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Non-linear Analysis of Functionally Graded Sector Plates with Simply Supported Radial Edges under Thermo-Mechanical Loading
, M.Sc. Thesis Sharif University of Technology ; Fallah Rajabzadeh, Famida (Supervisor)
Abstract
Problems with composite materials can indicate the lack of mechanical properties of the layers, especially in high temperature, which led to the expansion of functionally graded materials. The most important application of these materials is in high temperature environments .therefore the study of their behavior under mechanical and thermal loads in the range of small and large deformations is very important.The purpose of this research is to provide an analytical solution for nonlinear behavior of functionally graded circular sector plates under thermomechanical load.The material properties are graded through the plate thickness according to a power-law distribution of the volume fraction...
Multiscale Investigation of Plastic Behavior in Crystalline Metals
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor) ; Jahanshahi, Mohsen (Co-Advisor)
Abstract
In this study, a modern multiscale sequential molecular dynamics (MD) – finite element (FE) coupling method is proposed to represent the role of grain boundary (GB) planar defect on mechanical properties of crystalline structures at various temperatures. Different Grain Boundary misorientation angle is considered and the temperature varies from 0 up to 800 K. The embedded-atom method (EAM) many-body interatomic potential is implemented to consider pairwise interactions between atoms in the crystalline structures with face-centered-cubic (FCC) lattice structure at different temperatures. In addition, the Nose-Hoover thermostat is employed to adjust the fluctuation of temperature. The atomic...
Hyperelastic Modeling of Atomistic Continuum in the Presence of Inhomogeneity
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor) ; Jahanshahi, Mohsen (Supervisor)
Abstract
In this study, a pioneer multiscale hierarchical molecular dynamics (MD) – finite element (FE) coupling method is proposed to illustrate the influence of large deformation on mechanical properties of heterogeneous nano-crystalline structures. The embedded-atom method (EAM) of many-body interatomic potential is applied to evaluate pairwise interactions between atoms in the metallic alloys with face-centered-cubic (FCC) lattice structure at room temperature. In addition, the Nose-Hoover thermostat is used to control the instability of temperature. A weight average between the lattice parameters of atomic structures is utilized in order to calculate the equivalent lattice parameter. The...
Dynamic Modelling of Ductile Damage with Extended Finite Element Method
, Ph.D. Dissertation Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In this thesis, based on the combination of Extended Finite Element Method (X-FEM) and appropriate material constitutive models, an efficient method is proposed to model ductile fracture under quasi-static, cyclic and dynamic conditions. X-FEM is a novel method in which with the use of appropriate enrichment functions, discontinuity geometry is separated from the computational mesh and hence the need for a remeshing step is alleviated. The non-linear material behavior in the crack tip process zone can best be modeled with methods based on continuum damage mechanics. These methods model the ductile fracture mechanisms, phenomenologically. In this thesis, in order to model the ductile...
Modeling the Dynamic Contact with Large Deformations Using the G-ALE-FEM Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
Contact between different parts of a system and their interactions on each other is one of the most important phenomena that we face in modeling a variety of mechanical issues which should be carefully considered. Sometimes, this phenomenon occurs between different components in a phase and some other times between several phases, which, causes changes in the performance and response of the system. Therefore, in order to investigate its effect in particular on dynamic problems that are subject to severe changes over a short period of time, and to provide more effective methods for dealing with it, the subject of this research has been devoted to dynamic contact modeling with large...
The Effects of Temperature, Strain Rate and Number of Passes on Ecap Processing of WE43 Magnesium Alloy
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor) ; Akbarzadeh, Abbas (Supervisor)
Abstract
Equal Channel Angular Pressing (ECAP) is one of the most applicable severe plastic deformation procedures (SPD) which results in improvement of strength and ductility through grain refinement. WE43 magnesium alloy belongs to a group of alloys for medical industry because of its good biocompatibility. In this study, equal channel angular pressing was performed at different temperatures, strain rates and number of passes on strip-shape samples to achieve proper mechanical properties. Tensile properties, hardness and microstructural evolutions were evaluated and the results were analyzed according to the EDS test. Results shows that at 380 ℃ and 440 ℃ grain refinement was accomplished by...
Processing Nano Composite Structure of 1100 and 3004 Al Alloy Sheets Using ARB Technique and Study Influence of Heat Treatment on the Grain Structure
, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous (Supervisor)
Abstract
At this study, nano structure sheet composite produced by1100 and 3004 strips using Accumulative role banding then mechanical and physical properties of the composites were investigated. After surface preparation, primary composite samples produced by putting different layers on each other and then rolling. The rolling was occurred in two steps; thickness reduction at first and second step were about 50% and 34%, respectively. ARB process were done till ninth cycle for Primary composite samples. To investigate mechanical properties of the samples, hardness, micro hardness and tensile strength tests have been done. Furthermore, micro structure of selective samples were studied by light...
Study of Microstructure, Strengthening Mechanisms and Hot Deformation Behavior of Ultrafine-grained Al6063- Al203 Nanocomposites
, Ph.D. Dissertation Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
In this study, Al6063-Al203 nanocomposite powders were synthesized by reaction mechanical milling method. Nanometric reinforcement particles were formed via high- energy ball milling under a controlled oxygen containing atmosphere. Morphological and microstructural evolutions of nanocomposite powders were investigated by using X-ray diffraction (XRD), thermal analysis (DTA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods at different milling times. The results showed that mechanical milling stages were accelerated and the time for reaching steady- state condition was decreased by an increase in the oxygen content in the milling atmosphere. The in-situ...
Effect of Sever Plastic Deformation by Constrained Groove Pressing on Microstructure and Mechanical Properties of 3003 Aluminium Alloy
, M.Sc. Thesis Sharif University of Technology ; Kazeminejad, Mohsen (Supervisor)
Abstract
A severe plastic straining method, called constrained groove pressing, was used to improve the microstructure and mechanical properties of non-hardenable 3003 Al-Mn alloy. Williamson-Hall method was utilized to measure the grain size from X-ray diffraction patterns of deformed samples. The results show that ultra-fine grained 3003 alloy having grain size of 580nm can be successfully produced by constrained groove pressing at room temperature. Mechanical properties of sheets, examined by tensile test, were approximately exhibited 170% improvement in comparison with those of annealed sample. Also, comparing the achieved results with those of aluminium 1100 alloy confirmed the rapid rate of...
Thermo-Mechanical Behavior of Shape Memory Alloys Under Multiaxial Loadings: Constitutive Modeling and Numerical Implementation at Small and Finite Strains
, Ph.D. Dissertation Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
Abstract
Shape memory alloys (SMAs) are a type of smart materials which have unique features known as pseudo-elasticity, one-way and two-way shape memory eects. The interest in the mechanical behavior of SMAs is rapidly growing with the increasing number of potential industrial applications. The origin of SMA material features is a reversible thermo-elastic martensitic phase transformation between a high symmetry, austenitic phase and a low symmetry, martensitic phase. In most applications, SMAs experience general non-proportional thermo-mechanical loads. Thus, according to experimental observations, the so-called variant reorientation should be considered in the constitutive model development....
Investigation on Performance Based Seismic Design of Concentrically Braced Frames
, M.Sc. Thesis Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
Today, Stability review of existing structures is one of the most important problems that have underperformed in our country. Base of doing this important project is Instruction for Seismic Rehabilitation of Existing Buildings No.360. In these Criteria, Nonlinear Static Procedure (NSP) is the most popular analytical method. In this procedure, a building shall be modeled, analyzed, and evaluated as an assembly of elements and components. For modeling of components, in lieu of relationships derived from experiment or analysis, the generalized load-deformation with parameters a, b, c, shall be used for members of structure. These parameters were defined in Tables 5-6 and 5-7 for steel moment...
Free Vibration Analysis of Moderately Thick Rectangular Plate Made of Functionally Graded Material on Arbitrary Supports Using Extended Kantorovich Method
, M.Sc. Thesis Sharif University of Technology ; Kargarnovin, Mohammad Hossein (Supervisor) ; Mohammadi Aghdam, Mohamamd (Supervisor)
Abstract
In this study, free vibration analysis of moderately thick rectangular FG plates with general boundary conditions is investigated. Governing equations of motion are obtained based on the Mindlin plate theory. A semi analytical solution is presented for the governing equations using extended Kantorovich method (EKM). Results are compared and validated with available results in the literature. Effects of different parameters such as boundary conditions, material and geometrical parameters on natural frequencies of the FG plates are investigated
3D Reconstruction of Face Using Front View and Side View Images
, M.Sc. Thesis Sharif University of Technology ; Ramezanin, Rassul (Supervisor) ; Jamzad, Mansour (Co-Advisor)
Abstract
3D face modeling is currently a popular area in Computer Graphics and Computer Vision. Many techniques have been introduced for this purpose, such as using one or more cameras, 3D scanners, and many other systems of sophisticated hardware with related software. But the main goal is to find a good balance between visual reality and the cost of the system. In this thesis, reconstruction of a 3D human face from a pair of orthogonal views, front face and side face is studied. Unlike many other systems, facial feature points are obtained automatically from two photographs with the help of an Active shape model algorithm for the frontal face and an edge detection algorithm for side view of the...
Constitutive Modeling of Temperature and Strain Rate Dependent Behavior of Rubbers at Finite Deformations with Combined Physicalphenomenological Approach
, Ph.D. Dissertation Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Arghavani, Jamal (Co-Advisor)
Abstract
Wide applications of elastomeric (rubber-like) materials have led to significant interest of researchers to these materials. Elastomers as a great category of polymeric materials,posses specific properties such as large elastic deformations and energy absorption which make them suitable for aerospace and automotive applications as well as shock and vibration absorbers.In this thesis, an exponential strain energy function (SEF) has been proposed for elastomers which well reproduces the mechanical behavior of these materials and also the material parameters are related to the physical parameters of the material molecular network. This SEF has been concluded from a relation proposed for the...
Dynamic and Static Behavior of Anchored-block Flexible Retaining Structures
,
M.Sc. Thesis
Sharif University of Technology
;
Haeri, Mohsen
(Supervisor)
Abstract
Deformation induced by deep excavations is one of the most important factors in investigating function of retaining structure constructed in urban areas. Predicting content of deformation induced by deep excavations is a fundamental and important step in designing of retaining structures. A prestressed grouted ground anchor is a structural element installed in soil or rock that is used to transmit an applied tensile load into the ground. In this study, effective factors in deformation induced by deep excavation reinforced by method of anchoring is analyzed by application of numerical study based on finite element method by using PLAXIS software, and results are compared. The seismic...
Investigation of Texture Effects on the Deformation of Sheet Metals using Crystal Plasticity Theory
, M.Sc. Thesis Sharif University of Technology ; Assempour, Ahmad (Supervisor) ; Mehdigholi, Hamid (Co-Advisor)
Abstract
The orientations which predominate in a final orientation distribution resulted from a specific deformation mode are the ideal orientations. There is a set of ideal orientations for each of crystal structures under a predefined mode of deformation. Ideal orientations are one of the material characteristics in the applied mode of deformation. The material texture strongly influences its final properties and affects the material behaviour in the subsequent forming processes.
In this project, final texture of 1010 steel sheet resulted from simple tension mode of deformation is investigated computationally and experimentally. The calculated texture based on the simulation procedure is...
In this project, final texture of 1010 steel sheet resulted from simple tension mode of deformation is investigated computationally and experimentally. The calculated texture based on the simulation procedure is...
Computational Simulation of High Density Ratio Drop Deformation and Breakup, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Karbaschi, Mohsen (Supervisor)
Abstract
Deformation and breakup of drops are the basisof many interfacial flow studies and appear in a number of industrial applications, e.g., spray painting, spray combustion, emulsion, foam, sedimentation, and rain. Following their formation, drops may enter a region where hydrodynamicforces are large enough to cause their significant deformation and breakup. When a drop breaks apart into a multitude of small fragments due to disruptive hydrodynamicforces, the process is termed secondary atomization or breakup. Due to many engineering and scientific applications of multiphase and multi-component flows, they have been the main topic of many researchers for many years. Particularly, interfacial...
Free Vibration Analysis of FG Annular Sector Plates Using Extended Kantrovich Method
, M.Sc. Thesis Sharif University of Technology ; Fallah Rajabzadeh, Famida (Supervisor)
Abstract
In this study the free vibration of annular sector plates made of functional materials with using the extended Katrovich method is investigated for a variety of boundary conditions. For this purpose, based on the first order shear deformation theory and Hamilton's principle, equations of motion that they are five differential equations and coupled, are derived. Due to the difficulty of the equations obtained by applying extended kantrovich method on these equations, two ordinary differential equations obtained, the two categories combined fixed and simple boundary conditions will be solved by using generalized differential quadrature and in an iterative process system natural frequency is...
Study of Microstructure and Mechanical Properties of Austenitic Stainless Steel after Sheet Rolling Process
, M.Sc. Thesis Sharif University of Technology ; Serajzadeh, Siamak (Supervisor)
Abstract
Austenite in the 300 stainless steels is not a table phase in deformation processing during which martensite phase forms. This causes significant changes in the microstructures as well as the mechanical properties of deformed steel. In this work, the effects of rolling speed, reduction, temperature and strain pass on the strain-induced martensite during strip rolling operation of stainless steel 304L are studied. Cold rolling experiments under different speeds, reduction and temperature are conducted and then, the microstructural events and mechanical properties of the rolled steel are evaluated. For doing so, different testing techniques including tensile test, hardness measurement, optical...
Manufacturing of Composite and Nanostructured Thin Walled Tubes by ASB Process
,
M.Sc. Thesis
Sharif University of Technology
;
Akbarzadeh, Abbas
(Supervisor)
Abstract
In this study, utilizing the so-called “flow forming”, a cold-bonding process is developed to produce multi-layered thin-walled tubes and cylinders. In this process, which is entitled as “spin-bonding”, two layers of tubes are bonded by thickness reduction. Al/Al and Cu/Al tubes were bonded at various temperatures, thickness reductions, feed rates and roller attack angles. The bonding quality was examined by peel test, metallography and SEM fractography. Moreover, spin-bonding was accumulatively applied to aluminum tubes up to 4 cycles as a severe plastic deformation (SPD) for thin-walled tubes and cylinders entitled as “Accumulative Spin-Bonding” (ASB). Beside of experimental works,...