In order to obtain better quality cookies, food 3D printing technology was employed to prepare cookies. The texture, color, deformation, moisture content, and temperature of the cookie as evaluation indicators, the in...In order to obtain better quality cookies, food 3D printing technology was employed to prepare cookies. The texture, color, deformation, moisture content, and temperature of the cookie as evaluation indicators, the influences of baking process parameters, such as baking time, surface heating temperature and bottom heating temperature, on the quality of the cookie were studied to optimize the baking process parameters. The results showed that the baking process parameters had obvious effects on the texture, color, deformation, moisture content, and temperature of the cookie. All of the roasting surface heating temperature, bottom heating temperature and baking time had positive influences on the hardness, crunchiness, crispiness, and the total color difference(ΔE) of the cookie. When the heating temperatures of the surfac and bottom increased, the diameter and thickness deformation rate of the cookie increased. However,with the extension of baking time, the diameter and thickness deformation rate of the cookie first increased and then decreased. With the surface heating temperature of 180 ℃, the bottom heating temperature of 150 ℃, and baking time of 15 min, the cookie was crisp and moderate with moderate deformation and uniform color. There was no burnt phenomenon with the desired quality. Research results provided a theoretical basis for cookie manufactory based on food 3D printing technology.展开更多
The traditional printing checking method always uses printing control strips,but the results are not very well in repeatability and stability. In this paper,the checking methods for printing quality basing on image ar...The traditional printing checking method always uses printing control strips,but the results are not very well in repeatability and stability. In this paper,the checking methods for printing quality basing on image are taken as research objects. On the base of the traditional checking methods of printing quality,combining the method and theory of digital image processing with printing theory in the new domain of image quality checking,it constitute the checking system of printing quality by image processing,and expound the theory design and the model of this system. This is an application of machine vision. It uses the high resolution industrial CCD(Charge Coupled Device) colorful camera. It can display the real-time photographs on the monitor,and input the video signal to the image gathering card,and then the image data transmits through the computer PCI bus to the memory. At the same time,the system carries on processing and data analysis. This method is proved by experiments. The experiments are mainly about the data conversion of image and ink limit show of printing.展开更多
Flexible and wearable sensing devices have broad application prospects in bio-monitoring such as pulse measurement,motion detection and voice recognition.In recent years,many significant improvements had been made to ...Flexible and wearable sensing devices have broad application prospects in bio-monitoring such as pulse measurement,motion detection and voice recognition.In recent years,many significant improvements had been made to enhance the sensor’s performance including sensitivity,flexibility and repeatability.However,it is still extremely complicated and difficult to prepare a patterned sensor directly on a flexible substrate.Herein,inspired by typography,a lowcost,environmentally friendly stamping method for the mass production of transparent conductive carbon nanotube(CNT)film is proposed.In this dry transfer strategy,a porous CNT block was used as both the seal and the ink;and Ecoflex film was served as an object substrate.Welldesigned CNT patterns can be easily fabricated on the polymer substrate by engraving the target pattern on the CNT seal before the stamping process.Moreover,the CNT film can be directly used to fabricate ultrathin(300μm)strain sensor.This strain sensor possesses high sensitivity with a gauge factor(GF)up to 9960 at 85%strain,high stretchability(>200%)and repeatability(>5000 cycles).It has been used to measure pulse signals and detect joint motion,suggesting promising application prospects in flexible and wearable electronic devices.展开更多
Sand mold 3 D printing technology is an advanced manufacturing technology which has great flexible manufacturing ability. A multi-material composite sand mold can control the temperature field of metallic parts during...Sand mold 3 D printing technology is an advanced manufacturing technology which has great flexible manufacturing ability. A multi-material composite sand mold can control the temperature field of metallic parts during the pouring process, while the current sand mold 3 D printing technology can only fabricate a single material sand mold. The casting temperature field can not be adjusted by using single sand mold material with isotropous heat exchange ability during the pouring process. In this work, a kind of novel coating device was designed. Multi-material composite sand molds could be manufactured using the coating device according to the casting process demands of the final parts. The influences of curing agent content, coating velocity and scraper shape on compactness and surface roughness of the sand layer(silica sand and zircon sand) were studied. The shapes and sizes of transition intervals of two kinds of sand granules were also tested. The results show that, with the increase of the added volume of curing agent, the compactness of sand layer reduces and the surface roughness value rises. With the increase of the velocity of the coating device, the compactness of sand layer reduces and the surface roughness value rises similarly. In addition, the scraper with a dip angle of 72 degrees could increase the compactness value of the sand layer. The criteria of quality parmeters of the coating procedure are obtained. That is, the surface roughness(δ) of sand layer should be equal to or lesser than half of main size of the sand particles(Dm). The parameter H of the coating device which is the distance between the base of hopper and the surface of sand layer impacts the size of transition zone. The width of the transition zone is in direct proportion to the parameter H, qualitatively. Through the optimization of the coating device, high quality of multi-material sand layers can be obtained. This will provide a solution in manufacturing the multi-material composite sand mold.展开更多
A comprehensive assessment index system was established. The mechanical recycling process of printed circuit board was evaluated according to the comprehensive evaluation index system using the fuzzy analytic hierarch...A comprehensive assessment index system was established. The mechanical recycling process of printed circuit board was evaluated according to the comprehensive evaluation index system using the fuzzy analytic hierarchy process. A process assessment software system of mechanical recycling was established to evaluate different recycling technologies. And the software system was developed in the environment of VB6.0 and Access2000.展开更多
This paper describes the preparation and properties of TiN_x-SiO_2 double-layered antireflective(AR) coatings that were applied with print process. The coating material was analyzed and TiN_x was used instead of TiO_2...This paper describes the preparation and properties of TiN_x-SiO_2 double-layered antireflective(AR) coatings that were applied with print process. The coating material was analyzed and TiN_x was used instead of TiO_2 as high refractive material. The influence of solution concentration on AR property was studied. The testing result shows that the coatings using print process are featured with excellent mechanical property and the AR property is comparable to American Southwall AR product. It is expected that the study would promote the industrialization progress in AR coatings.展开更多
Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones ...Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones of InGa electrodes . After observing the Al paste physical and chemical behaviors during rising temperature by thermal analysis (DTA), the firing operation of Al electrodes could be divided into three main subsections: the temperature rising time (t-r), the peak firing temperature (T-p) and the hold time at peak firing temperature (t-h). The effects of these three parameters on final component properties were discussed in detail.展开更多
Ink-jet printing is a non-impact printing technology in which drops jetted from an orifice onto a designated position.This technology can digitally transport fluids containing cells precisely onto desired substrates t...Ink-jet printing is a non-impact printing technology in which drops jetted from an orifice onto a designated position.This technology can digitally transport fluids containing cells precisely onto desired substrates to construct three-dimensional organs.In order to obtain the stable uniform droplets,a stream is the key point of this technology.However,there are so many factors that affect the uniform droplet stream construction process:print parameters,material parameters,control method,etc.A good understanding of the various coupled transport processes that occur during bio-ink impact and spreading on bio-structure can improve the success of print-ability.This paper aims to obtain a good linear bio-structure with ink-jet printing technology.First,a typical droplet deposition process model is constructed;including droplet dynamics impact models and droplet diffusion cap models.Second,a model of successive droplet overlap,to form linear bio-structures,is constructed.Third,the finite element method is used to simulate the droplet impact,collision,and fusion process.Finally,the main influencing factors of the continuous injection printing process,namely the time interval between consecutive droplets and the droplet contact angles,are discussed.Sodium alginate is selected as bio-ink to verify the theory,and it is found that a good linear bio-structure could be obtained if the printing parameters are controlled optimally,i.e.,if the initial contact angle is set as 60 degrees and the trigger frequency is set as 150 kHz.With a proper printing speed and gel coating,a good survival rate of printed cells could be obtained.展开更多
Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aero...Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport industries.However,their widespread application is hindered by their low formability at room temperature due to limited slip systems.Cast Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high scrap.While casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain applications.Although metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast counterparts.Thus,MAM is a promising technique to produce Mg alloy parts.Directed energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive processes.However,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this technology.This review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and prospects.Furthermore,the predominant imperfections,notably inhomogeneous microstructure evolution and porosity,observed in Mg-alloy components manufactured through DED are discussed.Additionally,the preventive measures implemented to counteract the formation of these defects are explored.展开更多
In this study, indoor air quality (IAQ) assessments were carried out in a screen printing facility. The air sampling was conducted in press department, including two different types of screen printing machines: sem...In this study, indoor air quality (IAQ) assessments were carried out in a screen printing facility. The air sampling was conducted in press department, including two different types of screen printing machines: semi-automatic and automatic. Air samples were collected and analyzed in situ for 4 times, once per 2 hours, during working time of 8 hours. Analysis of the experimental data showed that ambient ozone concentrations slowly increases with the increasing of TVOCs concentration and intensive use of UV lamps during automatic screen printing process. Therefore, the detected concentration levels of ozone and VOCs were compared with the Occupational Safety and Health Administration (OSHA) and Serbian Regulation. Comparison of the two mentioned standard regulations, the ozone concentrations in indoor printing air were from 0.83 to 8.1 and 2.4 to 16.2 times higher in the relation to the prescribed PEL and maximum allowed concentration (MAC) values, respectively, while the concentrations of particular VOCs were much below the PEL prescribed by the OSHA.展开更多
The main characteristics, applications, the emphases of manufacturing process are introduced, and the research of new product of rigid-flex Printed Circuit Board (PCB) is also described. In particular, the plasma de...The main characteristics, applications, the emphases of manufacturing process are introduced, and the research of new product of rigid-flex Printed Circuit Board (PCB) is also described. In particular, the plasma desmear process, which is the crucial problems of manufacturing process, is discussed in detail. Samsung 4-layer rigid-flex PCB has been developed successfully, and the qualification rate reaches to 89.4%.展开更多
This study investigated the resilience of traditional concrete dams compared to 3D printed concrete dams(3DPC)when subjected to debris flow.Three types of dams,namely check dams,arch dams,and curve dams,were numerical...This study investigated the resilience of traditional concrete dams compared to 3D printed concrete dams(3DPC)when subjected to debris flow.Three types of dams,namely check dams,arch dams,and curve dams,were numerically analyzed using a three-dimensional Coupled Eulerian-Lagrangian(CEL)methodology.The research focused on critical factors such as impact force and viscous energy dissipation to compare dam performance.Additionally,the study examined the printing and service phases of 3DPC models,determining potential failure modes and analyzing printing parameters.The results demonstrated that 3DPC dams outperformed traditional concrete dams,with filament deposition orientation,perpendicular to the debris flow direction,identified as a pivotal factor.Infill percentage and pattern were also found to influence the behavior of 3DPC models.Notably,curved dams exhibited superior performance based on dam geometry.These findings have significant potential for advancing the development of resilient dam structures capable of withstanding debris flow impacts.展开更多
Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although i...Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although it is well known that ink rheology and processing parameters have a direct impact on the resolution and shape of the printed objects,the underlying mechanisms of these key factors on the printability and quality of DIW technique remain poorly understood.To tackle this issue,we systematically analyzed the printability and quality through extrusion mechanism modeling and experimental validating.Hybrid non-Newtonian fluid inks were first prepared,and their rheological properties were measured.Then,finite element analysis of the whole DIW process was conducted to reveal the flow dynamics of these inks.The obtained optimal process parameters(ink rheology,applied pressure,printing speed,etc)were also validated by experiments where high-resolution(<100μm)patterns were fabricated rapidly(>70 mm s^(-1)).Finally,as a process research demonstration,we printed a series of microstructures and circuit systems with hybrid inks and silver inks,showing the suitability of the printable process parameters.This study provides a strong quantitative illustration of the use of DIW for the high-speed preparation of high-resolution,high-precision samples.展开更多
Objective:To use three-dimensional(3D)printing technology to prepare Dashanzha Wan.Methods:The standard formula proportion of Dashanzha Wan was used to prepare printable materials(normally called the ink)for 3D printi...Objective:To use three-dimensional(3D)printing technology to prepare Dashanzha Wan.Methods:The standard formula proportion of Dashanzha Wan was used to prepare printable materials(normally called the ink)for 3D printing,and different doses and shapes of Dashanzha Wan were prepared.Then,the rheological properties,texture characteristics,scanning electron microscopy,and content of ursolic acid were evaluated.Results:Dashanzha Wan ink showed good shear thinning properties,which is very suitable for 3D printing.The printed sample had a beautiful and regular shape with high resolution.Meanwhile,ursolic acid content in 3D-printed Dashanzha Wan aligned with the ursolic acid content shown in the Pharmacopoeia of the People's Republic of China 2020.Conclusion:The 3D-printed Dashanzha Wan has a better texture,and can be shaped into various shapes according to individual needs,which would increase patients’interest when taking medicine.Moreover,3D printing of Dashanzha Wan could be easily integrated into the digital life system,enabling online customization or use at home.This study reveals that 3D printing technology is a promising method for the production of traditional Chinese medicine with personalized appearance,dosage,and texture,which is suitable for a broader population.展开更多
The soft robotics display huge advantages over their rigid counterparts when interacting with living organisms and fragile objects.As one of the most efficient actuators toward soft robotics,the soft pneumatic actuato...The soft robotics display huge advantages over their rigid counterparts when interacting with living organisms and fragile objects.As one of the most efficient actuators toward soft robotics,the soft pneumatic actuator(SPA)can produce large,complex responses with utilizing pressure as the only input source.In this work,a new approach that combines digital light processing(DLP)and injection-assisted post-curing is proposed to create SPAs that can realize different functionalities.To enable this,we develop a new class of photo-cross linked elastomers with tunable mechanical properties,good stretchability,and rapid curing speed.By carefully designing the geometry of the cavities embedded in the actuators,the resulting actuators can realize contracting,expanding,flapping,and twisting motions.In addition,we successfully fabricate a soft self-sensing bending actuator by injecting conductive liquids into the three-dimensional(3D)printed actuator,demonstrating that the present method has the potential to be used to manufacture intelligent soft robotic systems.展开更多
To response the demand for fine line in electronic products,additive manufacturing process integrated printing techniques and deposited methods to reach fine line circuit,with the merits of reduced material wastage,lo...To response the demand for fine line in electronic products,additive manufacturing process integrated printing techniques and deposited methods to reach fine line circuit,with the merits of reduced material wastage,low fabrication costs,and mass production advantage capability.Recently,we have developed additive process in fabricating circuit on flexible substrate through catalyst induced copper electroless deposition(ELD)method.The additive processes that integrated printing,activation,and metallization were applied to produce fine-line circuit with 5μm line width.The sample with ultraviolet(UV)activation shows better conductive property in comparison with the sample without activation after electroless deposited process.Accordingly,the results indicated that the reaction of catalyst induced electroless copper plating strongly depends on UV activation.The fine-line circuit exhibits a narrow line width circuit(around 5μm),lower resistance(6.2μΩ·cm),and mass production with low pollution in comparison with lithographic processes(with photoresist and acid pollution)with a high throughput system(R2R system)for the applications of double side flexible printed circuit board(FPCB).展开更多
基金Supported by Heilongjiang Provincial Fruit Tree Modernization Agro-industrial Technology Collaborative Innovation and Promotion System Project(2019-13)。
文摘In order to obtain better quality cookies, food 3D printing technology was employed to prepare cookies. The texture, color, deformation, moisture content, and temperature of the cookie as evaluation indicators, the influences of baking process parameters, such as baking time, surface heating temperature and bottom heating temperature, on the quality of the cookie were studied to optimize the baking process parameters. The results showed that the baking process parameters had obvious effects on the texture, color, deformation, moisture content, and temperature of the cookie. All of the roasting surface heating temperature, bottom heating temperature and baking time had positive influences on the hardness, crunchiness, crispiness, and the total color difference(ΔE) of the cookie. When the heating temperatures of the surfac and bottom increased, the diameter and thickness deformation rate of the cookie increased. However,with the extension of baking time, the diameter and thickness deformation rate of the cookie first increased and then decreased. With the surface heating temperature of 180 ℃, the bottom heating temperature of 150 ℃, and baking time of 15 min, the cookie was crisp and moderate with moderate deformation and uniform color. There was no burnt phenomenon with the desired quality. Research results provided a theoretical basis for cookie manufactory based on food 3D printing technology.
文摘The traditional printing checking method always uses printing control strips,but the results are not very well in repeatability and stability. In this paper,the checking methods for printing quality basing on image are taken as research objects. On the base of the traditional checking methods of printing quality,combining the method and theory of digital image processing with printing theory in the new domain of image quality checking,it constitute the checking system of printing quality by image processing,and expound the theory design and the model of this system. This is an application of machine vision. It uses the high resolution industrial CCD(Charge Coupled Device) colorful camera. It can display the real-time photographs on the monitor,and input the video signal to the image gathering card,and then the image data transmits through the computer PCI bus to the memory. At the same time,the system carries on processing and data analysis. This method is proved by experiments. The experiments are mainly about the data conversion of image and ink limit show of printing.
基金financially supported by National Natural Science Foundation of China(Grant No.51772335)Guangdong Youth Top-notch Talent Support Program(No.2015TQ01C201)the Fundamental Research Funds for the Central Universities.
文摘Flexible and wearable sensing devices have broad application prospects in bio-monitoring such as pulse measurement,motion detection and voice recognition.In recent years,many significant improvements had been made to enhance the sensor’s performance including sensitivity,flexibility and repeatability.However,it is still extremely complicated and difficult to prepare a patterned sensor directly on a flexible substrate.Herein,inspired by typography,a lowcost,environmentally friendly stamping method for the mass production of transparent conductive carbon nanotube(CNT)film is proposed.In this dry transfer strategy,a porous CNT block was used as both the seal and the ink;and Ecoflex film was served as an object substrate.Welldesigned CNT patterns can be easily fabricated on the polymer substrate by engraving the target pattern on the CNT seal before the stamping process.Moreover,the CNT film can be directly used to fabricate ultrathin(300μm)strain sensor.This strain sensor possesses high sensitivity with a gauge factor(GF)up to 9960 at 85%strain,high stretchability(>200%)and repeatability(>5000 cycles).It has been used to measure pulse signals and detect joint motion,suggesting promising application prospects in flexible and wearable electronic devices.
基金financially supported by the National Excellent Young Scientists Fund(NO.51525503)
文摘Sand mold 3 D printing technology is an advanced manufacturing technology which has great flexible manufacturing ability. A multi-material composite sand mold can control the temperature field of metallic parts during the pouring process, while the current sand mold 3 D printing technology can only fabricate a single material sand mold. The casting temperature field can not be adjusted by using single sand mold material with isotropous heat exchange ability during the pouring process. In this work, a kind of novel coating device was designed. Multi-material composite sand molds could be manufactured using the coating device according to the casting process demands of the final parts. The influences of curing agent content, coating velocity and scraper shape on compactness and surface roughness of the sand layer(silica sand and zircon sand) were studied. The shapes and sizes of transition intervals of two kinds of sand granules were also tested. The results show that, with the increase of the added volume of curing agent, the compactness of sand layer reduces and the surface roughness value rises. With the increase of the velocity of the coating device, the compactness of sand layer reduces and the surface roughness value rises similarly. In addition, the scraper with a dip angle of 72 degrees could increase the compactness value of the sand layer. The criteria of quality parmeters of the coating procedure are obtained. That is, the surface roughness(δ) of sand layer should be equal to or lesser than half of main size of the sand particles(Dm). The parameter H of the coating device which is the distance between the base of hopper and the surface of sand layer impacts the size of transition zone. The width of the transition zone is in direct proportion to the parameter H, qualitatively. Through the optimization of the coating device, high quality of multi-material sand layers can be obtained. This will provide a solution in manufacturing the multi-material composite sand mold.
文摘A comprehensive assessment index system was established. The mechanical recycling process of printed circuit board was evaluated according to the comprehensive evaluation index system using the fuzzy analytic hierarchy process. A process assessment software system of mechanical recycling was established to evaluate different recycling technologies. And the software system was developed in the environment of VB6.0 and Access2000.
文摘This paper describes the preparation and properties of TiN_x-SiO_2 double-layered antireflective(AR) coatings that were applied with print process. The coating material was analyzed and TiN_x was used instead of TiO_2 as high refractive material. The influence of solution concentration on AR property was studied. The testing result shows that the coatings using print process are featured with excellent mechanical property and the AR property is comparable to American Southwall AR product. It is expected that the study would promote the industrialization progress in AR coatings.
文摘Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones of InGa electrodes . After observing the Al paste physical and chemical behaviors during rising temperature by thermal analysis (DTA), the firing operation of Al electrodes could be divided into three main subsections: the temperature rising time (t-r), the peak firing temperature (T-p) and the hold time at peak firing temperature (t-h). The effects of these three parameters on final component properties were discussed in detail.
基金The work is financially supported by the National Natural Science Foundation of China(51805475,51675148)。
文摘Ink-jet printing is a non-impact printing technology in which drops jetted from an orifice onto a designated position.This technology can digitally transport fluids containing cells precisely onto desired substrates to construct three-dimensional organs.In order to obtain the stable uniform droplets,a stream is the key point of this technology.However,there are so many factors that affect the uniform droplet stream construction process:print parameters,material parameters,control method,etc.A good understanding of the various coupled transport processes that occur during bio-ink impact and spreading on bio-structure can improve the success of print-ability.This paper aims to obtain a good linear bio-structure with ink-jet printing technology.First,a typical droplet deposition process model is constructed;including droplet dynamics impact models and droplet diffusion cap models.Second,a model of successive droplet overlap,to form linear bio-structures,is constructed.Third,the finite element method is used to simulate the droplet impact,collision,and fusion process.Finally,the main influencing factors of the continuous injection printing process,namely the time interval between consecutive droplets and the droplet contact angles,are discussed.Sodium alginate is selected as bio-ink to verify the theory,and it is found that a good linear bio-structure could be obtained if the printing parameters are controlled optimally,i.e.,if the initial contact angle is set as 60 degrees and the trigger frequency is set as 150 kHz.With a proper printing speed and gel coating,a good survival rate of printed cells could be obtained.
文摘Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport industries.However,their widespread application is hindered by their low formability at room temperature due to limited slip systems.Cast Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high scrap.While casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain applications.Although metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast counterparts.Thus,MAM is a promising technique to produce Mg alloy parts.Directed energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive processes.However,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this technology.This review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and prospects.Furthermore,the predominant imperfections,notably inhomogeneous microstructure evolution and porosity,observed in Mg-alloy components manufactured through DED are discussed.Additionally,the preventive measures implemented to counteract the formation of these defects are explored.
文摘In this study, indoor air quality (IAQ) assessments were carried out in a screen printing facility. The air sampling was conducted in press department, including two different types of screen printing machines: semi-automatic and automatic. Air samples were collected and analyzed in situ for 4 times, once per 2 hours, during working time of 8 hours. Analysis of the experimental data showed that ambient ozone concentrations slowly increases with the increasing of TVOCs concentration and intensive use of UV lamps during automatic screen printing process. Therefore, the detected concentration levels of ozone and VOCs were compared with the Occupational Safety and Health Administration (OSHA) and Serbian Regulation. Comparison of the two mentioned standard regulations, the ozone concentrations in indoor printing air were from 0.83 to 8.1 and 2.4 to 16.2 times higher in the relation to the prescribed PEL and maximum allowed concentration (MAC) values, respectively, while the concentrations of particular VOCs were much below the PEL prescribed by the OSHA.
文摘The main characteristics, applications, the emphases of manufacturing process are introduced, and the research of new product of rigid-flex Printed Circuit Board (PCB) is also described. In particular, the plasma desmear process, which is the crucial problems of manufacturing process, is discussed in detail. Samsung 4-layer rigid-flex PCB has been developed successfully, and the qualification rate reaches to 89.4%.
基金supported by the National Natural Science Foundation of China(Grant no.42207232)the Sichuan Science and Technology Plan Project(2023YFS0444)+1 种基金the Transportation Technology Project of Sichuan Province(2021-A-04)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(SKLGP2021Z001,SKLGP2022Z023)。
文摘This study investigated the resilience of traditional concrete dams compared to 3D printed concrete dams(3DPC)when subjected to debris flow.Three types of dams,namely check dams,arch dams,and curve dams,were numerically analyzed using a three-dimensional Coupled Eulerian-Lagrangian(CEL)methodology.The research focused on critical factors such as impact force and viscous energy dissipation to compare dam performance.Additionally,the study examined the printing and service phases of 3DPC models,determining potential failure modes and analyzing printing parameters.The results demonstrated that 3DPC dams outperformed traditional concrete dams,with filament deposition orientation,perpendicular to the debris flow direction,identified as a pivotal factor.Infill percentage and pattern were also found to influence the behavior of 3DPC models.Notably,curved dams exhibited superior performance based on dam geometry.These findings have significant potential for advancing the development of resilient dam structures capable of withstanding debris flow impacts.
基金supported by National Natural Science Foundation of China(Nos.52188102,U2013213,51820105008)the Technology Innovation Project of Hubei Province of China under Grant No.2019AEA171+1 种基金The project of introducing innovative leading talents in Songshan Lake High-tech Zone,Dongguan City,Guangdong Province(No.2019342101RSFJ-G)the support from Flexible Electronics Research Center of HUST for providing experiment facility。
文摘Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although it is well known that ink rheology and processing parameters have a direct impact on the resolution and shape of the printed objects,the underlying mechanisms of these key factors on the printability and quality of DIW technique remain poorly understood.To tackle this issue,we systematically analyzed the printability and quality through extrusion mechanism modeling and experimental validating.Hybrid non-Newtonian fluid inks were first prepared,and their rheological properties were measured.Then,finite element analysis of the whole DIW process was conducted to reveal the flow dynamics of these inks.The obtained optimal process parameters(ink rheology,applied pressure,printing speed,etc)were also validated by experiments where high-resolution(<100μm)patterns were fabricated rapidly(>70 mm s^(-1)).Finally,as a process research demonstration,we printed a series of microstructures and circuit systems with hybrid inks and silver inks,showing the suitability of the printable process parameters.This study provides a strong quantitative illustration of the use of DIW for the high-speed preparation of high-resolution,high-precision samples.
基金supported by Seed Funding of the Beijing University of Chinese Medicine(90011451310034).
文摘Objective:To use three-dimensional(3D)printing technology to prepare Dashanzha Wan.Methods:The standard formula proportion of Dashanzha Wan was used to prepare printable materials(normally called the ink)for 3D printing,and different doses and shapes of Dashanzha Wan were prepared.Then,the rheological properties,texture characteristics,scanning electron microscopy,and content of ursolic acid were evaluated.Results:Dashanzha Wan ink showed good shear thinning properties,which is very suitable for 3D printing.The printed sample had a beautiful and regular shape with high resolution.Meanwhile,ursolic acid content in 3D-printed Dashanzha Wan aligned with the ursolic acid content shown in the Pharmacopoeia of the People's Republic of China 2020.Conclusion:The 3D-printed Dashanzha Wan has a better texture,and can be shaped into various shapes according to individual needs,which would increase patients’interest when taking medicine.Moreover,3D printing of Dashanzha Wan could be easily integrated into the digital life system,enabling online customization or use at home.This study reveals that 3D printing technology is a promising method for the production of traditional Chinese medicine with personalized appearance,dosage,and texture,which is suitable for a broader population.
基金the National Natural Science Foundation of China(Nos.11572002 and 12002032)the China Postdoctoral Science Foundation(Nos.BX20200056 and 2020M670149)。
文摘The soft robotics display huge advantages over their rigid counterparts when interacting with living organisms and fragile objects.As one of the most efficient actuators toward soft robotics,the soft pneumatic actuator(SPA)can produce large,complex responses with utilizing pressure as the only input source.In this work,a new approach that combines digital light processing(DLP)and injection-assisted post-curing is proposed to create SPAs that can realize different functionalities.To enable this,we develop a new class of photo-cross linked elastomers with tunable mechanical properties,good stretchability,and rapid curing speed.By carefully designing the geometry of the cavities embedded in the actuators,the resulting actuators can realize contracting,expanding,flapping,and twisting motions.In addition,we successfully fabricate a soft self-sensing bending actuator by injecting conductive liquids into the three-dimensional(3D)printed actuator,demonstrating that the present method has the potential to be used to manufacture intelligent soft robotic systems.
基金the ministry of economic affairs in Taiwan under the contract number:J353J11100,is gratefully acknowledged.
文摘To response the demand for fine line in electronic products,additive manufacturing process integrated printing techniques and deposited methods to reach fine line circuit,with the merits of reduced material wastage,low fabrication costs,and mass production advantage capability.Recently,we have developed additive process in fabricating circuit on flexible substrate through catalyst induced copper electroless deposition(ELD)method.The additive processes that integrated printing,activation,and metallization were applied to produce fine-line circuit with 5μm line width.The sample with ultraviolet(UV)activation shows better conductive property in comparison with the sample without activation after electroless deposited process.Accordingly,the results indicated that the reaction of catalyst induced electroless copper plating strongly depends on UV activation.The fine-line circuit exhibits a narrow line width circuit(around 5μm),lower resistance(6.2μΩ·cm),and mass production with low pollution in comparison with lithographic processes(with photoresist and acid pollution)with a high throughput system(R2R system)for the applications of double side flexible printed circuit board(FPCB).