Material extrusion additive manufacturing has rapidly grown in use for tissue engineering research since its adoption in the year 2000. It has enabled researchers to produce scaffolds with intricate porous geometries ...Material extrusion additive manufacturing has rapidly grown in use for tissue engineering research since its adoption in the year 2000. It has enabled researchers to produce scaffolds with intricate porous geometries that were not feasible with traditional manufacturing processes. Researchers can control the structural geometry through a wide range of customisable printing parameters and design choices including material, print path, temperature, and many other process parameters. Currently, the impact of these choices is not fully understood. This review focuses on how the position and orientation of extruded filaments, which sometimes referred to as the print path, lay-down pattern, or simply'scaffold design', affect scaffold properties and biological performance. By analysing trends across multiple studies, new understanding was developed on how filament position affects mechanical properties. Biological performance was also found to be affected by filament position, but a lack of consensus between studies indicates a need for further research and understanding. In most research studies, scaffold design was dictated by capabilities of additive manufacturing software rather than free-form design of structural geometry optimised for biological requirements. There is scope for much greater application of engineering innovation to additive manufacture novel geometries. To achieve this, better understanding of biological requirements is needed to enable the effective specification of ideal scaffold geometries.展开更多
Natural mechanical materials,such as bamboo and bone,often exhibit superior specific mechanical properties due to their hierarchical porous architectures.Using the principle of hierarchy as inspiration can facilitate ...Natural mechanical materials,such as bamboo and bone,often exhibit superior specific mechanical properties due to their hierarchical porous architectures.Using the principle of hierarchy as inspiration can facilitate the development of hierarchical mechanical metamaterials(HMMs)across multiple length scales via 3D printing.In this work,we propose self-similar HMMs that combine octet-truss(OCT)architecture as the first and second orders,with cubic architecture as the third or more orders.These HMMs were fabricated using stereolithography 3D printing,with the length sizes ranging from approximately 200µm to the centimeter scale.The compressive stress–strain behaviors of HMMs exhibit a zigzag characteristic,and the toughness and energy absorption can be significantly enhanced by the hierarchical architecture.The compressive moduli are comparable to that of natural materials,and the strengths are superior to that of most polymer/metal foams,alumina hollow/carbon lattices,and other natural materials.Furthermore,the flexural stress–strain curves exhibit a nonlinear behavior,which can be attributed to the hierarchical architecture and local damage propagation.The relatively high mechanical properties can be attributed to the synergistic effect of the stretch-dominated OCT architecture and the bending-dominated cube architecture.Lastly,an ultralight HMM-integrated unmanned aerial vehicle(HMM-UAV)was successfully designed and printed.The HMM-UAV is~85%lighter than its bulk counterpart,remarkably extending the flight duration time(~53%).This work not only provides an effective design strategy for HMMs but also further expands the application benchmark of HMMs.展开更多
Recent years are showing a rapid adoption of digital manufacturing techniques to the construction industry,with a focus on additive manufacturing.Although 3D printing for construction(3DPC)has notably advanced in rece...Recent years are showing a rapid adoption of digital manufacturing techniques to the construction industry,with a focus on additive manufacturing.Although 3D printing for construction(3DPC)has notably advanced in recent years,publications on the subject are recent and date a growth in 2019,indicating that it is a promising technology as it enables greater efficiency with fair consumption of material,minimization of waste generation,encouraging the construction industrialization and enhancing and accelerating the constructive process.This new building system not only gives an optimization of the building process but provides a new approach to the building design materiality.The direct connection between design and manufacturing allows the reduction in the number of the various construction phases needed.It is opening a new and wide range of options both formal and chromatic in customization,avoiding complex formworks,reducing costs and manufacturing time.The creative process has a strict and direct link with the constructive process,straightening design with its materiality.Cement-based materials lead the way,but new alternatives are being explored to further reduce its carbon footprint.In order to leverage its sustainability and enhance the system capacity,initiatives are being pursued to allow the reduction of the use of PC.Geopolimers are taking the first steps in 3DPC.Construction and Demolition Waste(CDW)materials are used to substitute natural aggregates.Even soil is being explored has a structural and aesthetic material.These research trends are opening a wider range of possibilities for architecture and design,broadening the spectrum of color,texture,and formal variations.The concern about textures and colours is not yet evident in many the structures already printed,opening the opportunity for future research.More can be done in the mixture and formal design of this building system,“discovering”other raw materials in others waste.This article aims to make a critical review of technologies,materials an展开更多
Three-dimensional(3D)functional graphenebased architecture with superior electrical conductivity and good mechanical strength has promising applications in energy storage and electrics.Viscoelasticity-adjustable inks ...Three-dimensional(3D)functional graphenebased architecture with superior electrical conductivity and good mechanical strength has promising applications in energy storage and electrics.Viscoelasticity-adjustable inks make it possible to achieve desired 3D architectures with interconnected and continuous interior networks by microextrusion printing.In this work,ultra-low-concentration graphene oxide(GO)inks of~15 mg·ml-1 have been obtained and demonstrated in direct 3D printing with a facile cross-linking(direct ink writing).The rheological behavior of the GO strategy by cations,which is the lowest concentration to achieve direct ink writing inks,could be adjusted from 1×10^(4) to 1×10^(5) Pa·s^(-1) with different concentrations of cations due to strong cross-linking networks between GO sheets and cations.Meanwhile,the specific strength and electrical conductivity of 3D-printed graphene architecture are notably enhanced,reaching up to 51.7×10^(3) N·m·kg^(-1)and 119 S·m^(-1),which are superior to conventional graphene aerogels.Furthermore,3D printing graphene-based architecture assembled in micro-superc apacitor exhibits excellent electrochemical performance,which can be ascribed to the effective ion transportation through the interconnected networks.The strategy demonstrated is useful in the design of complex-shaped,graphene-based architectures for scalable manufacturing of practical energy storage applications.展开更多
文摘Material extrusion additive manufacturing has rapidly grown in use for tissue engineering research since its adoption in the year 2000. It has enabled researchers to produce scaffolds with intricate porous geometries that were not feasible with traditional manufacturing processes. Researchers can control the structural geometry through a wide range of customisable printing parameters and design choices including material, print path, temperature, and many other process parameters. Currently, the impact of these choices is not fully understood. This review focuses on how the position and orientation of extruded filaments, which sometimes referred to as the print path, lay-down pattern, or simply'scaffold design', affect scaffold properties and biological performance. By analysing trends across multiple studies, new understanding was developed on how filament position affects mechanical properties. Biological performance was also found to be affected by filament position, but a lack of consensus between studies indicates a need for further research and understanding. In most research studies, scaffold design was dictated by capabilities of additive manufacturing software rather than free-form design of structural geometry optimised for biological requirements. There is scope for much greater application of engineering innovation to additive manufacture novel geometries. To achieve this, better understanding of biological requirements is needed to enable the effective specification of ideal scaffold geometries.
基金financial support of the National Natural Science Foundation of China(Grant No.51905350).
文摘Natural mechanical materials,such as bamboo and bone,often exhibit superior specific mechanical properties due to their hierarchical porous architectures.Using the principle of hierarchy as inspiration can facilitate the development of hierarchical mechanical metamaterials(HMMs)across multiple length scales via 3D printing.In this work,we propose self-similar HMMs that combine octet-truss(OCT)architecture as the first and second orders,with cubic architecture as the third or more orders.These HMMs were fabricated using stereolithography 3D printing,with the length sizes ranging from approximately 200µm to the centimeter scale.The compressive stress–strain behaviors of HMMs exhibit a zigzag characteristic,and the toughness and energy absorption can be significantly enhanced by the hierarchical architecture.The compressive moduli are comparable to that of natural materials,and the strengths are superior to that of most polymer/metal foams,alumina hollow/carbon lattices,and other natural materials.Furthermore,the flexural stress–strain curves exhibit a nonlinear behavior,which can be attributed to the hierarchical architecture and local damage propagation.The relatively high mechanical properties can be attributed to the synergistic effect of the stretch-dominated OCT architecture and the bending-dominated cube architecture.Lastly,an ultralight HMM-integrated unmanned aerial vehicle(HMM-UAV)was successfully designed and printed.The HMM-UAV is~85%lighter than its bulk counterpart,remarkably extending the flight duration time(~53%).This work not only provides an effective design strategy for HMMs but also further expands the application benchmark of HMMs.
基金supported by:Base Funding-UIDB/04708/2020 of the CONSTRUCT-Instituto de I&D em Estruturas e Construc¸o˜es-funded by national funds through the FCT/MCTES(PIDDAC)national funds through FCT e Fundac¸a˜o para a Cieˆncia e a Tecnologia,I.P.,under the Scientific Employment Stimulus-Institutional Call e CEECINST/00049/2018.
文摘Recent years are showing a rapid adoption of digital manufacturing techniques to the construction industry,with a focus on additive manufacturing.Although 3D printing for construction(3DPC)has notably advanced in recent years,publications on the subject are recent and date a growth in 2019,indicating that it is a promising technology as it enables greater efficiency with fair consumption of material,minimization of waste generation,encouraging the construction industrialization and enhancing and accelerating the constructive process.This new building system not only gives an optimization of the building process but provides a new approach to the building design materiality.The direct connection between design and manufacturing allows the reduction in the number of the various construction phases needed.It is opening a new and wide range of options both formal and chromatic in customization,avoiding complex formworks,reducing costs and manufacturing time.The creative process has a strict and direct link with the constructive process,straightening design with its materiality.Cement-based materials lead the way,but new alternatives are being explored to further reduce its carbon footprint.In order to leverage its sustainability and enhance the system capacity,initiatives are being pursued to allow the reduction of the use of PC.Geopolimers are taking the first steps in 3DPC.Construction and Demolition Waste(CDW)materials are used to substitute natural aggregates.Even soil is being explored has a structural and aesthetic material.These research trends are opening a wider range of possibilities for architecture and design,broadening the spectrum of color,texture,and formal variations.The concern about textures and colours is not yet evident in many the structures already printed,opening the opportunity for future research.More can be done in the mixture and formal design of this building system,“discovering”other raw materials in others waste.This article aims to make a critical review of technologies,materials an
基金financially supported by the National Natural Science Foundation of China(No.51802195)Chen Guang Scholar Project of Shanghai Education Commission(No.19CG53)。
文摘Three-dimensional(3D)functional graphenebased architecture with superior electrical conductivity and good mechanical strength has promising applications in energy storage and electrics.Viscoelasticity-adjustable inks make it possible to achieve desired 3D architectures with interconnected and continuous interior networks by microextrusion printing.In this work,ultra-low-concentration graphene oxide(GO)inks of~15 mg·ml-1 have been obtained and demonstrated in direct 3D printing with a facile cross-linking(direct ink writing).The rheological behavior of the GO strategy by cations,which is the lowest concentration to achieve direct ink writing inks,could be adjusted from 1×10^(4) to 1×10^(5) Pa·s^(-1) with different concentrations of cations due to strong cross-linking networks between GO sheets and cations.Meanwhile,the specific strength and electrical conductivity of 3D-printed graphene architecture are notably enhanced,reaching up to 51.7×10^(3) N·m·kg^(-1)and 119 S·m^(-1),which are superior to conventional graphene aerogels.Furthermore,3D printing graphene-based architecture assembled in micro-superc apacitor exhibits excellent electrochemical performance,which can be ascribed to the effective ion transportation through the interconnected networks.The strategy demonstrated is useful in the design of complex-shaped,graphene-based architectures for scalable manufacturing of practical energy storage applications.
