced solution from the Pareto front.In experimental validation,the parts printed using the optimized parameters exhibited excellent dimensional accuracy and printing efficiency.This study comprehensively considered optimizing the printing time and size to meet quality requirements while achieving higher printing efficiency and aiding in the realization of sustainable manufacturing in the field of AM.In addition,the printing of a specific prosthetic component was used as a case study,highlighting the high demands on both dimensional precision and printing efficiency.The optimized process parameters required significantly less printing time,while satisfying the dimensional accuracy requirements.This study provides valuable insights for achieving sustainable AM using FDM.展开更多
A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This pape...A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This paper investigates the thermal processing capability of lunar regolith without the addition of binders,with a focus on large-scale applications for the construction of lunar habitats and infrastructure.The study used a simulant of lunar regolith found on the Schr?dinger Basin in the South Pole region.This regolith simulant consists of20 wt%basalt and 80 wt%anorthosite.Experiments were conducted using a high power CO_(2)laser to sinter and melt the regolith in a 80 mm diameter laser spot to evaluate the effectiveness of direct large area thermal processing.Results indicated that sintering begins at approximately 1180℃and reaches full melt at temperatures above 1360℃.Sintering experiments with this material revealed the formation of dense samples up to 11 mm thick,while melting experiments successfully produced larger samples by overlapping molten layers and additive manufacturing up to 50 mm thick.The energy efficiency of the sintering and melting processes was compared.The melting process was about 10 times more energy efficient than sintering in terms of material consolidation,demonstrating the promising potential of laser melting technologies of anorthosite-rich regolith for the production of structural elements.展开更多
In-space 3D printing is transforming the manufacturing paradigm of space structures from ground-based production to in-situ space manufacturing,effectively addressing the challenges of high costs,long response times,a...In-space 3D printing is transforming the manufacturing paradigm of space structures from ground-based production to in-situ space manufacturing,effectively addressing the challenges of high costs,long response times,and structural size limitations associated with traditional rocket launches.This technology enables rapid on-orbit emergency repairs and significantly expands the geometric dimensions of space structures.High-performance polymers and their composites are widely used in in-space 3D printing,yet their implementation faces complex challenges posed by extreme space environmental conditions and limited energy or resources.This paper reviews the state-of-the-art in 3D printing of polymer and composites for on-orbit structure manufacturing.Based on existing research activities,the review focuses on three key aspects including the impact of extreme space environments on forming process and performance,innovative design and manufacturing methods for space structures,and on-orbit recycling and remanufacturing of raw materials.Some experiments that have already been conducted on-orbit and simulated experiments completed on the ground are systematically analyzed to provide a more comprehensive understanding of the constraints and objectives for on-orbit structure manufacturing.Furthermore,several perspectives requiring further research in future are proposed to facilitate the development of new in-space 3D printing technologies and space structures,thereby supporting increasingly advanced space exploration activities.展开更多
Additive manufacturing(AM)has revolutionized the production of metal bone implants,enabling unprecedented levels of customization and functionality.Recent advancements in surface-modification technologies have been cr...Additive manufacturing(AM)has revolutionized the production of metal bone implants,enabling unprecedented levels of customization and functionality.Recent advancements in surface-modification technologies have been crucial in enhancing the performance and biocompatibility of implants.Through leveraging the versatility of AM techniques,particularly powder bed fusion,a range of metallic biomaterials,including stainless steel,titanium,and biodegradable alloys,can be utilized to fabricate implants tailored for craniofacial,trunk,and limb bone reconstructions.However,the potential of AM is contingent on addressing intrinsic defects that may hinder implant performance.Techniques such as sandblasting,chemical treatment,electropolishing,heat treatment,and laser technology effectively remove residual powder and improve the surface roughness of these implants.The development of functional coatings,applied via both dry and wet methods,represents a significant advancement in surface modification research.These coatings not only improve mechanical and biological interactions at the implant-bone interface but also facilitate controlled drug release and enhance antimicrobial properties.Addition-ally,micro-and nanoscale surface modifications using chemical and laser techniques can precisely sculpt implant surfaces to promote the desired cellular responses.This detailed exploration of surface engineering offers a wealth of opportunities for creating next-generation implants that are not only biocompatible but also bioactive,laying the foundation for more effective solutions in bone reconstruction.展开更多
Laser powder bed fusion(L-PBF)is an advanced metal additive manufacturing process with an excellent capability for fabricating nickel-based superalloys.After solution aging(SA),the l-PBF nickel-based superalloys can m...Laser powder bed fusion(L-PBF)is an advanced metal additive manufacturing process with an excellent capability for fabricating nickel-based superalloys.After solution aging(SA),the l-PBF nickel-based superalloys can match the tensile properties with the conventional manufacturing process;however,its performance under long-life regime service conditions,especially at an elevated temperature of 650℃,has not yet been well understood,which restricts its promotion in industrial applications.In this study,combined with various techniques including X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and micro-computed tomography(micro-CT),the microstructure,phases,micro-texture,and internal defects of SA l-PBF nickel-based superalloys were analyzed,and tensile and cutting-edge fatigue tests with stress ratios R=-1 and 0.1 were performed at 25℃ and 650℃ to investigate the fatigue failure behavior.The results showed that the SA treatment promoted microstructural homogenization with vague laser scanning tracks.The synergistic effect of the γ',γ",and δ phases improved the mechanical and fatigue properties.Elevated temperatures and positive stress ratios promoted the occurrence of subsurface or internal failures.The four cracking modes include crack nucleation from the crystallographic facets,pore-assisted facetted crack nucleation,lack of fusion-induced crack nucleation,and inclusion-induced crack nucleation.At 650℃,the grains fractured along the maximum shear plane,formed a large number of highly inhomogeneous facets,which caused significant fluctuations.Finally,the phase transition processes during SA treatment and defect-related fatigue failure mechanisms were elucidated.This study provides key quality and testing data to support the advancement of l-PBF nickel-based superalloys and provides a foundation for their optimized design and industrial applications.展开更多
Interlayer heat accumulation(IHA)is major challenge in the laser powder bed fusion(LPBF)process,as it exacerbates the instability of melt pools,and compromises the quality of the as-built samples.Infrared radiation mo...Interlayer heat accumulation(IHA)is major challenge in the laser powder bed fusion(LPBF)process,as it exacerbates the instability of melt pools,and compromises the quality of the as-built samples.Infrared radiation monitoring is an effective method for exploring IHA.Based on the defined sequence features of interlayer infrared radiation intensity(IIRI),this study established a gated recurrent unit(GRU)neural network model for predicting IIRI in formed samples using machine learning to mitigate the IHA.The model trained on 316 L alloys achieved precise prediction results when transferred to the DZ125 superalloy,effectively managing various emergencies in the LPBF process.The truncated pyramid components were fabricated through parameter optimization based on IIRI prediction results.Compared with the non-optimized components,the CT results demonstrated a significant reduction in internal voids,with the relative density increasing from 91.6% to 98.5%.Additionally,surface roughness(Ra)decreased from 32.58μm to 19.91μm,while residual stress on the top surface was reduced from 169.21 MPa to 102.37 MPa.展开更多
The manufacturing sector has been transformed owing to additive manufacturing(AM),which has made it possible to create intricate,personalized items with little material waste.However,optimizing and enhancing AM proces...The manufacturing sector has been transformed owing to additive manufacturing(AM),which has made it possible to create intricate,personalized items with little material waste.However,optimizing and enhancing AM processes remain challenging owing to the intricacies involved in design,material selection,and process parameters.This review explores the integration of artificial intelligence(AI),machine learning(ML),and deep learning(DL)techniques to improve and innovate in the field of AM.AI-driven design optimization procedures offer innovative solutions for the 3D printing of complex geometries and lightweight structures.By leveraging machine learning(ML)algorithms,these procedures analyze extensive data from previous manufacturing processes to enhance efficiency and productivity.ML models facilitate design and production automation by learning from historical data and identifying intricate patterns that human operators may miss.Deep learning(DL)further augments this capacity by utilizing sophisticated neural networks to manage and interpret complex information and provide deeper insights into the manufacturing process.Integrating AI,ML,and DL into AM enables the creation of optimized,lightweight components that are crucial for reducing fuel consumption in the automotive and aviation industries.These advanced AI techniques optimize the design and production processes and enhance predictive modeling for process optimization and defect detection,leading to improved performance and reduced manufacturing costs.Therefore,integrating AI,ML,and DL into AM improves precision in component fabrication,enabling advanced material design innovations and opening new possibilities for innovation in product design and material science.This review discusses and highlights significant advancements and identifies future directions for applying AI,ML,and DL in AM.By leveraging these technologies,AM processes can achieve unprecedented levels of precision,customization,and productivity for analysis and modification.展开更多
Wire-feed direct metal deposition(DMD)additive manufacturing(AM)has demonstrated strong adaptability in microgravity environments,making it a preferred solution for in-situ space fabrication.However,space-oriented met...Wire-feed direct metal deposition(DMD)additive manufacturing(AM)has demonstrated strong adaptability in microgravity environments,making it a preferred solution for in-situ space fabrication.However,space-oriented metal AM faces significant constraints due to the high cost of Earth-to-space transport and must meet demanding requirements for miniaturization and low power consumption.This study proposes a metal fusion AM technique utilizing a Joule-laser hybrid heat source and investigates its forming mechanism and processing behavior.The influence of various process parameters on formation quality is thoroughly analyzed,and optimal conditions are identified.Experimental results indicate that,using a 0.3 mm diameter stainless steel wire,the hybrid heat source enables high-quality deposition at a low laser power of 50 W—reducing total power consumption by36%compared to single-laser wire melting.This study provides both theoretical and experimental support for developing low-power metal wire AM processes,contributing to the miniaturization and lightweighting of spaceborne AM equipment.展开更多
Wire arc additive manufacturing(WAAM)is one of the most promising approaches to manufacturing large and complex metal components owing to its low cost and high efficiency.However,pores and coarse columnar grains cause...Wire arc additive manufacturing(WAAM)is one of the most promising approaches to manufacturing large and complex metal components owing to its low cost and high efficiency.However,pores and coarse columnar grains caused by thermal accumulation in WAAM significantly decrease the strength and increase the anisotropy,preventing the achievement of both high strength and isotropy.In this study,the strength and anisotropy of AlMg-Sc-Zr alloys were improved by regulating heat input.The results indicated that as the heat input increased from 60 to 99 J/mm,all the components had lower porosity(lower than 0.04%),the size of the Al_(3)(Sc_(1-x),Zr_(x))phases decreased,and the number density increased.The average grain size gradually decreased,and the grain morphologies transformed from coarse equiaxed grain(CEG)+fine equiaxed grain(FEG)to FEG owing to the increase in Al_(3)(Sc_(1-x),Zr_(x))phases with increasing heat input.After heat treatment at 325℃for 6 h,high-density dispersed Al_(3)Sc phases(<10 nm)precipitated.The alloy possessed the highest strength at 79 J/mm,ultimate tensile strength(UTS)of approximately 423±3 MPa,and in-plane anisotropy of approximately 4.3%.At a heat input of 99 J/mm,the in-plane anisotropy decreased to 1.2%and UTS reached 414±5 MPa.The reduction in the CEG prolonged the crack propagation path,which improved the UTS in the vertical direction and reduced the anisotropy.Theoretical calculations indicated that the main strengthening mechanisms were solid solution and precipitation strengthening.This study lays the theoretical foundations for WAAM-processed high-strength and isotropic Al alloy components.展开更多
The emergence of additive manufacturing technology,particularly laser powder bed fusion,has revitalized NiTi alloy production.However,challenges arise regarding its mechanical properties and diminishing shape memory e...The emergence of additive manufacturing technology,particularly laser powder bed fusion,has revitalized NiTi alloy production.However,challenges arise regarding its mechanical properties and diminishing shape memory effect,which hinder its widespread application.Heat treatment has been identified as a method to enhance the performance of metallic materials in the realm of additive manufacturing.This process eliminates residual stress and enhances performance through precipitation strengthening.This study conducted a comprehensive annealing investigation on NiTi alloys to explore the impact of annealing time and temperature on the phase transformation behavior and shape memory performance.The mechanism underlying the performance enhancement was analyzed using scanning electron microscopy,energy-dispersive X-ray spectroscopy,electron backscatter diffraction,and transmission electron microscopy.The findings revealed that different annealing conditions resulted in multistep phase transformation behavior,with the 500℃-5 h sample exhibiting the best mechanical properties owing to the formation of nanoscale dispersed precipitates like Ni_(4)Ti_(3).However,higher temperatures led to larger precipitates,significantly weakening the properties of the NiTi alloy.Additionally,the annealing treatment did not have a notable impact on the grain size,texture strength,or direction.This study provides valuable insights for optimizing the heat treatment process of LPBF-NiTi alloys.展开更多
基金supported by National Key Research and Development Program of China(Grant No.2023YFB4604100)National Key Research and Development Program of China(Grant No.2022YFB3806104)+4 种基金Key Research and Development Program in Shaanxi Province(Grant No.2021LLRH-08-17)Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001)K C Wong Education Foundation of ChinaYouth Innovation Team of Shaanxi Universities of ChinaKey Research and Development Program of Shaanxi Province(Grant 2021LLRH-08-3.1).
文摘Ensuring the consistent mechanical performance of three-dimensional(3D)-printed continuous fiber-reinforced composites is a significant challenge in additive manufacturing.The current reliance on manual monitoring exacerbates this challenge by rendering the process vulnerable to environmental changes and unexpected factors,resulting in defects and inconsistent product quality,particularly in unmanned long-term operations or printing in extreme environments.To address these issues,we developed a process monitoring and closed-loop feedback control strategy for the 3D printing process.Real-time printing image data were captured and analyzed using a well-trained neural network model,and a real-time control module-enabled closed-loop feedback control of the flow rate was developed.The neural network model,which was based on image processing and artificial intelligence,enabled the recognition of flow rate values with an accuracy of 94.70%.The experimental results showed significant improvements in both the surface performance and mechanical properties of printed composites,with three to six times improvement in tensile strength and elastic modulus,demonstrating the effectiveness of the strategy.This study provides a generalized process monitoring and feedback control method for the 3D printing of continuous fiber-reinforced composites,and offers a potential solution for remote online monitoring and closed-loop adjustment in unmanned or extreme space environments.
基金supported by National Key R&D Program of China(Grant No.2022YFB4600500)Fundamental Research Funds for the Central Universitiesthe Program for Innovation Team of Shaanxi Province of China(Grant No.2023-CX-TD-17).
文摘In engineering,the demand for high energy absorption by structures subjected to impact loads is increasing.Balancing the limited space,manufacturing feasibility,and energy absorption capabilities is a key point in the design of many enclosed structures with energy absorption requirements.To achieve a lightweight design and controllable energy absorption by the structures,within a limited space,this study proposes a bio-inspired double-layer impact-resistant structure that can be manufactured by an additive manufacturing method(powder bed fusion),inspired by the microstructure of a woodpecker’s head.The structure is composed of two basic structural units:a quasi-circular ring and an oblique cylinder.The controllable energy absorption capabilities of the structure were studied through a combination of theoretical analyses,numerical simulations,and physical experiments.The results showed that,for the quasi-circular ring structure,the specific energy absorption range of 13-72 J/g could be effectively regulated by adjusting the structural parameters.The specific energy absorption range of 11-137 J/g could be effectively regulated for oblique cylindrical structures.Finally,the structure was applied to the design of engineering impact-resistant devices,proving the effectiveness of the controllable energy absorption of the structure.Moreover,the design process of the structure was optimized,laying a foundation for the structure to better serve engineering design applications.
基金supported by National Natural Science Foundation of China(Grant No.U2006218)Project of Construction and Support for High-Level Innovative Teams of Beijing Municipal Institutions(Grant No.BPHR20220124).
文摘SiC is a wave-absorbing material with good dielectric properties,high-temperature resistance,and corrosion resistance,which has great potential for development in the field of high-temperature wave-absorbing.However,SiC is limited by its low impedance-matching performance and single wave-absorbing mechanism.Therefore,compatible metamaterial technologies are required to enhance its wave-absorbing performance further.The electromagnetic wave(EMW)absorbing metamaterials can realize perfect absorption of EMWs in specific frequency bands and precise regulation of EMW phase,propagation mode,and absorption frequency bands through structural changes.However,the traditional molding methods for manufacturing complex geometric shapes require expensive molds,involve process complexity,and have poor molding accuracy and other limitations.Therefore,additive manufacturing(AM)technology,through material layered stacking to achieve the processing of materials,is a comprehensive multidisciplinary advanced manufacturing technology and has become the core technology for manufacturing metamaterials.This review introduces the principles and applications of different AM technologies for SiC and related materials,discusses the current status and development trends of various AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,summarizes the limitations and technological shortcomings of existing AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,and provides an outlook for the future development of related AM technologies.
文摘3D printing technology can realize the rapid fabrication of complicated structures with short production chain,which just meet the requirements for space manufacturing in the future.This Special Issue features the cutting-edge 3D printing technologies considering the space environment,focusing on the experimental validation and simulation on the 3D printing process and structural technologies,including whole process chain from raw materials,structural design,process,equipment,as well as functional verification.
文摘Additive Manufacturing(AM)has significantly impacted the development of high-performance materials and structures,offering new possibilities for industries ranging from aerospace to biomedicine.This special issue features pioneering research that integrates AI-driven methods with AM,enabling the design and fabrication of complex,optimized structures with enhanced properties.
基金supported by 40th DLR Parabolic Flight Campaign and within the project"Powder based Additive Manufacturing at reduced Gravitation"(Grant No.FKZ:50WM2068)European Space Agency,OSIP Off-Earth Manufacturing and Construction Campaign(Grant No.4000134280/21/NL/GLC/mk)。
文摘In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the production of parts and larger structures was investigated in detail.With different experimental setups in normal and microgravity,laser spots with diameters from 5 mm to 100 mm were realized to melt the regolith simulant EAC-1A and an 80%/20%mixture of TUBS-T and TUBS-M,which are used as a substitute for the actual lunar soil.In the experiments performed,the critical parameters are the size of the laser spot,the velocity of the laser spot on the surface of the powder bed,the gravity and the wettability of the powder bed by the melt.The stability of the melt pool as a function of these parameters was investigated and it was found that the formation of a stable melt pool is determined by gravity for large melt pool sizes in the range of 50 mm and by surface tension for small melt pool sizes in the range of a few mm.
文摘Additive manufacturing(AM)technology has revolutionized engineering field by enabling the creation of intricate,high-performance structures that were once difficult or impossible to fabricate.This transformative technology has particularly advanced the development of metamaterials-engineered materials whose unique properties arise from their structure rather than composition-unlocking immense potential in fields ranging from aerospace to biomedical engineering.
文摘Additive manufacturing(AM)is an advanced production method for layer-by-layer fabrication,offering a paradigm shift in manufacturing.However,the sustainability of AM processes is poor,since suppliers recommend reusing 50%-70%of reprocessed powder,contributing to a significant increase in material disposal.To explore the possibility of fully reusing the polymeric material,we conduct a comprehensive characterisation of the powder particulates,in combination with analysis of the final prints.Utilizing optical and scanning electron microscopes,we statistically evaluate the size,morphology,and shape of the particles.Furthermore,tensile strength and deformation of printed bars is evaluated,showcasing the impact of aging on the print properties.The findings reveal that consecutive reuse of used powder significantly influences dimensional accuracy of the printed parts.We detect a 30.63%relative value of shrinkage after six printing iterations,which corresponds to an absolute shrinkage increase by 0.98%.This is significant considering the standard shrinkage for the material used is already 3.2%.Additionally,parts that are printed with reused material exhibit a small increase in elongation at yield,as well as an unexpected rise in tensile strength.Significant agglomeration of small particles is observed in the aged powder,since there are particles of less than 10μm,which are not found in the virgin powder.These results contribute to a better understanding of the issues related to the reusing of aged material,and offer invaluable insights for mitigating the environmental impact that is associated with material disposal in AM.
基金supported by National Natural Science Foundation of the China Youth Program(Grant No.52205485)Sichuan Youth Fund Program of China(Grant No.2025ZNSFSC1275)the Young Scientific Research Team Cultivation Program of SUES(Grant No.QNTD202112)。
文摘Selective laser melting(SLM)plays a critical role in additive manufacturing,particularly in the fabrication of complex high-precision components.This study selects the AlSi10Mg alloy for its extensive use in the aerospace and automotive industries,which require lightweight structures with superior thermal and mechanical properties.The thermal load induces residual tensile stress,leading to a decline in the geometric accuracy of the workpiece and causing cracks that reduce the fatigue life of the alloy.The rapid movement of the laser heat source during the material formation creates a localized and inhomogeneous temperature field in the powder bed.Significant temperature gradients are generated,resulting in thermal stresses and distortions within the part,affecting the quality of the molding.Therefore,understanding the effects of processing parameters and scanning strategies on the temperature field in SLM is crucial.To address these issues,this study proposes a multiscale method for predicting the complex transient temperature field during the manufacturing process based on the heat-conduction equation.Considering the influence of temperature on the material properties,a temperature-prediction model for discontinuous scanning paths in SLM and a temperature field-calculation model for irregular scanning paths are developed.The models are validated using finite-element results and are in excellent agreement.The analytical model is then used to investigate the effects of the laser power,scanning speed,and scanning spacing on the temperature distribution.The results reveal that the peak temperature decreases exponentially with increasing scanning speed and increases linearly with increasing laser power.In addition,with increasing scanning spacing,the peak temperature of the adjacent tracks near the observation point decreases linearly.These findings are critical for optimizing the SLM-process parameters and improving the material-forming quality.
基金supported by National Natural Science Foundation of China(Grant Nos.52375348,52175331)National Natural Science Foundation of Shandong Province(Grant Nos.ZR2022ME014,ZR2020ZD04).
文摘Specially shaped permanent magnet structures can satisfy the requirements of equipment with limited space or unique shapes.Thereby,these optimize the distribution of magnetic fields.However,traditional manufacturing methods are limited by the mold design and insufficient material utilization.In this study,a polymer-based Nd_(2)Fe_(14)B(NdFeB)magnetic slurry was developed based on direct ink writing(DIW)3D printing technology.A rapidly volatilizable magnetic slurry was used to achieve 3D oriented controllable layering,thus realizing the direct molding fabrication of NdFeB permanent magnets with complex structures.By exploring and optimizing the 3D printing process parameters,specially shaped bonded NdFeB permanent magnet structures with high precision and shape fidelity were prepared.The test results indicated that the remnant magnetization of the printed magnets was proportional to the NdFeB content in the slurry,the coercivity closely matched that of the original powder,and the mechanical properties of the printed magnets were favorable.Building on this,a magnetically driven helical-structure robot was designed and printed to achieve stable motion in low-Reynolds-number fluids.This paper presents a new,low-cost solution for the room-temperature preparation of shape-bonded NdFeB permanent magnets.
基金supporteded by Natural Science Foundation of Shanghai(Grant No.22ZR1463900)State Key Laboratory of Mechanical System and Vibration(Grant No.MSV202318)the Fundamental Research Funds for the Central Universities(Grant No.22120220649).
文摘Additive manufacturing(AM),particularly fused deposition modeling(FDM),has emerged as a transformative technology in modern manufacturing processes.The dimensional accuracy of FDM-printed parts is crucial for ensuring their functional integrity and performance.To achieve sustainable manufacturing in FDM,it is necessary to optimize the print quality and time efficiency concurrently.However,owing to the complex interactions of printing parameters,achieving a balanced optimization of both remains challenging.This study examines four key factors affecting dimensional accuracy and print time:printing speed,layer thickness,nozzle temperature,and bed temperature.Fifty parameter sets were generated using enhanced Latin hypercube sampling.A whale optimization algorithm(WOA)-enhanced support vector regression(SVR)model was developed to predict dimen-sional errors and print time effectively,with non-dominated sorting genetic algorithm Ⅲ(NSGA-Ⅲ)utilized for multi-objective optimization.The technique for Order Preference by Similarity to Ideal Solution(TOPSIS)was applied to select a balanced solution from the Pareto front.In experimental validation,the parts printed using the optimized parameters exhibited excellent dimensional accuracy and printing efficiency.This study comprehensively considered optimizing the printing time and size to meet quality requirements while achieving higher printing efficiency and aiding in the realization of sustainable manufacturing in the field of AM.In addition,the printing of a specific prosthetic component was used as a case study,highlighting the high demands on both dimensional precision and printing efficiency.The optimized process parameters required significantly less printing time,while satisfying the dimensional accuracy requirements.This study provides valuable insights for achieving sustainable AM using FDM.
文摘A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This paper investigates the thermal processing capability of lunar regolith without the addition of binders,with a focus on large-scale applications for the construction of lunar habitats and infrastructure.The study used a simulant of lunar regolith found on the Schr?dinger Basin in the South Pole region.This regolith simulant consists of20 wt%basalt and 80 wt%anorthosite.Experiments were conducted using a high power CO_(2)laser to sinter and melt the regolith in a 80 mm diameter laser spot to evaluate the effectiveness of direct large area thermal processing.Results indicated that sintering begins at approximately 1180℃and reaches full melt at temperatures above 1360℃.Sintering experiments with this material revealed the formation of dense samples up to 11 mm thick,while melting experiments successfully produced larger samples by overlapping molten layers and additive manufacturing up to 50 mm thick.The energy efficiency of the sintering and melting processes was compared.The melting process was about 10 times more energy efficient than sintering in terms of material consolidation,demonstrating the promising potential of laser melting technologies of anorthosite-rich regolith for the production of structural elements.
基金supported by National Natural Science Foundation of China(Grant No.52205413)National Key Research and Development Program(Grant No.2022YFB3806101)+1 种基金K C Wong Education FoundationThe Youth Innovation Team of Shaanxi Universities。
文摘In-space 3D printing is transforming the manufacturing paradigm of space structures from ground-based production to in-situ space manufacturing,effectively addressing the challenges of high costs,long response times,and structural size limitations associated with traditional rocket launches.This technology enables rapid on-orbit emergency repairs and significantly expands the geometric dimensions of space structures.High-performance polymers and their composites are widely used in in-space 3D printing,yet their implementation faces complex challenges posed by extreme space environmental conditions and limited energy or resources.This paper reviews the state-of-the-art in 3D printing of polymer and composites for on-orbit structure manufacturing.Based on existing research activities,the review focuses on three key aspects including the impact of extreme space environments on forming process and performance,innovative design and manufacturing methods for space structures,and on-orbit recycling and remanufacturing of raw materials.Some experiments that have already been conducted on-orbit and simulated experiments completed on the ground are systematically analyzed to provide a more comprehensive understanding of the constraints and objectives for on-orbit structure manufacturing.Furthermore,several perspectives requiring further research in future are proposed to facilitate the development of new in-space 3D printing technologies and space structures,thereby supporting increasingly advanced space exploration activities.
基金supported by National Natural Science Foundation of China(Grant No.52275343)Natural Science Foundation of Zhejiang Province(Grant No.LY23E050003)Ningbo Youth Science and Technology Innovation Leading Talent Project(Grant No.2023QL021).
文摘Additive manufacturing(AM)has revolutionized the production of metal bone implants,enabling unprecedented levels of customization and functionality.Recent advancements in surface-modification technologies have been crucial in enhancing the performance and biocompatibility of implants.Through leveraging the versatility of AM techniques,particularly powder bed fusion,a range of metallic biomaterials,including stainless steel,titanium,and biodegradable alloys,can be utilized to fabricate implants tailored for craniofacial,trunk,and limb bone reconstructions.However,the potential of AM is contingent on addressing intrinsic defects that may hinder implant performance.Techniques such as sandblasting,chemical treatment,electropolishing,heat treatment,and laser technology effectively remove residual powder and improve the surface roughness of these implants.The development of functional coatings,applied via both dry and wet methods,represents a significant advancement in surface modification research.These coatings not only improve mechanical and biological interactions at the implant-bone interface but also facilitate controlled drug release and enhance antimicrobial properties.Addition-ally,micro-and nanoscale surface modifications using chemical and laser techniques can precisely sculpt implant surfaces to promote the desired cellular responses.This detailed exploration of surface engineering offers a wealth of opportunities for creating next-generation implants that are not only biocompatible but also bioactive,laying the foundation for more effective solutions in bone reconstruction.
基金supported by National Natural Science Foundation of China(Grant No.52175128)the State Key Laboratory for the Mechanical Behavior of Materials of China(Grant No.20232501).
文摘Laser powder bed fusion(L-PBF)is an advanced metal additive manufacturing process with an excellent capability for fabricating nickel-based superalloys.After solution aging(SA),the l-PBF nickel-based superalloys can match the tensile properties with the conventional manufacturing process;however,its performance under long-life regime service conditions,especially at an elevated temperature of 650℃,has not yet been well understood,which restricts its promotion in industrial applications.In this study,combined with various techniques including X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and micro-computed tomography(micro-CT),the microstructure,phases,micro-texture,and internal defects of SA l-PBF nickel-based superalloys were analyzed,and tensile and cutting-edge fatigue tests with stress ratios R=-1 and 0.1 were performed at 25℃ and 650℃ to investigate the fatigue failure behavior.The results showed that the SA treatment promoted microstructural homogenization with vague laser scanning tracks.The synergistic effect of the γ',γ",and δ phases improved the mechanical and fatigue properties.Elevated temperatures and positive stress ratios promoted the occurrence of subsurface or internal failures.The four cracking modes include crack nucleation from the crystallographic facets,pore-assisted facetted crack nucleation,lack of fusion-induced crack nucleation,and inclusion-induced crack nucleation.At 650℃,the grains fractured along the maximum shear plane,formed a large number of highly inhomogeneous facets,which caused significant fluctuations.Finally,the phase transition processes during SA treatment and defect-related fatigue failure mechanisms were elucidated.This study provides key quality and testing data to support the advancement of l-PBF nickel-based superalloys and provides a foundation for their optimized design and industrial applications.
基金supported by National Natural Science Foundation of China(Grant No.52275333)the Key Research&Development Program of China Hubei Province(Grant No.2023BAB089).
文摘Interlayer heat accumulation(IHA)is major challenge in the laser powder bed fusion(LPBF)process,as it exacerbates the instability of melt pools,and compromises the quality of the as-built samples.Infrared radiation monitoring is an effective method for exploring IHA.Based on the defined sequence features of interlayer infrared radiation intensity(IIRI),this study established a gated recurrent unit(GRU)neural network model for predicting IIRI in formed samples using machine learning to mitigate the IHA.The model trained on 316 L alloys achieved precise prediction results when transferred to the DZ125 superalloy,effectively managing various emergencies in the LPBF process.The truncated pyramid components were fabricated through parameter optimization based on IIRI prediction results.Compared with the non-optimized components,the CT results demonstrated a significant reduction in internal voids,with the relative density increasing from 91.6% to 98.5%.Additionally,surface roughness(Ra)decreased from 32.58μm to 19.91μm,while residual stress on the top surface was reduced from 169.21 MPa to 102.37 MPa.
文摘The manufacturing sector has been transformed owing to additive manufacturing(AM),which has made it possible to create intricate,personalized items with little material waste.However,optimizing and enhancing AM processes remain challenging owing to the intricacies involved in design,material selection,and process parameters.This review explores the integration of artificial intelligence(AI),machine learning(ML),and deep learning(DL)techniques to improve and innovate in the field of AM.AI-driven design optimization procedures offer innovative solutions for the 3D printing of complex geometries and lightweight structures.By leveraging machine learning(ML)algorithms,these procedures analyze extensive data from previous manufacturing processes to enhance efficiency and productivity.ML models facilitate design and production automation by learning from historical data and identifying intricate patterns that human operators may miss.Deep learning(DL)further augments this capacity by utilizing sophisticated neural networks to manage and interpret complex information and provide deeper insights into the manufacturing process.Integrating AI,ML,and DL into AM enables the creation of optimized,lightweight components that are crucial for reducing fuel consumption in the automotive and aviation industries.These advanced AI techniques optimize the design and production processes and enhance predictive modeling for process optimization and defect detection,leading to improved performance and reduced manufacturing costs.Therefore,integrating AI,ML,and DL into AM improves precision in component fabrication,enabling advanced material design innovations and opening new possibilities for innovation in product design and material science.This review discusses and highlights significant advancements and identifies future directions for applying AI,ML,and DL in AM.By leveraging these technologies,AM processes can achieve unprecedented levels of precision,customization,and productivity for analysis and modification.
基金supported by Key Research and Development Program of Sichuan province(Grant No.2025YFHZ0051)Open Fund of State Key Laboratory for Manufacturing Systems Engineering(Grant No.sk1ms2024008)。
文摘Wire-feed direct metal deposition(DMD)additive manufacturing(AM)has demonstrated strong adaptability in microgravity environments,making it a preferred solution for in-situ space fabrication.However,space-oriented metal AM faces significant constraints due to the high cost of Earth-to-space transport and must meet demanding requirements for miniaturization and low power consumption.This study proposes a metal fusion AM technique utilizing a Joule-laser hybrid heat source and investigates its forming mechanism and processing behavior.The influence of various process parameters on formation quality is thoroughly analyzed,and optimal conditions are identified.Experimental results indicate that,using a 0.3 mm diameter stainless steel wire,the hybrid heat source enables high-quality deposition at a low laser power of 50 W—reducing total power consumption by36%compared to single-laser wire melting.This study provides both theoretical and experimental support for developing low-power metal wire AM processes,contributing to the miniaturization and lightweighting of spaceborne AM equipment.
基金supported by National Key Research and Development Program(Grant No.2024YFB4609700)the National Natural Science Foundation of China(Grant No.52374365)。
文摘Wire arc additive manufacturing(WAAM)is one of the most promising approaches to manufacturing large and complex metal components owing to its low cost and high efficiency.However,pores and coarse columnar grains caused by thermal accumulation in WAAM significantly decrease the strength and increase the anisotropy,preventing the achievement of both high strength and isotropy.In this study,the strength and anisotropy of AlMg-Sc-Zr alloys were improved by regulating heat input.The results indicated that as the heat input increased from 60 to 99 J/mm,all the components had lower porosity(lower than 0.04%),the size of the Al_(3)(Sc_(1-x),Zr_(x))phases decreased,and the number density increased.The average grain size gradually decreased,and the grain morphologies transformed from coarse equiaxed grain(CEG)+fine equiaxed grain(FEG)to FEG owing to the increase in Al_(3)(Sc_(1-x),Zr_(x))phases with increasing heat input.After heat treatment at 325℃for 6 h,high-density dispersed Al_(3)Sc phases(<10 nm)precipitated.The alloy possessed the highest strength at 79 J/mm,ultimate tensile strength(UTS)of approximately 423±3 MPa,and in-plane anisotropy of approximately 4.3%.At a heat input of 99 J/mm,the in-plane anisotropy decreased to 1.2%and UTS reached 414±5 MPa.The reduction in the CEG prolonged the crack propagation path,which improved the UTS in the vertical direction and reduced the anisotropy.Theoretical calculations indicated that the main strengthening mechanisms were solid solution and precipitation strengthening.This study lays the theoretical foundations for WAAM-processed high-strength and isotropic Al alloy components.
基金supported by National Key R&D Program of China(Grant No.2022YFB4601701)74th Batch of General Funding from the China Postdoctoral Science Foundation(Grant No.2023M741341)+7 种基金5th Batch of Special Grants from the China Postdoctoral Science Foundation(before the station,Grant No.2023TQ0129)Postdoctoral Fellowship Program of CPSF(Grant No.GZB20230257)National Natural Science Foundation of China(Grant Nos.52375289,52205310)Natural Science Foundation of Shandong Province(Grant No.ZR2021QE263)Science and Technology Development Program of Jilin Province(Grant No.20230508045RC)Capital Construction Fund plan within the budget of Jilin Province(Grant No.2023C041-4)Chongqing Natural Science Foundation(Grant No.CSTB2022NSCQ-MSX0225)the Shandong Postdoctoral Science Foundation(Grant No.SDCX-ZG-202400238).
文摘The emergence of additive manufacturing technology,particularly laser powder bed fusion,has revitalized NiTi alloy production.However,challenges arise regarding its mechanical properties and diminishing shape memory effect,which hinder its widespread application.Heat treatment has been identified as a method to enhance the performance of metallic materials in the realm of additive manufacturing.This process eliminates residual stress and enhances performance through precipitation strengthening.This study conducted a comprehensive annealing investigation on NiTi alloys to explore the impact of annealing time and temperature on the phase transformation behavior and shape memory performance.The mechanism underlying the performance enhancement was analyzed using scanning electron microscopy,energy-dispersive X-ray spectroscopy,electron backscatter diffraction,and transmission electron microscopy.The findings revealed that different annealing conditions resulted in multistep phase transformation behavior,with the 500℃-5 h sample exhibiting the best mechanical properties owing to the formation of nanoscale dispersed precipitates like Ni_(4)Ti_(3).However,higher temperatures led to larger precipitates,significantly weakening the properties of the NiTi alloy.Additionally,the annealing treatment did not have a notable impact on the grain size,texture strength,or direction.This study provides valuable insights for optimizing the heat treatment process of LPBF-NiTi alloys.
