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superelement
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Vibration analysis of orthotropic rectangular plates using superelements
, Article Computer Methods in Applied Mechanics and Engineering ; Volume 191, Issue 19-20 , 2002 , Pages 2097-2103 ; 00457825 (ISSN) ; Sherafati Zangeneh, M ; Sharif University of Technology
Elsevier
2002
Abstract
In recent years, development of the superelements has significantly influenced the analysis of structural dynamics. One of the common implementation of this element has been in the analysis of plates and shells. In this paper, application of superelements in the vibration analysis of orthotropic rectangular plates with different boundary conditions is considered, in which bending and in-plane displacements are also included. Results of this study indicate that there is a good agreement between single superelement and 625 elements using conventional methods © 2002 Published by Elsevier Science B.V
Development of thermo-elastic tapered and spherical superelements
, Article Applied Mathematics and Computation ; Volume 265 , 2015 , Pages 380-399 ; 00963003 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
Elsevier Inc
2015
Abstract
Special superelements are often used to improve the computational efficiency and improve accuracy of finite element modeling. Structures with tapered and spherical geometry exist in many engineering problems. In this work, special tapered and spherical superelements are presented that can be used for modeling of tapered and spherical bodies in thermo mechanical analyses with computational efficiency. The performance of these superelements under thermal and structural loads is demonstrated by presenting several examples and comparing the results with those from conventional 3D brick elements, which shows high accuracy at reduced computational cost
Vibration analysis of FGM rings using a newly designed cylindrical superelement
, Article Scientia Iranica ; Volume 25, Issue 3B , 2018 , Pages 1179-1188 ; 10263098 (ISSN) ; Ahmadian, M. T ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
Rings are widely used in mechanical equipment, and their fitness may undergo some damage under severe vibration. In these structures, functionally graded rings can be used to optimize the resistance, energy consumption, and fitness. Due to their complexity, the finite-element analysis may be implemented using special elements. Enhancement of accuracy and minimization of time consumption play an important role in the analysis of these rings. In this study, a new cylindrical superelement for the FGM rings is designed and implemented to facilitate the vibration analysis of the rings. The power-law distribution is used for the modeling of the FGM rings in the thickness direction. Natural...
Simultaneusly Analysis of Torsional and Lateral Vibrations of Drillstrings using Cylindrical Superelement
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Firoozbakhsh, Keikhosrow (Co-Advisor)
Abstract
One of the most important parts of oil industry is drilling with rotating drillstrings. In a drillstring because of the contact between bit and formation, contact between drillstring and borehole wall, existence of drilling mud, misalignment in drillstring and stick-slip phenomenon; axial, lateral and torsional vibrations is created. These vibrations may lead to fatigue failures and abrasive wear of tubular, damaging the drill bit and borehole wall. In this thesis the drillsting vibrations is studied using finite element method. To this end, cylindrical superslement with C1 continuity is presented. By using the shape functions of this superelement; kinetic and potential energy of drillstring...
Optimization and Vibration Analysis of FGM Stiffened Cylinders by Application of Cylindrical Superelement
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor)
Abstract
Cylinders are one of the most applicable components in industry. According to the application of these elements, reinforcement and stiffening are the common ways to enhance mechanical properties of them. Nowadays, by advent of new materials such as functionally graded materials (FGMs), a novel method of improving these structures is discovered. By application of FGMs, many physical and mechanical characteristics of these structures can be modified. In this thesis, vibration analysis and frequency optimization of a stiffened cylinder made from FGMs are performed. FGM which is employed in this investigation is made from two different materials, to have better modal properties which cause in...
Thermo-elastic Development of Cylindrical and Spherical Superelements and Introduce a New Gigh Speed Angular Contact Bearing Superelement Model
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Angular contact bearings are utilized in many industrial types of machinery, including machine tools’ spindle. Spindle is one of the most important parts of a machine tool, which has a substantial impact on dynamic properties and stability of machining processes. Spindles’ motion takes place under guidance of bearings, which are mainly angular contact type. Since bearings’ loading under forces that are resulted from angular velocity and temperature increment are intensified, it is required to control the applied forces in operating situation, in order to predict the hardness, accuracy, efficiency, and life time of spindle. Thus, determining the dynamic performance of machine tool’s spindle,...
Application of a new cylindrical element formulation in finite element structural analysis of FGM hollow cylinders
, Article Finite Elements in Analysis and Design ; Volume 50 , March , 2012 , Pages 1-7 ; 0168874X (ISSN) ; Bonakdar, M ; Ahmadian, M. T ; Sharif University of Technology
Abstract
A finite element formulation is derived for the structural analysis of functionally graded hollow cylinders. The power-law distribution model is used for the composition of the constituent material in the thickness direction. According to property variation in FG cylinders, it is difficult to analyze them using the conventional element formulation. In order to facilitate the process of modeling and analyzing the FG cylinders, the finite element formulation is based on a newly designed cylindrical element. The new cylindrical element allows for property variations along the thickness, which results in considerable reduction of the required elements and eliminates the need to mesh the cross...
Design and application of a new tapered superelement for analysis of revolving geometries
, Article Finite Elements in Analysis and Design ; Volume 47, Issue 11 , November , 2011 , Pages 1242-1252 ; 0168874X (ISSN) ; Movahhedy, M. R ; Rezaei, M. M ; Sharif University of Technology
2011
Abstract
Structures of tapered geometry are customarily used in a variety of applications. The analysis of such structures is usually made through finite element method using traditional beam, shell or brick elements. In this paper, a new tapered superelement is presented that lends itself to modeling revolving geometries under lateral, axial and torsional loads. The presented tapered superelement has 16 nodes. The performance of this element under static and dynamic loading and in rotating condition is examined. It is shown that this element yields accurate results with higher computational efficiency compared to conventional elements. Furthermore, it is verified that a single tapered superelement...
Application of a new cylindrical element formulation in finite element structural analysis of FGM hollow cylinders
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 14 , 2009 , Pages 21-25 ; 9780791848753 (ISBN) ; Taghvaeipour, A ; Bonakdar, M ; Sharif University of Technology
2009
Abstract
Functionally graded materials are advanced composite materials consisting two or more material ingredients that are engineered to have a continuous spatial variation of properties. There are a few analytical methods available to solve the governing equations of FGM made structures, confined to some specific and limited shapes, loadings and boundary conditions. Hence the numerical methods such as FEM are used to treat these materials. In previous studies the finite element method was used to solve thin walled FG structures like shells and plates by modification of the conventional shell and plate elements. Solving the thick walled FG structures confronts some difficulties. One of the methods...
Development of a shell superelement for large deformation and free vibration analysis of composite spherical shells
, Article Engineering with Computers ; 2020 ; Hosseinzadeh, A ; Movahhedy, M. R ; Sharif University of Technology
Springer
2020
Abstract
Finite element analysis of huge and/or complicated structures often requires long times and large computational expenses. Superelements are huge elements that exploit the deformation theory of a specific problem to provide the capability of discretizing the problem with minimum number of elements. They are employed to reduce the computational cost while retaining the accuracy of results in FEM analysis of engineering problems. In this research, a new shell superelement is presented to study linear/nonlinear static and free vibration analysis of spherical structures with partial or full spherical geometries that exist in many industrial applications. Furthermore, this study investigates the...