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    A numerical investigation on the cure cycle of composite brake blocks

    , Article International Polymer Processing ; Volume 21, Issue 4 , 2006 , Pages 421-431 ; 0930777X (ISSN) Shojaei, A ; Sharif University of Technology
    Carl Hanser Verlag  2006
    Composite friction materials used in the braking system of vehicles are composed of different ingredients (typically up to 20 materials). The overall physical properties of these products are determined by the type and percentage of the individual ingredients in the final composition and consequently, may differ from one product to another. This paper studies the cure characteristics of railroad composite brake blocks during compression molding. Numerical simulations using the control volume/finite element method (CV/FEM) are utilized to predict temperature fields and cure conversion during the process. As railroad brake blocks are normally thick-sectioned parts, a three-dimensional modeling... 

    A quick proof of the 1, 2, 4, 8 theorem

    , Article Expositiones Mathematicae ; Volume 33, Issue 3 , 2015 , Pages 375-377 ; 07230869 (ISSN) Mahmoudi, M. G ; Sharif University of Technology
    Elsevier GmbH  2015

    Si/Si, Si/SiO2 and SiO2/SiO2 fusion wafer bonding

    , Article Scientia Iranica ; Volume 10, Issue 4 , 2003 , Pages 477-480 ; 10263098 (ISSN) Motieifar, A ; Rashidian, B ; Sharif University of Technology
    Sharif University of Technology  2003
    The wafer bonding process has many applications in the fabrication of microelectronic, optoelectronic, power and micromachined devices. In this article, fusion bonding of silicon wafers and study of their interface are reported for the first time in Iran. Also, the bonding of two silicon wafers, with one (or both) of the wafers having a thermally grown silicon dioxide layer, has been performed and tested. © Sharif University of Technology, October 2003  

    High performance of finite element method applied to plastic analysis of reinforced materials with application in optoelectronic devices

    , Article Journal of Optoelectronics and Advanced Materials ; Volume 17, Issue 9-10 , 2015 , Pages 1545-1548 ; 14544164 (ISSN) Monfared, V ; Daneshmand, S ; Fazaeli, D ; Sharif University of Technology
    National Institute of Optoelectronics  2015
    Finite element analysis of creeping short fiber composites is carried out in the second stage creep with application in microelectronic and optoelectronic/photonic devices. Prediction of the creep behavior is very significant for designing the optoelectronic and photonic composites with optical fibers. Study on the creep behavior is necessary for failure, fracture, fatigue, and creep resistance of the optoelectronic/photonic composites. The creep behavior of the short fiber composites is estimated by FEM. Study on the creep behavior is necessary for defect analysis and creep resistance of the short fiber composites. In this research work, prediction of the creep behavior of the short fiber... 

    Hybrid PP-EPR-GF composites. Part II: Fracture mechanisms

    , Article Plastics, Rubber and Composites ; Volume 32, Issue 10 , 2003 , Pages 439-444 ; 14658011 (ISSN) Zebarjad, S. M ; Bagheri, R ; Lazzeri, A ; Sharif University of Technology
    The fracture mechanism of hybrid iPP-EPR-GF composites has been studied by notched Charpy, three- and four-point bending fracture tests. The results of impact tests illustrate that increasing both temperature and EPR/GF ratio increases the impact energy of iPP-EPR-GF. Indeed, with increasing temperature, a brittle, ductile, transition temperature (BDTT) occurs. The results of a three-point bending test show that fracture toughness (KIC) can be improved by addition of both GF and EPR. Since the trend in the fracture toughness values is close to what would be expected by the rule of blends, it can be concluded that the use of both GF and EPR has no significant synergistic effect on toughening.... 

    Investigation of deformation mechanism in polypropylene/glass fiber composite

    , Article Journal of Applied Polymer Science ; Volume 87, Issue 13 , 2003 , Pages 2171-2176 ; 00218995 (ISSN) Zebarjad, S. M ; Bagheri, R ; Seyed Reihani, S. M ; Forunchi, M ; Sharif University of Technology
    A great amount of work has been done over the past few years to understand the structure-properties relationship in polypropylene/glass fiber composites. This is because of the very fast-growing rate of polypropylene applications in the automotive and other industries. This work focused on the role of glass fibers and fiber-matrix adhesion on deformation mechanism. Composites with different fiber content, with and without adhesion promoter, were fabricated. Tensile tests and microscopy techniques were conducted. Based on the results, a physical model has been proposed that illustrates the initiation and growth of the damage under static loading condition. According to this work, the... 

    Corrosion Behavior of Electroless Ni-B-TiO2 Composite Coatings

    , M.Sc. Thesis Sharif University of Technology Niksefat, Vahid (Author) ; Ghorbani, Mohammad (Supervisor)
    Usage of electroless Ni-B coatings as coatings with super hardness and wear resistance has been increased widely, but these coatings have low resistance to corrosion.In this project, in order to increase resistance to corrosion, titania powder of szie 200 to 300 nanometers is added to Ni-B coatings to make a composite coating of Ni-B-TiO2 that has better corrosion properties compared to Ni-B coatings. Ultrasonic use for creating composite coatings of Ni-B-TiO2 and the optimum ultrasonic and electroless bath conditions for creating optimum coating in terms of corrosion resistance are determined. These optimum conditions are as follows: speed of 300 rpm for substrate circulation in bath, 250 W... 

    Microstructural characterization of HIP consolidated NiTi–nano Al2O3 composites [electronic resource]

    , Article Journal of Alloys and Compounds ; 5 September 2014, Volume 606, Pages 21–26 Farvizi, M ; Ebadzadeh, T ; Vaezi, M. R ; Yoon, E. Y ; Kim, Y. J ; Kim, H. S ; Simchi, A. (Abdolreza) ; Sharif University of Technology
    The microstructure and phase transformational behavior of NiTi-based composites reinforced with 6 wt.% of α-alumina nanoparticles have been investigated. Two kinds of starting materials, elemental Ni–Ti and prealloyed austenitic NiTi, were used to prepare the composites. The samples were consolidated using a hot isostatic pressing method. The X-ray diffraction results showed that while unreinforced NiTi mainly contained B2 phase at room temperature, martensitic B19′ phase appeared in the microstructure after addition of the α-alumina nanoparticles. The differential scanning calorimetry measurements indicated that the martensitic transformation temperatures were elevated in the composite... 

    Interface formation and bond strength in 3Y-TZP/Cr composite bilayers produced by sinter–joining [electronic resource]

    , Article Materials Science and Engineering: A ; Volume 527, Issue 3, 15 January 2010, Pages 449–453 Dourandish, M ; Simchi, A. (Abdolreza) ; Hokamoto, K ; Tanaka, S ; Sharif University of Technology
    The mechanism of interface formation during sinter–joining of nanostructured yttria stabilized zirconia (27 nm) compacts with chromium powder was investigated. The effect of sintering atmosphere, i.e. argon or vacuum, was studied. Microstructural evaluation and phase formation was examined by scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), and micro-focused X-ray diffraction (MFXRD) methods. It is shown that spreading and evaporation–condensation mechanisms are responsible for the interface formation. An improved joint shear-strength was obtained after sintering in vacuum (74 MPa) compared with argon (41 MPa). The result of MFXRD indicated formation of Cr-island at... 

    Simulation of elasto-plastic deformations in composites by flow rules

    , Article Indian Journal of Science and Technology ; Vol. 7, issue. 2 , 2014 , pp. 180-184 ; ISSN: 09746846 Monfared, V ; Fazaeli, D ; Daneshmand, S ; Shafaghatian, N ; Sharif University of Technology
    In this paper, a novel model is proposed to predict stress behavior in the fibrous polymer composites under an applied tensile axial loading. Tangential stress is obtained by simulating between polymeric matrix flow (polyester) and fluid flow. In the other words, creep behavior of the petrochemical material or polymeric resin (matrix) is modeled using fluid flow theory. Furthermore, behavior of the shear stress is predicted by suitable mathematical functions. Finally, important relation is extracted by combining the solid and fluid mechanics formulations  

    Effect of hot extrusion on wear properties of Al-15wt.% Mg2Si in situ metal matrix composites

    , Article Materials and Design ; Volume 53 , January 2014 , Pages 774-781 Soltani, N ; Jafari Nodooshan, H. R ; Bahrami, A ; Pech-Canul, M. I ; Liub, W ; Wub, G ; Sharif University of Technology
    Al-15wt.% Mg2Si composites were prepared by in situ casting and characterized in wear tests. Previous to the extrusion of specimens at 470°C - varying extrusion ratio (7.4, 14.1 and 25), the as-cast composites were homogenized at 500°C for 5h, followed by slow furnace cooling. The microstructure, hardness and sliding wear behavior were characterized for both, the as-cast and hot extruded composites. Results show that increasing the extrusion ratio causes a significant improvement in hardness and wear resistance. This is ascribed to the observed decrease in average size and better distribution of Mg2Si particles, in tandem with a remarkable decrease in porosity percentages, which goes from... 

    Investigation of reinforced sic particles percentage on machining force of metal matrix composite

    , Article Modern Applied Science ; Volume 6, Issue 8 , 2012 , Pages 9-20 ; 19131844 (ISSN) Fathipour, M ; Zoghipour, P ; Tarighi, J ; Yousefi, R ; Sharif University of Technology
    MAS  2012
    In this study two-dimensional finite element models of Al/SiC metal matrix composites (MMC) by using of ABAQUS Explicit software are investigated. Chip formations and machining forces for three types of MMC with 5, 15 and 20% of SiC reinforcement particles were studied and compared with experimental data. The resulted chips in simulation and the generated chips in experiments have both continuous and saw tooth in appearance. On the other hand, the variation of the cutting forces with the cutting time in simulation and experiment have fluctuating diagram. This is due to the interaction between cutting tool and SiC particles during chip formation. ABAQUS explicit software was used for... 

    A new version of Zagreb indices

    , Article Filomat ; Volume 26, Issue 1 , 2012 , Pages 93-100 ; 03545180 (ISSN) Ghorbani, M ; Hosseinzade, M. A ; Sharif University of Technology
    The Zagreb indices have been introduced by Gutman and Trinajstić as M1(G) = ∑ v∈V (G) (dG(v))2 and M2(G) = ∑ uv∈E(G) dG(u)dG(v), where dG(u) denotes the degree of vertex u. We now define a new version of Zagreb indices as M1 *(G) = ∑ uv∈E(G) [εG(u) + εG(v)] and M2 * (G) = ∑ uv∈E(G) εG(u)εG(v), where εG(u) is the largest distance between u and any other vertex v of G. The goal of this paper is to further the study of these new topological index  

    Numerical study on the creep behavior of the metal matrix short fiber composites with application in optoelectronic and photonic devices

    , Article Optoelectronics and Advanced Materials, Rapid Communications ; Volume 9, Issue 9-10 , 2015 , Pages 1088-1092 ; 18426573 (ISSN) Monfared, V ; Daneshmand, S ; Fazaeli, D ; Sharif University of Technology
    FEM study is carried out for predicting the behavior of the short fiber composites in the steady state creep with application in optoelectronic and photonic devices. The study on the creep behavior is necessary in order for failure, fracture, fatigue, and creep resistance of the short fiber composites. In this article, the creep behavior of the short fiber composite is predicted under tensile axial loading by the numerical method. One of the significant applications of the work is in the short fiber composite designing and optimizing. Also, the available experimental results [10] are used for the FEM simulation  

    Novel high capacity swelling superabsorbent composite and its potential for controlled release of fertilizers

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 29, Issue 4 , 2010 , Pages 113-123 ; 10219986 (ISSN) Pourjavadi, A ; Soleyman, R ; Rezanejad Bardajee, G ; Sharif University of Technology
    A hydrophilic macromolecular network is prepared by performing graft opolymerization of poly (sodium acrylate) chains onto salep and silica gel. The reaction parameters affecting the water absorbency of the superabsorbent composite were optimized using Taguchi method. FT-IR spectroscopy and Thermo Gravimetric Analysis (TGA) were used for confirming the structure of the final product and morphology of the synthesized superabsorbent composite was examined by SEM. The swelling behavior of optimum superabsorbent composite was measured in various swelling media. In addition, swelling kinetics and on-off switching behavior were investigated. In order to evaluate the controlled release potential of... 

    Adsorption and oxidation study on arsenite removal from aqueous solutions by polyaniline/polyvinyl alcohol composite

    , Article Journal of Water Process Engineering ; Volume 14 , 2016 , Pages 101-107 ; 22147144 (ISSN) Roghani, M ; Nakhli, S. A. A ; Aghajani, M ; Rostami, M. H ; Borghei, S. M ; Sharif University of Technology
    Elsevier Ltd 
    In this study, the Polyaniline/Polyvinyl Alcohol (PANi/PVA) composite was examined for arsenite (As(III)) removal from aqueous solution. The effect of several parameters including PVA concetration (0–5 g/L), pH (1–13), adsorbent dosage (0.5–6 g/L), contact time (0–120 min), initial As(III) concentration (0.5–100 mg/L), and As(III) oxidation were evaluated on the adsorption efficiency. The results indicated that PVA has an effective role in increasing adsorptive capacity of PANi, by changing its morphology and extending its active surface sites. The adsorption process was pH dependent and As(III) removal consistently improved by increasing solution pH. Adsorption reached equilibrium within... 

    Cold compaction behavior and pressureless sinterability of ball milled WC and WC/Cu powders

    , Article Science of Sintering ; Volume 48, Issue 1 , 2016 , Pages 71-79 ; 0350820X (ISSN) Hashemi, S. R ; Ardestani, M ; Nemati, A ; Sharif University of Technology
    International Institute for the Science of Sintering (IISS)  2016
    In this research, cold compaction behavior and pressureless sinterability of WC, WC-10%wtCu and WC-30%wtCu powders were investigated. WC and WC/Cu powders were milled in a planetary ball mill for 20h. The milled powders were cold compacted at 100, 200, 300 and 400 MPa pressures. The compressibility behavior of the powders was evaluated using the Heckel, Panelli-Ambrosio and Ge models. The results showed that the PanelliAmbrosio was the preferred equation for description the cold compaction behavior of the milled WC and WC-30%wtCu powders. Also, the most accurate model for describing the compressibility of WC-10%wtCu powders was the Heckel equation. The cold compacts were sintered at 1400oC.... 

    The effect of additives on the properties of HAp-Al2O3nano-composite powders

    , Article Journal of Ceramic Processing Research ; Volume 17, Issue 10 , 2016 , Pages 1033-1041 ; 12299162 (ISSN) Tayebi, S ; Mirjalili, F ; Samadi, H ; Nemati, A ; Sharif University of Technology
    Hanyang University  2016
    Hydroxyapatite is the most important bio ceramic, due to its structure and chemical composition which is similar to bone. Since feeble fracture toughness, brittleness and low tensile strength have restricted their use, for overcoming this problem, they were often used as a secondary component. HAp-Al2O3 nano-composite powder combined the benefits of biocompatibility of HAp and high strength of Al2O3. When HAp-Al2O3 nano-composite powders were sintered at a higher temperature than 1100- 1200°C, HAp was decomposed and converted to the second phase of TCP, due to the formation of calcium aluminate increasing decomposition speed of HAp to TCP at higher degree than 1100-1200°C temperatures;... 

    Application of face-centered central composite design (FCCCD) in optimization of enzymatic decolorization of two azo dyes: A modeling vs. empirical comparison

    , Article Progress in Color, Colorants and Coatings ; Volume 12, Issue 3 , 2019 , Pages 179-190 ; 20082134 (ISSN) Kashefi, S ; Borghei, S. M ; Mahmoodi, N. M ; Sharif University of Technology
    Institute for Color Science and Technology  2019
    Biological treatment, especially enzymatic methods, can be employed for effective and environmental- friendly treatment of dye effluents. Laccase, belonging to the blue multi-copper oxidases category, can oxidize a wide variety of substrates, especially synthetic dyes. In this study, laccase was used to biodegrade two azo dyes, i.e., Direct Red 23 and Acid Blue 92. Before conducting the experiments, the laccase used in this study was enzymatically characterized. Face-centered central composite design (FCCCD) was used to optimize the main parameters of the decolorization process. The optimum conditions to maximize the bio-decolorization process of AB92 were X1=11.85 mg L-1, X2=5.10, and... 

    3-D FEM analysis of plastic behavior inside MMC composites considering damage theory

    , Article 25th Congress of the International Council of the Aeronautical Sciences 2006, Hamburg, 3 September 2006 through 8 September 2006 ; Volume 3 , 2006 , Pages 1759-1768 Abedian, A ; Farahpour, H ; Sharif University of Technology
    Curran Associates Inc  2006
    The delamination phenomenon has been studied in macroscopic scale by different approaches. Here, using micro-mechanical models, it is tried to find the possible relationship between the problem and the stress fields around a fiber. Using the ideas and the results on the free surface cracking of unidirectional composite, the FEM model is developed. The model verification is done by comparing the results by the results obtained in presence of damaged incorporated by the damage theory. Here, on the free surfaces fiber/matrix debonding is applied as a composite damage and the results show a good agreement with the available results