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torsional-buckling
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Torsional buckling of carbon nanopeapods
, Article Carbon ; Volume 45, Issue 5 , 2007 , Pages 952-957 ; 00086223 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2007
Abstract
Torsional buckling of carbon nanopeapods (carbon nanotubes filled with fullerenes) is studied using a continuum-based multi-layered shell model. The model takes into account non-bonded van der Waals interactions between nested fullerenes and the innermost layer of host nanotube. For nanopeapods with linearly arranged nested fullerenes, equivalent pressure distribution is proposed to model these interactions. Deriving explicit equations governing the torsional stability, it is concluded that the critical torsional load of a carbon nanopeapod is less than that of a carbon nanotube under otherwise identical geometric and mechanical conditions. Performing numerical calculations, it is also shown...
Experimental Study on Flexural and Shear Behavior of Steel Beams Using Carbon Laminate
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
There is a requirement for strengthening of steel structures due to undesirable design, wrong implementation, bad maintenance and changes in design codes. Many studies have been done on strengthening of concrete specimens but there is a need for reinforcement of steel specimens yet. In the present paper, results of an experimental study on strengthening and reinforcing of steel beams under mechanical loads have been presented. Totally, Sixteen steel specimens with span’s lengths of 0.2, 0.5 and 1 meter were reinforced by carbon laminates and subjected to -point bending load. Three failure modes of shear yielding, flexural yielding and lateral_torsional buckling in the beams were examined....
Torsional buckling of generally laminated conical shell
, Article Meccanica ; Volume 52, Issue 4-5 , 2017 , Pages 1051-1061 ; 00256455 (ISSN) ; Sharghi, H ; Kouchakzadeh, M. A ; Sharif University of Technology
Springer Netherlands
2017
Abstract
Buckling of generally laminated conical shells under uniform torsion with simply-supported boundary conditions is investigated. The Donnel type strain displacement relations are used to obtain potential strain energy of the shell and membrane stability equation is applied to acquire the external work done by torsion. The Ritz method is used to solve the governing equations and critical buckling loads are obtained. The accuracy of the results is validated in comparison of with other investigations and finite element method. The effects of lamination sequence, semi-vertex angle and length to radius ratio of the cone are evaluated and mode shapes are presented for two types of lamination...
Effects of temperature and torsion speed on torsional properties of single-walled carbon nanotubes
, Article Materials Science and Engineering C ; Volume 31, Issue 2 , March , 2011 , Pages 452-457 ; 09284931 (ISSN) ; Ban, E ; Banihashemi, P ; Abdolhosseini Qomi, M. J ; Sharif University of Technology
2011
Abstract
Carbon nanotubes (CNTs) are excellent candidates for torsional elements used in nanoelectro-mechanical systems (NEMS). Simulations show that after being twisted to a certain angle, they buckle and lose their mechanical strength. In this paper, classical molecular dynamics simulations are performed on single-walled carbon nanotubes (CNTs) to investigate the effects of torsion speed and temperature on CNT torsional properties. The AIREBO potential is employed to describe the bonded interactions between carbon atoms. The MD simulations clearly show that the buckling of CNTs in torsion is a reversible process, in which by unloading the buckled CNT in opposite direction, it returns to its...