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2017 World Conference on Materials Research and Application

作者： Yaling Zhao Ting Zhang Department of Mechanical Engineering Biomanufacturing CenterTsinghua University Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Key Laboratory for Advanced Materials Processing Technology Ministry of Education

As an emerging field,biomanufacturing has been widely integrated with life science,biomaterials science,information technology and manufacturing science to fabricate artificial tissue in vitro or in *** native tissue usually contains rich vascular networks,which can provide efficient oxygen and nutrition for the *** to realize vascularization of the artificial tissues is an important challenge for tissue engineering and regenerative *** we designed a double-layer hollow hydrogel microfibers fabrication platform which can encapsulate different cells in the outside shell layer and the inside layer based on the microfluidic *** a polydimethylsiloxane(PDMS) microfluidic spinning device,a double-layer hollow microfiber was *** changing the flow rates of the fluids,both the diameter of the hollow microfibers and the thickness of the microfiber shell were easily *** this process,different cells in different shell layer were successfully *** C2C12 cells were encapsulated in the outside shell layer with endothelial cells in the inside shell *** hollow structure provided a channel for further vascularization and perfusion of the tissue *** study may provide an approach to understand the mechanisms of angiogenesis and vasculogegesis in engineering artificial tissue.

关键词： biomanufacturing cardiac tissue engineering vascularization hollow microfibers microfluidic

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用于介观模拟电子束选区熔化的数据挖掘技术

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Engineering 2019年第4期 327-345页

作者：钱亚闫文韬林峰 Department of Mechanical Engineering Tsinghua University Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Tsinghua University Department of Mechanical Engineering National University of Singapore

在电子束选区熔化技术(EBSM)工艺中,制造部件的性质受到每一道熔道沉积质量的影响。然而,熔道的形成受到各种物理现象和工艺参数的支配,这些参数之间的相关性十分复杂,难以通过实验得出。近来,介观建模技术已成为模拟电子束(EB)熔化过... 详细信息

在电子束选区熔化技术(EBSM)工艺中,制造部件的性质受到每一道熔道沉积质量的影响。然而,熔道的形成受到各种物理现象和工艺参数的支配,这些参数之间的相关性十分复杂,难以通过实验得出。近来,介观建模技术已成为模拟电子束(EB)熔化过程以及揭示特定熔道形貌的形成机制的手段。尽管如此,人们对工艺参数与熔道特征之间的相关性尚未有定量的理解。本文从介观模拟的结果出发,研究了熔道的形态特征,同时引入了熔道宽度和高度等关键性描述指标,以便从数值上评估沉积质量。本文还定量研究了各种工艺参数的影响,从而导出了工艺条件和熔道特征之间的相关性。最后,本文提出了一种由介观建模和数据挖掘技术组成的仿真驱动优化框架,并讨论了框架的潜力和局限性。

关键词：电子束选区熔化介观模拟数据挖掘

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Microstructure and mechanical properties of Ti-6Al-4V components fabricated by laser micro cladding deposition

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Rare Metals 2015年第7期34卷 445-451页

作者： Bo Yao Xu-Long Ma Feng Lin Wen-Jun Ge Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Key Laboratory for Biomanufacturing and Rapid Forming Technology Department of Mechanical Engineering Tsinghua University Department of Mechanical Engineering Army Aviation Institute of Chinese People’s Liberation Army

Laser micro cladding deposition manufacturing(Ll CDM) is a newly developed rapid manufacturing method for *** Ll CDM technology adopts a novel powder feeding method based on alternating friction and inertia force, and this powder feeding method can effectively improve the accuracy and orientation of the powder injection, resulting in a smaller molten pool size and a higher cooling rate of liquid ***, the components fabricated by Ll CDM could obtain the finer microstructures and the improved mechanical *** is found that the components fabricated by Ll CDM are fully dense free of cracks or pores and exhibit columnar prior b grains with a finer acicular a0 phase *** microhardness(HV0.2) of the thin-wall component is HV 400–HV 500 in the majority part of the cross section and can reach about HV 850 in the top *** ultimate tensile strength(UTS) and elongation show insignificant dependence on the testing directions of the *** UTS is between 1,002 and 1,100 MPa, and the elongation is between 10.0 % and 14.7 %.

关键词： Laser micro cladding deposition Ti-6Al-4V Microstr

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Research of Customized Aortic Stent Graft Manufacture

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IOP Conference Series: Materials Science and Engineering 2017年第1期187卷

作者： Lei Zhang Xin Chen Muhan Liu Department of Mechanical Engineering Biomanufacturing Center Tsinghua University Beijing 100084 P.R.China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Beijing 100084 P.R.China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Beijing 100084 P.R.China

Thoracic descending aorta diseases include aortic dissection and aortic aneurysm, of which the natural mortality rate is extremely high. At present, endovascular aneurysm repair (EVAR) has been widely used as an effective means for the treatment of descending aortic disease. Most of the existing coating stents are standard design, which are unable to meet the size or structure of different patients. As a result, failure of treatment would be caused by dimensional discrepancy between stent and vessels, which could lead to internal leakage or rupture of blood vessels. Therefore, based on rapid prototyping sacrificial core – coating forming (RPSC-CF), a customized aortic stent graft manufactured technique has been proposed in this study. The aortic stent graft consists of film and metallic stent, so polyether polyurethane (PU) and nickel-titanium (NiTi) shape memory alloy with good biocompatibility were chosen. To minimum film thickness without degrading performance, effect of different dip coating conditions on the thickness of film were studied. To make the NiTi alloy exhibit super-elasticity at body temperature (37°C), influence of different heat treatment conditions on austenite transformation temperature (Af) and mechanical properties were studied. The results show that the customized stent grafts could meet the demand of personalized therapy, and have good performance in blasting pressure and radial support force, laying the foundation for further animal experiment and clinical experiment.

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Dual-Material Electron Beam Selective Melting:Hardware Development and Validation Studies

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Engineering 2015年第1期1卷 124-130页

作者： Chao Guo Wenjun Ge Feng Lin Department of Mechanical Engineering Tsinghua University Key Laboratory for Advanced Materials Processing Technology (Ministry of Education of China) Tsinghua University Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Tsinghua University

Electron beam selective melting （EBSM） is an additive manufacturing technique that directly fabricates three-dimensional parts in a layerwise fashion by using an electron beam to scan and melt metal powder. In recent years, EBSM has been successfully used in the additive manufacturing of a variety of materials. Previous research focused on the EBSM process of a single material. In this study, a novel EBSM process capable of building a gradient structure with dual metal materials was developed, and a powder-supplying method based on vibration was put forward. Two different powders can be supplied individually and then mixed. Two materials were used in this study： Ti6AI4V powder and Ti47AI2Cr2Nb powder. Ti6AI4V has excellent strength and plasticity at room temperature, while Ti47AI2Cr2Nb has excellent performance at high temperature, but is very brittle. A Ti6AI4V/Ti47AI2Cr2Nb gradient material was successfully fabricated by the developed system. The microstructures and chemical compositions were characterized by optical microscopy, scanning microscopy, and electron microprobe analysis. Results showed that the interface thickness was about 300 μm. The interface was free of cracks, and the chemical compositions exhibited a staircase-like change within the interface.

关键词： additive manufacturing electron beam selectivemelting gradient materials titanium alloy TiAI alloy

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The aligmnent technology in electrospinning and a novel method using variable magnetic fields

The aligmnent technology in electrospinning and a novel meth...

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第十一届全国再生医学(干细胞与组织工程)学术研讨会暨第七届全国组织工程与再生医学大会

作者： Kevin Firouzian Feng Lin Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Rapid Forming Center Department of Mechanical Engineering Tsinghua University Beijing 100084 P.R.China

With the development of nanotechnology research, and increased interest in the unique properties of nanomaterials, electrospinning research has gained a lot of attention in the past *** is a very versatile technology and has application potential in several diverse *** include, but not limited to, tissue engineering, filtration, wound dressings, and *** nanofiber generation via electrospinning involves the use of an electrestatically driven jet of polymer *** features of the process include a chaotic oscillation of the electrospinning jet and fibers typically collected as non-woven *** nanofibers offer several advantages over conventional techniques such as high surface area to volume ratio, high porosity, and the ability to alter fiber composition in order to get required *** deposition and fiber alignment are key requirements for many applications such as tissue engineering ***, much of current research focuses on methods of alignment using mechanically-(rotary collectors), electrically-(parallel electrodes), and magnetically (parallel magnets on top of collector region)assisted ***, several methods have been suggested to stabilize the chaotic oscillating motion of the electrospun *** results have been achieved in beth alignment and stabilization, however there is still room for improvement.A novel jet stabilization and controlled fiber deposition method is proposed using a variable magnetic field that is expected to improve the flexibility of fiber ***, experimental results will be presented in this report to show the validation of this new method.

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双金属电子束选区熔化的硬件开发与成形实验

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Engineering 2015年第1期 249-262页

作者：郭超葛文君林峰 Department of Mechanical Engineering Tsinghua University Key Laboratory for Advanced Materials Processing Technology(Ministry of Education of China) Tsinghua University Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Tsinghua University

电子束选区熔化(EBSM)是一种利用电子束扫描、熔化金属粉末逐层制造三维实体零件的增材制造技术。近年来,EBSM已经成功应用于多种材料的增材制造。现有EBSM工艺方面的研究主要聚焦于单种材料的成形,本研究提出一种能够利用两种粉末材料... 详细信息

电子束选区熔化(EBSM)是一种利用电子束扫描、熔化金属粉末逐层制造三维实体零件的增材制造技术。近年来,EBSM已经成功应用于多种材料的增材制造。现有EBSM工艺方面的研究主要聚焦于单种材料的成形,本研究提出一种能够利用两种粉末材料成形梯度结构的EBSM工艺,提出基于振动的粉末供给方法,并实现了两种粉末材料独立供给并混合。利用Ti6Al4V和Ti47Al2Cr2Nb两种材料进行成形。Ti6Al4V在室温下有很好的强度与塑性,而Ti47Al2Cr2Nb在高温下性能优良,但有很大的室温脆性。本研究提出的双金属EBSM工艺成功制备了Ti6Al4V/Ti47Al2Cr2Nb梯度结构,并利用光学显微镜、扫描电子显微镜、电子微探针分析等方法研究了该梯度结构的微观组织和化学成分。结果显示,梯度结构的截面厚度约为300μm,没有裂纹,化学成分在界面处呈阶梯式变化。

关键词：增材制造电子束选区熔化梯度材料钛合金钛铝合金

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The effect of scan pattern on microstructure evolution and mechanical properties in electron beam melting Ti47Al2Cr2Nb 25

The effect of scan pattern on microstructure evolution and m...

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25th Annual International Solid Freeform Fabrication Symposium " An Additive Manufacturing Conference, SFF 2014

作者： Ge, Wenjun Lin, Feng Guo, Chao Department of Mechanical Engineering Tsinghua University Beijing100084 China Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Tsinghua University Beijing100084 China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Tsinghua University Beijing100084 China

Ti47Al2Cr2Nb alloy square samples with dimensions of 20mmh20mmh5mm were fabricated by electron beam selective melting. In order to study the effect of electron beam scan pattern on the microstructure evolution, three different scan patterns were employed: S-shaped scan line, Z-shaped scan line and interlayer orthogonal S-shaped scan line. Microstructural and chemical analyses were conducted using optical microscopy, scanning electron microscopy and energy differential system. It is worth noting that the element Al loss rate was about 8% under different process parameters. As a result, the microstructures of EBSM Ti47Al2Cr2Nb samples were composed of columnar β grains, α/α2and α2/γ lamellar. Tensile tests were carried out to understand the mechanical properties to the corresponding microstructures. Ultimate Tensile Stress (UTS)at room temperature is much lower than that at a high temperature. © SFF *** rights reserved.

关键词： Chemical analysis

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Material molten time and its effect on material deposition during electron beam selective melting 25

Material molten time and its effect on material deposition d...

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25th Annual International Solid Freeform Fabrication Symposium " An Additive Manufacturing Conference, SFF 2014

作者： Guo, C. Ge, W.J. Lin, F. Department of Mechanical Engineering Tsinghua University Beijing100084 China Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Tsinghua University Beijing100084 China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Tsinghua University Beijing100084 China

Electron Beam Selective Melting (EBSM) is an additive manufacturing technology that directly fabricates parts from metal powders in a layer-by-layer fashion. The material molten time, which equals the total time that material keeps molten during scanning, is selected as an indicator for evaluating the effects of process parameters on material deposition. A finite elements model was established to simulate the molten time distribution within the scanning area for various parameters. Samples were fabricated using the same parameters in simulation. It's found that there is a strong relation between the molten time and material deposition behavior. Appropriate material molten time results in a dense and flat surface. Too little material molten time leads to a non-dense surface and internal pores, and too much material molten time leads to a distorted surface and coarsened microstructures. The material molten time increases with the increase of beam current and with the decrease of scanning velocity and length of scanning line. An optimized process which aims to obtain appropriate and homogeneous molten time within the scanning area is also developed to improve the deposition quality. © SFF *** rights reserved.

关键词： Additives

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Development of novel EBSM system for high-tech material additive manufacturing research 25

Development of novel EBSM system for high-tech material addi...

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25th Annual International Solid Freeform Fabrication Symposium " An Additive Manufacturing Conference, SFF 2014

作者： Guo, C. Lin, F. Ge, W.J. Zhang, J. Department of Mechanical Engineering Tsinghua University Beijing100084 China Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Tsinghua University Beijing100084 China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Tsinghua University Beijing100084 China

Electron beam is more appropriate for metal additive manufacturing (AM) than laser because of its high energy converting efficiency and high absorption for various materials. It becomes a preference for AM study of high-tech material with high melting point, high brittleness or graded material. A novel electron beam selective melting (EBSM) system with dual-material processing capability has been developed in Tsinghua University to meet the wide high-tech material AM research requirement. A vibration driven powder supplier was developed and the supplier had a high compatibility to various powders. A stable supplying rate and a supplying accuracy less than 7.5% were obtained with the supplier. Two powders can be supplied individually to obtain a mixture with tailored proportion for each powder layer. The mixture is homogenous and the actual proportion is close to the desired value. In order to prolong the spreading comb's lifetime and avoid tooth breaking, a low deformation powder spreading device was designed based on dual inclined combs and a one-way scraping mechanism. The system provides exchangeable building tanks with sizes of 100 ×100 ×100 mm3 and 250 ×250 ×250 mm3, which can save powder when the part is small and the powder is expensive. The novel EBSM system is capable of building parts with single material and has a potential of dual-material processing. © SFF *** rights reserved.

关键词： 3D printers

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