Artykuły w czasopismach: „Fabrication additive laser”

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Liu, Fwu Hsing, Wen Hsueng Lin, Yung Kang Shen i Jeou Long Lee. "Fabrication Inner Channel Ceramics Using Layer Additive Method". Key Engineering Materials 443 (czerwiec 2010): 528–33. http://dx.doi.org/10.4028/www.scientific.net/kem.443.528.

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This paper presents a layer additive method, ceramic laser curing, to form a ceramic part with inner channel features, by which silica powder is bonded by curing effect under disposal of a 20W CO2 laser. This process includes four steps: making slurry by mixing a binder with ceramic powder, paving the slurry on the surface of a platform, scanning the paved slurry layer via laser beam, removing the un-cured slurries from the solidified ceramic component. This process needed only low laser power to build ceramic parts by using “curing effect”. The deflection and shrinkage of ceramics could be decreased, also the distortion due to post sintering process was avoidable. The inner channel structures were support by ceramic slurries to avoid the sagged deflection and to maintain the dimensional accuracy. The maximum flexural strength of the cured specimen was 4.7 MPa. This process has potential to fabricate inner complex ceramic components for industrial applications.

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Andre, J., G. De Demo, K. Molina, S. Le Tacon, C. Chicanne i M. Theobald. "Application of Additive Manufacturing for Laser Target Fabrication". Fusion Science and Technology 73, nr 2 (23.01.2018): 149–52. http://dx.doi.org/10.1080/15361055.2017.1406246.

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Hu, D., H. Mei i R. Kovacevic. "Improving solid freeform fabrication by laser-based additive manufacturing". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 216, nr 9 (1.09.2002): 1253–64. http://dx.doi.org/10.1243/095440502760291808.

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Solid freeform fabrication (SFF) methods for metal part building, such as three-dimensional laser cladding, are generally less stable and less repeatable than other rapid prototyping methods. A large number of parameters govern the three-dimensional laser cladding process. These parameters are sensitive to the environmental variations, and they also influence each other. This paper introduces the research work in Research Center for Advanced Manufacturing (RCAM) to improve the performance of its developed three-dimensional laser cladding process: laser-based additive manufacturing (LBAM). Metal powder delivery real-time sensing is studied to achieve a further controllable powder delivery that is the key technology to build a composite material or alloy with a functionally gradient distribution. An opto-electronic sensor is designed to sense the powder delivery rate in real time. The experimental results show that the sensor's output voltage has a good linear relationship with the powder delivery rate. A closed-loop control system is also built for heat input control in the LBAM process, based on infrared image sensing. A camera with a high frame rate (up to 800frame/s) is installed coaxially to the top of the laser—nozzle set-up. A full view of the infrared images of the molten pool can be acquired with a short nozzle—substrate distance in different scanning directions, eliminating the image noise from the metal powder. The closed-loop control results show a great improvement in the geometrical accuracy of the built feature.

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Saunders, Jacob, Mohammad Elbestawi i Qiyin Fang. "Ultrafast Laser Additive Manufacturing: A Review". Journal of Manufacturing and Materials Processing 7, nr 3 (5.05.2023): 89. http://dx.doi.org/10.3390/jmmp7030089.

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Ultrafast lasers are proven and continually evolving manufacturing tools. Concurrently, additive manufacturing (AM) has emerged as a key area of interest for 3D fabrication of objects with arbitrary geometries. Use of ultrafast lasers for AM presents possibilities for next generation manufacturing techniques for hard-to-process materials, transparent materials, and micro- and nano-manufacturing. Of particular interest are selective laser melting/sintering (SLM/SLS), multiphoton lithography (MPL), laser-induced forward transfer (LIFT), pulsed laser deposition (PLD), and welding. The development, applications, and recent advancements of these technologies are described in this review as an overview and delineation of the burgeoning ultrafast laser AM field. As they mature, their adoption by industry and incorporation into commercial systems will be facilitated by process advancements such as: process monitoring and control, increased throughput, and their integration into hybrid manufacturing systems. Recent progress regarding these aspects is also reviewed.

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Zhou, Weiwei, Xiaohao Sun, Kengo Tsunoda, Keiko Kikuchi, Naoyuki Nomura, Kyosuke Yoshimi i Akira Kawasaki. "Powder fabrication and laser additive manufacturing of MoSiBTiC alloy". Intermetallics 104 (styczeń 2019): 33–42. http://dx.doi.org/10.1016/j.intermet.2018.10.012.

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Millon, Célia, Arnaud Vanhoye i Anne-Françoise Obaton. "Ultrasons laser pour la détection de défauts sur pièces de fabrication additive métallique". Photoniques, nr 94 (listopad 2018): 34–37. http://dx.doi.org/10.1051/photon/20189434.

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La fabrication additive (FA), notamment la FA de pièces métalliques, connait un essor dans les secteurs de pointe comme l’aéronautique ou le médical de par les possibilités accrues en termes de complexité géométrique, de fonctionnalités ou encore de personnalisation des pièces. Cependant, les poudres métalliques et la fusion laser mis en oeuvre dans certains procédés lors de la fabrication conduisent parfois à des défauts, comme par exemple des manques de fusion. Pour réduire les coûts de production engendrés par des pièces finies mais non conformes, la fabrication de ces pièces appelle à développer un contrôle en ligne. Les ultrasons laser (UL), non destructifs et sans contact, sont une piste prometteuse : ils combinent la sensibilité d’un contrôle par ultrasons avec la flexibilité d’un système optique.

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Alhamdi, Ismail, Anwar Algamal, Abdalmageed Almotari, Majed Ali, Umesh Gandhi i Ala Qattawi. "Fe-Mn-Al-Ni Shape Memory Alloy Additively Manufactured via Laser Powder Bed Fusion". Crystals 13, nr 10 (17.10.2023): 1505. http://dx.doi.org/10.3390/cryst13101505.

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Fe-Mn-Al-Ni is an Fe-based shape memory alloy (SMA) featuring higher stability and low temperature dependency of superelasticity stress over a wide range of temperatures. Additive manufacturing (AM) is a promising technique for fabricating Fe-SMA with enhanced properties, which can eliminate the limitations associated with conventional fabrication and allow for the manufacture of complicated shapes with only a single-step fabrication. The current work investigates the densification behavior and fabrication window of an Fe-Mn-Al-Ni SMA using laser powder bed fusion (LPBF). Experimental optimization was performed to identify the optimum processing window parameters in terms of laser power and scanning speed to fabricate Fe-Mn-Al-Ni SMA samples. Laser remelting was also employed to improve the characteristics of Fe-Mn-Al-Ni-fabricated samples. Characterization and testing techniques were carried out to assess the densification behavior of Fe-Mn-Al-Ni to study surface roughness, density, porosity, and hardness. The findings indicated that using a laser power range of 175–200 W combined with a scanning speed of 800 mm/s within the defined processing window parameters can minimize the defects with the material and lead to decreased surface roughness, lower porosity, and higher densification.

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Kumar, Pankaj, i Gazanfar Mustafa Ali syed. "Emerging trend in manufacturing of 3D biomedical components using selective laser sintering: A review". E3S Web of Conferences 184 (2020): 01047. http://dx.doi.org/10.1051/e3sconf/202018401047.

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Additive manufacturing (also known as 3D printing) process is an emerging technique for the fabrication of biomedical components. Selective laser sintering or melting is one of the widely used additive printing technology for manufacturing of metallic and non-metallic components used in the industry. This review paper presents, a summary of the published research papers on the fabrication of biomedical components using selective laser sintering technique. Therefore, author meticulously attempted to investigate individual biocompatible material-wise review which includes Ti6Al4V, Ti-7.5 Mo alloy, β-Ti35Zr28Nb, PEEK, PA2200, and Polyamide/Hydroxyapatite. In addition, this article also explores the effects of the various laser sintering process parameters such as laser power, scanning speed, density of the material on the mechanical properties, tribological properties, porosity and surface roughness of the fabricated alloy. Moreover, the author also investigated challenges and future prospective of the laser processing of biomedical implants.

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Bi, Gunjun. "Special Issue on Advancements in Laser-Based Additive Manufacturing Technologies". Applied Sciences 13, nr 3 (24.01.2023): 1529. http://dx.doi.org/10.3390/app13031529.

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Behrens, Ailke, Jan Stieghorst, Theodor Doll i Ulrich P. Froriep. "Laser-Facilitated Additive Manufacturing Enables Fabrication of Biocompatible Neural Devices". Sensors 20, nr 22 (19.11.2020): 6614. http://dx.doi.org/10.3390/s20226614.

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Current personalized treatment of neurological diseases is limited by availability of appropriate manufacturing methods suitable for long term sensors for neural electrical activities in the brain. An additive manufacturing process for polymer-based biocompatible neural sensors for chronic application towards individualized implants is here presented. To process thermal crosslinking polymers, the developed extrusion process enables, in combination with an infrared (IR)-Laser, accelerated curing directly after passing the outlet of the nozzle. As a result, no additional curing steps are necessary during the build-up. Furthermore, the minimal structure size can be achieved using the laser and, in combination with the extrusion parameters, provide structural resolutions desired. Active implant components fabricated using biocompatible materials for both conductive pathways and insulating cladding keep their biocompatible properties even after the additive manufacturing process. In addition, first characterization of the electric properties in terms of impedance towards application in neural tissues are shown. The printing toolkit developed enables processing of low-viscous, flexible polymeric thermal curing materials for fabrication of individualized neural implants.

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Ravichander, Bharath Bhushan, Atabak Rahimzadeh, Behzad Farhang, Narges Shayesteh Moghaddam, Amirhesam Amerinatanzi i Mehrshad Mehrpouya. "A Prediction Model for Additive Manufacturing of Inconel 718 Superalloy". Applied Sciences 11, nr 17 (30.08.2021): 8010. http://dx.doi.org/10.3390/app11178010.

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Inconel 718 is a nickel-based superalloy and an excellent candidate for the aerospace, oil, and gas industries due to its high strength and corrosion resistance properties. The machining of IN718 is very challenging; therefore, the application of additive manufacturing (AM) technology is an effective approach to overcoming these difficulties and for the fabrication of complex geometries that cannot be manufactured by the traditional techniques. Selective laser melting (SLM), which is a laser powder bed fusion method, can be applied for the fabrication of IN718 samples with high accuracy. However, the process parameters have a high impact on the properties of the manufactured samples. In this study, a prediction model is developed for obtaining the optimal process parameters, including laser power, hatch spacing, and scanning speed, in the SLM process of the IN718 alloy. For this purpose, artificial neural network (ANN) modeling with various algorithms is employed to estimate the process outputs, namely, sample height and surface hardness. The modeling results fit perfectly with the experimental output, and this consequently proves the benefit of ANN modeling for predicting the optimal process parameters.

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Liu, Fwu Hsing, Wen Hsueng Lin, Ruey Tsung Lee, Hsiu Ping Wang i Hsiu Ling Hsu. "Fabrication of Bioceramic Scaffolds for Tissue Engineering Using Additive Manufacturing Technology". Advanced Materials Research 706-708 (czerwiec 2013): 118–21. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.118.

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In this paper, the hydroxyapatite (HA) based bioceramic materials were used in a rapid prototyping (RP) system to fabrication bioceramic bone scaffold for tissue engineering (TE) using an additive manufacturing (AM) technology. When the bioceramic slurry is sintered via the processing parameters of an 85 mm/s laser scanning speed, 24.5 W of laser power, 10 kHz of scanning frequency, and 2500 Cp of slurry viscosity, a porous bone scaffold can be fabricated under a lower laser power energy. Results indicate that the bending strength of the scaffold was 14.2 MPa, which could be improved by heat-treatment at 1200 °C for 2 hour. MTT method and SEM observations confirmed that the fabricated bone scaffolds possess suitable biocompatibility and mechanical properties, allowing smooth adhesion and proliferation of osteoblast-like cells. Therefore, the fabricated bone scaffolds have great potential for development in tissue engineering.

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Li, Yan, Dichen Li, Bingheng Lu, Dajing Gao i Jack Zhou. "Current status of additive manufacturing for tissue engineering scaffold". Rapid Prototyping Journal 21, nr 6 (19.10.2015): 747–62. http://dx.doi.org/10.1108/rpj-03-2014-0029.

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Purpose – The purpose of this paper is to review the current status of additive manufacturing (AM) used for tissue engineering (TE) scaffold. AM processes are identified as an effective method for fabricating geometrically complex objects directly from computer models or three-dimensional digital representations. The use of AM technologies in the field of TE has grown rapidly in the past 10 years. Design/methodology/approach – The processes, materials, precision, applications of different AM technologies and their modified versions used for TE scaffold are presented. Additionally, future directions of AM used for TE scaffold are also discussed. Findings – There are two principal routes for the fabrication of scaffolds by AM: direct and indirect routes. According to the working principle, the AM technologies used for TE scaffold can be generally classified into: laser-based; nozzle-based; and hybrid. Although a number of materials and fabrication techniques have been developed, each AM technique is a process based on the unique property of the raw materials applied. The fabrication of TE scaffolds faces a variety of challenges, such as expanding the range of materials, improving precision and adapting to complex scaffold structures. Originality/value – This review presents the latest research regarding AM used for TE scaffold. The information available in this paper helps researchers, scholars and graduate students to get a quick overview on the recent research of AM used for TE scaffold and identify new research directions for AM in TE.

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Aydogan, Beytullah, i Himanshu Sahasrabudhe. "Enabling Multi-Material Structures of Co-Based Superalloy Using Laser Directed Energy Deposition Additive Manufacturing". Metals 11, nr 11 (27.10.2021): 1717. http://dx.doi.org/10.3390/met11111717.

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Cobalt superalloys such as Tribaloys are widely used in environments that involve high temperatures, corrosion, and wear degradation. Additive manufacturing (AM) processes have been investigated for fabricating Co-based alloys due to design flexibility and efficient materials usage. AM processes are suitable for reducing the manufacturing steps and subsequently reducing manufacturing costs by incorporating multi-materials. Laser directed energy deposition (laser DED) is a suitable AM process for fabricating Co-based alloys. T800 is one of the commercially available Tribaloys that is strengthened through Laves phases and of interest to diverse engineering fields. However, the high content of the Laves phase makes the alloy prone to brittle fracture. In this study, a Ni-20%Cr alloy was used to improve the fabricability of the T800 alloy via laser DED. Different mixture compositions (20%, 30%, 40% NiCr by weight) were investigated. The multi-material T800 + NiCr alloys were heat treated at two different temperatures. These alloy chemistries were characterized for their microstructural, phase, and mechanical properties in the as-fabricated and heat-treated conditions. SEM and XRD characterization indicated the stabilization of ductile phases and homogenization of the Laves phases after laser DED fabrication and heat treatment. In conclusion, the NiCr addition improved the fabricability and structural integrity of the T800 alloy.

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KISHIMOTO, Satoshi, Makoto WATANABE i Hiroyasu TANIGAWA. "Fabrication of porous structural Metallic devices by Laser Additive Manufacturing". Proceedings of Mechanical Engineering Congress, Japan 2020 (2020): S04104. http://dx.doi.org/10.1299/jsmemecj.2020.s04104.

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Kuroiwa, Y., D. Kono i Y. Oda. "INVESTIGATION ON THERMAL DEFORMATION IN LASER ADDITIVE MANUFACTURING". MM Science Journal 2021, nr 3 (30.06.2021): 4584–90. http://dx.doi.org/10.17973/mmsj.2021_7_2021063.

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In metal additive manufacturing, a metal material is melted by a concentrated heat source such as a laser. Therefore, thermal deformation occurs in the fabrication, which causes deterioration of shape accuracy and crack of the workpiece. In this study, a method to systematically reduce the thermal deformation was discussed. The mechanism of thermal deformation caused by stacking and lining up the bead was investigated using finite element simulations and experiments. Based on the obtained results and thermal deformation theory in welding, a method to reduce the thermal deformation was proposed and the validity of the method was demonstrated by simulation.

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Costa, José, Elsa Sequeiros, Maria Teresa Vieira i Manuel Vieira. "Additive Manufacturing". U.Porto Journal of Engineering 7, nr 3 (30.04.2021): 53–69. http://dx.doi.org/10.24840/2183-6493_007.003_0005.

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Additive manufacturing (AM) is one of the most trending technologies nowadays, and it has the potential to become one of the most disruptive technologies for manufacturing. Academia and industry pay attention to AM because it enables a wide range of new possibilities for design freedom, complex parts production, components, mass personalization, and process improvement. The material extrusion (ME) AM technology for metallic materials is becoming relevant and equivalent to other AM techniques, like laser powder bed fusion. Although ME cannot overpass some limitations, compared with other AM technologies, it enables smaller overall costs and initial investment, more straightforward equipment parametrization, and production flexibility.This study aims to evaluate components produced by ME, or Fused Filament Fabrication (FFF), with different materials: Inconel 625, H13 SAE, and 17-4PH. The microstructure and mechanical characteristics of manufactured parts were evaluated, confirming the process effectiveness and revealing that this is an alternative for metal-based AM.

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Shiva, S., IA Palani, CP Paul i B. Singh. "Laser annealing of laser additive–manufactured Ni-Ti structures: An experimental–numerical investigation". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 232, nr 6 (5.08.2016): 1054–67. http://dx.doi.org/10.1177/0954405416661582.

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Tailored structures of Ni-Ti shape memory alloys for micro-electro-mechanical systems can be fabricated using laser additive manufacturing, and requisite homogeneous microstructure for predictive design and fabrication of micro-electro-mechanical systems devices can be achieved by annealing. Investigation has been performed on the laser annealing of laser additive–manufactured Ni-Ti structures using a pulsed green laser through numerical simulation and experimental studies. The parametric dependence showed that a laser energy density of 1100 mJ cm−2 has a considerable influence in annealing of Ni-Ti structures. The surface morphology, phase transformation temperature and microstructure of laser-annealed Ni-Ti structures were studied with scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. Laser energy density of 1100 mJ cm−2 was used for annealing the samples as identified in the simulation. Surface annealing of Ni-Ti led to a uniform surface of the material with an increase in grain size and surface roughness. A decrease in the micro-hardness of the samples was obtained as a result of laser annealing. Thus, the investigations demonstrated the improved properties of laser additive–manufactured Ni-Ti structures by laser annealing.

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Boschetto, Alberto, Luana Bottini, Luciano Macera i Somayeh Vatanparast. "Additive Manufacturing for Lightweighting Satellite Platform". Applied Sciences 13, nr 5 (22.02.2023): 2809. http://dx.doi.org/10.3390/app13052809.

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Lightweight structures with an internal lattice infill and a closed shell have received a lot of attention in the last 20 years for satellites, due to their improved stiffness, buckling strength, multifunctional design, and energy absorption. The geometrical freedom typical of Additive Manufacturing allows lighter, stiffer, and more effective structures to be designed for aerospace applications. The Laser Powder Bed Fusion technology, in particular, enables the fabrication of metal parts with complex geometries, altering the way the mechanical components are designed and manufactured. This study proposed a method to re-design the original satellite structures consisting of walls and ribs with an enclosed lattice design. The proposed new structures must comply with restricted requirements in terms of mechanical properties, dimensional accuracy, and weight. The most challenging is the first frequency request which the original satellite design, based on traditional fabrication, does not satisfy. To overcome this problem a particular framework was developed for locally thickening the critical zones of the lattice. The use of the new design permitted complying with the dynamic behavior and to obtain a weight saving maintaining the mechanical properties. The Additive Manufacturing fabrication of this primary structure demonstrated the feasibility of this new technology to satisfy challenging requests in the aerospace field.

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Stornelli, Giulia, Paolo Folgarait, Maria Rita Ridolfi, Domenico Corapi, Christian Repitsch, Orlando Di Pietro i Andrea Di Schino. "Feasibility Study of Ferromagnetic Cores Fabrication by Additive Manufacturing Process". Materials Proceedings 3, nr 1 (18.02.2021): 28. http://dx.doi.org/10.3390/iec2m-09241.

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Currently, the commercial production of ferromagnetic cores involves staking thin sheets of soft magnetic material, alternating with dielectric material to reduce the eddy current losses. High silicon FeSi steels show excellent soft magnetic properties. Anyway, their workability decreases Si content increases thus imposing a technological limit in the production of thin sheets up to 3.5–4% Si. The additive manufacturing (AM) process based on laser powder bed fusion (L-PBF) offers the possibility to redesign the magnetic components, compared to conventional design, allowing to act on the chemical composition of magnetic materials and on the geometry of the components. In the case of FeSi alloys, the additive technology allows to overcome the limit of Si content opening new perspectives for the production of ferromagnetic cores with high magnetic performance. In this work the feasibility study on the production of FeSi magnetic steel components by L-PBF technology is reported. Two variants of FeSi steels, with Si content of 3.0 wt.% and 6.5 wt.%, were considered. The effect of process parameters on the densification of manufactured parts was investigated. The best operating window has been identified for both steel chemical compositions, in terms of laser scan speed and power.

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Hitzler, Leonhard, Philipp Williams, Markus Merkel, Wayne Hall i Andreas Öchsner. "Correlation between the Energy Input and the Microstructure of Additively Manufactured Cobalt-Chromium". Defect and Diffusion Forum 379 (listopad 2017): 157–65. http://dx.doi.org/10.4028/www.scientific.net/ddf.379.157.

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Powder-bed based additive manufacturing techniques are of high interest for the medical sector and recent trial studies have shown their feasibility. Due to the rapid improvements made in the machinery and the related changes in the type and characteristics of the utilized power source, optimizations regarding the fabrication parameters tend to differ amongst various machines. In this study, a parameter optimization was undertaken for a biocompatible dental CoCrMo alloy on a SLM 280HL machine, featuring a 400 W fibre laser. It was shown that the availability of higher laser powers enables a more energy efficient fabrication. Moreover, parameter sets for fast and economic fabrication, as well as for high density and fine-grained microstructure, were defined.

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Hu, Xingjian, Fan Yang, Mingzhao Guo, Jiayun Pei, Haiyan Zhao i Yujun Wang. "Fabrication of polyimide microfluidic devices by laser ablation based additive manufacturing". Microsystem Technologies 26, nr 5 (26.11.2019): 1573–83. http://dx.doi.org/10.1007/s00542-019-04698-4.

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Saha, Sourabh K., Dien Wang, Vu H. Nguyen, Yina Chang, James S. Oakdale i Shih-Chi Chen. "Scalable submicrometer additive manufacturing". Science 366, nr 6461 (3.10.2019): 105–9. http://dx.doi.org/10.1126/science.aax8760.

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High-throughput fabrication techniques for generating arbitrarily complex three-dimensional structures with nanoscale features are desirable across a broad range of applications. Two-photon lithography (TPL)–based submicrometer additive manufacturing is a promising candidate to fill this gap. However, the serial point-by-point writing scheme of TPL is too slow for many applications. Attempts at parallelization either do not have submicrometer resolution or cannot pattern complex structures. We overcome these difficulties by spatially and temporally focusing an ultrafast laser to implement a projection-based layer-by-layer parallelization. This increases the throughput up to three orders of magnitude and expands the geometric design space. We demonstrate this by printing, within single-digit millisecond time scales, nanowires with widths smaller than 175 nanometers over an area one million times larger than the cross-sectional area.

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Song, Changhui, Aibing Huang, Yongqiang Yang, Zefeng Xiao i Jia-kuo Yu. "Effect of energy input on the UHMWPE fabricating process by selective laser sintering". Rapid Prototyping Journal 23, nr 6 (17.10.2017): 1069–78. http://dx.doi.org/10.1108/rpj-09-2015-0119.

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Purpose This study aims to achieve customized prosthesis for total joint arthroplasty and total hip arthroplasty. Selective laser sintering (SLS) as additive manufacturing could enable small-scale fabrication of customized Ultra High Molecular Weight Polyethylene (UHMWPE) components; however, the processes for SLS of UHMWPE need to be improved. Design/methodology/approach This paper begins by improving the preheating system of the SLS fabricating equipment and then fabricating cuboids with the same size and cuboids with same volume and different size to study the warpage, demonstrating the effect of the value and uniformity of the preheating temperature on component fabrication. Warpage, density and tensile properties are investigated from the perspective of energy input density. Finally, complicated industrial parts are produced effectively by using optimized technological parameters. Findings The results show that components can be fabricated effectively after the optimization of the SLS technological parameters i.e. the preheating temperature the laser power the scanning interval and the scanning speed. The resulting warpage was found to be less than 0.1 mm along with the density as 83.25 and the tensile strength up to 14.1 Mpa. UHMWPE sample parts with good appearance and strength are obtained after ascertaining the effect of each factor on the fabrication of the sample parts. Originality/value It is very challenging to fabricate UHMWPE sample parts by SLS. This is a new step in the fabrication of customized UHMWPE sample parts.

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Lee, Eo Ryeong, Se Eun Shin, Naoki Takata, Makoto Kobashi i Masaki Kato. "Manufacturing Aluminum/Multiwalled Carbon Nanotube Composites via Laser Powder Bed Fusion". Materials 13, nr 18 (5.09.2020): 3927. http://dx.doi.org/10.3390/ma13183927.

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This study provides a novel approach to fabricating Al/C composites using laser powder bed fusion (LPBF) for a wide range of structural applications utilizing Al-matrix composites in additive manufacturing. We investigated the effects of LPBF on the fabrication of aluminum/multiwalled carbon nanotube (Al/MWCNT) composites under 25 different conditions, using varying laser power levels and scan speeds. The microstructures and mechanical properties of the specimens, such as elastic modulus and nanohardness, were analyzed, and trends were identified. We observed favorable sintering behavior under laser conditions with low energy density, which verified the suitability of Al/MWCNT composites for a fabrication process using LPBF. The size and number of pores increased in specimens produced under high energy density conditions, suggesting that they are more influenced by laser power than scan speed. Similarly, the elastic modulus of a specimen was also more affected by laser power than scan speed. In contrast, scan speed had a greater influence on the final nanohardness. Depending on the laser power used, we observed a difference in the crystallographic orientation of the specimens by a laser power during LPBF. When energy density is high, texture development of all samples tended to be more pronounced.

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Koppunur, Rakesh, Kiran Kumar Dama, Uzwalkiran Rokkala, Balaji Thirupathi, N. V. S. S. Sagar i Bhiksha Gugulothu. "Design and Fabrication of Patient-Specific Implant for Maxillofacial Surgery Using Additive Manufacturing". Advances in Materials Science and Engineering 2022 (28.08.2022): 1–7. http://dx.doi.org/10.1155/2022/7145732.

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Patient-specific implants are well known for fixing the fracture for bone repairs. However, the exact fixation of the fabricated implant to the patients is a challenging task. To overcome this problem, in the present study two kinds of designs are developed and fabricated. Based on the exact fitting to the patient’s oral system, the best design is selected to fabricate. Computed tomography (CT) scan data of the patient oral anatomy is converted into a 3D model using the DICOM Software “Slicer 3D.” The patient-specific maxillofacial implant is fabricated using fused filament fabrication (FFF) and direct metal laser sintering (DMLS) techniques. Before fabricating real time product, a prototype is fabricated at the initial stage using FFF. Later, stress distribution and displacement of the implant was investigated using a FEM simulation. The conclusion of the present work results are potential for FFF of patient-specific implants out of Ti-6Al-4V.

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Wiste, T., O. Maliuk, V. Tikhonchuk, T. Lastovicka, J. Homola, K. Chadt i S. Weber. "Additive manufactured foam targets for experiments on high-power laser–matter interaction". Journal of Applied Physics 133, nr 4 (28.01.2023): 043101. http://dx.doi.org/10.1063/5.0121650.

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Additive manufactured (AM) foams in the context of high-power laser–matter interaction have emerged as a topic of significant interest. Printed foam targets provide a highly controlled environment for laser interaction and permit a high degree of versatility in terms of average density, spatial structure, and materials. These features are of great value to a variety of applications, including inertial confinement fusion and generation of intense x-rays and gamma rays. This paper describes an approach to the design and fabrication of AM foams for laser–plasma interaction experiments, including the selection of cellular structure, optimization of mechanical properties using a finite element approach, and foam printing on dielectric and conducting substrates.

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Jones, Jason B., David I. Wimpenny i Greg J. Gibbons. "Additive manufacturing under pressure". Rapid Prototyping Journal 21, nr 1 (19.01.2015): 89–97. http://dx.doi.org/10.1108/rpj-02-2013-0016.

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Purpose – This paper aims to investigate the effects on material properties of layer-by-layer application of pressure during fabrication of polymeric parts by additive manufacturing (AM). Although AM, also known popularly as 3D printing, has set a new standard for ease of use and minimal restraint on geometric complexity, the mechanical part properties do not generally compare with conventional manufacturing processes. Contrary to other types of polymer processing, AM systems do not normally use (in-process) pressure during part consolidation. Design/methodology/approach – Tensile specimens were produced in Somos 201 using conventional laser sintering (LS) and selective laser printing (SLP) – a process under development in the UK, which incorporates the use of pressure to assist layer consolidation. Findings – Mechanical testing demonstrated the potential to additively manufacture parts with significantly improved microstructure and mechanical properties which match or exceed conventional processing. For example, the average elongation at break and ultimate tensile strength of a conventionally laser-sintered thermoplastic elastomer (Somos 201) increased from 136 ± 28 per cent and 4.9 ± 0.4 MPa, to 513 ± 35 per cent and 10.4 ± 0.4 MPa, respectively, when each layer was fused with in-process application of pressure (126 ± 9 kPa) by SLP. Research limitations/implications – These results are based on relatively small sample size, but despite this, the trends observed are of significant importance to the elimination of voids and porosity in polymeric parts. Practical implications – Layerwise application of pressure should be investigated further for defect elimination in AM. Originality/value – This is the first study on the effects of layerwise application of pressure in combination with area-wide fusing.

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Newkirk, Joseph W., i F. Frank Liou. "High Performance Materials by Laser Deposition". Materials Science Forum 783-786 (maj 2014): 2365–69. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2365.

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Additive Manufacturing using laser deposition has a great deal of attractiveness as a fabrication technique for metals and alloys. The combination of a high heat input, small molten volume, and incremental addition also is well suited for the production of high performance alloys and composites. The high cooling rates inherent in the process produces refined microstructures, leading to excellent as-deposited mechanical properties in conventional alloys. The high heating rates and cooling rates potentially lends itself to structurally amorphous alloys, functionally gradient materials, and nanostructured materials, among other more exotic metallic materials. By monitoring the process a map of the quality of the build can be recorded for quality assurance and validation. Flaws detected during fabrication can then be repaired in-situ. Realizing this potential will require a combination of modeling, experimental validation, and new design paradigms. Together this will lead to the greatest properties and functionalities in future products.

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Kalman, Les, i Lyndsay Desimone. "A novel workflow for indirect cobalt-chromium restorations using additive manufacturing without digital design". Journal of Dental Research, Dental Clinics, Dental Prospects 15, nr 3 (25.08.2021): 147–51. http://dx.doi.org/10.34172/joddd.2021.025.

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This preliminary investigation explored additive manufacturing to fabricate cobalt-chromium onlay restorations without the use of digital design. Extracted molars were prepared for four-surface onlays followed by the conventional approach for the fabrication of provisionals. The provisionals were digitized with an intraoral scanner, and stereolithography (STL) files were fabricated with additive manufacturing in cobalt-chromium, utilizing selective laser melting (SLM). Onlays were bonded to the corresponding tooth. Restorations were polished after cementation and assessed with photography, radiography, and a clinical post-cementation checklist. Cementation was unremarkable; marginal adaption and surface finish were generally acceptable. A simple, efficient, and inexpensive alternative workflow for the fabrication of indirect restorations without using the digital design is proposed.

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Goll, Dagmar, Felix Trauter, Timo Bernthaler, Jochen Schanz, Harald Riegel i Gerhard Schneider. "Additive Manufacturing of Bulk Nanocrystalline FeNdB Based Permanent Magnets". Micromachines 12, nr 5 (10.05.2021): 538. http://dx.doi.org/10.3390/mi12050538.

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Lab scale additive manufacturing of Fe-Nd-B based powders was performed to realize bulk nanocrystalline Fe-Nd-B based permanent magnets. For fabrication a special inert gas process chamber for laser powder bed fusion was used. Inspired by the nanocrystalline ribbon structures, well-known from melt-spinning, the concept was successfully transferred to the additive manufactured parts. For example, for Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8 (excess rare earth (RE) = Nd, Pr; the amount of additives was chosen following Magnequench (MQ) powder composition) a maximum coercivity of µ0Hc = 1.16 T, remanence Jr = 0.58 T and maximum energy density of (BH)max = 62.3 kJ/m3 have been achieved. The most important prerequisite to develop nanocrystalline printed parts with good magnetic properties is to enable rapid solidification during selective laser melting. This is made possible by a shallow melt pool during laser melting. Melt pool depths as low as 20 to 40 µm have been achieved. The printed bulk nanocrystalline Fe-Nd-B based permanent magnets have the potential to realize magnets known so far as polymer bonded magnets without polymer.

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Polozov, Igor, Victoria Sokolova, Anna Gracheva i Anatoly Popovich. "Tailoring the Microstructure of Laser-Additive-Manufactured Titanium Aluminide Alloys via In Situ Alloying and Parameter Variation". Metals 13, nr 8 (9.08.2023): 1429. http://dx.doi.org/10.3390/met13081429.

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Titanium aluminide (TiAl) alloys have emerged as promising materials for high-temperature applications due to their unique combination of high-temperature strength, low density, and excellent oxidation resistance. However, the fabrication of TiAl alloys using conventional methods is challenging due to their high melting points and limited ductility. Selective laser melting (SLM), an additive manufacturing technique, offers a viable solution for producing TiAl alloys with intricate geometries and the potential for tailoring their microstructure. This study investigates the effect of in situ copper alloying and multiple laser scans on the microstructure and mechanical properties of TiAl-based alloys fabricated using SLM. The results demonstrate that copper alloying enhances the formation of the α2-Ti3Al phase, refines the microstructure, and improves the mechanical properties of TiAl alloys. Multiple laser scans allow for the creation of distinct microstructural regions within a single component, enabling the tailoring of properties that are suitable for specific operating conditions. The findings provide valuable insights into the fabrication and optimization of TiAl intermetallic alloys with diverse applications.

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Wu, Gang, Long Chen, Chun Ling Deng i Kun Wei. "Fabrication of Ofloxacin/PLGA Microsphere for Bone Tuberculosis Therapy". Advanced Materials Research 647 (styczeń 2013): 176–80. http://dx.doi.org/10.4028/www.scientific.net/amr.647.176.

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The purpose of this research was to use mesoporous silicon (mpSi) as internal phase additive to improve the hydrophilic ofloxacin loaded by the hydrophobic PLGA materials through a double emulsion (water-in-oil-in-water) solvent extraction/evaporation method. Laser distribution analysis displayed low impact of MS additive on the final particles size. When compared to particle loading efficiency of none internal phase additives, MS internal phase group showed higher loading efficiency, and it increased with MS amounts inside the microparticles. All the burst releases of MS internal phase groups were severe than none MS group and was directly related the MS amount inside the microsphere. The release rate was increasing with the MS amounts added into the internal phase.

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Krzyzanowski, Michal, Dmytro Svyetlichnyy i Szymon Bajda. "Additive Manufacturing of Multi Layered Bioactive Materials with Improved Mechanical Properties: Modelling Aspects". Materials Science Forum 1016 (styczeń 2021): 888–93. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.888.

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Multilayered laminate structures obtained by coating of ultrafine-grained metallic materials with bioactive and multifunctional composite coatings are considered for biomedical applications. Laser-assisted densification of multiple materials using laser cladding and selective laser melting is an alternative route to reduce the risk of early implant failure allowing for faster and cheaper fabrication. To understand the cooperative relationships between different factors that cam influence the manufacture of such bioactive laminates reflecting in their bioactivity and mechanical properties, the multi scale numerical modelling is applied. This work presents resent advances on development of integrated numerical models including generation, melting and solidification of the powder bed, considering surface flow, wettability, surface tension and other physical phenomena, specific mechanical and thermo-mechanical aspects and microstructure evolution.

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Mahmud, Asif, Nicolas Ayers, Thinh Huynh i Yongho Sohn. "Additive Manufacturing of SS316L/IN718 Bimetallic Structure via Laser Powder Bed Fusion". Materials 16, nr 19 (1.10.2023): 6527. http://dx.doi.org/10.3390/ma16196527.

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Laser powder bed fusion (LPBF) is a popular additive manufacturing (AM) technique that has demonstrated the capability to produce sophisticated engineering components. This work reports the crack-free fabrication of an SS316L/IN718 bimetallic structure via LPBF, along with compositional redistribution, phase transformations and microstructural development, and nanohardness variations. Constituent intermixing after LPBF was quantitatively estimated using thermo-kinetic coefficients of mass transport and compared with the diffusivity of Ni in the austenitic Fe-Ni system.

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Zhang, Kai, Lei Wang i Xiao Feng Shang. "Evaluation of the Stability and Precision of Powder Delivery during Laser Additive Manufacturing". Applied Mechanics and Materials 380-384 (sierpień 2013): 4348–52. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.4348.

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The fabrication of metal parts is the backbone of the modern manufacturing industry. Laser forming is combination of five common technologies: lasers, rapid prototyping (RP), computer-aided design (CAD), computer-aided manufacturing (CAM), and powder metallurgy. The resulting process creates part by focusing an industrial laser beam on the surface of processing work piece to create a molten pool of metal. A small stream of powdered alloy is then injected into the molten pool to build up the part gradually. By moving the laser beam back and forth and tracing out a pattern determined by a CAD, the solid metal part is fabricated line by line, one layer at a time. By this method, a material having a very fine microstructure due to rapid solidification process can be produced. In the present work, a type of direct laser deposition process, called Laser Metal Deposition Shaping (LMDS), has been employed and developed to fabricate metal parts. In the LMDS process, the powder delivery system is an important component to perform the powder transport from powder storage box to powder nozzle, which supplies the raw material for the as-deposited metal parts. Consequently, the stability and precision of powder delivery during LMDS is essential to achieve the metal parts with high quality, so it is critical to evaluate the main factors closely related to the stability and precision of powder delivery. The shielding gas flow and the powder feeding rate were ascertained through experimental measure and formula calculation. The results prove that the suitable shielding gas flow and powder feeding rate can promote the stability and precision of powder delivery, which is the basis for the fabrication of as-deposited metal parts with flying colors.

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Ignjatović Stupar, Danijela, Grégoire Robert Chabrol, Abdoul Razak Ibrahim Baraze, Sylvain Lecler, Alexandre Tessier, Cutard Thierry i Jocelyne Brendle. "Feasibility of additive manufacturing processes for lunar soil simulants". Advanced Technologies & Materials 47, nr 1 (30.06.2022): 39–43. http://dx.doi.org/10.24867/atm-2022-1-007.

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Combination of In-situ Resource Utilization (ISRU) and on-site Additive Manufacturing (AM) is one of the “outer space applied technologies” candidates where free shape fabrication from micro (e.g., tools) to mega scale (e.g. lunar habitats) will allow in coming future to settle the Moon or potentially other celestial bodies. Within this research, Selected Laser Melting (SLM) of lunar soil (regolith) simulants (LHS-1 LMS-1 and JSC-2A) using a continuous wave 100 W 1090 nm fiber laser was applied. The resulting samples were mechanically and optically characterized. A numerical multiphysics model was developed to understand the heat transfer and optimize the SLM process. Results obtained are in good agreement with the numerical model. The physical and chemical characteristics of the various materials (granulometry, density, composition, and thermal properties) have a strong impact on the AM parameters.

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Murr, Lawrence E., Sara M. Gaytan, Diana A. Ramirez, Edwin Martinez, Jennifer Hernandez, Krista N. Amato, Patrick W. Shindo, Francisco R. Medina i Ryan B. Wicker. "Metal Fabrication by Additive Manufacturing Using Laser and Electron Beam Melting Technologies". Journal of Materials Science & Technology 28, nr 1 (styczeń 2012): 1–14. http://dx.doi.org/10.1016/s1005-0302(12)60016-4.

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Eyers, Daniel Roy, Shwe Pyi Soe i Wan Ahmad Yusmawiza. "Laser Sintering for the Fabrication of Architectural Models". Advanced Materials Research 576 (październik 2012): 637–40. http://dx.doi.org/10.4028/www.scientific.net/amr.576.637.

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Additive Manufacturing technologies are widely employed in the production of models for a range of industries. However, to-date little explicit research attention has examined the way in which the Laser Sintering technologies can be used in the specific application of architectural models. To evaluate the suitability of the process, this research develops a SWOT analysis of the Laser Sintering technologies for this application, highlighting not only the current advantages and disadvantages, but also future opportunities and threats which can be observed. From this assessment, the paper demonstrates the use of LS through the implementation of a four-stage model, supported by two examples of commercially produced architectural models.

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Du, Zhenglin, Hui-Chi Chen, Ming Jen Tan, Guijun Bi i Chee Kai Chua. "Effect of nAl2O3 on the part density and microstructure during the laser-based powder bed fusion of AlSi10Mg composite". Rapid Prototyping Journal 26, nr 4 (8.02.2020): 727–35. http://dx.doi.org/10.1108/rpj-05-2019-0136.

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Purpose In recent years, additive manufacturing techniques have attracted much research attention because of their ability to fabricate customised parts with complex geometry. The range of composites suitable for laser-based powder bed fusion technique is limited, and has not been investigated yet. This paper aims to study the fabrication of AlSi10Mg reinforced with nAl2O3 using the laser-based powder bed fusion technique. Design/methodology/approach An experimental approach was used to investigate the densification of AlSi10Mg–nAl2O3 composites using laser-based powder bed fusion technique. Optimisation of the porosity was performed, and microstructure evolution was evaluated. Findings In this study, laser volumetric energy density (approximately 109 J/mm3) was found to be required for the fabrication of AlSi10Mg–nAl2O3 composites with a relative volumetric density approximating 99%. The use of laser volumetric energy density resulted in larger grains. Columnar grain structure was observed via the use of electron backscatter diffraction mapping. Originality/value This paper examines the processing of new aluminium composite material suitable for the fabrication via the laser-based powder bed fusion technique.

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Christakopoulos, Fotis, Paul M. H. van Heugten i Theo A. Tervoort. "Additive Manufacturing of Polyolefins". Polymers 14, nr 23 (26.11.2022): 5147. http://dx.doi.org/10.3390/polym14235147.

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Polyolefins are semi-crystalline thermoplastic polymers known for their good mechanical properties, low production cost, and chemical resistance. They are amongst the most commonly used plastics, and many polyolefin grades are regarded as engineering polymers. The two main additive manufacturing techniques that can be used to fabricate 3D-printed parts are fused filament fabrication and selective laser sintering. Polyolefins, like polypropylene and polyethylene, can, in principle, be processed with both these techniques. However, the semi-crystalline nature of polyolefins adds complexity to the use of additive manufacturing methods compared to amorphous polymers. First, the crystallization process results in severe shrinkage upon cooling, while the processing temperature and cooling rate affect the mechanical properties and mesoscopic structure of the fabricated parts. In addition, for ultra-high-molecular weight polyolefins, limited chain diffusion is a major obstacle to achieving proper adhesion between adjunct layers. Finally, polyolefins are typically apolar polymers, which reduces the adhesion of the 3D-printed part to the substrate. Notwithstanding these difficulties, it is clear that the successful processing of polyolefins via additive manufacturing techniques would enable the fabrication of high-end engineering products with enormous design flexibility. In addition, additive manufacturing could be utilized for the increased recycling of plastics. This manuscript reviews the work that has been conducted in developing experimental protocols for the additive manufacturing of polyolefins, presenting a comparison between the different approaches with a focus on the use of polyethylene and polypropylene grades. This review is concluded with an outlook for future research to overcome the current challenges that impede the addition of polyolefins to the standard palette of materials processed through additive manufacturing.

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Wang, Shutong, Junjie Yang, Guoliang Deng i Shouhuan Zhou. "Femtosecond Laser Direct Writing of Flexible Electronic Devices: A Mini Review". Materials 17, nr 3 (24.01.2024): 557. http://dx.doi.org/10.3390/ma17030557.

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By virtue of its narrow pulse width and high peak power, the femtosecond pulsed laser can achieve high-precision material modification, material additive or subtractive, and other forms of processing. With additional good material adaptability and process compatibility, femtosecond laser-induced application has achieved significant progress in flexible electronics in recent years. These advancements in the femtosecond laser fabrication of flexible electronic devices are comprehensively summarized here. This review first briefly introduces the physical mechanism and characteristics of the femtosecond laser fabrication of various electronic microdevices. It then focuses on effective methods of improving processing efficiency, resolution, and size. It further highlights the typical progress of applications, including flexible energy storage devices, nanogenerators, flexible sensors, and detectors, etc. Finally, it discusses the development tendency of ultrashort pulse laser processing. This review should facilitate the precision manufacturing of flexible electronics using a femtosecond laser.

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Perera, Josage Chathura, Bhaskaran Gopalakrishnan, Prakash Singh Bisht, Subodh Chaudhari i Senthil Sundaramoorthy. "A Sustainability-Based Expert System for Additive Manufacturing and CNC Machining". Sensors 23, nr 18 (9.09.2023): 7770. http://dx.doi.org/10.3390/s23187770.

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The objective of this research study is to develop a set of expert systems that can aid metal manufacturing facilities in selecting binder jetting, direct metal laser sintering, or CNC machining based on viable products, processes, system parameters, and inherent sustainability aspects. For the purposes of this study, cost-effectiveness, energy, and auxiliary material usage efficiency were considered the key indicators of manufacturing process sustainability. The expert systems were developed using the knowledge automation software Exsys Corvid®V6.1.3. The programs were verified by analyzing and comparing the sustainability impacts of binder jetting and CNC machining during the fabrication of a stainless steel 316L component. According to the results of this study, binder jetting is deemed to be characterized by more favorable indicators of sustainability in comparison to CNC machining, considering the fabrication of components feasible for each technology.

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Reyes Donoso, Gonzalo, Magdalena Walczak, Esteban Ramos Moore i Jorge Andres Ramos-Grez. "Towards direct metal laser fabrication of Cu-based shape memory alloys". Rapid Prototyping Journal 23, nr 2 (20.03.2017): 329–36. http://dx.doi.org/10.1108/rpj-02-2016-0017.

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Purpose The purpose of this paper is to explore the possibility of producing Cu-based shape memory alloys (SMA) by means of direct metal laser fabrication (DMLF). Design/methodology/approach The fabrication approach consists of the combination of laser melting of a metallic powder with heating treatment in a controlled inert atmosphere. Three prospective Cu-Al-Ni alloy compositions were tested, and the effects of laser power, as well as laser exposure time, were verified. Findings All the processed materials were found to attain microstructures and phase change transformation temperatures typical of this type of SMA. Practical implications Further development of this technique will allow for fabrication of large elements with considerable shape memory effect, which are currently not viable due to high cost of nitinol. Originality/value This work showed a proof of concept toward the development of DMLF-based additive manufacturing of near net shape components of Cu-based SMAs from elemental powders.

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Jayakumar, Arunkumar. "An Assessment on Additive Manufacturing Technique to Fabricate Integral PEM Fuel Cell/Electrolyser Component". MATEC Web of Conferences 172 (2018): 04005. http://dx.doi.org/10.1051/matecconf/201817204005.

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Additive Manufacturing (AM) is a reliable technique to build multifunctional components with any complex geometry. The present paper assesses the role of two vital AM techniques, namely Selective Laser Sintering (SLS) and Selective Laser Melting (SLM) in the fabrication of integral Polymer Electrolyte Membrane (PEM) fuel cell/electrolyser component. Thus, the paper integrates the state-of-the-art technologies, namely additive manufacturing and fuel cell/electrolyser engineering. The US department of energy (US-DoE) target can be comprehensively accomplished for the fuel cell/electrolyser stack components in a cost-effective approach. The fundamental PEM fuel cell/electrolyser components considered in the present study are the bipolar plate and gas diffusion layer (GDL).

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Zafar, Muhammad Qasim, Jinnan Wang, Zhenlin Zhang, Chaochao Wu, Haiyan Zhao, Ghulam Hussain i Ninshu Ma. "Thermomechanical Process Simulation and Experimental Verification for Laser Additive Manufacturing of Inconel®718". Materials 16, nr 7 (24.03.2023): 2595. http://dx.doi.org/10.3390/ma16072595.

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Laser cladding has emerged as a promising technique for custom-built fabrications, remanufacturing, and repair of metallic components. However, frequent melting and solidification in the process cause inevitable residual stresses that often lead to geometric discrepancies and deterioration of the end product. The accurate physical interpretation of the powder consolidation process remains challenging. Thermomechanical process simulation has the potential to comprehend the layer-by-layer additive process and subsequent part-scale implications. Nevertheless, computational accuracy and efficacy have been serious concerns so far; therefore, a hybrid FEM scheme is adopted for efficient prediction of the temperature field, residual stress, and distortion in multilayer powder-fed laser cladding of Inconel®718. A transient material deposition with powder material modeling is schematized to replicate the fabrication process. Moreover, simulation results for residual stress and distortion are verified with in-house experiments, where residual stress is measured with XRD (X-Ray Diffraction) and geometric distortion is evaluated with CMM (Coordinate Measuring Machine). A maximum tensile residual stress of 373 ± 5 MPa is found in the vicinity of the layer right in the middle of the substrate and predicted results are precisely validated with experiments. Similarly, a 0.68 ± 0.01 mm distortion is observed with numerical simulation and showed a precise agreement with experimental data for the same geometry and processing conditions. Conclusively, the implemented hybrid FEM approach demonstrated a robust and accurate prediction of transient temperature field, residual stresses, and geometric distortion in the multilayer laser cladding of Inconel®718.

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Maboudi, M., M. Gerke, N. Hack, L. Brohmann, P. Schwerdtner i G. Placzek. "CURRENT SURVEYING METHODS FOR THE INTEGRATION OF ADDITIVE MANUFACTURING IN THE CONSTRUCTION PROCESS". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B4-2020 (25.08.2020): 763–68. http://dx.doi.org/10.5194/isprs-archives-xliii-b4-2020-763-2020.

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Abstract. The Technical University of Braunschweig (Brunswick) and Technical University of Munich were successful to establish a Collaborative Research Centre called “Additive Manufacturing in Construction (AMC) – The Challenge of Large Scale” starting from 2020 and funded by the German Research Foundation (DFG). The aim of this project is “to create the basic conditions for the introduction of additive manufacturing in construction, and thus to pave the way for the use of resource-efficient constructions with a high level of design freedom”. Surveying engineering (geodetic surveying, photogrammetry, laser scanning and GNSS) plays a major role in one of the sub-projects called “Integration of Additive Manufacturing in the Construction Process”. This paper aims at introducing the large scale AMC with the main focus on investigating the role of surveying engineering in this topic which will be a topic of high interest in the coming years in the digital fabrication within construction field. After a short introduction on additive manufacturing in construction, this paper will present the general aims and structure of the Collaborative Research Centre. Thereupon, the importance of geometric quality inspection and establishing and transferring different coordinate systems during the Additive Manufacturing (AM) construction steps (elements fabrication, installation and whole structure/building control) and the role of geodetic surveying, photogrammetry, laser scanning and GNSS will be outlined. This will be presented within a subproject called “C06: Integration of Additive Manufacturing in the Construction Process” and potentials and challenges for integrating surveying engineering in component and building level additive manufacturing in construction are mentioned.

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Belle, Stefan, Babette Goetzendorfer i Ralf Hellmann. "Challenges in a Hybrid Fabrication Process to Generate Metallic Polarization Elements with Sub-Wavelength Dimensions". Materials 13, nr 22 (22.11.2020): 5279. http://dx.doi.org/10.3390/ma13225279.

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We report on the challenges in a hybrid sub-micrometer fabrication process while using three dimensional femtosecond direct laser writing and electroplating. With this hybrid subtractive and additive fabrication process, it is possible to generate metallic polarization elements with sub-wavelength dimensions of less than 400 nm in the cladding area. We show approaches for improving the adhesion of freestanding photoresist pillars as well as of the metallic cladding area, and we also demonstrate the avoidance of an inhibition layer and sticking of the freestanding pillars. Three-dimensional direct laser writing in a positive tone photoresist is used as a subtractive process to fabricate free-standing non-metallic photoresist pillars with an area of about 850 nm × 1400 nm, a height of 3000 nm, and a distance between the pillars of less than 400 nm. In a subsequent additive fabrication process, these channels are filled with gold by electrochemical deposition up to a final height of 2200 nm. Finally, the polarization elements are characterized by measuring the degree of polarization in order to show their behavior as quarter- and half-wave plates.

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Chen, Xiao, Jie Yin, Xuejian Liu, Aidong Xia i Zhengren Huang. "Fabrication of Core-Shell Chopped Cf-Phenolic Resin Composite Powder for Laser Additive Manufacturing of Cf/SiC Composites". Polymers 13, nr 3 (1.02.2021): 463. http://dx.doi.org/10.3390/polym13030463.

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Laser additive manufacturing is a promising technique for the preparation of complex-shaped SiC composites. High-quality powders are critical for high-precision laser printing. In this work, core-shell Cf @phenolic resin (PR) composites for selective laser sintering of carbon fiber reinforced silicon carbide (Cf/SiC) composites were fabricated by surface modification using 3-aminopropyltriethoxy silane coupling agent (KH550) in combination with planetary ball milling. PR coated uniformly on the fiber surface to form a core-shell structure. The effects of PR on the morphology, elemental composition, interfacial interactions, and laser absorption of the core-shell composite powder were investigated in detail. Results indicated that the composite powder exhibited good laser absorption within the infrared band.

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Ladani, Leila, Jafar Razmi i Maryam Sadeghilaridjani. "Fabrication of Cu-CNT Composite and Cu Using Laser Powder Bed Fusion Additive Manufacturing". Powders 1, nr 4 (12.10.2022): 207–20. http://dx.doi.org/10.3390/powders1040014.

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Additive manufacturing (AM) as a disruptive technique has offered great potential to design and fabricate many metallic components for aerospace, medical, nuclear, and energy applications where parts have complex geometry. However, a limited number of materials suitable for the AM process is one of the shortcomings of this technique, in particular laser AM of copper (Cu) is challenging due to its high thermal conductivity and optical reflectivity, which requires higher heat input to melt powders. Fabrication of composites using AM is also very challenging and not easily achievable using the current powder bed technologies. Here, the feasibility to fabricate pure copper and copper-carbon nanotube (Cu-CNT) composites was investigated using laser powder bed fusion additive manufacturing (LPBF-AM), and 10 × 10 × 10 mm3 cubes of Cu and Cu-CNTs were made by applying a Design of Experiment (DoE) varying three parameters: laser power, laser speed, and hatch spacing at three levels. For both Cu and Cu-CNT samples, relative density above 90% and 80% were achieved, respectively. Density measurement was carried out three times for each sample, and the error was found to be less than 0.1%. Roughness measurement was performed on a 5 mm length of the sample to obtain statistically significant results. As-built Cu showed average surface roughness (Ra) below 20 µm; however, the surface of AM Cu-CNT samples showed roughness values as large as 1 mm. Due to its porous structure, the as-built Cu showed thermal conductivity of ~108 W/m·K and electrical conductivity of ~20% IACS (International Annealed Copper Standard) at room temperature, ~70% and ~80% lower than those of conventionally fabricated bulk Cu. Thermal conductivity and electrical conductivity were ~85 W/m·K and ~10% IACS for as-built Cu-CNT composites at room temperature. As-built Cu-CNTs showed higher thermal conductivity as compared to as-built Cu at a temperature range from 373 K to 873 K. Because of their large surface area, light weight, and large energy absorbing behavior, porous Cu and Cu-CNT materials can be used in electrodes, catalysts and their carriers, capacitors, heat exchangers, and heat and impact absorption.

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