Loading...
Search for:
elasticity
0.015 seconds
Total 952 records
Modeling and analysis of AN ultra light slow flyer with variable shape control surfaces using shape memory alloy actuators
, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 2 , 2004 , Pages 153-162 ; 0791841731 (ISBN); 9780791841730 (ISBN) ; Alemohamad, S. H ; Khiabani, R. H ; Khalighi, Y ; Sharif University of Technology
American Society of Mechanical Engineers
2004
Abstract
Applying flexible variable shape control surfaces (wing and elevator) structures is a way to increase efficiency and maneuverability of the planes, which is recently under research. In this paper, modeling of the flight of an unmanned ultra light plane is discussed. The modeling is done based on a real ultra light plane presented recently. To increase maneuverability of the plane, flexible variable shape structures are designed for the wing and the elevator. In design procedure, having an ultra light plane is considered. The elevator and the wing are used as control surfaces for longitudinal and lateral maneuvers respectively. Shape memory alloys (SMA) are used for reshaping the flexible...
Elastic-plastic modeling of kinematic hardening materials based on F = FeFp decomposition and the logarithmic strain tensor
, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 337-342 ; 0791841731 (ISBN); 9780791841730 (ISBN) ; Naghdabadi, R ; Sharif University of Technology
American Society of Mechanical Engineers
2004
Abstract
In this paper, based on the multiplicative decomposition of the deformation gradient tensor an elastic-plastic modeling of kinematic hardening materials is introduced. In this model, the elastic constitutive equation as well as the flow rule and hardening equation are expressed in terms of the corotational rate of the elastic and plastic logarithmic strains. As an application, the simple shear problem is solved and the stress components are plotted versus shear displacement for a kinematic hardening material
Thermal stress analysis of concrete arch dams due to enviromental action
, 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 393-402 ; 02725673 (ISSN) ; Ghaemian, M ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2004
Abstract
A three-dimensional finite element analysis was carried out to determine the annual variation of temperature and thermal stresses of a concrete arch dam. Appropriate heat transfer boundary conditions in the dam body were used for air and reservoir temperature as well as solar radiation variations. Karaj arch dam in Iran was used as a case study. The rate of convergence of the numerical solution is examined. Results of the finite element analysis show that probable cracks occur in a very narrow region of the downstream face. Thermal loads have the most significant effects for causing downstream cracks in comparison with self-weigh and hydrostatic loads. The cracked areas of downstream face...
Vibration and frequency analysis of non-uniform Timoshenko beams subjected to axial forces
, Article 2003 ASME International Mechanical Engineering Congress, Washington, DC, 15 November 2003 through 21 November 2003 ; Volume 116, Issue 2 , 2003 , Pages 1057-1064 ; 15214613 (ISSN) ; Mehdigholi, H ; Esmailzadeh, E ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2003
Abstract
Dynamic and stability analysis of non-uniform Timoshenko beam under axial loads is carried out. In the first case of study, the axial force is assumed to be perpendicular to the shear force, while for the second case the axial force is tangent to the axis of the beam column. For each case, a pair of differential equations coupled in terms of the flexural displacement and the angle of rotation due to bending was obtained. The parameters of the frequency equation were determined for various boundary conditions. Several illustrative examples of uniform and non-uniform beams with different boundary conditions such as clamped supported, elastically supported, and free end mass have been...
Comparison of the experimental behavior of a shape memory alloy in compression and tension
, Article 2003 ASME International Mechanical Engineering Congress, Washington, DC., 15 November 2003 through 21 November 2003 ; Volume 68 , 2003 , Pages 471-478 ; 07334230 (ISSN) ; Ghorashi, M ; Inman, D. J ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2003
Abstract
The concept of Shape Memory Alloy (SMA) has been a subject of extensive research in the recent few years. In many SMA applications, wire elements have been used in order to control structural specifications like shape and stiffness. Since a wire can only be subjected to tensile forces, the available theoretical models for SMA discuss only the tensile loading. The present paper is an endeavor to overcome this shortcoming. It gives experimental results for tension and compression tests on specimens (having different geometries) made of an identical shape memory alloy. The corresponding results are compared with each other. Using stress-strain diagrams, several important material properties are...
Free edge stress analysis of general cross-ply composite laminates under extension and thermal loading
, Article Composite Structures ; Volume 60, Issue 1 , 2003 , Pages 91-103 ; 02638223 (ISSN) ; Nosier, A ; Sharif University of Technology
2003
Abstract
An elasticity formulation for finite general cross-ply (symmetric and unsymmetric) laminates subjected to extension and/or a layerwise temperature distribution is developed. It is shown that the edge-effect problem of such laminates is actually a quasi-threedimensional problem and its stress analysis can be restricted to a generic two-dimensional cross-section of the laminates. A layerwise theory is used to investigate analytically the interlaminar stresses near the free edges of general cross-ply composite laminates. The results obtained from this theory are compared with those available in the literature. It is found that the theory can predict very accurately the stresses in the interior...
Large elastic-plastic deformation analysis of rectangular plates
, Article New and Emerging Computational Methods: Applications to Fracture, Damage and Reliability (2002 ASME Prssure Vessels and Piping Conference), Vancouver, BC, 5 August 2002 through 9 August 2002 ; Volume 438 , 2002 , Pages 153-159 ; 0277027X (ISSN) ; Shahi, M ; Sharif University of Technology
2002
Abstract
The purpose of this paper is to find a fast and simple solution for the large deformation of rectangular plates considering elastic-plastic behavior. This analysis contains material and geometric nonlinearities. For geometric nonlinearity the concept of load analogy is used. In this method the effect of nonlinear terms of lateral displacement is considered as suitable combination of additional fictitious lateral load, edge moment and in-plane forces acting on the plate. Variable Material Property (V.M.P.) method has been used for analysis of material nonlinearity. In this method, the basic relations maintain the form of stress-strain elastic formula, while material properties are modified to...
Periodicity in the response of nonlinear plate, under moving mass
, Article Thin-Walled Structures ; Volume 40, Issue 3 , 2002 , Pages 283-295 ; 02638231 (ISSN) ; Rahimzadeh Rofooei, F ; Mofid, M ; Mehri, B ; Sharif University of Technology
2002
Abstract
The dynamics of nonlinear thin plates under influence of relatively heavy moving masses is considered. By expansion of the solution as a series of mode functions, the governing equations of motion are reduced to an ordinary differential equation for time development of vibration amplitude, which is Duffing's oscillator with time varying coefficients. Through the application of Banach's fixed-point theorem, the periodic solutions are predicted. The method presented in this paper is general so that the response of plate to moving force systems can also be considered. © 2002 Published by Elsevier Science Ltd
Loading and unloading behaviour of a thermoplastic disc
, Article International Journal of Pressure Vessels and Piping ; Volume 78, Issue 9 , 2001 , Pages 637-645 ; 03080161 (ISSN) ; Shirazi, R ; Sharif University of Technology
2001
Abstract
The calculation of loading and residual stresses, and associated strains and displacements, are reported for shrink fitted rotating discs at elevated temperatures. A range of material behaviour is considered including unloading described by an actual material curve, or modelled by isotropic of kinematic hardening with a variable Bauschinger effect. Various collapse loads are obtained and discussed for design boundaries. The influence of reloading on the residual stresses is also studied. It is shown that after the first few loadings of a disc, the residual stress field becomes constant. © 2001 Elsevier Science Ltd. All rights reserved
A plasticity model for metal powder forming processes
, Article International Journal of Plasticity ; Volume 17, Issue 12 , 2001 , Pages 1659-1692 ; 07496419 (ISSN) ; Khoei, A. R ; Sharif University of Technology
2001
Abstract
In this paper, a double-surface plasticity model, based on a combination of a convex yield surface consisting of a failure envelope, such as a Mohr-Coulomb yield surface and, a hardening cap model, is developed for the nonlinear behaviour of powder materials in the concept of a generalized plasticity formulation for the description of cyclic loading. This model reflects the yielding, frictional and densification characteristics of powder along with strain and geometrical hardening which occur during the compaction process. The solution yields details on the powder displacement from which it is possible to establish the stress state in the powder and the densification is derived from...
First order decoupling of equations of motion formultibody systems consisting of rigid and elastic bodies
, Article Iranian Journal of Science and Technology, Transaction B: Technology ; Volume 24, Issue 3 , 2000 , Pages 342-343 ; 03601307 (ISSN) ; Fahimi, F ; Sharif University of Technology
2000
Abstract
An improved method for deriving elastic generalized coordinates is considered and Kane's equations of motion for multibody systems consisting of an arbitrary number of rigid and elastic bodies are presented. The equations are in general form and are applicable for any desired holonomic system. Flexibility in choosing generalized speeds in terms of generalized coordinate derivatives in Kane's method is used. It is shown that proper choice of a congruency transformation between generalized coordinate derivatives and generalized speeds leads to first order decoupled equations of motion for holonomic multibody systems consisting of an arbitrary number of rigid and elastic bodies. In order to...
Mathematical modeling of anisotropic hyperelastic cylindrical thick shells by incorporating thickness deformation and compressibility with application to arterial walls
, Article International Journal of Structural Stability and Dynamics ; Volume 22, Issue 13 , 2022 ; 02194554 (ISSN) ; Asghari, M ; Sharif University of Technology
World Scientific
2022
Abstract
This paper is devoted to mathematical modeling of anisotropic hyperelastic thick cylindrical shells like arteries by taking into account the volume compressibility and through-the-thickness deformation. To describe the hyperelastic behavior of this kind of shells and extract their constitutive relations, the modified anisotropic (MA) model is employed, which is able to characterize compressible behavior of hyperelastic materials like soft tissues. By considering the arterial segment as a thick cylindrical shell, the higher order thickness deformation shell theory together with nonlinear Green's strains are exploited to express its deformations and capture the thickness stretching effect. The...
Theoretical analysis of rotary hyperelastic variable thickness disk made of functionally graded materials
, Article Structural Engineering and Mechanics ; Volume 45, Issue 1 , 2022 , Pages 39-49 ; 12254568 (ISSN) ; Mahdavi Adeli, M ; Zamani, F ; Haghshenas Gorgani, H ; Sharif University of Technology
Techno-Press
2022
Abstract
This research investigates a rotary disk with variable cross-section and incompressible hyperelastic material with functionally graded properties in large hyperelastic deformations. For this purpose, a power relation has been used to express the changes in cross-section and properties of hyperelastic material. So that (m) represents the changes in cross-section and (n) represents the manner of changes in material properties. The constants used for hyperelastic material have been obtained from experimental data. The obtained equations have been solved for different m, n, and (angular velocity) values, and the values of radial stresses, tangential stresses, and elongation have been compared....
Elastic responses of bi-material media reinforced by interfacial thin films under asymmetric loading
, Article International Journal of Solids and Structures ; Volume 254-255 , 2022 ; 00207683 (ISSN) ; Jarfi, H ; Eskandari, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this paper, the elastic solution to the problem of an isotropic bi-material full-space reinforced by a perfectly bonded thin film across the media interface and subjected to arbitrary asymmetric interfacial loading is addressed. To not include any simplifications, the thin film is first considered as a layer having a finite thickness, and with the aid of Fourier expansion of Muki's potential functions in Hankel transformed space, the formulation of the problem is obtained for a tri-material full-space. Then, knowing that the flexural stiffness of the thin film is negligible, its thickness and shear modulus are assumed to tend to zero and infinity, respectively, such that its in-plane...
Forced and free vibrational analysis of viscoelastic nanotubes conveying fluid subjected to moving load in hygro-thermo-magnetic environments with surface effects
, Article Archives of Civil and Mechanical Engineering ; Volume 22, Issue 4 , 2022 ; 16449665 (ISSN) ; Alibeigloo, A ; Borjalilou, V ; Koochakianfard, O ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Forced and free vibrational analyses of viscoelastic nanotubes containing fluid under a moving load in complex environments incorporating surface effects are conducted based on the nonlocal strain gradient theory and the Rayleigh beam model. To model the internal nanoflow, the slip boundary condition is employed. Adopting the Galerkin discretization approach, the reduced-order dynamic model of the system is acquired. Analytical and numerical methods are exploited to determine the dynamic response of the system. The impacts of geometry, scale parameter ratio, Knudsen number, fluid velocity, rotary inertia parameter, viscoelastic parameter, surface residual stress, surface elastic modulus, and...
Analysis of torsional vibrations on the resolver under eccentricity in pmsm drive system
, Article IEEE Sensors Journal ; Volume 22, Issue 22 , 2022 , Pages 21592-21599 ; 1530437X (ISSN) ; Feizhoseini, S ; Nasiri Gheidari, Z ; Behzad, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Since any error in the rotor angle caused by the resolver affects the entire permanent magnet synchronous motor (PMSM) control drive system, it is necessary to investigate its effect on mechanical vibrations. Torsional vibration is accordingly considered in the following study. Thereby, first, the effect of resolver errors on the harmonic content of motor current and, subsequently, torque ripple (TR) was investigated. Then, dynamical modeling is done for the generator-motor-resolver set to get the mechanical frequency response (FR) resulting from the resolver errors. Based on the above modeling, the dynamic equations (DEQs) of the system were derived, and the mechanical characteristics of...
simulation of thermo-hydro-mechanical processes at Soultz-sous-Forêts
, Article Energies ; Volume 15, Issue 24 , 2022 ; 19961073 (ISSN) ; Singh, M ; Mahyapour, R ; Tangirala, S. K ; Bär, K ; Sass, I ; Sharif University of Technology
MDPI
2022
Abstract
Porosity and permeability alteration due to the thermo-poro-elastic stress field disturbance from the cold fluid injection is a deciding factor for longer, more economic, and safer heat extraction from an enhanced geothermal system (EGS). In the Soultz-sous-Forêts geothermal system, faulted zones are the main flow paths, and the resulting porosity–permeability development over time due to stress reorientation is more sensitive in comparison with the regions without faulted zones. Available operational and field data are combined through a validated numerical simulation model to examine the mechanical impact on the pressure and temperature evolution. Results shows that near the injection...
Melt electrowriting of PLA, PCL, and composite PLA/PCL scaffolds for tissue engineering application
, Article Scientific Reports ; Volume 12, Issue 1 , 2022 ; 20452322 (ISSN) ; Seifi, S ; Akbari, A ; Mohammadi, K ; Shamloo, A ; Movahhedy, M. R ; Sharif University of Technology
Nature Research
2022
Abstract
Fabrication of well-ordered and bio-mimetic scaffolds is one of the most important research lines in tissue engineering. Different techniques have been utilized to achieve this goal, however, each method has its own disadvantages. Recently, melt electrowriting (MEW) as a technique for fabrication of well-organized scaffolds has attracted the researchers’ attention due to simultaneous use of principles of additive manufacturing and electrohydrodynamic phenomena. In previous research studies, polycaprolactone (PCL) has been mostly used in MEW process. PCL is a biocompatible polymer with characteristics that make it easy to fabricate well-arranged structures using MEW device. However, the...
Modified Green–Lindsay analysis of an electro-magneto elastic functionally graded medium with temperature dependency of materials
, Article Mechanics of Time-Dependent Materials ; Volume 26, Issue 4 , 2022 , Pages 871-890 ; 13852000 (ISSN) ; Razavinasab, S. M ; Sharif University of Technology
Institute for Ionics
2022
Abstract
This article presents a modified Green–Lindsay (MG-L) thermoelasticity model considering temperature and strain rate. Previously, this model has been developed based on the Green–Lindsay theory of thermoelasticity using strain and temperature rate dependent thermoelastic equations. This study analyzes stress and thermal wave propagation of a functionally graded medium exposed to an electromagnetic field and a thermal shock. All magnetic, elastic, and thermal features of the medium are considered to vary in the longitudinal direction. Additionally, the properties of the material are dependent on the temperature in the form of a cubic function. Using the large displacement formulation and the...
A comprehensive mathematical simulation of the composite size-dependent rotary 3D microsystem via two-dimensional generalized differential quadrature method
, Article Engineering with Computers ; Volume 38 , 2022 , Pages 4181-4196 ; 01770667 (ISSN) ; Zhao, Y ; Pishbin, M ; Habibi, M ; Bashir, M. O ; Issakhov, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
In this study, frequency simulation and critical angular velocity of a size-dependent laminated rotary microsystem using modified couple stress theory (MCST) as the higher-order elasticity model is undertaken. The centrifugal and Coriolis impacts due to the spinning are taken into account. The size-dependent thick annular microsystem's computational formulation, non-classical governing equations, and corresponding boundary conditions are obtained by using the higher-order stress tensors and symmetric rotation gradient to the strain energy. By using a single material length scale factor, the most recent non-classical approach captures the size-dependency in the annular laminated microsystem....