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Prediction of Temperature Distribution and Flow Behavior in Hot Extrusion of AA6061-%5 SiCp Composite
, M.Sc. Thesis Sharif University of Technology ; Serajzadeh, Siamak (Supervisor)
Abstract
In this study, hot extrusion of AA6061-%5 SiCp composite has been predicted and flow behavior of material during deformation process has been investigated. At the first step, hot compression tests have been carried out to obtain the flow behavior of the material at different temperatures and strain rates. In the next step, an FE-based temperature-displacement coupled model by employing ABAQUS software has been proposed in order to solve the energy and heat transfer equations and to determine the required energy and force for the extrusion process. Experimental investigations have also been performed to verify the proposed model. Comparison between the results from the model and the...
Simulated and experimental investigation of stretch sheet forming of commercial AA1200 aluminum alloy
, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Vol. 24, issue. 2 , February , 2014 , pp. 484-490 ; Khalili, K ; Mohammadsadeghi, B ; Arabi, H ; Sharif University of Technology
Abstract
The simulation and experimental results obtained from stretching test of a commercial sheet of AA1200 aluminum alloy were compared and evaluated. Uniaxial tensile tests were carried out to obtain the required input parameters for simulation. Finite element analysis of the forming process was carried out using Abaqus/Explicit by considering von Mises and Hill-1948 yield criteria. Simulation results including punch force and strain distribution were compared and validated with the experimental results. The results reveal that using anisotropic yield criteria for simulation has a better match in both cases with the experiments
Fluid-structure interaction analysis of airflow in pulmonary alveoli during normal breathing in healthy humans
, Article Scientia Iranica ; Volume 23, Issue 4 , 2016 , Pages 1826-1836 ; 10263098 (ISSN) ; Saidi, M. S ; Sharif University of Technology
Sharif University of Technology
Abstract
In this work, the human lung alveoli are idealized by a three dimensional honeycomb like geometry and a fluid-structure analysis is performed to study the normal breathing mechanics. In contrast to previous works in which the inlet flow rate is predefined, in this model, we have applied a negative pressure on the outside surface of the alveolus which causes air to flow in and out of the alveolus. The integration of the experimental curve of breathing flow rate was used to approximate the shape of the external applied pressure. Our Fluid-Structure Interaction (FSI) model has an advantage over other literature since it addresses both the fluid dynamics and solid mechanics, simultaneously. The...
Effect of creep on high-order shear deformable beams
, Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2187-2202 ; 10263098 (ISSN) ; Beheshti Aval, S. B ; Vafai, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
A powerful and now theoretical approach is used to obtain an expression for the effect of creep on reinforced concrete shear deform able beams. First, a method is proposed for Ruler-Bernoulli beam to analyze the long-term behavior of concrete beams based on linear strain theory. Second, a formulation has been developed to analyze the strain distribution in shear deformablo concrete beams. Finally, three numerical examples are included in order to compare well-known codes with the proposed method. The comparison of the proposed method, FEM, codes, and experimental works demonstrates that the proposed analytical procedure can effectively simulate creep behavior of reinforced concrete beams....
Effect of creep on high-order shear deformable beams
, Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2187-2202 ; 10263098 (ISSN) ; Beheshti Aval, S. B ; Vafai, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
A powerful and now theoretical approach is used to obtain an expression for the effect of creep on reinforced concrete shear deform able beams. First, a method is proposed for Ruler-Bernoulli beam to analyze the long-term behavior of concrete beams based on linear strain theory. Second, a formulation has been developed to analyze the strain distribution in shear deformablo concrete beams. Finally, three numerical examples are included in order to compare well-known codes with the proposed method. The comparison of the proposed method, FEM, codes, and experimental works demonstrates that the proposed analytical procedure can effectively simulate creep behavior of reinforced concrete beams....
Study on Hot Extrusion of AA2017-10%SiCp
, M.Sc. Thesis Sharif University of Technology ; Serajzade, Siamak (Supervisor)
Abstract
In this study, hot extrusion of AA2017-10%SiC¬p composite during deformation process and effect of deformation parameters on mechanical properties have been investigated. At the first step, hot compression tests have been carried out to obtain the flow behavior of the material at different temperatures and strain rates. The activation energy of hot deformation was calculated 296 Kj/mol. In the next step, by using a finite element model in ABAQUS software and the results of uniaxial hot compression test behavior of AA2017 and AA2017-10%SiC¬p during hot and warm extrusion have been investigated. By using it temperature gradient and velocity field and strain distribution were predicted. In the...
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...
Development of an inverse finite element method with an initial guess of linear unfolding
, Article Finite Elements in Analysis and Design ; Vol. 79, issue , 2014 , p. 1-8 ; Bostan Shirin, M ; Assempour, A ; Sharif University of Technology
Abstract
An inverse finite element method (IFEM) has been developed for estimation of the blank size and prediction of the strain distribution in sheet metal forming. In the inverse method the nodal coordinates in the final shape are known and their corresponding positions on the initial blank should be determined. The developed method deals with logarithmic large strains of membrane triangular elements, virtual work principle and a new approach for friction modeling. This method leads to a system of nonlinear equations which is highly sensitive to the initial guess. In order to avoid the converging problems, especially in the quasi-vertical walls, an appropriate initial guess is introduced. The...
Some improvements on the unfolding inverse finite element method for simulation of deep drawing process
, Article International Journal of Advanced Manufacturing Technology ; Vol. 72, issue. 1-4 , 2014 , pp. 447-456 ; ISSN: 02683768 ; Assempour, A ; Sharif University of Technology
Abstract
The linear unfolding inverse finite element method (IFEM) has been modified and enhanced by implementing large deformation relations. The method is helpful to predict forming severity of the part that should be deep drawn as well as its blank shape and strain distribution in preliminary design stage. The approach deals with minimization of potential energy and large deformation relations with membrane elements. To reduce the computation time, the part is unfolded properly on the flat sheet and treated as 2D problem. Moreover, the nonlinear stress-strain relationship of plastic material properties has been considered to increase the accuracy of the results. An experiment set up has been...
Estimation of the initial blank shape and strain distribution for complicated geometries in sheet metal forming by a nonlinear inverse finite element method
, Article SAE Technical Papers ; 2012 ; Assempour, A ; Sharif University of Technology
SAE
2012
Abstract
A nonlinear inverse finite element method is developed for estimation of initial blank shape and strain distribution in final shape. This method often based on implicit static algorithms, causes sometimes convergence problems because of strong nonlinearities. In order to avoid the converging problems, especially in the quasi vertical walls, an appropriate initial guess is introduced. By using this initial guess, the number of iterations in the nonlinear numerical solution is decreased, solution speed is significantly increased and complicated geometries can be analyzed by this method with good accuracy. Application to a Srail part shows good agreement between commercially available finite...
Stress analysis of internal carotid artery with low stenosis level: the effect of material model and plaque geometry
, Article Journal of Mechanics in Medicine and Biology ; Volume 17, Issue 6 , 2017 ; 02195194 (ISSN) ; Ghorbannia Hassankiadeh, A ; Sharif University of Technology
Abstract
Stress concentration in carotid stenosis has been proven to assist plaque morphology in disease diagnosis and vulnerability. This work focuses on numerical analysis of stress and strain distribution in the cross-section of internal carotid artery using a 2D structure-only method. The influence of four different idealized plaque geometries (circle, ellipse, oval and wedge) is investigated. Numerical simulations are implemented utilizing linear elastic model along with four hyperelastic constitutive laws named neo-Hookean, Ogden, Yeoh and Mooney-Rivlin. Each case is compared to the real geometry. Results show significant strength of oval and wedged geometries in predicting stress and strain...
Study of Shear Lag Effect on Non-rectangular RC Shear Walls
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
The present study aims to evaluate the effect of the shear-lag on non-rectangular RC shear walls and develop equations to determine the axial stress and strain distributions and calculate the effective flange width. Research has shown that a non-rectangular shear wall under a lateral load experiences the largest axial stress and strain in the flange-web cojunction. This phenomenon is referred to as the shear-lag effect and reduces the bending capacity of the shear wall. As a result, the effective flange width is typically defined to consider the shear lag effect. The present work first reviewed the literature on the effects of shear lag on non-rectangular RC shear walls. Then, flanged shear...
Softening behaviour of alumina reinforced copper processed by equal channel angular pressing
, Article Materials Science and Technology (United Kingdom) ; Volume 30, Issue 2 , February , 2014 , Pages 220-226 ; ISSN: 02670836 ; Maghsoudi, M. H ; Serajzadeh, S ; Sharif University of Technology
Abstract
In this present work, the softening behaviour of Cu-1·1 wt-%Al2O3 alloy containing nanometric alumina particles was investigated. Single pass equal channel angular pressing was first applied on cylindrical specimens, and then, the deformed samples were subjected to annealing treatments in the temperature range of 700-1000°C. Afterwards, finite element analysis, microstructural observations, Vickers hardness and shear punch testing were employed to study strain distribution as well as the recrystallisation behaviour of the examined alloy. It was found that the alloy is softened at 800°C or above, which shows its high thermal stability. Furthermore, a very fine completely recrystallised...
Comparison of the effects of different implant apical designs on the magnitude and distribution of stress and strain in bone: A finite element analysis study
, Article Journal of Long-Term Effects of Medical Implants ; Vol. 24, issue. 2-3 , 2014 , p. 109-120 ; Lafzi, A ; Raoofi, S ; Khademi, M ; Amid, R ; Movahhedy, M. R ; Torabi, H ; Sharif University of Technology
Abstract
Objectives: The aim of this study was to investigate the effects of implant design on the apex area and on stress and stress patterns within surrounding bone. Methods: Three commercially available implants with the same diameter (3.5 mm), same length (10-11 mm), and same complement abutment were selected for modeling as follows: (1) flat apical design with light tapering degree, (2) dome-shaped apical design with light tapering, and (3) flat apical design with intense tapering in one-third of the apical area. According to human cone-beam computed tomography (CBCT), the bone was modeled using a cortical thickness of 2 mm and cancellous bone. Forces of 100 N and 300 N in the vertical and 15°...
Fatigue life estimation of bolt clamped and interference fitted-bolt clamped double shear lap joints using multiaxial fatigue criteria
, Article Materials and Design ; Volume 43 , 2013 , Pages 327-336 ; 02641275 (ISSN) ; Chakherlou, T. N ; Farrahi, G. H ; Alderliesten, R. C ; Sharif University of Technology
2013
Abstract
In this paper seven different multiaxial fatigue criteria based on stress, strain and energy were employed to estimate the fatigue lives of double shear lap joint specimens of aluminum 2024-T3 with bolt clamped and interference fitted-bolt clamped fastener holes. Detailed finite element (FE) simulations were conducted to obtain the stress and strain distributions in the joint to be used to as basic data in estimating the fatigue lives using multiaxial fatigue criteria. The estimated lives were compared with available experimental fatigue test results to investigate the capability of the criteria in predicting the fatigue lives. The results showed that the accuracy of life estimation for any...
Strain field and extrusion load in ECAE process of bi-metal circular cross section
, Article Applied Mathematical Modelling ; Volume 36, Issue 5 , 2012 , Pages 2128-2141 ; 0307904X (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
2012
Abstract
In this paper the previous velocity field proposed by the authors for the prediction of strain field and deformation load of circular cross section billet in ECAE process has been extended to take into account the deformation behavior of bimetal circular billet in the same process. Accordingly, using Bezier method, as a robust method for determining the geometry of the streamlines, the strain field developed in the circular bimetal billet is calculated. Then, based on the kinematically admissible velocity and strain fields and using the upper bound theorem the ECAE load is predicted. It was found that at constant inner corner angle of ECAE die, with decreasing of outer curve corner the...
Applying elastic unfolding technique in nonlinear inverse finite element method for sheet forming modeling
, Article Advanced Materials Research, 8 July 2011 through 11 July 2011 ; Volume 341-342 , July , 2012 , Pages 242-246 ; 10226680 (ISSN) ; 9783037852521 (ISBN) ; Assempour, A ; Sharif University of Technology
2012
Abstract
A simplified efficient finite element method called the inverse approach (IA) has been developed to estimate initial blank and strain distribution in sheet metal forming. This algorithm is an inverse method since the position of points in final shape is known and their corresponding position in the initial blank should be determined. This approach deals with the geometric compatibility of finite elements, plastic deformation theory, and virtual work principle. This method often based on implicit static algorithms, sometimes causes convergence problems because of strong nonlinearities. This paper introduces an initial guess to speed up the convergence of Newton- Raphson solution. The...
An investigation into the deformation behaviour of AA6061-5% SiC p composite during and after hot extrusion process
, Article Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications ; Volume 225, Issue 1 , 2011 , Pages 22-31 ; 14644207 (ISSN) ; Mirjalili, A ; Serajzadeh, S ; Sharif University of Technology
Abstract
In this study, hot extrusion of AA6061-5% SiCp composite was studied to determine the composite thermo-mechanical behaviour during deformation and the mechanical properties of extruded composite. Hot compression tests were first carried out to obtain the flow stress behaviour of the composite at different temperatures and strain rates. Then a mathematical model was used to estimate the required energy as well as to predict temperature and strain distributions during the process. Finally, hot extrusion experiments were performed in order to verify the predictions and, also, tensile and hardness testing were conducted to evaluate mechanical properties of extruded material. Comparison between...
A new model for prediction the strain field and extrusion pressure in ECAE process of circular cross section
, Article Applied Mathematical Modelling ; Volume 34, Issue 7 , 2010 , Pages 1901-1917 ; 0307904X (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
2010
Abstract
In this research in order to predict the strain distribution and extrusion load in equal channel angular extrusion (ECAE) process of circular cross section a new three dimensional kinematically admissible velocity field has been developed based on Bezier formulation. The strain distribution in deformation zone and the effects of various terms on extrusion load were determined. The results were compared both with the experimental and numerically predicted results reported in the literature. It was found that extrusion pressure decreases with increasing both the die angle and the outer curved corner angle and increases with increasing the friction coefficient. Also, it was exhibited that...
An analytical study on the elastic-plastic pure bending of a linear kinematic hardening curved beam
, Article International Journal of Mechanical Sciences ; Volume 144 , 2018 , Pages 274-282 ; 00207403 (ISSN) ; Arghavani, J ; Eskandari, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this study, an analytical solution is presented for elastic-plastic pure bending of a linear kinematic hardening curved beam with rectangular cross section both in monotonic loading and unloading. Compared to exact plane plasticity solution (already reported in the literature in loading) which needs solution of a system of equations, the proposed method is based on the hyperbolic strain distribution on the cross section which yields a simple approximate solution. To this end, we employ Winkler's theory, and assume plane cross sections remain plane after loading proved by the exact elasticity and plasticity solutions for pure bending of curved beams with rectangular cross section. At the...