In recent few years, significant improvement has been made in developing largescale 3 D printer to accommodate the need of industrial-scale 3 D printing. Cementitious materials that are compatible with 3 D printing pr...In recent few years, significant improvement has been made in developing largescale 3 D printer to accommodate the need of industrial-scale 3 D printing. Cementitious materials that are compatible with 3 D printing promote rapid application of this innovative technique in the construction field with advantages of cost effective, high efficiency, design flexibility and environmental friendly. This paper firstly reviews existing 3 D printing techniques that are currently being used in commercial3 D printers. It then summarizes three latest development of largescale 3 D printing systems and identifies their relationships and limiting factors. Thereafter, critical factors that are used to evaluate the workability and printable performance of cementitious materials are specified. Easy-extrusive, easy-flowing, well-buildable, and proper setting time are significant for cementitious material to meet the critical requirements of a freeform construction process. Finally, main advantages, potential applications and the prospects of future research of 3 D printing in construction technology are suggested. The objective of this work is to review current design methodologies and operational constraints of largescale 3 D printing system and provide references for optimizing the performance of cementitious material and promote its responsible use with largescale 3 D printing technology.展开更多
Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the world.America Makes,as th...Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the world.America Makes,as the National Additive Manufacturing Innovation Institute,is the nation’s leading and collaborative partner in AM/3DP technology research,discovery,creation,and innovation,working efficiently to innovate and accelerate AM/3DP to increase America’s global manufacturing competitiveness(https://americamakes.us).German展开更多
This study aims to understand the distribution of reinforcement material in the matrix,evaluate the adherence between layers,and determine the air gap between printing roads.We printed the specimen with two different ...This study aims to understand the distribution of reinforcement material in the matrix,evaluate the adherence between layers,and determine the air gap between printing roads.We printed the specimen with two different composite materials,Polylactic Acid(PLA)reinforced with acrylic particles,and another filament reinforced with short carbon fibers.For the observations of the samples,we used a Confocal Microscope.We estimated the porosity of the material by comparing the expected mass with that achieved after manufacture.By pixel count,after binarization,we found the average percentage of acrylate particulate.They showed fair distribution through the PLA matrix even after the manufacturing process.The determination of fibers alignment was made by binarization of image,together with k-means and edge detection.This combination of methods allows estimating the fiber alignment by orientation straight lines.The manufacturing process did not offer good alignment of the fibers,even with the filament initially well aligned.展开更多
The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to this.Against this background,...The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to this.Against this background,based on the classical Park cement exothermic model of hydration,we propose and construct a numerical model of the first exothermic peak,taking into account the proportions of C_(3)S,C_(3)A and quicklime in particular.The calculated parameters are calibrated by means of relevant published exothermic test data.It is found that this developed model offers a good simulation of the first exothermic peak of hydration for C_(3)S and C_(3)A proportions from 0 to 100% of cement clinker and reflects the effect of quicklime content at 8%-10%.The unique value of this research is provision of an important computational tool for applications that are sensitive to the first exothermic peak of hydration,such as 3D printing.展开更多
3D printing technology is an emerging technology.It constructs solid bodies by stacking materials layer by layer,and can quickly and accurately prepare bone tissue engineering scaffolds with specific shapes and struct...3D printing technology is an emerging technology.It constructs solid bodies by stacking materials layer by layer,and can quickly and accurately prepare bone tissue engineering scaffolds with specific shapes and structures to meet the needs of different patients.The field of life sciences has received a great deal of attention.However,different 3D printing technologies and materials have their advantages and disadvantages,and there are limitations in clinical application.In this paper,the technology,materials and clinical applications of 3D printed bone tissue engineering scaffolds are reviewed,and the future development trends and challenges in this field are prospected.展开更多
As a physical interface,a prosthetic liner is commonly used as a transition material between the residual limb and the stiff socket.Typically made from a compliant material such as silicone,the main function of a pros...As a physical interface,a prosthetic liner is commonly used as a transition material between the residual limb and the stiff socket.Typically made from a compliant material such as silicone,the main function of a prosthetic liner is to protect the residual limb from injuries induced by load-bearing normal and shear stresses.Compared to conventional liners,custom prosthetic lower-extremity(LE)liners have been shown to better relieve stress concentrations in painful and sensitive regions of the residual limb.Although custom LE liners have been shown to offer clinical benefits,no review article on their design and efficacy has yet been written.To address this shortcoming in the literature,this paper provides a comprehensive survey of custom LE liner materials,design,and fabrication methods.First,custom LE liner materials and components are summarized,including a description of commercial liners and their efficacy.Subsequently,digital methods used to design and fabricate custom LE liners are addressed,including residual limb biomechanical modeling,finite element-based design methods,and 3-D printing techniques.Finally,current evaluation methods of custom/commercial LE liners are presented and discussed.We hope that this review article will inspire further research and development into the design and manufacture of custom LE liners.展开更多
基金supported by the National Major Research Instrument Development Project of the National Natural Science Foundation of China(51627812)the opening project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology,KFJJ13-11M)
文摘In recent few years, significant improvement has been made in developing largescale 3 D printer to accommodate the need of industrial-scale 3 D printing. Cementitious materials that are compatible with 3 D printing promote rapid application of this innovative technique in the construction field with advantages of cost effective, high efficiency, design flexibility and environmental friendly. This paper firstly reviews existing 3 D printing techniques that are currently being used in commercial3 D printers. It then summarizes three latest development of largescale 3 D printing systems and identifies their relationships and limiting factors. Thereafter, critical factors that are used to evaluate the workability and printable performance of cementitious materials are specified. Easy-extrusive, easy-flowing, well-buildable, and proper setting time are significant for cementitious material to meet the critical requirements of a freeform construction process. Finally, main advantages, potential applications and the prospects of future research of 3 D printing in construction technology are suggested. The objective of this work is to review current design methodologies and operational constraints of largescale 3 D printing system and provide references for optimizing the performance of cementitious material and promote its responsible use with largescale 3 D printing technology.
基金supported by the National Natural Science Foundation of China (51575267 and 51322509)the National Key Research and Development Program ‘‘Additive Manufacturing and Laser Manufacturing’’ (2016YFB1100101)+5 种基金the Top-Notch Young Talents Program of China, the NSFC-DFG Sino-German Research Project (GZ 1217)the Key Research and Development Program of Jiangsu Provincial Department of Science and Technology of China (BE2016181)the 333 High-level Talents Training Project (BRA2015368), the Aeronautical Science Foundation of China (2015ZE52051)the Outstanding Youth Foundation of Jiangsu Province of China (BK20130035)the Program for New Century Excellent Talents in University (NCET-13-0854)the Fundamental Research Funds for the Central Universities (NE2013103, NP2015206 and NZ2016108)
文摘Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the world.America Makes,as the National Additive Manufacturing Innovation Institute,is the nation’s leading and collaborative partner in AM/3DP technology research,discovery,creation,and innovation,working efficiently to innovate and accelerate AM/3DP to increase America’s global manufacturing competitiveness(https://americamakes.us).German
文摘This study aims to understand the distribution of reinforcement material in the matrix,evaluate the adherence between layers,and determine the air gap between printing roads.We printed the specimen with two different composite materials,Polylactic Acid(PLA)reinforced with acrylic particles,and another filament reinforced with short carbon fibers.For the observations of the samples,we used a Confocal Microscope.We estimated the porosity of the material by comparing the expected mass with that achieved after manufacture.By pixel count,after binarization,we found the average percentage of acrylate particulate.They showed fair distribution through the PLA matrix even after the manufacturing process.The determination of fibers alignment was made by binarization of image,together with k-means and edge detection.This combination of methods allows estimating the fiber alignment by orientation straight lines.The manufacturing process did not offer good alignment of the fibers,even with the filament initially well aligned.
基金financially supported by the National Natural Science Foundation of China(Grant No.52178240)the Shanghai Scientific Research Program(No.21DZ1200401).
文摘The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to this.Against this background,based on the classical Park cement exothermic model of hydration,we propose and construct a numerical model of the first exothermic peak,taking into account the proportions of C_(3)S,C_(3)A and quicklime in particular.The calculated parameters are calibrated by means of relevant published exothermic test data.It is found that this developed model offers a good simulation of the first exothermic peak of hydration for C_(3)S and C_(3)A proportions from 0 to 100% of cement clinker and reflects the effect of quicklime content at 8%-10%.The unique value of this research is provision of an important computational tool for applications that are sensitive to the first exothermic peak of hydration,such as 3D printing.
基金funded by Versus Arthritis UK(Grant No.21977)European Commission via a H2020-MSCA-RISE programme(BAMOS,Grant No.734156)+1 种基金Innovative UK via Newton Fund(Grant No.102872)Engineering and Physical Science Research Council(EPSRC)via DTP CASE programme(Grant No.EP/T517793/1).
文摘3D printing technology is an emerging technology.It constructs solid bodies by stacking materials layer by layer,and can quickly and accurately prepare bone tissue engineering scaffolds with specific shapes and structures to meet the needs of different patients.The field of life sciences has received a great deal of attention.However,different 3D printing technologies and materials have their advantages and disadvantages,and there are limitations in clinical application.In this paper,the technology,materials and clinical applications of 3D printed bone tissue engineering scaffolds are reviewed,and the future development trends and challenges in this field are prospected.
基金supported by the Fundamental Research Funds for the Central Universities(Grant number JKF-YG-22-B010)the National Institutes of Health(Grant number 5R01EB024531-03).
文摘As a physical interface,a prosthetic liner is commonly used as a transition material between the residual limb and the stiff socket.Typically made from a compliant material such as silicone,the main function of a prosthetic liner is to protect the residual limb from injuries induced by load-bearing normal and shear stresses.Compared to conventional liners,custom prosthetic lower-extremity(LE)liners have been shown to better relieve stress concentrations in painful and sensitive regions of the residual limb.Although custom LE liners have been shown to offer clinical benefits,no review article on their design and efficacy has yet been written.To address this shortcoming in the literature,this paper provides a comprehensive survey of custom LE liner materials,design,and fabrication methods.First,custom LE liner materials and components are summarized,including a description of commercial liners and their efficacy.Subsequently,digital methods used to design and fabricate custom LE liners are addressed,including residual limb biomechanical modeling,finite element-based design methods,and 3-D printing techniques.Finally,current evaluation methods of custom/commercial LE liners are presented and discussed.We hope that this review article will inspire further research and development into the design and manufacture of custom LE liners.