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Total 187 records

    Effects of number of layers and adhesive ductility on impact behavior of laminates

    , Article Materials Letters ; Volume 58, Issue 22-23 , 2004 , Pages 2721-2724 ; 0167577X (ISSN) Tekyeh Marouf, B ; Bagheri, R ; Mahmudi, R ; Sharif University of Technology
    2004
    Abstract
    Laminated composites are made using different routes, including adhesive bonding. In this investigation, Aluminum layers are bonded together using epoxy adhesive (neat, rubber-modified and filled-epoxy). In phase one of this investigation, the influence of number of layers and adhesive ductility have been studied on dynamic behavior of composites. The results of impact behavior of laminates indicate that the impact energy increases with the number of layers. Also, it can be concluded that there is much more sensitivity of the impact energy of the composite to the number of the layers than that to the adhesive composition. © 2004 Elsevier B.V. All rights reserved  

    Biomedical engineering of polysaccharide-based tissue adhesives: Recent advances and future direction

    , Article Carbohydrate Polymers ; Volume 295 , 2022 ; 01448617 (ISSN) Shokrani, H ; Shokrani, A ; Seidi, F ; Munir, M. T ; Rabiee, N ; Fatahi, Y ; Kucinska Lipka, J ; Saeb, M. R ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Tissue adhesives have been widely used for preventing wound leaks, sever bleeding, as well as for enhancing drug delivery and biosensing. However, only a few among suggested platforms cover the circumstances required for high-adhesion strength and biocompatibility, without toxicity. Antibacterial properties, controllable degradation, encapsulation capacity, detectability by image-guided procedures and affordable price are also centered to on-demand tissue adhesives. Herein we overview the history of tissue adhesives, different types of polysaccharide-based tissue adhesives, their mechanism of gluing, and different applications of polysaccharide-based tissue adhesives. We also highlight the... 

    Continuum model of actin-myosin flow

    , Article 2013 20th Iranian Conference on Biomedical Engineering, ICBME 2013 ; December , 2013 , Pages 98-102 Nikmaneshi, M. R ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
    IEEE Computer Society  2013
    Abstract
    The front part of a cell is divided to two regions called lamellum and lamellipodium (lamellipodial). This part plays an essential role for cell migration. Indeed, there are many protein filaments called actin in lamellum and lamellipodium, which induce the cell motion with polymerization in the leading edge of the cell. The actin filaments adhere to the extracellular matrix (ECM) by means of focal adhesions and they have contact by myosin motor proteins. The myosin motor proteins cause actin retrograde and anterograde flow exerted contractile stress on them. The focal adhesions exert frictional stress on the actin filaments. In this work, we developed a two-dimensional continuum model of... 

    Study and Preparation of Two-Component Urethane_Based Adhesives for Using in Membrane Technology

    , M.Sc. Thesis Sharif University of Technology Safari, Masoud (Author) ; Musavi, Abbas (Supervisor) ; Soltanieh, Mohammad (Supervisor)
    Abstract
    Membrane Technology is rapidly growing all over the world because of many applications. In all of this applications , use of adhesive ( between membranes and wall ) is necessary. selection of appropriate adhesive for membrane is very important in order to membrane has best performance and lifetime .Adhesives used in membrane technology must have good adhesion and suitable hardness . One of the newest adhesives used in membrane technology is two-component polyurethane adhesive. PU adhesives make strong and durable bond and have good flexibility which is an advantage for membrane technology.MDI isocyanate is used in most of commercial PU adhesives’ formulation. But in this study , modified MDI... 

    Metallurgical challenges in carbon nanotube-reinforced metal matrix nanocomposites

    , Article Metals ; Volume 7, Issue 10 , 2017 ; 20754701 (ISSN) Azarniya, A ; Safavi, M. S ; Sovizi, S ; Azarniya, A ; Chen, B ; Madaah Hosseini, H. R ; Ramakrishna, S ; Sharif University of Technology
    Abstract
    The inclusion of carbon nanotubes (CNTs) into metallic systems has been the main focus of recent literature. The aim behind this approach has been the development of a new property or improvement of an inferior one in CNT-dispersed metal matrix nanocomposites. Although it has opened up new possibilities for promising engineering applications, some practical challenges have restricted the full exploitation of CNTs’ unique characteristics. Non-uniform dispersion of CNTs in the metallic matrix, poor interfacial adhesion at the CNT/metal interface, the unfavorable chemical reaction of CNTs with the matrix, and low compactability are the most significant challenges, requiring more examination.... 

    Model of contact friction based on extreme value statistics

    , Article Friction ; Volume 7, Issue 4 , 2019 , Pages 327-339 ; 22237690 (ISSN) Malekan, A ; Rouhani, S ; Sharif University of Technology
    Tsinghua University Press  2019
    Abstract
    We propose a model based on extreme value statistics (EVS) and combine it with different models for single-asperity contact, including adhesive and elasto-plastic contacts, to derive a relation between the applied load and the friction force on a rough interface. We determine that, when the summit distribution is Gumbel and the contact model is Hertzian, we obtain the closest conformity with Amonton’s law. The range over which Gumbel distribution mimics Amonton’s law is wider than that of the Greenwood–Williamson (GW) model. However, exact conformity with Amonton’s law is not observed for any of the well-known EVS distributions. Plastic deformations in the contact area reduce the relative... 

    Failure procedure in epoxy adhesive joining composite plates

    , Article Iranian Journal of Science and Technology - Transactions of Mechanical Engineering ; 2020 Fazel, D ; Kadivar, M. H ; Zohoor, H ; Farid, M ; Hematiyan, M. R ; Sharif University of Technology
    Springer  2020
    Abstract
    In this paper, several numerical simulations are performed to study the failure of epoxy adhesive joining composite plates. Different geometries for the joint and its edge are considered, and the effects of these geometries on the failure load are investigated. Moreover, the joints are subjected to different types of loading in order to determine the failure load. The failure theories of composite materials are implemented into the finite element software ABAQUS, and the failure propagation in the joint is studied. © 2020, Shiraz University  

    Increasing the interfacial adhesion in poly(methyl methacrylate)/carbon fibre composites by laser surface treatment

    , Article Polymers and Polymer Composites ; Volume 14, Issue 6 , 2006 , Pages 585-589 ; 09673911 (ISSN) Nematollahzadeh, A ; Mousavi, S. A. S ; Tilaki, R. M ; Frounchi, M ; Sharif University of Technology
    Rapra Technology Ltd  2006
    Abstract
    The impact strength of poly(methyl methacrylate)/caibon (long) fibre composites for denture prosthesis applications was improved by fibre surface treatment. The carbon fibre surfaces were modified by Nd:YAG laser irradiation at 1064 nm wavelength. Laser light intensity was adjusted at 100 mj per pulse that only changed the fibre surface roughness and did not lead to fibre rupture, as verified by scanning electron microscopy. Increased surface roughness of the fibres improved the adhesion of poly(methyl methacrylate) to the fibre surface. Adhesion between the fibres and poly(methyl methacrylate) was evaluated by a tear-off method and by scanning electron microscopy. The results also suggest... 

    Mechanical properties of martensitic stainless steel weld/adhesive hybrid bonds

    , Article Science and Technology of Welding and Joining ; Volume 23, Issue 3 , 2018 , Pages 227-233 ; 13621718 (ISSN) Pouranvari, M ; Safikhani, E ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    Abstract
    Hybrid weld-adhesive bonding (AB) was used as an approach to improve the mechanical properties of martensitic stainless steel resistance spot welds. The weld fusion zone in both techniques was composed of predominantly martensite and δ-ferrite. It was found that the presence of adhesive does not induce excess hardening effect in the fusion zone. It was shown that hybrid AB/resistance spot welding) i.e. weld-bonding) technique can double the peak load and energy absorption of the joints compared to those of the resistance spot welds. To obtain high performance weld-bonded joints, heat generation during welding should be controlled to produce weld bonds with large fusion zone size, but without... 

    The effect of rippled graphene sheet roughness on the adhesive characteristics of a collagen-graphene system

    , Article International Journal of Adhesion and Adhesives ; Volume 64 , 2016 , Pages 9-14 ; 01437496 (ISSN) Heidari, H ; Shamloo, A ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    A great amount of effort has been made in order to reach a more precise understanding of the adhesion phenomenon that happens as a vital component of several biological systems. Therefore, a firm understanding of the important factors that influence this phenomenon is of special importance in triggering the adhesive characteristics of different biological, bio-inspired and synthetic materials in fields such as tissue engineering. In this study the adhesive characteristics of a multi-material system consisting of the frequently used synthetic material, graphene, in the form of armchair-configuration sheets, and an important biological filament which is type 1 Collagen consisting of 3 alpha... 

    Modeling and simulation of oil well stimulation by high power ultrasonic irradiation

    , Article Acta Acustica united with Acustica ; Volume 103, Issue 3 , 2017 , Pages 411-420 ; 16101928 (ISSN) Khorram, A ; Ahmad Ramazani, S. A ; Jamshidi, S ; Moghaddam, A. K ; Sharif University of Technology
    S. Hirzel Verlag GmbH  2017
    Abstract
    Ultrasonic waves have been extensively used in many industrial applications including clean devices, pipes and vessels. A clear extension of this usage is the removal of wellbore contaminants by exposing it to high-power ultrasonic waves. In this paper, a mathematical model for ultrasonic propagation through the porous medium around the wellbore is presented. The equations of wave propagation are written in a cylindrical coordinate according to Biot theory and the induced stress in the rock are calculated at each point using finite difference approach Comparison of imposed local stresses with adhesion forces between scales and rock, the properties of ultrasonic transducer, such as frequency... 

    Effect of reduced graphene oxide reinforcement on creep behavior of adhesively bonded joints

    , Article Mechanika ; Volume 23, Issue 5 , 2017 , Pages 646-652 ; 13921207 (ISSN) Marami, G ; Nazari, S. A ; Faghidian, S. A ; Vakili Tahami, F ; Sharif University of Technology
    Kauno Technologijos Universitetas  2017
    Abstract
    The creep behaviour of adhesively bonded joints is one of the major concerns in modern industry due to their application at relatively high temperature. In this re-search, the effect of added RGO on the creep behaviour of the Araldite 2011 adhesive is investigated. Uni-axial creep tests have been carried out on neat Araldite 2011 and RGO added adhesive at different stress and temperature levels. It has been shown that adhesive with RGO particles demonstrate higher creep resistance. Also, general time hardening models are developed for both materials and their constitutive coefficients have been determined using creep test data. Based on these models, the creep behavior of single lap joints... 

    Chitosan interphase around nanodiamond: Insight from equilibrium molecular dynamics

    , Article Diamond and Related Materials ; Volume 104 , 2020 Aranifard, S ; Shojaei, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    In the context of nanodiamond/chitosan (ND/CS) nanocomposites and utilizing atomistic molecular dynamics, the interaction mechanism of adsorbed CS layer around a model ND has been investigated at three level of hydration: in bulk of water, water as a droplet, and completely dry condition. The effect of amination and carboxylation of ND has been studied. To ensure that the comparison of these model systems is meaningful (energetically and geometrically), the CS interphases around NDs were characterized through holistic concentration profiles and density distribution maps. Our results revealed that in a completely dry condition or hydrated by a molecularly small droplet, both of the... 

    Obtaining strain-rate dependent traction-separation law parameters of epoxy adhesive joints and predicting fracture for dissimilar bonding adherends

    , Article International Journal of Adhesion and Adhesives ; Volume 118 , 2022 ; 01437496 (ISSN) Darvishi, I ; Nourani, A ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    This study investigated the mode I fracture behavior of double cantilever beam (DCB) epoxy adhesive joints with similar adherends on the both sides (i.e., aluminum-aluminum or copper-copper) at different strain rates; i.e., quasi-static (∼10−3 s−1), low (∼7 s−1) and intermediate (∼14 s−1) rates. The fracture energy of the DCB joint in Al-adhesive-Al specimens decreased (i.e., by ∼62%, p = 0.0013) with an increase in the applied strain rate from quasi-static to low values, while it remained almost unchanged with further increase of stain rate to intermediate range (p > 0.05). For Cu-adhesive-Cu cases, however, the fracture energy was found to be almost insensitive to the applied strain rate... 

    Adhesion and Viscoelestisity of EVA Hot Melt Adhesive

    , M.Sc. Thesis Sharif University of Technology Bank, Mohammad Mahdi (Author) ; Frounchi, Masuod (Supervisor) ; Dadbin, Susan (Supervisor)
    Abstract
    A series of poly(ethylene-co-vinyl acetate) (EVA)-based hot melt adhesives containing either a raw rosin or a hydrogenated rosin ester have been prepared to investigate variation of viscosity, softening point and peel adhesion with composition. Adhesion of the prepared hot melt adhesive to the substrate was characterized by T-peel strength test. Increasing rosin had a prominent effect on the adhesion. Viscosity decreased and softening point increased as the wax content increased. Addition of zinc borate as a flame retardant decreased T-peel energy and increased the viscosity and softening point of the samples. Higher peeling strength accompanied with a good softening point and viscosity... 

    Adhesive and cohesive properties by indentation method of plasma-sprayed hydroxyapatite coatings

    , Article Applied Surface Science ; Volume 253, Issue 11 , 2007 , Pages 4960-4965 ; 01694332 (ISSN) Mohammadi, Z ; Ziaei Moayyed, A. A ; Mesgar, A. S. M ; Sharif University of Technology
    Elsevier  2007
    Abstract
    Adhesive and cohesive properties of the plasma-sprayed hydroxyapatite (HA) coatings, deposited on Ti-6Al-4V substrates by varying the plasma power level and spray distance (SD), were evaluated by an indentation method. The crystallinity and the porosity decreased with increasing both of these two parameters. The microhardness value, Young's modulus (E) and coating fracture toughness (K C ) were found to increase with a combinational increase in spray power and SD. The Knoop and Vickers indentation methods were used to estimate E and K C , respectively. The critical point at which no crack appears at the interface was determined by the interface indentation test. This was used to define the... 

    Fracture behavior of multi-layered composites under impact loading

    , Article Materials Science and Engineering A ; Volume 448, Issue 1-2 , 2007 , Pages 20-24 ; 09215093 (ISSN) Tekyeh Marouf, B ; Bagheri, R ; Sharif University of Technology
    2007
    Abstract
    In this investigation, aluminum layers are bonded together using epoxy adhesive. The adhesive is modified using different additives and the influence of adhesive composition on interfacial fracture energy is measured via double cantilever beam (DCB) test. To characterize the mechanical behavior of the adhesive, compression and impact tests were incorporated. The results of compression and impact tests show that compressive and impact properties of adhesives are functions of type and content of modifier. In the DCB test, it was observed that while addition of rubber particles increase interfacial fracture energy of epoxy, incorporating SiC particles decrease this parameter. Also, the results... 

    Study of scratch resistance in homo- and co-polypropylene filled with nanometric calcium carbonate

    , Article Materials Science and Engineering A ; Volume 445-446 , 2007 , Pages 526-536 ; 09215093 (ISSN) Zokaei, S ; Lesan Khosh M., R ; Bagheri, R ; Sharif University of Technology
    2007
    Abstract
    In this study, homo- and co-polypropylene were modified by nanometric calcium carbonate and the effect of additive on scratch resistance was evaluated. Results of this study show that the length of scratch curvature can be considered as an acceptable criterion to evaluate the scratch resistance of polymers. Also, it was found that addition of calcium carbonate to homo-polypropylene increases scratch resistance of this polymer, but its effect on co-polypropylene is insignificant. Based on the results of this work, one may claim that incorporation of nanometric particles with good adhesion to the matrix and well dispersion might be effective in enhancement of scratch resistance. Formation of... 

    Granisetron Transdermal Drug Delivery System

    , M.Sc. Thesis Sharif University of Technology Dehbini, Hamid Reza (Author) ; Abdekhodaie, Mohammad Jafar (Supervisor) ; Taghizadeh, Mojtaba (Supervisor)
    Abstract
    Transdermal drug delivery systems are products which are known to have ability to pass drugs through the skin and into the blood, so medicine effects appear as a result. During the past two decades, many scientists interested in drug delivery through the skin. Constant blood plasma level and avoiding first-pass metabolism are advantages of this system compared to oral and intravenous systems. The biggest problem in the development of these systems, is impermeability of Stratum corneum, the outermost layer of the epidermis. In this study, design and evaluation of in vitro transdermal drug delivery system for granisetron serve as treatment of nausea and vomiting was performed. For this... 

    Investigation and Synthesis of Zn-Ni-Mn Three Cationic Electrophosphate Coating

    , M.Sc. Thesis Sharif University of Technology Alimi, Zahra (Author) ; Ghorbani, Mohamad (Supervisor)
    Abstract
    The purpose of this study was to create a three-cationic electro phosphate coating of zinc-nickel-manganese by cathodic method and to investigate the effect of operating variables on the properties of zinc-nickel-manganese tri-cationic electro phosphate coating. Hence, the effects of variables such as coating acidity, coating thickness, coating temperature, coating time and concentration of manganese were studied in the bath on the properties such as coating morphology, corrosion resistance, coating thickness. Coating morphology was characterized by scanning electron microscopy and corrosion resistance by polarization test. The pH values of 1.4, 1.8, 2 and 2.2 were selected, and the results...