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3D Bioprinting of oxygenated cell-laden gelatin methacryloyl constructs
, Article Advanced Healthcare Materials ; Volume 9, Issue 15 , 2020 ; Darabi, M. A ; Nasiri, R ; Sangabathuni, S ; Ertas, Y. N ; Alem, H ; Hosseini, V ; Shamloo, A ; Nasr, A. S ; Ahadian, S ; Dokmeci, M. R ; Khademhosseini, A ; Ashammakhi, N ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
Cell survival during the early stages of transplantation and before new blood vessels formation is a major challenge in translational applications of 3D bioprinted tissues. Supplementing oxygen (O2) to transplanted cells via an O2 generating source such as calcium peroxide (CPO) is an attractive approach to ensure cell viability. Calcium peroxide also produces calcium hydroxide that reduces the viscosity of bioinks, which is a limiting factor for bioprinting. Therefore, adapting this solution into 3D bioprinting is of significant importance. In this study, a gelatin methacryloyl (GelMA) bioink that is optimized in terms of pH and viscosity is developed. The improved rheological properties...
A framework for multi-objective optimisation of 3D part-build orientation with a desired angular resolution in additive manufacturing processes
, Article Virtual and Physical Prototyping ; Volume 14, Issue 1 , 2019 , Pages 19-36 ; 17452759 (ISSN) ; Khodaygan, S ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
In additive manufacturing processes, the part build orientation (PBO) is one of the most important factors that can affect the characteristics of the quality product such as the amount of support structure and the surface roughness. In most previous methods, the optimal PBO cannot be determined with high precision and accuracy in 3D space. In this paper, to find the precise and accurate optimal PBO with a desired angular accuracy, a new Taguchi-based method, called the Zooming-Taguchi method, is proposed. The proposed simulation-based method can precisely find the optimal PBO in absence of the noise effects. In order to find the optimal PBO with the desired angular resolution, the zooming...
An efficient scanning algorithm for improving accuracy based on minimising part warping in selected laser sintering process
, Article Virtual and Physical Prototyping ; Volume 14, Issue 1 , 2019 , Pages 59-78 ; 17452759 (ISSN) ; Movahhedy, M. R ; Khodaygan, S ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
In the selective laser sintering (SLS) method, layers of powder are scanned by a laser beam and sintered. The thermal gradients created by laser heating and the subsequent cooling of the sintered sections results in thermal stresses and part warping in the final part. Thermal gradients are dependent on the scanning algorithm, in particular, the scan vector length. In this work, an efficient scanning algorithm for the SLS process is presented with the aim to minimise the part warping in the final part due to thermally induced residual stresses, while maintaining the production time at a minimum. The proposed algorithm is implemented in a finite element simulation and scanning parameters...
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...
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...
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...
Depicting additive manufacturing from a global perspective; Using Cloud manufacturing paradigm for integration and collaboration
, Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 229, Issue 12 , September , 2015 , Pages 2216-2237 ; 09544054 (ISSN) ; Houshmand, M ; Sharif University of Technology
SAGE Publications Ltd
2015
Abstract
Globalization is one of the widely considered factors in today's manufacturing industries. This paradigm may be adopted for new technologies such as additive manufacturing. Additive manufacturing has been identified as an innovative manufacturing technology in recent years. The characteristics of this manufacturing technology, especially its support for quick design to manufacturing, have dominated it as an efficient generation of manufacturing techniques for today's global manufacturing paradigm. This article discusses the requirements and necessities of additive manufacturing with respect to a globalized perspective. Considering the two major requirements studied as integration of...
Design and characterization of an orthotropic accordion cellular honeycomb as one-dimensional morphing structures with enhanced properties
, Article Journal of Sandwich Structures and Materials ; Volume 24, Issue 3 , 2022 , Pages 1726-1745 ; 10996362 (ISSN) ; Ashrafian, M. M ; Fotouhi, M ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
This study develops the governing equations and characterizes the mechanical properties of a new orthotropic accordion morphing honeycomb structure containing periodic arrays of U-type beams reinforced with glass fibers. Castigliano’s second theorem is modified to develop the analytical equations to predict the deformation behavior of a single orthotropic ply under a combined axial, bending, and shear loadings. Accordingly, the elastic properties of the orthotropic structure including elastic stiffness, shear stiffness, and in-plane Poisson’s ratios are calculated by the developed equations. The honeycomb structure is manufactured by 3D printing, and the samples are subjected to tensile...
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,...
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...
An autonomous framework for interpretation of 3D objects geometric data using 2D images for application in additive manufacturing
, Article PeerJ Computer Science ; Volume 7 , 2021 , Pages 1-32 ; 23765992 (ISSN) ; Houshmand, M ; Valilai, O. F ; Sharif University of Technology
PeerJ Inc
2021
Abstract
Additive manufacturing, artificial intelligence and cloud manufacturing are three pillars of the emerging digitized industrial revolution, considered in industry 4.0. The literature shows that in industry 4.0, intelligent cloud based additive manufacturing plays a crucial role. Considering this, few studies have accomplished an integration of the intelligent additive manufacturing and the service oriented manufacturing paradigms. This is due to the lack of prerequisite frameworks to enable this integration. These frameworks should create an autonomous platform for cloud based service composition for additive manufacturing based on customer demands. One of the most important requirements of...
A 3D-printed hybrid nasal cartilage with functional electronic olfaction
, Article Advanced Science ; Volume 7, Issue 5 , 2020 ; Kiaee, K ; Vela Jarquin, D ; De la Garza Hernández, R. L ; Wang, T ; Joshi, S ; Rezaei, Z ; de Melo, B. A. G ; Ge, D ; Mannoor, M. S ; Shin, S. R ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
Advances in biomanufacturing techniques have opened the doors to recapitulate human sensory organs such as the nose and ear in vitro with adequate levels of functionality. Such advancements have enabled simultaneous targeting of two challenges in engineered sensory organs, especially the nose: i) mechanically robust reconstruction of the nasal cartilage with high precision and ii) replication of the nose functionality: odor perception. Hybrid nasal organs can be equipped with remarkable capabilities such as augmented olfactory perception. Herein, a proof-of-concept for an odor-perceptive nose-like hybrid, which is composed of a mechanically robust cartilage-like construct and a biocompatible...
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...
Advanced steel powder for direct metal laser sintering
, Article European Powder Metallurgy Congress and Exhibition, Euro PM 2005, Prague, 2 October 2005 through 5 October 2005 ; Volume 3 , 2005 , Pages 35-40 ; 9781899072187 (ISBN) ; Pohl, H ; Simchi, A ; Alcantara, B ; Sharif University of Technology
European Powder Metallurgy Association (EPMA)
2005
Abstract
Recent advances in material issues for Direct Metal Laser Sintering (DMLS) process are presented. The concept is to decrease the powder particle size with the aim of enhancing the sintering kinetics and improving the surface quality of the produced parts. The outcome is particularly suitable for overcoming existing limitations with the rapid tooling, e.g. manufacturing of mould inserts for injection moulding and die casting, by the DMLS process. The powder composition was adapted near to the conventional P/M steels in order to get identical properties with a favourable price. Such novel powder material provides an opportunity to considerably reduce the product development time for P/M...
Direct metal laser sintering of Fe-C-Cu steel powder
, Article European Powder Metallurgy Congress and Exhibition, Euro PM 2005, Prague, 2 October 2005 through 5 October 2005 ; Volume 3 , 2005 , Pages 41-47 ; 9781899072187 (ISBN) ; Petzoldt, F ; Pohl, H ; European Powder Metallurgy Association ; Sharif University of Technology
European Powder Metallurgy Association (EPMA)
2005
Abstract
Cu-alloyed sintered steels are one of the main product groups in ferrous powder metallurgy (P/M). To expand the application of P/M technology to different sectors of industry and to create new market, it is believed that rapid prototyping and short serial production of sintered parts for functional testing is important. In the present work, rapid prototyping of sintered Fe-C-Cu steel powders by direct metal laser sintering (DMLS) process was studied. Fe, Fe-0.8%C, Fe-2%Cu, Fe-4%Cu, Fe-0.8%C-2%Cu-0.35%P powders were laser sintered in widely varying conditions. The densification and microstructural features of the sintered parts were evaluated. The results revealed that rapid prototyping of...
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...
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...
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...
Additive manufacturing of Ti–6Al–4V parts through laser metal deposition (LMD): Process, microstructure, and mechanical properties
, Article Journal of Alloys and Compounds ; Volume 804 , 2019 , Pages 163-191 ; 09258388 (ISSN) ; Colera, X. G ; Mirzaali, M. J ; Sovizi, S ; Bartolomeu, F ; St Weglowski, M. K ; Wits, W. W ; Yap, C. Y ; Ahn, J ; Miranda, G ; Silva, F. S ; Madaah Hosseini, H. R ; Ramakrishna, S ; Zadpoor, A. A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
As one of the most important additive manufacturing (AM) techniques, laser metal deposition (LMD) has been extensively studied specially during the last few years. Similar to other AM techniques, the quality of LMD parts is highly dependent on the processing parameters that need to be optimized so as to obtain geometrically accurate parts as well as favorable microstructures and, thus, mechanical properties. The present review paper therefore aims to present a critical analysis and overview of the relationship between processing parameters, microstructure, and mechanical properties of LMD components made from the Ti–6Al–4V alloy. Moreover, we discuss the applications of LMD parts in the...
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...