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Investigation of rheological behaviour of 316L stainless steel-3 wt-%TiC powder injection moulding feedstock
, Article Powder Metallurgy ; Volume 48, Issue 2 , 2005 , Pages 144-150 ; 00325899 (ISSN) ; Simchi, A ; Bagheri, R ; Sharif University of Technology
2005
Abstract
The rheological behaviour of powder injection moulding feedstock comprising of 316L stainless steel and 3 wt-%TiC powders was studied using a capillary rheometer. The flowability and the sensitivity of viscosity to shear rate and temperature of the feedstock were investigated and compared with those of the binder system and the 316L SS PIM feedstock. The general rheological indexes were examined through relevant equations and the influence of TiC addition on the mouldability of the 316L SS feedstock was determined. It was found that all the feedstocks are basically pseudoplastic but the values of flow behaviour index n are influenced by the TiC addition, the solid volume fraction and the...
3-D simulation of mold filling with κ-ε turbulence modeling
, Article Proceedings of the 14th IASTED International Conference on Applied Simulation and Modelling, Benalmadena, 15 June 2005 through 17 June 2005 ; 2005 , Pages 437-442 ; 0889864691 (ISBN) ; Babaei, R ; Asgary, K ; Davami, P ; Hamza M. H ; Sharif University of Technology
2005
Abstract
In this work the SOLA-VOF method was used to solve the Navier-Stokes equations and track the free surface. For modeling the turbulence phenomena in the mold filling κ-ε model was used. In this method solving domain was discreted to three regions includes: laminar sub layer, boundary layer and internal region. The simulation results were shown to be in a good agreement with the experimental results
Investigation of vacuum annealing effects on physical-mechanical properties of thermoplastic parts
, Article Materials and Design ; Volume 26, Issue 1 , 2005 , Pages 89-93 ; 02613069 (ISSN) ; Mousavi, S ; Sharif University of Technology
Elsevier Ltd
2005
Abstract
Impact and tensile strength of polystyrene and nylon 6 samples, which have been produced by injection molding before and after annealing in different conditions are obtained. Polystyrene samples that are heated on vacuum conditions can deform highly even in temperatures much less than polystyrene glass temperature. This phenomenon is reduced significantly by heating samples to annealing temperature in atmospheric pressure and then removing air from sample environment in constant temperature. Deformation problems for nylon were not so important but due to high temperature implied for annealing of nylon parts, some color change due to oxidative degradation are observed. So for nylon parts a...
High performance Dyneema® fiber laminate for impact resistance/macro structural composites
, Article Journal of Thermoplastic Composite Materials ; Volume 25, Issue 4 , 2012 , Pages 403-414 ; 08927057 (ISSN) ; Yazdanirad, M ; Mirhabibi, A ; Sharif University of Technology
2012
Abstract
UHMWPE composite materials are increasingly used in armors design due to their high strength-to-weight ratios and energy absorption capacities. In this study the effect of production parameters upon the terminal ballistic properties of UHMWPE composite were examined under different conditionings. The composite armor plate laminates were produced by hot pressing with three different pressing times from 10-30 minutes and the laminates conditioned at +115, +125, and +135°C. The molding temperature of SK66 fiber composite has the main direct effect on the ballistic absorption energy, so the relation of molding temperature with the adhesive bonding force between layers, the thickness of the...
Plastic injection molding dies using hybrid additively manufactured 420/CX stainless steels: electrochemical considerations
, Article npj Materials Degradation ; Volume 6, Issue 1 , 2022 ; 23972106 (ISSN) ; Samei, J ; Sanjari, M ; Jahanbakht, M ; Amirkhiz, B. S ; Mohammadi, M ; Sharif University of Technology
Nature Publishing Group
2022
Abstract
This research focused on the corrosion resistance and microstructure of hybrid additively manufactured (HAM) samples of AISI 420/CX (420/CX SS) stainless steels. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott–Schottky analyses as well as the electrochemical noise (EN) technique were used to evaluate the electrochemical behavior of the as-built and heat-treated HAM parts in NaCl solution. The results showed a more protective passive layer formed on the CX SS side. The distribution of Cr-rich M23C6 carbides in matrix of 420 SS side resulted in a lower corrosion resistance compared to the CX SS side. The noise data analysis confirmed an increase in the...
Cosintering of powder injection molding parts made from ultrafine WC-Co and 316L stainless steel powders for fabrication of novel composite structures
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 41, Issue 1 , 2010 , Pages 233-241 ; 10735623 (ISSN) ; Petzoldt, F ; Sharif University of Technology
Abstract
Sintering response and phase formation during sintering of WC-Co/316L stainless steel composites produced by assembling of powder injection molding (PIM) parts were studied. It is shown that during cosintering a significant mismatch strain (>4 pct) is developed in the temperature range of 1080 °C to 1350 °C. This mismatch strain induces biaxial stresses at the interface, leading to interface delamination. Experimental results revealed that sintering at a heating rate of 20 K/min could be used to decrease the mismatch strain to <2 pct. Meanwhile, WC is decomposed at the contact area and the diffusion of C and Co into the iron lattice results in the formation of a liquid and MC and M6C...
Numerical Simulation and Optimal Design in Gating System
, M.Sc. Thesis Sharif University of Technology ; Tavakoli, Rouhollah (Supervisor) ; Davami, Parviz (Supervisor)
Abstract
A gating system is network of canals which leads molten metal to mold cavity. Fluid flow during mold filling is highly complex, involving transients, combined and divided flows at junctions, simultaneous heat transfer during fluid flow, turbulence, momentum exchange and energy loss. In case of non-uniform fluid flow at ingates, it causes week mechanical properties, and non-directional solidification. Accordingly, it cause riser insufficiency . In this Work by solving Bernoulli equations, fluid flow at each ingate was obtained and Genetic Algorithm was utilized for fluid flow optimization. Using this optimization method leads to reach to ideal design, simultaneously SUTCAST software was used...
Investigation of Resin Flow in Vacuum Infusion Process (VIP)
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor)
Abstract
The use of Vacuum Infusion Process (VIP) in some industries , to achieve optimal injection strategy is based on trial and error and it comes to the production of defective and unusable parts.The main problem is that no resin penetrate in some areas and creat dry spots and unsaturated resin regions Because of inadequate or incorrect positioning of the resin inlet and air outlet.Simulation is a powerful tool for understanding and identifying the behavior of resin flow and thereby save time and cost.In this research,in order to avoid the empirical testing of different injection techniques and avoid wasting time and cost in traditional methods of trial and error,the use of vacuum...
Flow Control in Vacuum Assisted Resin Transfer Molding
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
Vacuum assisted resin transfer molding (VARTM) is one of the most efficient and low cost process in composite industries. In this process, the preform is covered by a flexible vacuum bag and resin flows into the mold with applying vacuum pressure at the vent. The main objective in VARTM process is preventing voids and dry spots formation in final composite part because these defects may significantly deteriorate the mechanical properties of a structure. Flow front is an important parameter in this process which have a high influence on the void formation. Resin flow control is required to prevent dry spots or micro voids during the VARTM process. In general, the flow control is classified...
Asymptotic behaviour of a subwavelength nanoconducting layer
, Article Journal of Optics A: Pure and Applied Optics ; Volume 8, Issue 8 , 2006 , Pages 639-646 ; 14644258 (ISSN) ; Rashidian, B ; Sharif University of Technology
2006
Abstract
Recently, the interaction of electromagnetic waves with conducting interfaces has been studied and several applications have been proposed. In these structures a free two-dimensional interface charge layer is generated at the dielectric interfaces and interesting phenomena are observed. In this paper, the effect of finite charge layer thickness and its asymptotic behaviour towards the conducting interface, where the thin charge layer is modelled via a surface conductivity σs, is thoroughly studied for the first time. Two different regimes are considered: first, propagation of optical waves through subwavelength free charge layers and their corresponding reflection and transmission...
Three-dimensional process cycle simulation of composite parts manufactured by resin transfer molding
, Article Composite Structures ; Volume 65, Issue 3-4 , 2004 , Pages 381-390 ; 02638223 (ISSN) ; Ghaffarian, S. R ; Karimian, S. M. H ; Sharif University of Technology
2004
Abstract
A process cycle of resin transfer molding (RTM) consists of two sequential stages, i.e. filling and curing stages. These two stages are interrelated in non-isothermal processes so that the curing stage is dominated by the resin flow as well as temperature and conversion distributions during the filling stage. Therefore, it is necessary to take into account both filling and curing stages to analyze the process cycle accurately. In this paper, a full three-dimensional process cycle simulation of RTM is performed. Full three-dimensional analysis is necessary for thick parts or parts having complex shape. A computer code is developed based on the control volume/finite element method (CV/FEM)....
Biodecolourization and Biodetoxification of Dye-containing Wastewaters from Textile Dyeing by the Native Fungal Strain Phanerochaete Chrysosporium and Trametes Species
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mehdi (Supervisor) ; Mosavi, Abas (Supervisor) ; Ghobadi Nehad, Zahra (Co-Supervisor)
Abstract
Treatment of Wastewater of textile industries has been always challenging due to the high organic matter which is a suitable substrate for the growth of microorganisms. Also, discharge of wastewater into the open water causes water adsorbing more sunlight, raising water temperature and therefor decreasing dissolved oxygen. In addition, the acidity of wastewater decreases the quality of agricultural soil. Among wastewater treatment methods, biological methods are cheaper, environment friendly, and produce less by product. Among all the microorganism responsible for biological treatment, fungi and enzymes are more applicable. Especially white-rot fungi are the most effective microorganism to...
Effect of porosity variation in determination of stagnant and dispersion thermal conductivities in the resin transfer molding process
, Article Heat Transfer Research ; Volume 43, Issue 7 , 2012 , Pages 651-667 ; 10642285 (ISSN) ; Rabani, R ; Kermani, M. J ; Sharif University of Technology
2012
Abstract
A numerical analysis for determination of the stagnant and dispersion thermal conductivities in the Resin Transfer Molding (RTM) process is presented. A solution was obtained for the momentum and energy equations, which are used in this study and which represent the Brinkman- Forchheimer-extended Darcy model, and one-temperature energy equation. Subject to the appropriate boundary conditions, the governing equations are solved by the finite volume method on a collocated grid. In order to satisfy the pressure-velocity coupling in the solution, the SIMPLE algorithm was used and for determining the mass flux flowing past the cell faces, the Rhie-Chow interpolation was applied. Both constant and...
Effect of pressure on heat transfer coefficient at the metal/mold interface of A356 aluminum alloy
, Article International Communications in Heat and Mass Transfer ; Volume 39, Issue 5 , 2012 , Pages 705-712 ; 07351933 (ISSN) ; Jabbari, M ; Davami, P ; Sharif University of Technology
Abstract
The aim of this paper is to correlate interfacial heat transfer coefficient (IHTC) to applied external pressure, in which IHTC at the interface between A356 aluminum alloy and metallic mold during the solidification of casting under different pressures were obtained using the inverse heat conduction problem (IHCP) method. The method covers the expedient of comparing theoretical and experimental thermal histories. Temperature profiles obtained from thermocouples were used in a finite difference heat flow program to estimate the transient heat transfer coefficients. The new simple formula was presented for correlation between external pressure and heat transfer coefficient. Acceptable...
Thermoplastic starch/ethylene vinyl alcohol/forsterite nanocomposite as a candidate material for bone tissue engineering
, Article Materials Science and Engineering C ; Volume 69 , 2016 , Pages 301-310 ; 09284931 (ISSN) ; Bagheri, R ; Eslami, M ; Amiri, M ; Shokrgozar, M. A ; Mehrjoo, M ; Sharif University of Technology
Elsevier Ltd
Abstract
Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples,...
Numerical modeling of splashing and air entrapment in high-pressure die casting
, Article International Journal of Advanced Manufacturing Technology ; Volume 39, Issue 3-4 , 2008 , Pages 219-228 ; 02683768 (ISSN) ; Babaei, R ; Attar, E ; Shahinfar, S ; Davami, P ; Sharif University of Technology
2008
Abstract
High-pressure die casting (HPDC) is one of the most important manufacturing processes. Air porosity in HPDC parts has many serious effects upon the casting quality. A 3D single-phase code based on the SOLA-VOF algorithm is used for the continuous phase advection during mold filling. In this research, a computational model based on concentration transport equation is used for calculation of air porosity distribution and a mixed VOF-Lagrange algorithm is developed in order to model splashing in HPDC. Finally, Schmid's experimental tests are used to verify the modelling results and the comparison between the experimental data and simulation results has shown a good agreement. © 2007...
Improved advection algorithm of computational modeling of free surface flow using structured grids
, Article Computer Methods in Applied Mechanics and Engineering ; Volume 195, Issue 7-8 , 2006 , Pages 775-795 ; 00457825 (ISSN) ; Abdollahi, J ; Homayonifar, P ; Varahram, N ; Davami, P ; Sharif University of Technology
2006
Abstract
In the present study a finite difference method has been developed to model the transient fluid flow and heat transfer. A single fluid has been selected for modeling of mold filling and The SOLA-VOF 3D technique was modified to increase the accuracy of simulation of filling phenomena for shape castings. The model was then evaluated with the experimental methods. Refereeing to the experimental and simulation results a good consistency and the accuracy of the suggested model are confirmed. © 2005 Published by Elsevier B.V
Study the sintering behavior of nanocrystalline 3Y-TZP/430L stainless-steel composite layers for co-powder injection molding
, Article Journal of Materials Science ; Volume 44, Issue 5 , 2009 , Pages 1264-1274 ; 00222461 (ISSN) ; Simchi, A ; Sharif University of Technology
2009
Abstract
Recently, co-powder injection molding process (2C-PIM) has attained considerable interest to fabricate complex-shaped functional materials. The aim of this work is to study the sintering compatibility between nanocrystalline yttria-stabilized zirconia (3Y-TZP) and PIM grade 430L stainless steel (SS) powders, which is the utmost important step in the 2C-PIM process. To evaluate the mismatch strain development during the co-sintering, the isothermal and nonisothermal behaviors of the ceramic and metal powders were studied. Small bilayers of 3Y-TZP/430L were made by a powder metallurgy technique and the feasibility of simultaneous sintering and joining of the composite layer was examined....
Numerical Modeling of Vacuum Assisted Resin Transfer Moulding
, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim (Supervisor) ; Taheri, Bahram (Co-Advisor)
Abstract
Here, we have simulated isothermal vacuum assisted resin transfer moulding (VARTM) using a control volume/finite element scheme. Two dimensional and dimensional (shell geometries) spatial discretization is used. Resin motion through fibers is enforced by vacuum negative pressure in downstream. The governing equations are mass conservation and well known Darcy equation. Using an unstructured triangular grid, complex geometries could be modelled. Application of a quasi-steady algorithm results in a system of linear equation for pressure distribution. This system must be solved in each time step. The point successive over-relaxation (PSOR) scheme is used to solve the system of linear...
Studying of Laccase Immobilization on Nanoparticles for Bisphenol A Removal
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mehdi (Supervisor) ; Ghobadi Nejad, Zahra (Co-Supervisor)
Abstract
Bisphenol A is one of Endocrine Disturbing Chemicals. Enzymatic removal of bisphenol A is an interesting and green method. However, application of enzymes has been hampered due to lower operational stability and lots of difficulties in recovery and recycling. Enzyme immobilization can ba an innovative approach to circumvent these drawbacks. Laccase from Trametes hirsuta used for Bisphenol A removal. Firstly, magnetic nanoparticles were synthesized by coprecipitation method and aminofunctionalized by (3-aminopropyl)-mmethoxysilane. Subsequently, laccase was precipitated with i-propanol in the presence of aminofunctionalized nanoparticles and followed by addition of glutaraldehyde to the final...