Loading...
Search for:
3d-printers
0.007 seconds
Total 36 records
Shear band propagation in honeycombs: numerical and experimental
, Article Rapid Prototyping Journal ; Volume 24, Issue 2 , 2018 , Pages 477-484 ; 13552546 (ISSN) ; Bagheri, R ; Altstadt, V ; Sharif University of Technology
Emerald Group Publishing Ltd
2018
Abstract
Purpose: Hexagonal honeycombs with meso-metric cell size show excellent load bearing and energy absorption potential, which make them attractive in many applications. However, owing to their bend-dominated structure, honeycombs are susceptible to deformation localization. The purpose of this study is to provide insight about shear band propagation in struts of 3D-printed honeycombs and its relation to the achieved macroscopic mechanical behavior. Design/methodology/approach: Hexagonal honeycombs and unit cell models are 3D-printed by fused deposition modeling (FDM). The samples are exposed to compression loading and digital image correlation technique and finite element analyses are...
Production and characterization of Ti6Al4V/CaP nanocomposite powder for powder-based additive manufacturing systems
, Article Powder Technology ; Volume 386 , 2021 , Pages 319-334 ; 00325910 (ISSN) ; Ekrami, A ; Badrossamay, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Ti64/CaP nanocomposite powder was fabricated and characterized for use in powder-bed 3D printing. The microstructure and phase composition, morphology, particle size distribution, sphericity, flow behavior and dispersion of the as-fabricated particles on the building plate of the 3D printer were investigated. The results confirmed a uniform distribution of nanostructured calcium phosphate particles on the surface of primary Ti64 ones. Calcium phosphate appears as an octa-calcium phosphate phase. The morphology of the particles was shown as spherical, and their sphericity was better than the as-received Ti64 particles. The particle size distribution of nanocomposite powder indicated a smaller...
Pore structure evolution during sintering of HDPE particles
, Article Polymer ; Volume 183 , 2019 ; 00323861 (ISSN) ; Pircheraghi, G ; Foudazi, R ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Sintering is a processing technique in which loose particles consolidate at elevated temperatures to form porous monoliths. Sintering is also a critical stage in recent additive manufacturing method like selective laser sintering. In this study, using an affordable alternative to X-ray tomography technique, we analyze the pore structure evolution in sintered parts made of nascent high-density polyethylene (HDPE) particles in terms of pore surface genus and pore surface curvature. Also, we investigate the underlying microstructural development and macroscopic properties of sintered parts. It is observed that pore structure and macroscopic permeability are strongly influenced by the...
Plasticity in polymeric honeycombs made by photo-polymerization and nozzle based 3D-printing
, Article Polymer Testing ; Volume 63 , 2017 , Pages 163-167 ; 01429418 (ISSN) ; Bagheri, R ; Avila Gray, L ; Altstädt, V ; Drechsler, K ; Sharif University of Technology
Abstract
Study of the plastic deformation in polymeric honeycombs can pave the way for understanding the deformation localization in more complex cellular structures, which have received progressive attention in the past few years. This study compares the strain localization in deforming honeycombs made by two cost-effective 3D-printing technologies. Hexagonal honeycombs and their unit cell models were 3D-printed by both PolyJet™, using a photo-crosslinkable polymer, and fused deposition modeling (FDM) using a thermoplastic material. The state of the art digital image correlation (DIC) technique was employed as the experimental route in order to calculate the strain field during the deformation of...
Numerical and analytical simulation of multilayer cellular scaffolds
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 42, Issue 5 , 2 May , 2020 ; Rahmati, S ; Nikkhoo, M ; Haghpanahi, M ; Akbari, J ; Sharif University of Technology
Springer
2020
Abstract
Due to the advent and maturity of the additive manufacturing technology, it is possible now to construct complex microstructures with unprecedented accuracy. In addition, to the influence of network unit cell types and porosities in recent years, researchers have studied the number of scaffold layers fabricated by additive manufacturing on mechanical properties. The objective of this paper is to assess the numerical and analytical simulations of the multilayer scaffolds. For this purpose, 54 different regular scaffolds with a unit cell composed of multilayer scaffolds were simulated under compressive loading and compared with the analytical relationships based on the Euler–Bernoulli and...
Nanomedicine and advanced technologies for burns: Preventing infection and facilitating wound healing
, Article Advanced Drug Delivery Reviews ; Volume 123 , 2018 , Pages 33-64 ; 0169409X (ISSN) ; Sahandi Zangabad, P ; Moosavi Basri, S. M ; Sahandi Zangabad, K ; Ghamarypour, A ; Aref, A. R ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
Elsevier B.V
2018
Abstract
According to the latest report from the World Health Organization, an estimated 265,000 deaths still occur every year as a direct result of burn injuries. A widespread range of these deaths induced by burn wound happens in low- and middle-income countries, where survivors face a lifetime of morbidity. Most of the deaths occur due to infections when a high percentage of the external regions of the body area is affected. Microbial nutrient availability, skin barrier disruption, and vascular supply destruction in burn injuries as well as systemic immunosuppression are important parameters that cause burns to be susceptible to infections. Topical antimicrobials and dressings are generally...
Multi-criteria optimization of the part build orientation (PBO) through a combined meta-modeling/NSGAII/TOPSIS method for additive manufacturing processes
, Article International Journal on Interactive Design and Manufacturing ; 2017 , Pages 1-15 ; 19552513 (ISSN) ; Golmohammadi, A. H ; Sharif University of Technology
Abstract
Additive manufacturing (AM), is a new technology for the manufacturing of the physical parts through an additive manner. In the AM process, the orientation pattern of the part is an important variable that significantly influences the product properties such as the build time, the surface roughness, the mechanical strength, the wrinkling, and the amount of support material. The build time and the surface roughness are the more important criteria than others that can be considered to find the optimum orientation of parts. The designers and manufacturing engineers usually attempt to find an optimum solution to reach the product with high quality at the minimum time. Determining the optimum...
Multi-criteria optimization of the part build orientation (PBO) through a combined meta-modeling/NSGAII/TOPSIS method for additive manufacturing processes
, Article International Journal on Interactive Design and Manufacturing ; Volume 12, Issue 3 , 2018 , Pages 1071-1085 ; 19552513 (ISSN) ; Golmohammadi, A. H ; Sharif University of Technology
Springer-Verlag France
2018
Abstract
Additive manufacturing (AM), is a new technology for the manufacturing of the physical parts through an additive manner. In the AM process, the orientation pattern of the part is an important variable that significantly influences the product properties such as the build time, the surface roughness, the mechanical strength, the wrinkling, and the amount of support material. The build time and the surface roughness are the more important criteria than others that can be considered to find the optimum orientation of parts. The designers and manufacturing engineers usually attempt to find an optimum solution to reach the product with high quality at the minimum time. Determining the optimum...
Microfluidic-assisted fiber production: Potentials, limitations, and prospects
, Article Biomicrofluidics ; Volume 16, Issue 6 , 2022 ; 19321058 (ISSN) ; Nilghaz, A ; Saadatmand, M ; Naeimirad, M ; Demello, A. J ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
Besides the conventional fiber production methods, microfluidics has emerged as a promising approach for the engineered spinning of fibrous materials and offers excellent potential for fiber manufacturing in a controlled and straightforward manner. This method facilitates low-speed prototype synthesis of fibers for diverse applications while providing superior control over reaction conditions, efficient use of precursor solutions, reagent mixing, and process parameters. This article reviews recent advances in microfluidic technology for the fabrication of fibrous materials with different morphologies and a variety of properties aimed at various applications. First, the basic principles, as...
Microengineered poly(HEMA) hydrogels for wearable contact lens biosensing
, Article Lab on a Chip ; Volume 20, Issue 22 , 2020 , Pages 4205-4214 ; Zhang, S ; Cui, Q ; Ni, J ; Wang, X ; Cheng, X ; Alem, H ; Tebon, P ; Xu, C ; Guo, C ; Nasiri, R ; Moreddu, R ; Yetisen, A. K ; Ahadian, S ; Ashammakhi, N ; Emaminejad, S ; Jucaud, V ; Dokmeci, M.R ; Khademhosseini, A ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
Microchannels in hydrogels play an essential role in enabling a smart contact lens. However, microchannels have rarely been created in commercial hydrogel contact lenses due to their sensitivity to conventional microfabrication techniques. Here, we report the fabrication of microchannels in poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels that are used in commercial contact lenses with a three-dimensional (3D) printed mold. We investigated the corresponding capillary flow behaviors in these microchannels. We observed different capillary flow regimes in these microchannels, depending on their hydration level. In particular, we found that a peristaltic pressure could reinstate flow in...
Hybrid anisotropic pentamode mechanical metamaterial produced by additive manufacturing technique
, Article Applied Physics Letters ; Volume 117, Issue 6 , 2020 ; Movahhedy, M. R ; Shishkovsky, I ; Hedayati, R ; Sharif University of Technology
American Institute of Physics Inc
2020
Abstract
Pentamode metamaterials are a type of extremal designer metamaterials, which are able to demonstrate extremely high rigidity in one direction and extremely high compliance in other directions. Pentamodes can, therefore, be considered as building blocks of exotic materials with any arbitrarily selected thermodynamically admissible elasticity tensor. The pentamode lattices can then be envisioned to be combined to construct intermediate extremal materials, such as quadramodes, trimodes, and bimodes. In this study, we constructed several primary types of anisotropic pentamode lattices (with midpoint positioning of 10%, 15%, 20%, 25%, 30%, 35%, and 42% of the main unit cell diagonal) and then...
Flexible flow line scheduling considering machine eligibility in a digital dental laboratory
, Article International Journal of Production Research ; Volume 58, Issue 21 , 2020 , Pages 6513-6531 ; Fatahi Valilai, O ; Houshmand, M ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Introduction of digital solutions has made dentistry more efficient and effective in response to patients’ demands. Moreover, digital solution helps participants to manage daily workflow simpler than traditional practices. Scanners, CAD/CAM software, CNC machines and 3D printers are components of digital solutions in current dentistry. Responding to patients as quickly as possible is essential in medical fields and dentistry has similar situations. On the other hand, demands in dentistry are highly customized that it makes managing orders more difficult because each order needs special design and production. Thus, this paper assesses orders in digital dentistry and develops a mathematical...
Ferrofluid droplet formation from a nozzle using alternating magnetic field with different magnetic coil positions
, Article Journal of Magnetism and Magnetic Materials ; Volume 498 , 2020 ; Bijarchi, M. A ; Shafii, M. B ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Ferrofluid has been used in many fields, such as microfluidics, droplet formation, and heat transfer, due to its potential to be attracted in the presence of a magnetic field. Droplet formation, itself, has many applications such as emulsions, 3D micro-printers, MEMS, and electro-sprays. In this study, the mechanism of ferrofluid droplet formation from the nozzle in the presence of an alternating magnetic field was investigated. The magnetic coil was fixed at different angles with respect to gravity and the effect of the alternating magnetic field and the angle of the magnetic coil axis with respect to gravity on the produced droplet volume, satellite droplet, and droplet formation frequency...
Fabrication of porosity-graded biocompatible structures by 3D printing of Co-Cr-Mo alloy
, Article European Powder Metallurgy Congress and Exhibition, Euro PM 2007, Toulouse, 15 October 2007 through 17 October 2007 ; Volume 3 , 2007 , Pages 255-260 ; 9781899072293 (ISBN) ; Simchi, A ; Godlinski, D ; Sharif University of Technology
European Powder Metallurgy Association (EPMA)
2007
Abstract
Manufacturing of complex-shaped bimetals utilizing two-color powder injection molding (2C-PIM) and three-dimensional printing (3DP) processes, which basically involve sintering of a powder/binder mixture, has been attracted a great interest. This article addresses sintering of biocompatible Co-Cr-Mo alloy for manufacturing stepwise porosity-graded composite structures. Such composite structures provide strength at the core and a porous layer for the tissue growth. To evaluate the process, two grades of gas atomized Co-Cr-Mo powder with an average particle size of 19 and 63 μm were used. Isothermal and nonisothermal sintering behavior of the loose powders under hydrogen and argon atmospheres...
Fabrication of hierarchically porous silk fibroin-bioactive glass composite scaffold via indirect 3D printing: Effect of particle size on physico-mechanical properties and in vitro cellular behavior
, Article Materials Science and Engineering C ; Volume 103 , 2019 ; 09284931 (ISSN) ; Alemzadeh, I ; Tamjid, E ; Khafaji, M ; Vossoughi, M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In order to regenerate bone defects, bioactive hierarchically scaffolds play a key role due to their multilevel porous structure, high surface area, enhanced nutrient transport and diffusion. In this study, novel hierarchically porous silk fibroin (SF) and silk fibroin-bioactive glass (SF-BG) composite were fabricated with controlled architecture and interconnected structure, by combining indirect three-dimensional (3D) inkjet printing and freeze-drying methods. Further, the effect of 45S5 Bioactive glass particles of different sizes (<100 nm and 6 μm) on mechanical strength and cell behavior was investigated. The results demonstrated that the hierarchical structure in this scaffold was...
Fabrication of a highly ordered hierarchically designed porous nanocomposite via indirect 3D printing: Mechanical properties and in vitro cell responses
, Article Materials and Design ; Volume 88 , 2015 , Pages 924-931 ; 02641275 (ISSN) ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Design and development of biodegradable scaffolds with highly uniform and controlled internal structure that stimulate tissue regeneration are the focus of many studies. The aim of this work is to apply a modified three-dimensional (3D) printing process to fabricate polymer-matrix composites with controlled internal architecture. Computationally-designed plaster molds with various pore sizes in the range of 300-800. μm were prepared by employing 3D printing of a water-based binder. The molds were converted to ε-polycaprolactone (PCL) and PCL/bioactive glass (BG) composite scaffolds by solvent casting and freeze drying methods. Optical and electron microscopy studies revealed that the pore...
Evaluation of a polymer-steel laminated sheet composite structure produced by friction stir additive manufacturing (FSAM) technology
, Article Polymer Testing ; Volume 90 , 2020 ; Khodabakhshi, F ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Laminated polymer-steel composites are promising layered materials for practical applications in the automotive industry considering their superior crush resistance capacity in terms of enhanced damping potential. In this research, the sheet lamination (SL) route of friction stir additive manufacturing (FTAM) technology was implemented for the production of a poly-methyl-methacrylate (PMMA) polymer matrix composite structure as reinforced by textile stainless steel layers, and feeding of PMMA granulates inside the stirred region. Layers bonding and the soundness of composite formation during fabrication of the laminated structure were studied. Possible chemical interactions between the steel...
Effects of plate contouring quality on the biomechanical performance of high tibial osteotomy fixation: A parametric finite element study
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 236, Issue 3 , 2022 , Pages 356-366 ; 09544119 (ISSN) ; Farahmand, F ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
Locking plates have threaded holes, in which threaded-head screws are affixed. Hence, they do not need to be in intimate contact with underlying bone to provide fixation. There are, however, reports that a large distance between the plate and the bone might cause clinical complications such as delayed union or nonunion, screw pull out, and screw and plate breakage. Considering the diversity in the capabilities and costs of different plate customization techniques, the purpose of this study was to investigate the effect of the plate contouring quality on the biomechanical performance of high tibial osteotomy (HTO) fixation. A finite element model of proximal tibia was developed in Abaqus,...
Effect of laser additive manufacturing parameters on hardness and geometry of Inconel 625 parts manufactured by direct laser metal deposition
, Article Optik ; Volume 249 , 2022 ; 00304026 (ISSN) ; Akbari, J ; Moradi, M ; Malekshahi Beiranvand, Z ; Sharif University of Technology
Elsevier GmbH
2022
Abstract
This research investigates the effect of process parameters on the geometry and properties of In625 parts, manufactured by the direct laser metal deposition (DLMD) process. For this purpose, eight parts, consisting of 5 layers on top of each other, were manufactured, and the effect of laser power, laser focal plane position, and scanning speed on the height, width, and surface smoothness of each of them was investigated using design of experiment (DOE). The experimental results showed that the height of the parts manufactured by 800 W/mm and 200 W/mm of energy density is 3.69 mm and 6.12 mm, respectively. The thickness of the parts manufactured by 80 W/mm and 200 W/mm of energy density is...
Effect of building direction on high strain-rate compressive behavior of heat-treated LPBF-maraging steels using Split Hopkinson pressure bar apparatus
, Article Materials Science and Engineering A ; Volume 835 , 2022 ; 09215093 (ISSN) ; Pirgazi, H ; Sanjari, M ; Seraj, P ; Odeshi, A ; Kestens, L. A. I ; Mohammadi, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Rod-shaped samples of maraging steel were additively fabricated in vertical and horizontal directions using laser powder bed fusion technique. The samples were first aged at 490 °C for 6 h and then subjected to dynamic compressive tests using Split Hopkinson Pressure Bar apparatus. The dynamic compression tests were conducted on vertical samples at strain rates of 190, 460, 810, 1100, 1300 s−1. However, the high strain rate tests were performed at strain rates of 120, 615, 745, 890, 2200 s−1 on horizontal samples. After applying the compressive impact loads on the samples, it was found that although horizontally built samples exhibit higher dynamic strength, vertically built samples show...