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    Analysis of Photo-Mechanical Response of Light Sensitive Homogeneous Hydrogels

    , M.Sc. Thesis Sharif University of Technology Jafari Khoshnabadi, Mohammad Amin (Author) ; Naghdabadi, Reza (Supervisor)
    Abstract
    Light-sensitive hydrogels are advanced materials with modern applications that have the ability to deform with light radiation at specific frequencies. Numerous studies have been conducted to identify the behavior and deformation of these materials. Most studies have experimentally investigated the light-sensitive behavior of hydrogels. On the other hand, modeling the behavior of light-sensitive hydrogels is very complicated, so that the use of these models is possible only in certain cases. Therefore, in the present study, the existing studies have been reviewed in order to simplify the relationships governing the deformation of light-sensitive hydrogels. In this regard, the deformation... 

    A time-dependent finite element formulation for thick shape memory polymer beams considering shear effects

    , Article International Journal of Applied Mechanics ; Volume 10, Issue 4 , 2018 ; 17588251 (ISSN) Eskandari, A. H ; Baghani, M ; Sohrabpour, S ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2018
    Abstract
    In this paper, employing a thermomechanical small strain constitutive model for shape memory polymers (SMP), a beam element made of SMPs is presented based on the kinematic assumptions of Timoshenko beam theory. Considering the low stiffness of SMPs, the necessity for developing a Timoshenko beam element becomes more prominent. This is due to the fact that relatively thicker beams are required in the design procedure of smart structures. Furthermore, in the design and optimization process of these structures which involves a large number of simulations, we cannot rely only on the time consuming 3D finite element analyses. In order to properly validate the developed formulations, the numeric... 

    Mechanical response of single and double-helix SMA wire ropes

    , Article Mechanics of Advanced Materials and Structures ; Volume 29, Issue 26 , 2022 , Pages 5393-5406 ; 15376494 (ISSN) Vahidi, S ; Arghavani, J ; Choi, E ; Ostadrahimi, A ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    In this paper, based on three-dimensional phenomenological model and using a user-defined material subroutine mechanical behavior of shape memory alloy (SMA) wire ropes (or cables) and their components have been studied through implicit solution method in Abaqus software. Material parameters have been extracted using available experimental data and numerical simulations. Due to the convoluted geometry and interwire contact status within a cable, a finite element analysis is firstly performed for a 1 × 37 steel wire rope to validate modeling and mechanical interactions of a wire rope. Afterwards, superelastic and shape memory effect cables with different constructions (7 × 7 and 1 × 27) are... 

    A numerical approach to study the post-yield softening in cellular solids: role of microstructural ordering and cell size distribution

    , Article Acta Mechanica ; Volume 228, Issue 6 , 2017 , Pages 2005-2016 ; 00015970 (ISSN) Goodarzi Hosseinabadi, H ; Bagheri, R ; Altstadt, V ; Sharif University of Technology
    Springer-Verlag Wien  2017
    Abstract
    Designing meta-materials and cellular solids with biomimetic structures has received increasing attention in the past few years partially due to advances in additive manufacturing techniques that have enabled the fabrication of advanced materials with arbitrarily complex microarchitectures and novel functionalities. To impact on this trend, it is essential to develop our understanding about the role of microstructure on mechanical responses of these structures. Although a large literature exists on the general subject, the role of microstructure on the post-yield instability is not yet adequately documented. This research introduces a numerical approach to study the post-yield instability in... 

    Effects of vertical and pinch rolling on residual stress distributions in wire and arc additively manufactured components

    , Article Journal of Materials Engineering and Performance ; Volume 29, Issue 4 , 2020 , Pages 2073-2084 Tangestani, R ; Farrahi, G. H ; Shishegar, M ; Pourbagher Aghchehkandi, B ; Ganguly, S ; Mehmanparast, A ; Sharif University of Technology
    Springer  2020
    Abstract
    Residual stresses are inherent in parts manufactured using the wire + arc additive manufacturing (WAAM) technique, resulting in unpredictable mechanical response and structural integrity (Colegrove et al.: J Mater Process Technol 213:1782-1791, 2013). An effective post-processing technique, which enhances the mechanical properties of WAAM parts, is rolling. This study investigates the vertical and pinch rolling effects on residual stress distribution in WAAM components. Initially, a WAAM model was created using a thermo-mechanical finite element modelling approach and validated against the experimental results. Subsequent to the validation of the model, the effect of the main parameters... 

    Finite-element modeling of thermal aspects in high speed cold strip rolling

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 231, Issue 8 , 2017 , Pages 1350-1362 ; 09544054 (ISSN) Koohbor, B ; Moaven, K ; Sharif University of Technology
    SAGE Publications Ltd  2017
    Abstract
    An integrated model based on finite-element method has been proposed to examine the mechanical and thermal responses of strips and work-rolls in tandem and reverse cold rolling operations. The model has been developed such that the influence of various process parameters, such as lubrication, rolling speed, frictional state and back-up rolls, can be examined. Thermal behaviors of the rolled material and the work-rolls have been analyzed using stream-line upwind Petrov-Galerkin approach, in order to make the model applicable to high-speed rolling processes, as well. The results have been compared to the actual on-line measurements and shown to be of acceptable accuracy. Such modeling approach... 

    Finite element modeling of thermal and mechanical stresses in work-rolls of warm strip rolling process

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 230, Issue 6 , 2016 , Pages 1076-1086 ; 09544054 (ISSN) Koohbor, B ; Sharif University of Technology
    SAGE Publications Ltd 
    Abstract
    An integrated mathematical model was developed to study the thermo-mechanical behavior of strips and work-rolls during warm rolling process of steels. A two-dimensional finite element analysis was first employed to solve for the thermo-mechanical response of the rolled strip under steady-state conditions. The calculated roll pressure and temperature fields were then used to apply proper boundary conditions for solving the governing thermo-mechanical problem for the work-roll. The obtained results indicate that in warm strip rolling of steels, the thermal and mechanical stresses developed within the work-roll are comparable; however, the more significant influence is due to heating and... 

    Healthy and diseasedin vitromodels of vascular systems

    , Article Lab on a Chip ; Volume 21, Issue 4 , 2021 , Pages 641-659 ; 14730197 (ISSN) Hosseini, V ; Mallone, A ; Nasrollahi, F ; Ostrovidov, S ; Nasiri, R ; Mahmoodi, M ; Haghniaz, R ; Baidya, A ; Salek, M. M ; Darabi, M. A ; Orive, G ; Shamloo, A ; Dokmeci, M. R ; Ahadian, S ; Khademhosseini, A ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Abstract
    Irregular hemodynamics affects the progression of various vascular diseases, such atherosclerosis or aneurysms. Despite the extensive hemodynamics studies on animal models, the inter-species differences between humans and animals hamper the translation of such findings. Recent advances in vascular tissue engineering and the suitability ofin vitromodels for interim analysis have increased the use ofin vitrohuman vascular tissue models. Although the effect of flow on endothelial cell (EC) pathophysiology and EC-flow interactions have been vastly studied in two-dimensional systems, they cannot be used to understand the effect of other micro- and macro-environmental parameters associated with... 

    Process optimization and kinetics for leaching of cerium, lanthanum and neodymium elements from iron ore waste's apatite by nitric acid

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 27, Issue 2 , 2017 , Pages 420-428 ; 10036326 (ISSN) Ferdowsi, A ; Yoozbashizadeh, H ; Sharif University of Technology
    Nonferrous Metals Society of China  2017
    Abstract
    The leaching of rare earth elements (REEs) including cerium, lanthanum and neodymium from apatite concentrate obtained from iron ore wastes by nitric acid was studied. The effects of nitric acid concentration, solid to liquid ratio and leaching time on the recoveries of Ce, La and Nd were investigated using response surface methodology. The results showed that the acid concentration and solid to liquid ratio have significant effect on the leaching recoveries while the time has a little effect. The maximum REE leaching recoveries of 66.1%, 56.8% and 51.7% for Ce, La and Nd, respectively were achieved at the optimum leaching condition with 18% nitric acid concentration, 0.06 solid to liquid... 

    Parametric study of strain rate effects on nanoparticle-reinforced polymer composites

    , Article Journal of Nanomaterials ; Volume 2016 , 2016 ; 16874110 (ISSN) Soltannia, B ; Haji Gholami, I ; Masajedian, S ; Mertiny, P ; Sameoto, D ; Taheri, F ; Sharif University of Technology
    Hindawi Publishing Corporation  2016
    Abstract
    Crashworthiness, energy absorption capacity, and safety are important factors in the design of lightweight vehicles made of fiber-reinforced polymer composite (FRP) components. The relatively recent emergence of the nanotechnology industry has presented a novel means to augment the mechanical properties of various materials. As a result, recent attempts have contemplated the use of nanoparticles to further improve the resiliency of resins, especially when resins are used for mating FRP components. Therefore, a comprehensive understanding of the response of nanoreinforced polymer composites, subjected to various rates of loading, is of paramount importance for developing reliable structures.... 

    Shear band propagation in honeycombs: numerical and experimental

    , Article Rapid Prototyping Journal ; Volume 24, Issue 2 , 2018 , Pages 477-484 ; 13552546 (ISSN) Goodarzi Hosseinabadi, H ; 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... 

    Effect of thermal cycles on mechanical response of pultruded glass fiber reinforced polymer profiles of different geometries

    , Article Composite Structures ; Volume 223 , 2019 ; 02638223 (ISSN) Jafari, A ; Ashrafi, H ; Bazli, M ; Ozbakkaloglu, T ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    This study investigates the effect of Thermal cycles on the mechanical properties of GFRP pultruded profiles with different geometries. Bending specimens consisted of I-shaped and U-channel profiles that were tested in three-point bending along their both principal weak and strong axes, whereas box profiles and laminates were used in compression and tension tests, respectively. Each specimen was exposed to a range of thermal cycles, between −20 °C and 20 °C. The failure modes of the profiles were closely investigated at both major and minor scales. Results were analyzed using ANOVA to determine the influence of each factor and a model was developed to predict the strength retention of... 

    Examination of chondroitinase ABC I immobilization onto dextran-coated Fe3O4 nanoparticles and its in-vitro release

    , Article Journal of Biotechnology ; Volume 309 , 2020 , Pages 131-141 Askaripour, H ; Vossoughi, M ; Khajeh, K ; Alemzadeh, I ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    Chondroitinase ABC I (cABC I) has received notable attention in treatment of spinal cord injuries and its application as therapeutics has been limited due to low thermal stability at physiological temperature. In this study, cABC I enzyme was immobilized on the dextran-coated Fe3O4 nanoparticles through physical adsorption to improve the thermal stability. The nanoparticles were characterized using XRD, SEM, VSM, and FTIR analyses. Response surface methodology and central composite design were employed to assess factors affecting the activity of immobilized cABC I. Experimental results showed that pH 6.3, temperature 24 °C, enzyme/support mass ratio 1.27, and incubation time 5.7 h were the... 

    Investigation of thermo-mechanical response of a geothermal pile through a small-scale physical modelling

    , Article 2nd International Conference on Energy Geotechnics, ICEGT 2020, 20 September 2020 through 23 September 2020 ; Volume 205 , 2020 Hashemi Senejani, H ; Ghasemi Fare, O ; Yazdani Cherati, D ; Jafarzadeh, F ; Sharif University of Technology
    EDP Sciences  2020
    Abstract
    Energy piles have been used around the world to harvest geothermal energy to heat and cool residential and commercial buildings. In order to design energy geo-structures, thermo-mechanical response of the geothermal pile must be carefully understood. In this paper, a small scale physical model is designed and a series of heating thermal cycles with various vertical mechanical loads are performed. The instrumented pile is installed inside a dry sand bed. Changes in pile head displacement, shaft strains and pile and sand temperatures are monitored using an LVDT, strain gauges and thermocouples, respectively. Prolonged heating cycles, which would continue until boundary temperature changes,... 

    Interrelation between mechanical response, strain field, and local free volume evolution in glassy polymers: seeking the atomistic origin of post-yield softening

    , Article Express Polymer Letters ; Volume 12, Issue 1 , January , 2018 , Pages 2-12 ; 1788618X (ISSN) Goodarzi Hosseinabadi, H ; Bagheri, R ; Gigl, T ; Hugenschmidt, C ; Raps, D ; Altstadt, V ; Sharif University of Technology
    BME-PT and GTE  2018
    Abstract
    A set of complementary experiments are used for the first time to elucidate the interrelation between the mechanical properties, the strain field, and the free volume evolution during non-homogenous compression of aglassy polymer. Two sets of quenched and annealed polystyrene samples, having different free volume histories, are notched and exposed to compression. The variation of both the strain field and the free volume are measured on a microscopic scale via digital image correlation in case of strain and Doppler broadening spectroscopy of positron annihilation line in case of free volume measurements. Eventually, the interplay between the local evolution of free-volume, the local strain... 

    A study on subsequent static aging and mechanical properties of hot-Rolled AA2017

    , Article Journal of Materials Engineering and Performance ; Vol. 23, issue. 8 , 2014 , p. 2894-2904 Khalili, L ; Serajzadeh, S ; Sharif University of Technology
    Abstract
    In this work, the effects of rolling parameters, cooling media, and deformation path on mechanical properties and aging behavior of hot-rolled AA2017 were studied. First, hot-rolling experiments were conducted under different working conditions, and the rolled strips were then aged at room temperature for up to 57 days during which hardness and tensile tests were carried out to record the changes in the mechanical properties of the alloy. Furthermore, due to the importance of static recrystallization on subsequent aging behavior, the rate of recrystallization was also computed. To this end, a mathematical model was developed to predict thermomechanical responses during hot rolling using the... 

    On the influence of deformation rate and cooling media on the static strain aging of a warm-rolled low carbon steel

    , Article International Journal of Material Forming ; Volume 6, Issue 3 , February , 2013 , Pages 417-422 ; 19606206 (ISSN) Koohbor, B ; Ohadi, D ; Sharif University of Technology
    2013
    Abstract
    An investigation was performed on the static strain aging behavior of warm-rolled low carbon steel during a nearly 1-year aging period, from the view point concerning with influence of changing the deformation speed and cooling media. Mechanical response of the examined material during aging period was evaluated through variations occurred in strength and hardness of the warm-deformed steel. It was shown that changing the rolling speed as well as cooling rate, may result in the occurrence of different metallurgical phenomena, consequently altering the aging kinetics of the material. It was also found that by increasing rolling speed, an increase in the value of hardness and UTS takes place,... 

    Modeling and experimental study on friction stir welding of artificially aged AA2017 plates

    , Article Materials and Manufacturing Processes ; Volume 28, Issue 6 , 2013 , Pages 683-688 ; 10426914 (ISSN) Mirjalili, A ; Serajzadeh, S ; Jamshidi Aval, H ; Kokabi, A. H ; Sharif University of Technology
    2013
    Abstract
    Thermo-mechanical responses, developed microstructure, and mechanical properties in friction stir welding (FSW) of artificially aged AA2017 plates were investigated. A finite element analysis was first employed to evaluate hot deformation behavior of the alloy during welding. Also, hardness, yield strength, and microstructure of the welded alloy were examined using the results of the model and experimental testing. It was found that strain and temperature fields during welding are asymmetrically distributed and the maximum temperature locates in advancing side. Furthermore, considerable grain refinement is observed in the stir zone where recrystallized grains in the range of 3 to 8 m are... 

    Nanoparticle enhanced solders for increased solder reliability

    , Article Materials Research Society Symposium Proceedings, 28 November 2011 through 2 December 2011, Boston, MA ; Volume 1424 , 2012 , Pages 115-120 ; 02729172 (ISSN) ; 9781605114019 (ISBN) Mokhtari, O ; Roshanghias, A ; Ashayer, R ; Kotadia, H. R ; Khomamizadeh, F ; Kokabi, A.H ; Clode, M. P ; Miodownik, M ; Mannan, S. H ; Sharif University of Technology
    2012
    Abstract
    Due to environmental concerns traditional eutectic tin-lead solder is gradually being replaced in electronic assemblies by "lead-free" solders. During this transition, nanoparticle technology is also being investigated to see whether improvements in joint reliability for high temperature applications can be made. Nanoparticles can be used to harden the solder via Zener pinning of the grain boundaries and reduce fatigue failure. This paper explores the effects of adding Silica nanoparticles to SnAgCu solder, and how the mechanical properties induced in the solder vary with temperature. It is found that above 100°C the mechanical response and microstructure of the normal and nanoparticle... 

    Effect of pore geometry and loading direction on deformation mechanism of rapid prototyped scaffolds

    , Article Acta Materialia ; Volume 60, Issue 6-7 , 2012 , Pages 2778-2789 ; 13596454 (ISSN) Amirkhani, S ; Bagheri, R ; Zehtab Yazdi, A ; Sharif University of Technology
    2012
    Abstract
    Rapid prototyping is a promising technique for producing tissue engineering scaffolds due to its capacity to generate predetermined forms and structures featuring distinct pore architectures. The objective of this study is to investigate the influences of different pore geometries and their orientation with respect to the compressive loading direction on mechanical responses of scaffolds. Plastic models of scaffolds with cubic and hexagonal unit cells were fabricated by three-dimensional (3-D) printing. An in situ imaging technique was utilized to study the progressive compressive deformation of the scaffold models. In both cubic and hexagonal geometries, organized buckling patterns relevant...