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thermal-expansion
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Total 43 records
Soil-structure Interaction in Geothermal Foundations
, M.Sc. Thesis Sharif University of Technology ; Khosravi, Ali (Supervisor)
Abstract
Regarding the issue that significant amount of energy consumption in the world is dedicated to heating and cooling of the buildings, by using traditional methods of heating and cooling, the environment is facing serious problems like green house gases. There were various techniques for decreasing the amount of contaminants stem from this process. Heat-exchanger energy piles are one of the most common methods that will result in economic usage of energy resources. Assessing the long-term behavior of the energy piles requires comprehensive understanding of the complex interaction between soil and pile subjected to mechanical and thermal loadings. Several numerical and analytical methods have...
Performance of Unbonded Post-Tensioned Concrete Slab Subjected to Temperature Variations
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Tests have shown that concrete post-tensioned slab under heat condition suffer a significant reduction in stiffness and strength. Design and implementation of post-tensioned concrete slabs with large spans of industrial structures exposed to extreme variation in temperature can be possible with detailed research on its behavior under heating condition. In this study numerical modelling of PT concrete slabs with unbonded tendons under heating condition was created based on available test results in the literature. A parametric study has been carried out and the results are presented for concrete coefficient thermal expansion, thermal contact conductance between the concrete and the cables,...
Application of a Thermo-Plastic Constitutive Model for Coupled THM Analysis of Behavior of Saturated Soils
, M.Sc. Thesis Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
Effects of temperature on the behavior of soils and rocks have been studied widely in recent years. Following the need for understanding the effects of temperature on the behavior of clayey soils, several experimental and numerical studies on thermo-mechanical behavior of clayey soils have been carried out and a number of thermo-mechanical constitutive models have been developed for saturated and unsaturated clayey soils. In this research, a two-yield surface thermo-plastic constitutive model developed by Abuel-Naga et al. (2007, 2009), has been chosen for THM analysis of the behavior of saturated clayey soils. This constitutive model is based on Modified Cam-Clay (MCC) model. The MCC model...
The Effect of Cobalt on Thermal Expansion and Metallurgical Properties of LM13 Alloy
, M.Sc. Thesis Sharif University of Technology ; Varahram, Naser (Supervisor)
Abstract
LM13 Aluminum alloys contain Silicon, Copper, magnesium and Nickel. This alloys have been widely used in automobile pistons. For this application thermal expansion coefficient is one important characteristics other than mechanical properties. In this project replacing Cobalt with Nickel to improve alloy thermal and mechanical properties in piston applications by different cobalt contents. Cobalt contents is 0, 0.15, 0.55 and 0.77 Wt%. Because of oxidation magnesium content decrease into 0.98, 0.74, 0.61 and 0.48 Wt%. Thermal expansion coefficient and UTS first increase and after 0.55 Cobalt Wt% show decrease But yield strength and hardness increase as cobalt content increase. Microscopic...
Thermo-mechanical modeling of high speed spindles
, Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 282-293 ; 10263098 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
2012
Abstract
Prediction of the thermo-mechanical behavior of machine-tool spindles is essential in the reliable operation of high speed machine tools. In particular, the performance of these high speed spindles is dependent on their thermal behavior. The main source of heat generation in the spindle is the friction torque in angular contact ball bearings. This paper presents an effort to develop a comprehensive model of high speed spindles that includes viable models for the mechanical and thermal behavior of its major components, i.e., bearings, shaft and housing. Spindle housing and shaft are treated as six-degree-of-freedom Timoshenko beam elements. Bearings are modeled as two-node elements with five...
Relief of edge effects in bi-adhesive composite joints
, Article Composites Part B: Engineering ; Volume 108 , 2017 , Pages 153-163 ; 13598368 (ISSN) ; Tahani, M ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
Three-dimensional thermo-mechanical stress analysis of composite joints with bi-adhesive bonding is presented using the full layerwise theory. Based on three-dimensional elasticity theory, sets of fully coupled governing differential equations are derived using the principle of minimum total potential energy and are simultaneously solved using the state space approach. Results show that bi-adhesive bonding substantially relieves the edge effects. Moreover, series of parametric studies reveal the nonlinear effects of bonding length ratio and the relative stiffness and coefficient of thermal expansion of the mid- and side-adhesives. It is also concluded that the optimum design of a bi-adhesive...
Oxidized graphitic carbon nitride nanosheets as an effective adsorbent for organic dyes and tetracycline for water remediation
, Article Journal of Alloys and Compounds ; Volume 809 , 2019 ; 09258388 (ISSN) ; Villar Rodil, S ; Paredes, J. I ; Zaker Moshfegh, A. R ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Graphitic carbon nitride (g-C3N4) is promising as adsorbent for water remediation as its chemical structure allows a variety of mechanisms to interact with wastewater pollutants. However, several issues, such as low specific surface area and insufficient dispersibility in water, have to be tackled to achieve a competitive performance in such use. Previous attempts to improve the features of g-C3N4as an adsorbent have relied on carbon doping and exfoliation in the solid phase by thermal expansion. Here, we demonstrate that exfoliation in the liquid phase by a combination of oxidation and sonication allows preparing g–C3N4–based materials with improved dispersibility in water, increased...
The critical voltage of a GPL-reinforced composite microdisk covered with piezoelectric layer
, Article Engineering with Computers ; 2020 ; Ebrahimi, F ; Elianddy Bin Supeni, E ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Springer
2020
Abstract
In this research, electrically characteristics of a graphene nanoplatelet (GPL)-reinforced composite (GPLRC) microdisk are explored using generalized differential quadrature method. Also, the current microstructure is coupled with a piezoelectric actuator (PIAC). The extended form of Halpin–Tsai micromechanics is used to acquire the elasticity of the structure, whereas the variation of thermal expansion, Poisson’s ratio, and density through the thickness direction is determined by the rule of mixtures. Hamilton’s principle is implemented to establish governing equations and associated boundary conditions of the GPLRC microdisk joint with PIAC. The compatibility conditions are satisfied by...
The critical voltage of a GPL-reinforced composite microdisk covered with piezoelectric layer
, Article Engineering with Computers ; Volume 37, Issue 4 , 2021 , Pages 3489-3508 ; 01770667 (ISSN) ; Ebrahimi, F ; Elianddy Bin Supeni, E ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this research, electrically characteristics of a graphene nanoplatelet (GPL)-reinforced composite (GPLRC) microdisk are explored using generalized differential quadrature method. Also, the current microstructure is coupled with a piezoelectric actuator (PIAC). The extended form of Halpin–Tsai micromechanics is used to acquire the elasticity of the structure, whereas the variation of thermal expansion, Poisson’s ratio, and density through the thickness direction is determined by the rule of mixtures. Hamilton’s principle is implemented to establish governing equations and associated boundary conditions of the GPLRC microdisk joint with PIAC. The compatibility conditions are satisfied by...
Effect of rubber particle cavitation on the mechanical properties and deformation behavior of high-impact polystyrene
, Article Journal of Applied Polymer Science ; Volume 104, Issue 2 , 2007 , Pages 1110-1117 ; 00218995 (ISSN) ; Zokaei, S ; Bagheri, R ; Sharif University of Technology
2007
Abstract
Rubber particle cavitation has been the focus of many investigations because it dramatically affects the mechanical properties of polymeric blends. In this work, the effect of rubber particle cavitation on the mechanical behavior of high-impact polystyrene was studied. The extent of cavitation in rubber particles was varied via different thermal contraction/expansion cycles in the range of -100 to 23°C. Tensile, creep, and Charpy impact tests were conducted to evaluate the effects of the degree of cavitation on the general mechanical properties. The notch-tip damage zone and deformation micromechanisms were also investigated by a transmitted optical microscopy technique to reveal the effects...
Effect of SiO2 content on Y-TZP/Al2O3 ceramic-nanocomposite properties as potential dental applications
, Article Ceramics International ; Volume 46, Issue 8 , 2020 , Pages 10910-10916 ; SharifianJazi, F ; Esmaeilkhanian, A ; Moradi, M ; Safi Samghabadi, A. H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) have been widely applied in fixed partial prostheses as well as dental uses i.e. a substructure for crowns. However, Y-TZP has limited applications, which is due to the presence of defects in its microstructure introduced during the manufacturing process. Accordingly, due to Y-TZP limitations, the novel (X)Y-TZP- 20Al2O3-(80-X) SiO2 (X = 65, 70 and 75) ceramic nanocomposites were successfully fabricated via the powder metallurgy method. X-ray diffraction (XRD) patterns of commercial powders showed the stabilization of monoclinic zirconia (ZM) by increasing the silica content. In order to determine the fracture load and micro-bending...
Extension of linear isotherm regularity to long chain primary, secondary and tertiary alcohols, ketones and 1-carboxylic acids by group contribution method
, Article Fluid Phase Equilibria ; Volume 234, Issue 1-2 , 2005 , Pages 11-21 ; 03783812 (ISSN) ; Kalantar, Z ; Sharif University of Technology
2005
Abstract
In this work, the group contribution approach has been used in combination with the linear isotherm regularity (LIR) equation of state to estimate pvT properties of primary, secondary and tertiary alcohols, ketones and 1-carboxylic acid. In addition, the isothermal compressibility and thermal expansion coefficient of these compounds have been predicted. We assume each of these organic compounds as a hypothetical mixture of methyl, methylene and a functional group, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state (EOS) has been extended to such a hypothetical mixture. Three basic compounds, namely propane,...
Characterization of nanocrystalline CuCo2 O4 spinel prepared by sol–gel technique applicable to the SOFC interconnect coating
,
Article
Applied Physics A: Materials Science and Processing
;
Volume 119, Issue 2
,
May
,
2015
,
Pages 727-734
;
09478396 (ISSN)
; Askari, M
; Ghorbanzadeh, M
;
Sharif University of Technology
Springer Verlag
2015
Abstract
CuCo2 O4 spinel nanopowders were synthesized by sol–gel method. The optimal values of pH and molar ratio of citric acid to metal ions (RC), and the influence of the calcination temperature and time were investigated. As-prepared materials were characterized by XRD, TGA, DSC, FE-SEM and electrical and coefficient of thermal expansion (CTE) measurements. It was found that pH = 4.5 and RC = 1 are the optimum conditions to produce pure CuCo2 O4 nanopowders. The electrical conductivity was increased remarkably from 15.2 to 27.5 S cm−1 with an increase in temperature from 500 to 800 °C. Over the temperature range of 25–800 °C, the CTE of...
Parallelization of the Lattice Boltzmann model in simulating buoyancy-driven convection heat transfer
, Article 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; Volume 375, Issue 1 , 2004 , Pages 305-312 ; 02725673 (ISSN) ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2004
Abstract
The main objective of the current work is to utilize Lattice Boltzmann Method (LBM) for simulating buoyancy-driven flow considering the hybrid thermal lattice Boltzmann equation (HTLBE). After deriving the required formulations, they are validated against a wide range of Rayleigh numbers in buoyancy-driven square cavity problem. The performance of the method is investigated on parallel machines using Message Passing Interface (MPI) library and implementing domain decomposition technique to solve problems with large order of computations. The achieved results show that the code is highly efficient to solve large scale problems with excellent speedup. Copyright © 2004 by ASME
Molecular dynamics study of the thermal expansion coefficient of silicon
, Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 380, Issue 48 , 2016 , Pages 4039-4043 ; 03759601 (ISSN) ; Mohagheghian, E ; Rasouli, A ; Sharif University of Technology
Elsevier, B. V
2016
Abstract
Due to the growing applications of silicon in nano-scale systems, a molecular dynamics approach is employed to investigate thermal properties of silicon. Since simulation results rely upon interatomic potentials, thermal expansion coefficient (TEC) and lattice constant of bulk silicon have been obtained using different potentials (SW, Tersoff, MEAM, and EDIP) and results indicate that SW has a better agreement with the experimental observations. To investigate effect of size on TEC of silicon nanowires, further simulations are performed using SW potential. To this end, silicon nanowires of different sizes are examined and their TEC is calculated by averaging in different directions ([100],...
Thermal residual stresses in silicon thin film solar cells under operational cyclic thermal loading: A finite element analysis
, Article Solar Energy ; Volume 135 , 2016 , Pages 366-373 ; 0038092X (ISSN) ; Dehghany, M ; Sohrabpour, S ; Naghdabadi, R ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In manufacturing amorphous silicon solar cells, thin films are deposited at high temperatures (200-400 °C) on a thick substrate using sputtering and plasma enhanced chemical vapor deposition (PECVD) methods. Since the thin films and substrate have different thermal expansion coefficients, cooling the system from deposition temperature to room temperature induces thermal residual stresses in both the films and substrate. In addition, these stresses, especially those having been induced in the amorphous silicon layer can change the carrier mobility and band gap energy of the silicon and consequently affect the solar cell efficiency. In this paper, a 2D finite element model is proposed to...
Buckling and frequency responses of a graphene nanoplatelet reinforced composite microdisk
, Article International Journal of Applied Mechanics ; Volume 11, Issue 10 , 2019 ; 17588251 (ISSN) ; Habibi, M ; Safarpour, H ; Safarpour, M ; Foong, L. K ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2019
Abstract
This is the first research on the vibration and buckling analysis of a graphene nanoplatelet composite (GPLRC) microdisk in the framework of a numerical based generalized differential quadrature method (GDQM). The stresses and strains are obtained using the higher-order shear deformable theory (HOSDT). Rule of the mixture is employed to obtain varying mass density, thermal expansion, and Poisson's ratio, while the module of elasticity is computed by modified Halpin-Tsai model. Governing equations and boundary conditions of the GPLRC microdisk are obtained by implementing Extended Hamilton's principle. The results show that outer to inner ratios of the radius (Ro/Ri), ratios of length scale...
Thermal buckling responses of a graphene reinforced composite micropanel structure
, Article International Journal of Applied Mechanics ; Volume 12, Issue 1 , 2020 ; Aliakbarlou, H ; Jebeli, M ; Noormohammadiarani, O ; Habibi, M ; Safarpour, H ; Foong, L. K ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2020
Abstract
This is the first research on the thermal buckling analysis of graphene nanoplatelets reinforced composite (GPLRC) doubly curved open cylindrical micropanel in the framework of numerical-based two-dimensional generalized differential quadrature method (2D-GDQM). Additionally, the small-scale effects are analyzed based on nonlocal strain gradient theory (NSGT). The stresses and strains are obtained using the high-order shear deformable theory (HOSDT). The rule of mixture is employed to obtain varying thermal expansion, and Poisson's ratio, while module of elasticity is computed by modified Halpin-Tsai model. In addition, nonlinear temperature changes along the GPLRC micropanel's thickness...
A particular criterion for progressive failure analysis of carbon/phenolic tape-wounded conic shells
, Article International Journal of Damage Mechanics ; Volume 30, Issue 8 , 2021 , Pages 1238-1260 ; 10567895 (ISSN) ; Karimian, M ; Jafari, H. R ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
Conic shell structures are widely used in aerospace industries. In the literature various models have been proposed to failure analysis of composite materials. Clearly, each model has a favorable range of applications. In this paper tensile, compressive, shear and thermal expansion properties of tape-wounded Carbon/Phenolic composites are firstly measured at various temperatures in range 23–200°C. The captured properties are then taken into account to progressive failure analysis of a conic Carbon/Phenolic structure under internal pressure and thermal loadings. For this end, a particular failure criterion is proposed to predict failure in the composite structures with a reasonable margin of...
Thermo-hydro-mechanical modeling of fracturing porous media with two-phase fluid flow using X-FEM technique
, Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 44, Issue 18 , October , 2020 , Pages 2430-2472 ; Mortazavi, S. M. S ; Sharif University of Technology
John Wiley and Sons Ltd
2020
Abstract
In this paper, a fully coupled thermo-hydro-mechanical model is presented for two-phase fluid flow and heat transfer in fractured/fracturing porous media using the extended finite element method. In the fractured porous medium, the traction, heat, and mass transfer between the fracture space and the surrounding media are coupled. The wetting and nonwetting fluid phases are water and gas, which are assumed to be immiscible, and no phase-change is considered. The system of coupled equations consists of the linear momentum balance of solid phase, wetting and nonwetting fluid continuities, and thermal energy conservation. The main variables used to solve the system of equations are solid phase...