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viscoelastic-properties
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Study of Viscoelastic Property of Fluid with Optical Tweezers
, M.Sc. Thesis Sharif University of Technology ; Seyed Reihani, Nader (Supervisor)
Abstract
Viscoelastic properties of biological fluid play an important role on biological organs. As an example we all know that Red blood cells must have high flexibility to pass thorough thin capillary.This high flexibility come partially from cytoplasm and 2 dimensional membrane and partially from polymeric fluid inside the cell(hemoglobin). So, for recognizing mechanical properties of a whole cell we also need to study the same properties just for fluid inside the cell. for this general purpose through this project we are going to measure viscoelastic properties of any polymeric fluid by optical tweezers which has an ability for measuring displacement of micron particle with accuracy of nm. first...
Effect of ultrasonic irradiation on rheological properties of asphaltenic crude oils
, Article Petroleum Science ; Volume 9, Issue 1 , March , 2012 , Pages 82-88 ; 16725107 (ISSN) ; Ramazani, A ; Najafi, I ; Davachi, S. M ; Sharif University of Technology
2012
Abstract
In this work, the rheological changes of several crude oil samples exposed to ultrasonic waves for different time intervals in addition to the effect of temperature on viscosity behavior of heavy crude oils were investigated using a series of steady shear flow and oscillatory tests. The colloidal structural evolutions of flocs in oil samples were illustrated by analysis of the size distribution of flocculated asphaltene particles (confocal microscopy tests). The rheological investigations indicate that the ultrasonic irradiation dissolved heavy components in crude oil. After ultrasonic treatment, the Kouh-e-Mond crude oil was found to be pseudoplastic. In addition, confocal microscopy...
Investigation of the Recovery Time and Hyper-Viscoelastic Properties of the Brain Tissue
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor)
Abstract
FE simulations have been widely used to investigate the response of the brain tissue in various circumstances. The accuracy of the material models critically affects the results of the numerical simulation. However, despite the numerous studies aiming for the material modeling of the brain, there is still divergence between the results reported in the literature. A part of this discrepancy is due to the inherent difference between samples. Nonetheless, another part of it is resulted from the differences between testing protocols used by researchers. In some protocols multiple mechanical tests are performed on each sample. Enough recovery time should be considered between consecutive test...
The Study on Relationship between Viscoelastic Properties and Drug Release of Wound Dress Polyvinyl Alcohol Hydrogel
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
Abstract
Wound is a defect or failure in the skin texture which occurs as a result of physical or heat injuries or physiological conditions. The wound dress as a temporary cover can improve wound healing process and due to the unique properties, hydrogels have become appropriate choice for this application. Hydrogel’s structure allows drug to be loaded in the wound dress. Hydrogel wound dress should have adequate fluidity to cover wound’s bed and make full contact with the skin. Sufficient cohesion and strength is also necessary to allow the wound dress to remove from wound completely. Therefore, the study on the viscoelastic properties of hydrogel is important. In this study, polyvinyl alcohol...
Modeling and Sensitivity Analysis of Heavy Vehicles Tire With Target of Determining Stiffness and Damping Characteristics
, M.Sc. Thesis Sharif University of Technology ; Saadat Foumani, Mahmoud (Supervisor) ; Fallah Rajabzadeh, Famida (Supervisor)
Abstract
Tire is one component of the suspension system and has beneficial effects on reducing vibrations caused to the vehicle. This study aims to determine the factors affecting the damping and stiffness of the tire is carried out. The modeling of factors were identified. For testing the modeling effort is to be made to the instruments used to measure the damping and stiffness of the tires. To make the structural static analysis, dynamic and modal was to have sufficient structural strength and the displacements and stresses are sensibly placed. Factors that have influence on the hardness of the ring diameter, the outer diameter of the tire, tire pressure, tire tread depth, tire wall thickness,...
Passive Measurement of Viscoelastic Properties of the Healthy Red Blood Cell by Optical Tweezers
, M.Sc. Thesis Sharif University of Technology ; Seyyed Reihani, Nader (Supervisor)
Abstract
Blood is one of the most important biological organs. Red blood cell (RBC), as the most abundant cell of blood, plays an important role at life of the living bodies. Unique mechanical properties of RBCs enable them to pass through very narrow vessels. Any abnormality in these mechanical properties will disorder the function of the cell and many diseases affect these properties too. Studying the mechanical properties of RBCs is very importantin that it could result in a disease diagnostic method in a single-cell level. In this thesis we have tried to measure the viscoelastic properties of a single RBC by an optical trap through a passive method. This measurement is made through studying the...
Application of exact continuum size-dependent theory for stability and frequency analysis of a curved cantilevered microtubule by considering viscoelastic properties
, Article Engineering with Computers ; Volume 37, Issue 4 , 2021 , Pages 3629-3648 ; 01770667 (ISSN) ; Habibi, M ; Tounsi, A ; Safarpour, H ; Safa, M ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
The stability analysis of cantilevered curved microtubules in axons regarding various size elements and using the generalized differential quadrature method for solving equations is reported. The impacts of covering MAP Tau proteins along with cytoplasm are taken into account as the elastic medium. Curved cylindrical nanoshell considering thick wall is used to model the microtubules. The factor of length scale (l/R = 0.2) used in modified couple stress theory would result in more accuracy when it comes to comparison with experiments, while alternative theories presented in this paper provide less precise outcomes. Due to the reported precise results, at the lower value of the time-dependent...
An Investigation into Effects of Components Ratio and Nano/micro Sized ZnO Particles on Evolution of Transesterification Reaction, Compatiblization and Modification of PET/PC Blends Structure
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
Abstract
Polycarbonate (PC) and polyethylene-terephthalate (PET) are important engineering thermoplastics. During last decades these polymers and their blends have been studied extensively due to their wide range of applications. Blends of PET and PC combine mechanical properties and chemical resistance together, which make applicable in various components such as automotive, electrical and of medical parts. It has been accepted that PET/PC immiscible blends are subjected to transesterification reactions during thermal processing, which produces PET-PC copolymer chains. In fact, scissioning and substitution of ester/carbonate functional groups of PC and PET at the interface, transforms the initial...
Plaque structure affects mechanical stress distribution within blood vessels
, Article Proceedings of the IASTED International Conference on Biomedical Engineering, BioMed 2014 ; 2014 , pp. 239-243 ; Mehboudi, N ; Abdollahi, M ; Shamloo, A ; Naghdabadi, R ; Sharif University of Technology
Abstract
The main goal of this study is to investigate the effects of plaque structure on its stress distribution. Rupture of plaque causes cerebrovascular diseases which lead to high mortality rates all over the world. Computers are powerful tools to understand the mechanism of plaque rupture. In this study, 3D fluid structure interaction simulation is constructed in ABAQUS 6.13 to clarify the relation between stress distribution of plaque and its structure. A model of common carotid artery with distributed stenosis was chosen for the simulation. To investigate the effects of plaque structure on stress distribution, thickness of fibrous cap and lipid core size were varied in the stenosis....
Electrical bending instability in electrospinning visco-elastic solutions
, Article Journal of Polymer Science, Part B: Polymer Physics ; Volume 54, Issue 11 , 2016 , Pages 1036-1042 ; 08876266 (ISSN) ; Bonn, D ; Ejtehadi, M. R ; Iraji Zad, A ; Sharif University of Technology
John Wiley and Sons Inc
Abstract
The electrical bending instability in charged liquid jets is the phenomenon determining the process of electrospinning. A model of this phenomenon is lacking however, mostly due to the complicated interplay between the viscosity and elasticity of the solution. To investigate the bending instability, we performed electrospinning experiments with a solution of polyethylene oxide in water/ethanol. Using a fast camera and sensitive multimeter, we deduced an experimental dispersion relation describing the helix pitch length as a function of surface charge. To understand this relation, we developed a theoretical model for the instability for a wide range of visco-elastic materials, from conducting...
Poly (vinyl alcohol)/nano-diamond composite films and hydrogels prepared by gamma ray
, Article Journal of Polymer Engineering ; Volume 38, Issue 9 , 2018 , Pages 857-862 ; 03346447 (ISSN) ; Dadbin, S ; Haddadi, S ; Sharif University of Technology
De Gruyter
2018
Abstract
Poly (vinyl alcohol) and nano-diamond, PVA/ND, hydrogels were prepared and assessed as prosthetic material suitable for replacement of the nucleus pulposus. The hydrogels were prepared by gamma irradiation at various doses (15 kGy, 25 kGy, 35 kGy, 45 kGy) and at various ND concentrations ranging from 0.25 wt.% to 3 wt.%. Extent of gelation, equilibrium water content, and viscoelastic properties of swelled hydrogels at definite water contents were measured and examined as a function of ND concentration as well as gamma dose. According to viscoelastic measurements, the strength of hydrogels increased considerably over that of pure PVA at a low concentration of ND. By increasing irradiation...
Application of exact continuum size-dependent theory for stability and frequency analysis of a curved cantilevered microtubule by considering viscoelastic properties
, Article Engineering with Computers ; 2020 ; Habibi, M ; Tounsi, A ; Safarpour, H ; Safa, M ; Sharif University of Technology
Springer
2020
Abstract
The stability analysis of cantilevered curved microtubules in axons regarding various size elements and using the generalized differential quadrature method for solving equations is reported. The impacts of covering MAP Tau proteins along with cytoplasm are taken into account as the elastic medium. Curved cylindrical nanoshell considering thick wall is used to model the microtubules. The factor of length scale (l/R = 0.2) used in modified couple stress theory would result in more accuracy when it comes to comparison with experiments, while alternative theories presented in this paper provide less precise outcomes. Due to the reported precise results, at the lower value of the time-dependent...
Evaluation of interfacial layer properties in the polystyrene/silica nanocomposite
, Article Journal of Applied Polymer Science ; Volume 119, Issue 4 , August , 2011 , Pages 2039-2047 ; 00218995 (ISSN) ; Farzi, G ; Kalaee, M. R ; Zabihpoor, M ; Sharif University of Technology
2011
Abstract
Processing conditions and final mechanical properties of polymer nanocomposites are affected by their interfacial layers behavior. However, it is impossible to determine directly the properties of these layers by dynamic rheometry tests. In this work, the interfacial layers properties are evaluated for polystyrene containing silica nanoparticles by the concept of glass-transition temperature shift. The samples were prepared via solution-mixing method and dynamic rheometry was used to determine the viscoelastic behavior of filled polymers in the melt state. This initial step showed that addition of silica particles increased the glass-transition temperature. By preference, decrease in the...
Development of a stress-mode sensitive viscoelastic constitutive relationship for asphalt concrete: experimental and numerical modeling
, Article Mechanics of Time-Dependent Materials ; 2016 , Pages 1-35 ; 13852000 (ISSN) ; Tabatabaee, N ; Jahanbakhsh, H ; Jahangiri, B ; Sharif University of Technology
Springer Netherlands
Abstract
Asphalt binder is responsible for the thermo-viscoelastic mechanical behavior of asphalt concrete. Upon application of pure compressive stress to an asphalt concrete specimen, the stress is transferred by mechanisms such as aggregate interlock and the adhesion/cohesion properties of asphalt mastic. In the pure tensile stress mode, aggregate interlock plays a limited role in stress transfer, and the mastic phase plays the dominant role through its adhesive/cohesive and viscoelastic properties. Under actual combined loading patterns, any coordinate direction may experience different stress modes; therefore, the mechanical behavior is not the same in the different directions and the asphalt...
Development of a stress-mode sensitive viscoelastic constitutive relationship for asphalt concrete: experimental and numerical modeling
, Article Mechanics of Time-Dependent Materials ; Volume 21, Issue 3 , 2017 , Pages 383-417 ; 13852000 (ISSN) ; Tabatabaee, N ; Jahanbakhsh, H ; Jahangiri, B ; Sharif University of Technology
Springer Netherlands
2017
Abstract
Asphalt binder is responsible for the thermo-viscoelastic mechanical behavior of asphalt concrete. Upon application of pure compressive stress to an asphalt concrete specimen, the stress is transferred by mechanisms such as aggregate interlock and the adhesion/cohesion properties of asphalt mastic. In the pure tensile stress mode, aggregate interlock plays a limited role in stress transfer, and the mastic phase plays the dominant role through its adhesive/cohesive and viscoelastic properties. Under actual combined loading patterns, any coordinate direction may experience different stress modes; therefore, the mechanical behavior is not the same in the different directions and the asphalt...
Melt compounding of thermoplastic polyurethanes incorporating 1D and 2D carbon nanofillers
, Article Polymer - Plastics Technology and Engineering ; Volume 56, Issue 7 , 2017 , Pages 732-743 ; 03602559 (ISSN) ; Pedrazzoli, D ; Pircheraghi, G ; Manas Zloczower, I ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
Thermoplastic polyurethane nanocomposites incorporating carbon nanotubes and graphene nanoplatelets were prepared through melt blending and compression molding, and the compounding process was optimized taking into account the different physical properties of one-dimensional carbon nanotubes and two-dimensional graphene nanoplatelets. Filler dispersion was further improved in the case of carbon nanotubes by noncovalent surface modification using a specific surfactant. The well-dispersed nanofillers favored enhanced phase separation in the thermoplastic polyurethane, leading to a better microstructure, which is able to improve the load transfer and maximize the tensile and viscoelastic...
Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 66, Issue 3 , 2017 , Pages 105-114 ; 00914037 (ISSN) ; Tamjid, E ; Simchi, A ; Bonakdar, S ; Stroeve, P ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
In this study, injectable PEG-based hydrogels containing Laponite particles with mechanical and structural properties close to the natural articular cartilage are introduced. The nanocomposites are fabricated by imide ring opening reactions utilizing synthesized copolymers containing PEG blocks and nanoclay through a two-step thermal poly-(amic acid) process. Butane diamine is used as nucleophilic reagent and hydrogels with interconnected pores with sizes in the range of 100–250 µm are prepared. Improved viscoelastic properties compared with the conventional PEG hydrogels are shown. Evaluation of cell viability utilizing human mesenchymal stem cells determines cytocompatibility of the...
Curcumin incorporated PVA-borax dual delivery hydrogels as potential wound dressing materials—Correlation between viscoelastic properties and curcumin release rate
, Article Journal of Applied Polymer Science ; Volume 135, Issue 45 , 2018 ; 00218995 (ISSN) ; Pircheraghi, G ; Bagheri, R ; Sharif University of Technology
John Wiley and Sons Inc
2018
Abstract
Poly(vinyl alcohol) (PVA) is a biocompatible polymer which can be physically crosslinked by Borax to form hydrogel. PVA-Borax (PB) hydrogel is a promising candidate for drug delivery system. Therefore, it is necessary to find the quantitative relationship between drug release rate and network structure of PB hydrogels to predict and control drug release rate. In this work, at first step the optimum ratio of Borax: PVA was determined by studying the interactions between PVA chains and Borax molecules by means of Fourier transform infrared spectroscopy, while viscoelastic properties of prepared PB hydrogels were measured in the oscillatory shear flow field. In the following, curcumin as a...
Atorvastatin treatment softens human red blood cells: an optical tweezers study
, Article Biomedical Optics Express ; Volume 9, Issue 3 , 2018 ; 21567085 (ISSN) ; Babaei, M ; Azadbakht, A ; Pazoki Toroudi, H ; Mashaghi, A ; Moosavi Movahedi, A. A ; Seyed Reihani, .N ; Sharif University of Technology
OSA - The Optical Society
2018
Abstract
Optical tweezers are proven indispensable single-cell micro-manipulation and mechanical phenotyping tools. In this study, we have used optical tweezers for measuring the viscoelastic properties of human red blood cells (RBCs). Comparison of the viscoelastic features of the healthy fresh and atorvastatin treated cells revealed that the drug softens the cells. Using a simple modeling approach, we proposed a molecular model that explains the drug-induced softening of the RBC membrane. Our results suggest that direct interactions between the drug and cytoskeletal components underlie the drug-induced softening of the cells. © 2018 Optical Society of America
Nonlinear vibration analysis of fractional viscoelastic cylindrical shells
, Article Acta Mechanica ; Volume 231, Issue 11 , 2020 , Pages 4683-4700 ; Haddadpour, H ; Shakouri, M ; Sharif University of Technology
Springer
2020
Abstract
Nonlinear vibrations of viscoelastic thin cylindrical shells are studied in this paper. The viscoelastic properties are modeled using the Kelvin–Voigt fractional-order constitutive relationship. Based on the nonlinear Love thin shell theory, the structural dynamics of the cylindrical shell is modeled by using the Newton’s second law, and the Galerkin method is used to discretize the nonlinear partial differential equations into the set of nonlinear ordinary differential equations. The method of multiple scales is used to solve the nonlinear ordinary differential equations, and the amplitude–frequency and phase–frequency equations are extracted. The obtained results are verified with...