Search for: viscoelasticity
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    Modeling and Manipulation of Intracytoplasmic Cell Injection

    , M.Sc. Thesis Sharif University of Technology Moshtaghi, Behnam (Author) ; Ahmadian, Mohammad Taghi (Supervisor)
    The injection process on cell is a very accurate and sensitive operation. This method is used for several new invented approaches such as tracytoplasmic Cell Injection or drug delivery. Controlling the injection force in micro scale is one of the problems of mentioned operations. Current huge and expensive laboratorial devices are helping the operators to do injection operation with :nore success. In this study a simple and novel microelectromechanical (MEMS) mechanism for doing injection process automatically on the biological cells is proposed. In order to controlling this device properly, we should model and simulate the operation condition from initial position to final condition. This... 

    Three Dimensional Dynamic Model of Human Patellofemoral Joint

    , M.Sc. Thesis Sharif University of Technology Akbar, Mohammad (Author) ; Farahmand, Farzam (Supervisor) ; Saadat Foumani, Mahmoud (Supervisor)
    Patellofemoral joint has an important role in knee extension. Because of this joint importance and complicated mechanical behavior, a lot of mathematical models have been used, to obtain a better understand of this joint, considering this joint as a part of knee joint or as a separate joint. Although these works have comprehensively studied the patellofemoral joint but they don’t emphasis on dynamic aspects. Also there is no work to compare the experimental and theoretical results calculated from one specified subject knee.In this study, the kinematic and dynamic of patellofemoral joint has been studied, constructing a three dimensional dynamic model of patellofemoral joint and experimental... 

    Panel Flutter Analysis of Cylindrical Constrained Layer Damping (CLD) Panels

    , M.Sc. Thesis Sharif University of Technology Sadeghmanesh, Mostafa (Author) ; Haddadpour, Hassan (Supervisor)
    The purpose of this study is to analytically study the aeroelastic characteristics of the cylindrical shells fully treated with passive constrained layer damping (PCLD) to indicate the effects of various parameters on the behavior of such structures. Constraining the viscoelastic layers increases the amount of dissipated energy and the bending stiffness of the structure without considerable change of the weight.
    A thin shell theory in conjunction with the Donell assumptions is employed for the shell and the constraining layer (CL) and the first order shear deformation theory (FSDT) is used for the viscoelastic layer to construct the model. The effects of rotary inertia and shear... 

    Rheological Evaluation of Ageing Properties of Modified Bitumens

    , M.Sc. Thesis Sharif University of Technology Naderi, Koorosh (Author) ; Tabatabaee, Nader (Supervisor)
    Bitumen ageing is one of the principal factors causing the deterioration of asphalt pavements. Ageing is a complex process that is affected by different parameters.With the rapid growth of modified binders in road paving applications over the past twodecades, it is important to study the ageing properties of these binders. A number of laboratory methods are used tosimulatethe bitumenageing at various stages of the production and service of hot mix asphalt.Recent studies have shown that Superpave testing protocol does not fully address the ageing of modified binders. To study the ageing properties of modified binders, three different types of binder modifiers, plastomer, elastomer, and ground... 

    Developing the MIDA Method for Structures Equipped with Dampers and Exerting this Method on a Structure with SCVDs Damper

    , M.Sc. Thesis Sharif University of Technology Zafarkhah, Elyar (Author) ; Mofid, Masood (Supervisor)
    Determining nonlinear dynamic behavior of structures is always one of the main goals of structure and earthquake engineers. The Modal Incremental Dynamic Analysis (MIDA) is one of the newest methods for analyzing the seismic behavior of structures. Indeed, this method has superseded the exact IDA method which is too complicated and prolix. Although, this method represents approximate results, high accuracy, fastness and low cost procedure made it an efficient and useful technique. Many researchers have used this method and investigated the accuracy of that and achieved proper results. Up to now no one has applied this method on structures which are equipped with dampers. In the procedure of... 

    An Analytical Approach to Nonlinear Vibrations of a Three-Layered Sandwich Beam with a Viscoelastic Core, under the Effects of Internal Resonance, Employing MMS

    , M.Sc. Thesis Sharif University of Technology PashaJavid, Babak (Author) ; Haddadpour, Hassan (Supervisor)
    Vibrations with high amplitudes in continuous systems and models with multiple degrees of freedom, in specific conditions, is concomitant with a phenomenon called internal resonance. In the presence of this phenomenon, energy is transferred from one directly excited mode to the other vibrating modes of the structure results in response of the structure to be combination of the excited modes. In that situation occurrence of the internal resonance may decrease the level of undesired vibrations of the structure. This behavior is of interest especially in sandwich structures with viscoelastic cores that are designated to improve the damping characteristics of the structure and the property may... 

    Numerical and Analytical Study of Mixing in Y-shaped Micromixers: Electroosmotic and Poiseuille Flow of PTT Fluids

    , M.Sc. Thesis Sharif University of Technology Reshadi, Milad (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Mozaffari, Ali Asghar (Supervisor)
    Dissemination of an analyte under the laminar flows plays a major role in measuring and assessment of biological fluids such as sample preparation in the context of microfluidic systems. Due to the development of manufacturing technology in the Lab-on-a-chip devices, the production of rectangular microchannels with finite aspect ratios and micron and submicron sizes has been provided by which the effect of electrokinetic phenomena on concentration distribution will be magnified in these systems. On the other hand, these biofluids are viscoelastic and show extraordinary flow behaviors, not existing in Newtonian fluids and adopting appropriate constitutive equations these exotic flow behaviors... 

    Analysis and Simulation of Three-Dimensional Torsional Viscous Dampers

    , M.Sc. Thesis Sharif University of Technology Matbou, Farshad (Author) ; Behzad, Mehdi (Supervisor)
    Torsional vibrations of internal combustion engines and reciprocating compressors, is one of the challenges in the design process. It can reduce power of productivity, equipment operating lifetime and increase noise of the system. Torsional viscous damper is a method to reduce torsional vibrations in rotating equipment. In this study, three-dimensional simulations of torsional viscous damper is performed as a matter of FSI, with consider harmonic excitation on the external walls and calculation of damping response inertia ring in CFX software. The viscoelastic non-Newtonian model properties of damping fluid is calculated in MATLAB software with respect to viscoelastic parameters. For... 

    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 Ghahramanzadeh Asl, Hadi (Author) ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
    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... 

    Experimental Investigation of Fluid Placement and Diversion for Matrix Acidizing

    , M.Sc. Thesis Sharif University of Technology Eghdam, Alireza (Author) ; Ayatollahi, Shahabaldin (Supervisor) ; Shad, Saeed (Supervisor)
    Acidizing efficiency depends on various factors such as formation properties, reservoir and stimulation fluid types and injection scenario. Among these factors, heterogeneity of reservoir’s formation (layered reservoirs and permeability variation versus depth) strongly affect acidizing performance. Accordingly, applying a reliable technique that distribute stimulation fluid uniformly is essential. The aim of carbonate matrix acidizing is to improve fluid flow specially in low permeability zones. Stimulation fluid cannot enter into the low permeability layer due to existence of high permeability layers which are in contact with low permeability ones. So, the stimulation fluid should be... 

    The Study on Relationship between Viscoelastic Properties and Drug Release of Wound Dress Polyvinyl Alcohol Hydrogel

    , M.Sc. Thesis Sharif University of Technology Rezvan, Gelareh (Author) ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
    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... 

    Analitical and Numerical Investigation of Mechanical Response of Steel Cable

    , M.Sc. Thesis Sharif University of Technology Babaei Darabad, Saman (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Although many aspects of helical strand have been carried out, there are still some situations which need more studies. Based on previous studies of wire rope the constitutive equations regarding the rope tension and torque to the rope deformations are carried out. In which constitutive constants depend on both the rope material and geometry of the rope. Equations of motion for straghit rope loaded simultaneously in tension and torque are derived, and with using extensional-torsional deformations in both side of the rope, dynamic stiffness matrix is derived. Some experimental results and currently models are compared with my research model numerically. Finally, mechanic response of helically... 

    Theoretical and Experimental Investigation of Flow behavior of Nanofield Viscoelastic Fluids in Contraction Flow

    , M.Sc. Thesis Sharif University of Technology Behrang, Arash (Author) ; Ramazani Saatatabadi, Ahmad (Supervisor)
    In this work, the viscoelastic fluids flow and their short fiber suspensions has been modeled in contraction geometry using conformation models, these models predict behavior of polymeric chains in contraction geometry. Prediction of viscoelastic fluids flow through a contraction is very important, especially in polymer processing where a polymer melt in barrel of an extruder is going to pass through a narrow die. We expect to see an eddy in each corner of barrel. The result has shown that increasing of De number enhances the eddy magnitude; also with making acute angle, we see decreasing of eddy magnitude. Normal stresses and velocity were investigated in contraction and their results had... 

    Model Based Control of a Laparoscopic Instrument for Safe and Effective Grasping of Spleen Tissue

    , M.Sc. Thesis Sharif University of Technology Abdi, Elahe (Author) ; Farahmand, Farzam (Supervisor) ; Durali, Mohammad (Supervisor)
    In the present dissertation model based grasping of soft tissue with the laparoscopic gripper, tissue deformation under the applied load and control of the tissue-instrument interaction have been studied. As the first step a cantilevered beam under bending and tension has been modeled statically and dynamically using the meshless EFG based method. Results show that an increase in the number of nodes at the displacement boundary and the area of force insertion improves the accuracy of the predicted displacement in the model compared to the analytical solution. In the second step the model is developed for a hemisphere under vertical and lateral compression. Comparison of the deformation of... 

    Modeling and Sensitivity Analysis of Heavy Vehicles Tire With Target of Determining Stiffness and Damping Characteristics

    , M.Sc. Thesis Sharif University of Technology Lahe Motlagh, Peyman (Author) ; Saadat Foumani, Mahmoud (Supervisor) ; Fallah Rajabzadeh, Famida (Supervisor)
    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,... 

    Study of the Effects of Rrest Time and Loading Time on Viscoplastic Strain of Asphalt Concrtee

    , M.Sc. Thesis Sharif University of Technology Jahangiri, Behnam (Author) ; Tabatabaei, Nader (Supervisor)
    Asphalt concrete exhibits viscoelastic and viscoplastic behavior which is dependent on rate and temperature. To model this behavior, various mechanical modelshave been presented in which total strain, as the response of the applied stress, is decomposed by various researchers to recoverable and permanent strains.Accumulation and expansion of permanent response result in rutting which is a dominant and prevalent distress in hot mixed asphalt (HMA) in hot climates. The available models are not capable of accurately calculate the viscoplastic strain under cyclic loading.
    To close this gap, recovered viscoelastic strain at rest (unloading) period was introduced. This parameter accounted for... 

    Evaluation of the Performance of Viscoelastic Dampers in Controlling the Seismic Induced Response of Structures

    , M.Sc. Thesis Sharif University of Technology Gholami, Adel (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
    In the present study, the performance of Viscoelastic Dampers in reducing the seismic response of the structures was investigated. For this purpose, first the effect of added damping to the system was studied. Number of 3-D steel structural models, with and without eccentricity which are designed with the 2800 code (first edition) and 519 code provisions that is not satisfied the provisions of the code-2800(third edition) is considered. It is assume that this system is located on a relatively stiff soil (soil type II based on Iranian Seismic Standard Code - 2800), a number of compatible earthquake records also considered to be used in the parametric studies. The results indicate that in... 

    Investigation of Mechanical Properties of Healthy Red Blood Cells using Optical Tweezers

    , M.Sc. Thesis Sharif University of Technology Azadbakht, Ali (Author) ; Seyed Reihani, Nader (Supervisor) ; Moosavi-Movahhedi, Ali Akbar (Co-Advisor)
    Red blood cells (RBC, erythrocytes) are cells with an average diameter of 8 microns, the thickness of 2-3 microns and the volume of 90 fl. The biconcave shape of red blood cells,together with cell membrane flexibility, enables them to pass the capillaries whose diameter is considerably less than 8 micrometers. Mechanical properties of RBC are related to their membrane and cytoskeleton, which consists of spectrin network. Optical tweezers is able to exert very precise forces to erythrocytes using beed as a handle. In this report, we studied mechanical properties of RBC such as elasticity and viscoelasticity using single trap optical tweezers with beads with antibody coated in order to attach... 

    Passive Measurement of Viscoelastic Properties of the Healthy Red Blood Cell by Optical Tweezers

    , M.Sc. Thesis Sharif University of Technology Motaghian, Melika (Author) ; Seyyed Reihani, Nader (Supervisor)
    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... 

    Experimental Investigation to Determine the Main Parameters for Viscoelastic Surfactant (VES) Injection for Acid Diversion in Reservoirs and Improving Their Design Conditions

    , M.Sc. Thesis Sharif University of Technology Habibi, Reza (Author) ; Ayatollahi, Shahab (Supervisor) ; Bazargan, Mohammad (Co-Advisor)
    The success of matrix acid production operations and its proper efficiency is one of the main challenges for oil and gas companies. The heterogeneity of the reservoir formation (especially the permeability difference) in the area around the well due to the presence of different reservoir layers results in the non-uniform distribution of acid among them and adds acidizing challenges. In order to improve production conditions, stimulation fluid transfer to the low permeability layer, which is the main target of acidizing. In this study, a new generation of chemical diverter, called Viscoelastic Surfactant, has been used. These materials have two components of elastic and viscous behavior, and...