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Axial buckling of imperfect cylindrical steel silos with isotropic walls under stored solids loads: FE analyses versus Eurocode provisions
, Article Engineering Failure Analysis ; Volume 137 , 2022 ; 13506307 (ISSN) ; Maleki, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Stored solids loads on silo vertical walls are composed of two orthogonal components: the horizontal component that internally pressurizes the silo and the vertical wall frictional component that causes axial compression. For an imperfect cylinder, the elastic axial buckling resistance may be considerably raised by a uniform internal pressure as it alleviates the detrimental effect of the geometrical imperfections. However, at high internal pressures, the combination of axial compression and circumferential tension may result into a plastic instability that is commonly termed elephant's foot buckling. Both stabilizing and destabilizing effects of internal pressure are taken into account by...
Complexity of Density Dependencies of Thermal- and Internal- Pressure Compared to that of Total Pressure
, M.Sc. Thesis Sharif University of Technology ; Parsafar, Gholamabbas (Supervisor) ; Goharshadi, Elaheh (Supervisor)
Abstract
A simple equation of state (EoS) has recently been introduced (J. Phys. Chem. B 2009, 113, 11977–11987) as (Z-1) v^2=e+f⁄ρ+gρ^2, where Z≡pv⁄RT is the compressibility factor, v=1⁄ρ is molar volume, and e, f, and g are temperature dependent parameters. This EoS has been found to be accurate for all types of nano- and bulk- solids and bulk fluids, in the entire temperature and pressure ranges for which experimental data are reported, except for the isotherms within the critical region.
The aim of this work is to investigate the validity of a 3-term expression similar to the mentioned EoS for both thermal and internal contributions to the compressibility factor, separately. Such...
The aim of this work is to investigate the validity of a 3-term expression similar to the mentioned EoS for both thermal and internal contributions to the compressibility factor, separately. Such...
A numerical study of swage autofrettage of thick-walled tubes
, Article Materials and Design ; Volume 28, Issue 3 , 2007 , Pages 804-815 ; 02613069 (ISSN) ; Movahhedy, M. R ; Mashreghi, A. R ; Sharif University of Technology
Elsevier Ltd
2007
Abstract
Swage autofrettage process is used for internal forming and sizing of thick-walled tubes designed to withstand high internal pressures. In this process, a mandrel with a diameter slightly larger than that of the tube is pressed inside the tube and in so doing, creates the internal profile. This paper presents an experimental and numerical study of this process. Two dimensional axi-symmetric and three dimensional finite element analyses are used to investigate the effects of workpiece and mandrel geometry on the forming load and part quality. Experiments are carried out to validate the numerical results. © 2005 Elsevier Ltd. All rights reserved
Complexity of density dependencies of thermal and internal pressure compared to that of total pressure
, Article Industrial and Engineering Chemistry Research ; Volume 52, Issue 23 , May , 2013 , Pages 8034-8045 ; 08885885 (ISSN) ; Parsafar, G ; Sharif University of Technology
2013
Abstract
A simple equation of state (EoS) has recently been introduced (J. Phys. Chem. B2009, 113, 11977-11987) as (Z - 1)v2 = e + f/ρ + gρ2, where Z ≡ pv/RT is the compressibility factor, v = 1/ρ is molar volume, and e, f, and g are temperature dependent parameters. This EoS has been found to be accurate for all types of nano and bulk solids and bulk fluids, in the entire temperature and pressure ranges for which experimental data are reported, except for the isotherms within 1 ≤ T r = T/Tc ≤ 1.1 for the spherical and near spherical species and for a wider temperature range for the cylindrical molecules. The aim of this work is to investigate the validity of a three-term expression similar to the...
An analytical solution for optimum design of shrink-fit multi-layer compound cylinders
, Article International Journal of Applied Mechanics ; Volume 4, Issue 4 , December , 2012 ; 17588251 (ISSN) ; Arghavani, J ; Hematiyan, M. R ; Sharif University of Technology
2012
Abstract
In this paper, employing an analytical method, optimum design of multi-layer compound cylinders is investigated. To this end, considering Tresca criterion, maximum shear stress in each layer is minimized. Analytical relations for optimum values of a layer dimension, residual pressures and radial interferences are derived. A technique for shrink-fitting of layers is also proposed and relationships for radial interferences, residual pressures and required temperature differences during the shrink-fitting process are derived. Three different examples are presented to show the effectiveness of the proposed method. It is shown that increasing the number of layers makes shear stress distribution...
thermo-Elasto-Plastic Analysis of Spherical and Cylindrical FG Reservoirs Subjected to Temperature Gradient and Internal Pressure Loading
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Design of thick-walled spherical and cylindrical vessels as fluids containers of high gradient thermal loading is a challenging issue. Using these tanks in high pressure and temperature gradient, particularly in chemical industries, needs to use new methods in design. Elasto-Plastic solution for thick-walled hollow spherical and cylindrical tanks made of FG materials subjected to internal pressure and temperature loading is presented. The power law modeling is used for through-the-thickness variation of mechanical properties. This method is using the new advanced materials with high pressure and thermal strength in fabricating these vessels. One of these materials is functionally graded (FG)...
Design a new spherical super element to static and modal analysis of spherical structures
, Article Proceedings of the ASME Design Engineering Technical Conference, 28 August 2011 through 31 August 2011 ; Volume 1, Issue PARTS A AND B , August , 2011 , Pages 493-497 ; 9780791854785 (ISBN) ; Ahmadian, M. T ; Sharif University of Technology
2011
Abstract
Hollow Spherical Structures such as spherical pressure vessels are widely used in industries. Using faster numerical methods to solve these spherical problems has been one of the research interests in the last decade. Super elements are elements capable of producing the same accurate result in comparison with several conventional elements. In this paper, a new spherical super element is designed and implemented to study the static deformation and modal analysis of a spherical structure. In the static analysis mean of the inner radial displacements of the hollow structure under the internal pressure is evaluated. also performing the modal analysis, natural frequencies of the structure under...
Analysis of Al A359/SiCp functionally graded cylinder subjected to internal pressure and temperature gradient with elastic-plastic deformation
, Article Journal of Thermal Stresses ; Volume 34, Issue 10 , May , 2011 , Pages 1054-1070 ; 01495739 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2011
Abstract
In this article, an analytical elastic-plastic solution for thick-walled cylinders made of Functionally Graded Materials (FGMs) subjected to internal pressure and thermal loading is presented. Based on the experimental results, a mathematical model to predict the yielding through the thickness of FG AlA359/SiCp cylinder is developed. It is shown that under the temperature gradient loading, there is a point in the cylinder where the circumferential stress changes from compressive to tensile. The position of this point depends on the geometry and material properties of the FG cylinder and is independent of the temperature gradient
Elastic Analysis of Banana Shaped Crack in Transversely Isotropic Media under Non-Uniform Internal Pressure
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor)
Abstract
This research investigates the presence of banana shaped crack in transversely isotropic media under internal pressure and calculates the stress intensity coefficients. In the beginning, the equations of equilibrium, along with the constitutive equations governing the transversely isotropic media and the boundary conditions of the problem, are determined. Then, by using a three-dimensional mapping, the non-centered banana shaped crack is turned into a centered crack. In the following, we solve the problem analytically by using the Fabrikant's potential functions for transversely isotropic environment, and by the method provided by Fabrikant rewriting the boundary conditions in terms of these...
An exact analysis for the hoop elasticity and pressure-induced twist of CNT-nanovessels and CNT-nanopipes
, Article Mechanics of Materials ; Volume 82 , 2015 , Pages 47-62A ; 01676636 (ISSN) ; Shodja, H. M ; Sharif University of Technology
Elsevier
2015
Abstract
Carbon nanotubes (CNTs) with and without end caps may be used for fluid storage and transport, respectively, referred to as CNT-nanovessel and CNT-nanopipe. The determination of the stiffness in the hoop (circumferential) and radial directions, ideal hoop strength, and hoop stress-strain curve of such nanostructures is of particular interest. Due to the proposed viewpoint, a chiral free-standing single-walled CNT (SWCNT) has a natural angle of twist and natural extension along the axis of the tube. For example, for the SWCNT (9,3) with diameter of 0.85 nm and chirality angle of 13.9°, the natural angle of twist per unit length is 1.45×10-3 rad/nm. Previously, only Vercosa et al. (2010) who...
Design of thick-walled cylindrical vessels under internal pressure based on elasto-plastic approach
, Article Materials and Design ; Volume 30, Issue 9 , 2009 , Pages 3537-3544 ; 02641275 (ISSN) ; Kargarnovin, M. H ; Naghdabadi, R ; Sharif University of Technology
2009
Abstract
By considering the Bauschinger effect and the yield criterion of Tresca, an exact elasto-plastic analytical solution for a thick-walled cylindrical vessel made of elastic linear-hardening material is derived. Having the working pressure and geometric dimensions of the vessel, the distribution of the hoop and equivalent stresses are optimized in the way that the distribution of stresses becomes smooth in the vessel wall. Based on two optimizing methods of the hoop and equivalent stresses, the best autofrettage pressure is determined. It is shown that this pressure is more than the working pressure and depends on the three following variables: Bauschinger effect, working pressure and geometric...
Creep damage evaluation of thick-walled spheres using a long-term creep constitutive model
, Article Journal of Mechanical Science and Technology ; Volume 23, Issue 10 , 2009 , Pages 2577-2582 ; 1738494X (ISSN) ; Shokouhi, N ; Sharif University of Technology
2009
Abstract
This paper describes a numerical model developed for the computation of creep damages in a thick-walled sphere subjected to an internal pressure and a thermal gradient. The model predicts the creep damage histories during the life of the sphere, owing to variations in stresses with time and through-thickness variations. The creep damage fraction is based on the Robinson's linear life fraction damage rule, which has been incorporated in a nonlinear time-dependent stress analysis. Following the stress histories, the effective stress histories are obtained and the creep damages are calculated and summed during the life of the sphere. The material long-term creep properties up to the rupture and...