Search for: bond-strength
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    Enhancement of brick-mortar shear bond strength using environmental friendly mortars

    , Article Construction and Building Materials ; Volume 195 , 2019 , Pages 28-40 ; 09500618 (ISSN) Azimi Resketi, N ; Toufigh, V ; Sharif University of Technology
    Elsevier Ltd  2019
    Usage of masonry system in many regions of the world like the Eastern Mediterranean, the Middle East, India, and China is still significantly high, despite their highly energy and intensive emission. Most of the failures in this system are caused by low ductility of cement mortars. This type of failure could be seen in masonry structures in areas in east Iran after Kermanshah earthquake in 2017. The present study investigates the shear bond characteristics of structures constructed by masonry using green materials. “Taftan” natural pozzolan and two types of rice husk ash (RHA) were used in mix design of used mortars as green materials. In this investigation, a modified direct shear test... 

    Growth rate of intermetallic compounds in Al/Cu bimetal produced by cold roll welding process

    , Article Journal of Alloys and Compounds ; Volume 319, Issue 1-2 , 2001 , Pages 233-241 ; 09258388 (ISSN) Abbasi, M ; Karimi Taheri, A ; Salehi, M. T ; Sharif University of Technology
    The aim of this article is to study the growth rate of intermetallic compounds at the interface of cold roll bonded Al/Cu bimetal at 250°C and compare the results with a similar study performed on friction welding of Al to Cu. Samples of tri-layered Cu-Al-Cu composite were produced by the cold roll welding process and heat treated at constant temperature of 250°C for 1 to 1000 h. The thickness, morphology and composition of the intermetallic compound at the interface of Cu and Al were studied by optical and scanning electron microscope and EDX analyzer. The presence of various intermetallic compounds (Cu3Al, Cu4Al3, CuAl and CuAl2) was detected and the priority of formation of each compound... 

    The long-term evaluation of FRPs bonded to timber

    , Article European Journal of Wood and Wood Products ; Volume 76, Issue 6 , 2018 , Pages 1623-1636 ; 00183768 (ISSN) Toufigh, V ; Yarigarravesh, M ; Mofid, M ; Sharif University of Technology
    This research investigated the long-term environmental effects on bond strength at the interface between fiber- reinforced polymers (FRPs) and timber. A total of 581 timber specimens were bonded with seven types of FRP sheets (unidirectional and bidirectional glass, carbon, aramid, and hybrids) using a wet lay-up technique. The specimens were exposed to acidic, alkaline, fresh water, and sea water solutions with pH of 2.5, 7, 7.25, 10, and 12.5 for 1, 3, 6, 9, and 12 months. A chamber was also used to simulate ultraviolet radiation after 6 months. A series of single-lap shear tests were then conducted to determine the interfacial bond strength reduction. The results showed that bidirectional... 

    Properties and mechanism of Al/St bimetal tube bonding produced by cold spin-bonding (CSB) process

    , Article Transactions of the Indian Institute of Metals ; Volume 70, Issue 10 , 2017 , Pages 2673-2682 ; 09722815 (ISSN) Samandari, M ; Abrinia, K ; Akbarzadeh, A ; Bulaqi, H. A ; Faraji, G ; Sharif University of Technology
    Spin-bonding is a novel tube cladding method for fabrication of bilayer tubes based on flow-forming process. The bimetal Al/St tubular components have extensive application in different industries. In this paper, an Al/St bimetal tube was successfully produced at different thickness reductions from 35 to 65% and mechanical and metallurgical aspects of the joint were investigated. Peeling tests were done to investigate the strength of the bond. The results showed that an increase in the thickness reduction led to a significant increase in the bond strength. Besides, the bonding mechanism between Al as inner tube to St as an outer one resulting from spin-bonding process was investigated. The... 

    The influence of roll bonding parameters on the bond strength of Al-3003/Zn soldering sheets

    , Article Materials Science and Engineering A ; Volume 487, Issue 1-2 , 25 July , 2008 , Pages 417-423 ; 09215093 (ISSN) Movahedi, M ; Madaah Hosseini, H. R ; Kokabi, A. H ; Sharif University of Technology
    Al-3003/Zn bi-layer soldering sheets were produced using roll bonding process at different reductions in both cold and hot conditions. The bond strengths of the bi-layer sheets were measured by peel test before and after supplemental annealing treatment. The peeled surfaces were examined using optical and scanning electron microscopy. The results indicate that by increasing the reduction in thickness during rolling and/or the annealing treatment the bond strength improves. Additionally, the decrease of initial sheet thickness and increase of rolling temperature can effectively improve the bond strength. Microscopic examinations show that the fracture type of Al-3003/Zn sheets is... 

    Bond strength and mechanical properties of three-layered St/AZ31/St composite fabricated by roll bonding

    , Article Materials and Design ; Volume 88 , 2015 , Pages 880-888 ; 02641275 (ISSN) Abedi, R ; Akbarzadeh, A ; Sharif University of Technology
    The aim of this research is bonding of three-layered St/AZ31/St composite by roll-bonding process. The roll-bonding process was performed at three preheating temperatures, 340, 400 and 450°C, with thickness reduction of 30 to 68% and different thicknesses of intermediate layer (AZ31). In order to improve the bonding strength, the as-rolled specimens were annealed at constant temperature of 375°C. For evaluation of bond strength and investigating the formation of a diffusion layer, the results of peel test and microscopic images were studied. Tensile specimens were prepared along the rolling direction to measure the mechanical properties of the composite. The results showed that by increasing... 

    Damage Detection and Evaluation of Repair Materials and Techniques for Concrete Bridges

    , M.Sc. Thesis Sharif University of Technology Karimi, Roya (Author) ; Joghataie, Abdoreza (Supervisor)
    Poor maintenance of concrete bridges in the past years in Iran, caused serious damages, so most of them need rehabilitation. The majority of repaired members are exposed to repeated damage because compatibility of repair material to substrate concrete not considered as well as weather and loading conditions. This study attempts to improve the repair achievement and durability of concrete bridges. This investigation contains two phases: preliminary study and experimental phase. Preliminary study attends to detect different types of damages of concrete bridges and their causes along with their propagation. The next part of this study discusses about various types of repair materials. In... 

    Investigation on Stainless Steel - Copper Roll Bonding

    , M.Sc. Thesis Sharif University of Technology Bagherian Talkhoonche, Nasrolla (Author) ; Akbarzade, Abbas (Supervisor)
    Roll bonding process is commonly used for the production of multilayer sheets. In the present study, using the roll bonding process, two layer sheets of copper - stainless steel were produced. In this case bonding strength was measured by peeling test at different statges and the quality of bonding was evaluated by SEM and Stereo Electron Microscope. The cross-sections of the bonding of rolled and annealed samples was investigated by optical microscopy. Also using EDAX analysis and EDS, the chemical composition of formed transition layer and the size of its interface at different temperature are measured respectively and the change in mechanical properties was investigated by tensile test... 

    A new method for producing bimetallic rods

    , Article Materials Letters ; Volume 61, Issue 19-20 , 2007 , Pages 4110-4113 ; 0167577X (ISSN) Eivani, A. R ; Karimi Taheri, A ; Sharif University of Technology
    In this research, a new method for producing bimetallic rods is introduced. The method is a new application of equal channel angular extrusion (ECAE) process. Advantages of using this method can be expressed as; good dimensional control on both the core and clad layer, possibility of performing the process in more than one pass which can result in larger bonding strength, and the possibility of performing the process in different temperatures which is critical for producing most of the bimetallic joints as well as aluminum-copper joint. The shear strength obtained using this method is compared with the same final product produced by general extrusion process. While the shear strength after... 

    Role of Molecular Weight and Molecular Weight Distribution on Weldability and Joint Strength of Polypropylene by Hot Plate Welding

    , M.Sc. Thesis Sharif University of Technology Azhdari, Moein (Author) ; Kokabi, Amir Hossein (Supervisor) ; Bagheri, Reza (Supervisor)
    In this study, role of molecular weight and Molecular Weight Distribution (MWD) on joint strength of polypropylene was investigated by hot plate welding. Standard tensile specimens of three different co-polypropylene with low, medium and high Melt Flow Index (MFI) values (MR230C, 440L and 548R respectively) were injected and welded after cutting. Hot plate welding device was used to join specimens. Melt Flow Index and dynamic rheology tests were employed in order to study the rheological behavior of polymers melt. Furthermore tensile test was done to investigate joint strength of specimens at 150, 175 and 200 ͦ C. It was observed that in constant temperature, increasing viscosity (typically... 

    Phenylcyclopropane energetics and characterization of its conjugate base: Phenyl substituent effects and the C-H bond dissociation energy of cyclopropane

    , Article Journal of Organic Chemistry ; Volume 81, Issue 19 , 2016 , Pages 9175-9179 ; 00223263 (ISSN) Fattahi, A ; Lis, L ; Kass, S. R ; Sharif University of Technology
    American Chemical Society 
    The α-C-H bond dissociation energy (BDE) of phenylcyclopropane (1) was experimentally determined using Hess' law. An equilibrium acidity determination of 1 afforded ΔH°acid = 389.1 ± 0.8 kcal mol-1, and isotopic labeling established that the α-position of the three-membered ring is the favored deprotonation site. Interestingly, the structure of the base proved to be a key factor in correctly determining the proper ionization site (i.e., secondary amide ions are needed, and primary ones and OH- lead to incorrect conclusions since they scramble the deuterium label). An experimental measurement of the electron affinity of 1-phenylcyclopropyl radical (EA = 17.5 ± 2.8 kcal mol-1) was combined... 

    Solute redistribution during transient liquid phase bonding of IN738LC with BNi-3 interlayer

    , Article Materials Science and Technology ; Volume 24, Issue 4 , 2008 , Pages 449-456 ; 02670836 (ISSN) Mosallaee, M ; Ekrami, A ; Ohsasa, K ; Matsuura, K ; Sharif University of Technology
    Redistribution of alloying elements in the transient liquid phase (TLP) bonding zone of IN738LC/ BNi-3/IN738LC was studied to investigate microstructural evolution in this area. Wavelength dispersive spectrometry and electron probe microanalysis revealed that, during non-isothermal solidification in the TLP bonding zone, enrichment of residual liquid phase with the positive segregating elements caused formation of intermetallic in the bonding zone. Scanning electron microscopy observation Indicated that the redistribution of alloying elements, between TLP bonding zone and base alloy, resulted In formation of a γ′ boundary layer, containing high density of fine γ′, around the bonding zone.... 

    Effect of iron particle size on the diffusion bonding of Fe-5%Cu powder compact to wrought carbon steels

    , Article Materials and Design ; Volume 29, Issue 2 , 2008 , Pages 411-417 ; 02613069 (ISSN) Fillabi, M. G ; Simchi, A ; Kokabi, A. H ; Sharif University of Technology
    Elsevier Ltd  2008
    In the present work, diffusion bonding of Fe-5%Cu powder compact to wrought carbon steels was studied. Effects of iron particle size and carbon content of the solid component on the bond strength, which is the maximum shear stress required to obtain separation at the interface, were investigated. Atomized iron powders with the mean particle size of 36, 56, 90, 106, and 148 μm and wrought steels with 0.22, 0.33, and 0.47 wt% carbon content were used. To evaluate the bonding zone, "ring shear" test, standard metallography technique, and micro-hardness test were employed. The results showed a profound effect of carbon content of the solid steel on the diffusion bonding process. It is suggested... 

    An investigation of deformation behavior and bonding strength of bimetal strip during rolling

    , Article Mechanics of Materials ; Volume 37, Issue 5 , 2005 , Pages 531-542 ; 01676636 (ISSN) Manesh, H. D ; Taheri, A. K ; Sharif University of Technology
    A mathematical model for cold rolling of two-layer strip is proposed using the upper bound theorem to investigate the plastic deformation behavior of the strip at the roll gap. The effects of total thickness reduction on the rolling power, rolling force, thickness reductions of each layer, and bonding strength of bimetal strip are discussed. Furthermore, experiments on two-layer strip rolling are conducted by employing aluminum-tin alloy and mild steel as the layers of the two-layer strips. It is found that all of theoretical predictions are in good agreement with the experimental measurements. Through the study, it becomes clear that the proposed analytical model is applicable for... 

    Strength assessment and bonding study of aluminum short fiber-reinforced gypsum composites

    , Article International Journal of Damage Mechanics ; Volume 21, Issue 1 , January , 2012 , Pages 129-149 ; 10567895 (ISSN) Mohandesi, J. A ; Sangghaleh, A ; Nazari, A ; Sharif University of Technology
    In this study, tensile strength of gypsum-based composite with aluminum fibers up to 15 vol.% was studied. To increase the interfacial bond strength between fibers and matrix, aluminum fibers were anodized under different conditions. Single fiber pull-out tests were carried out to investigate the bond strength. The interface was examined by scanning electron microscope. The ability of the composites to withstand longitudinal tensile load was also studied by tensile tests of dog bone-shaped, randomly oriented fiber-reinforced gypsum. By the introduction of aluminum fibers in gypsum as a randomly oriented composite, considerable increment in the strength is achieved and the toughness of the... 

    Investigation on the bond strength of Al-1100/St-12 roll bonded sheets, optimization and characterization

    , Article Materials and Design ; Volume 32, Issue 6 , 2011 , Pages 3143-3149 ; 02641275 (ISSN) Movahedi, M ; Kokabi, A. H ; Seyed Reihani, S. M ; Sharif University of Technology
    Al-1100/St-12 aluminum clad steel sheets were produced using roll bonding process at different reductions in thickness and with various supplemental annealing treatments. Experiments were conducted by applying the Taguchi method to obtain optimum condition for maximizing the joint strength. The joint strengths of the bi-layer sheets were evaluated by peel test. The Al/Fe intermetallic phases at the joint interface and the peeled surfaces were examined using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) and Vickers microhardness test were performed to characterize the intermetallic compounds. The results indicate that at the optimum condition of 0.50 reduction in... 

    A molecular dynamics study of bond strength and interface conditions in the Al / Al 2 O 3 metal-ceramic composites

    , Article Computational Materials Science ; Volume 109 , November , 2015 , Pages 200-208 ; 09270256 (ISSN) Sazgar, A ; Movahhedy, M. R ; Mahnama, M ; Sohrabpour, S ; Sharif University of Technology
    Elsevier  2015
    Abstract High ductility of metals as well as high strength of ceramics has made the metal/ceramic composites an attractive material for many applications requiring high strength to weight ratios. An important issue in using this material is the behavior of the material and its ceramic-metal interface under various loading, especially at high strain rate. To provide a better understanding of the interface conditions, in this work, a molecular dynamics study of the interface behavior in Al/α-Al2O3 composite as the result of tensile and shear loadings is presented. For this purpose, the reactive force field (ReaxFF) potential function is utilized. The effects of... 

    A novel spin-bonding process for manufacturing multilayered clad tubes

    , Article Journal of Materials Processing Technology ; Volume 210, Issue 3 , 2010 , Pages 510-517 ; 09240136 (ISSN) Mohebbi, M. S ; Akbarzadeh, A ; Sharif University of Technology
    Utilizing the so-called tube spinning, a cold-bonding process entitled as "spin-bonding" is developed to produce seamless thin-walled clad tubes and cylinders. By this method, two layers of AA 1050 tubes were successfully bonded together to form a clad tube at room temperature. Based on mechanical aspects of the tube spinning process, the mechanism of spin-bonding is explained in two stages: surface preparation before occurrence of a stable bond and bond strengthening thereafter. The effects of process temperature, thickness reduction, feed rate and roller attack angle as the parameters of tube spinning on the bond strength are studied. It is shown that the bond strength increases by... 

    Experimental and analytical evaluation of FRPs bonded to masonry-long term

    , Article Surface and Coatings Technology ; Volume 344 , 25 June , 2018 , Pages 729-741 ; 02578972 (ISSN) Yarigarravesh, M ; Toufigh, V ; Mofid, M ; Sharif University of Technology
    Elsevier B.V  2018
    This research investigated the long-term environmental effects on the bond at the interface between fiber-reinforced polymer (FRP) and a masonry brick. Seven types of FRP fabrics were used and placed on the masonry brick using the wet lay-up technique. Unidirectional and bidirectional fibers made of aramid, carbon, and glass and also combination of these fabrics were used. A total of 525 specimens were exposed to five chemical solutions with pH values of 2.5, 7, 10, 12.5 and substitution sea water for 1, 3, 6, 9 and 12 months. A chamber was also used to simulate the ultraviolent (UV) radiation on the specimens. A series of single-lap shear tests were performed on these specimens to determine... 

    The effects of elevated temperatures on the performance of concrete-filled pultruded GFRP tubular columns

    , Article Thin-Walled Structures ; Volume 169 , 2021 ; 02638231 (ISSN) Tabatabaeian, M ; Khaloo, A ; Azizmohammadi, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Usage of concrete-filled pultruded glass fiber-reinforced polymer (GFRP) tubes (CFPGT) as columns can increase the service life of structures. However, marine structures such as oil platforms are always prone to fire because of the low resistance to the elevated temperatures. The purpose of this investigation is to evaluate the effects of concrete core strength (30 and 60 MPa), and exposure temperature (25, 100, 200, 300, and 400 °C) and time (60 and 120 min) on the compressive and bond behavior of CFPGTs. The properties of unexposed and exposed concrete core, pultruded GFRP hollow tubes, and CFPGTs were determined via compressive and disk-split tests. Also, the push-out test was used to...