• Structural Engineering and Mechanics
• /
• v.24 no.2
• /
• pp.269-273
• /
• 2006

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.8
• /
• pp.862-869
• /
• 2007

The compressive and torsional buckling behavior of carbon nanotube bundles at room temperature is examined with classical molecular dynamics simulation. The critical compressive load and stiffness of a single carbon nanotube in the bundle are found to be similar to those of individual carbon nanotubes. However, the critical torsional moment and stiffness of a single carbon nanotube in the bundle are found to be higher than those of individual carbon nanotubes. In addition, this study demonstrates that van der Waals interactions between the nanotubes in the bundle significantly affect the critical compressive load of the nanotube bundle.

• Structural Engineering and Mechanics
• /
• v.4 no.5
• /
• pp.529-540
• /
• 1996

The dynamic buckling mechanism of a single-degree-of-freedom dissipative/nondissipative gradient system is thoroughly studied, employing energy criteria. The model is chosen in such a manner, that its corresponding static response is associated with all types of distinct critical points. Under a suddenly applied load of infinite duration, it is found that dynamic buckling, occurring always through a saddle, leads to an escaped motion, which is finally attracted by remote stable equilibrium positions, belonging sometimes also to complementary paths. Moreover, although the existence of initial imperfection changes the static behaviour of the system from limit point instability to bifurcation, it is established that the proposed model is dynamically stable in the large, regardless of the values of all other parameters involved.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.10a
• /
• pp.53-60
• /
• 1999

The bending buckling behavior of circular cylindrical shell is studied. The classical analysis by Love type solution and the package program LUSAS for the structural analysis are used to estimate the critical stresses of circular cylindrical shells under axial compression and bending loads. In this paper, the Love type of buckling equation is carefully investigated and numerical results are presented for a wide range of radius-to-thickness (R/t) ratios and length-to-radius (L/R) ratios. These results show that the maximum critical bending stress is about 30~80% greater than the critical compressive stress

• Structural Engineering and Mechanics
• /
• v.19 no.2
• /
• pp.231-236
• /
• 2005

This study considers the buckling of orthotropic cylindrical thin shells with material nonhomogeneity in the thickness direction, under torsion, which is a power function of time. The dynamic stability and compatibility equations are obtained first. Applying Galerkin's method then applying Ritz type variational method to these equations and taking the large values of loading parameters into consideration, analytic solutions are obtained for critical parameter values. Using those results, the effects of the periodic and power variations of Young's moduli and density, ratio of Young's moduli variations, loading parameters variations and the power of time in the torsional load expression variations are studied via pertinent computations. It is concluded that all these factors contribute to appreciable effects on the critical parameters of the problem in question.

• Structural Engineering and Mechanics
• /
• v.57 no.5
• /
• pp.861-876
• /
• 2016

The determination of the critical buckling load of multistory structures is important since this load is used in second order analysis. It is more realistic to determine the critical buckling load of multistory structures using the whole system instead of independent elements. In this study, a method is proposed for designating the system critical buckling load of torsion-free structures of which the load-bearing system consists of frames and shear walls. In the method presented, the multistory structure is modeled in accordance with the continuous system calculation model and the differential equation governing the stability case is solved using the differential transform method (DTM). At the end of the study, an example problem is solved to show the conformity of the presented method with the finite elements method (FEM).

• Steel and Composite Structures
• /
• v.48 no.2
• /
• pp.145-161
• /
• 2023

This study investigates the influences of porosity on the stability of the orthotropic laminated plates under uniaxial and biaxial loadings based on the hyperbolic shear deformation theory. Three different porosity distribution are considered with three specific functions through the plate thickness. The stability equations of porous orthotropic laminated plates are derived by the virtual work principle. Applying the Galerkin method to partial differential equations, the critical buckling load relation of porous orthotropic laminated plates is obtained. After validating the accuracy of the proposed formulation in accordance with the available literature, a parametric analysis is performed to observe the sensitivity of the critical buckling load to shear deformation, porosity, orthotropy, loading factor, and different geometric properties.

• Steel and Composite Structures
• /
• v.26 no.3
• /
• pp.273-287
• /
• 2018

Buckling and free vibration analysis of sandwich micro plate (SMP) integrated with piezoelectric layers embedded in orthotropic Pasternak are investigated in this paper. The refined Zigzag theory (RZT) is taken into consideration to model the SMP. Four different types of functionally graded (FG) distribution through the thickness of the SMP core layer which is reinforced with single-wall carbon nanotubes (SWCNTs) are considered. The modified couple stress theory (MCST) is employed to capture the effects of small scale effects. The sandwich structure is exposed to a two dimensional magnetic field and also, piezoelectric layers are subjected to external applied voltages. In order to obtain governing equation, energy method as well as Hamilton's principle is applied. Based on an analytical solution the critical buckling loads and natural frequency are obtained. The effects of volume fraction of carbon nanotubes (CNTs), different distributions of CNTs, foundation stiffness parameters, magnetic and electric fields, small scale parameter and the thickness of piezoelectric layers on the both critical buckling loads and natural frequency of the SMP are examined. The obtained results demonstrate that the effects of volume fraction of CNTs play an important role in analyzing buckling and free vibration behavior of the SMP. Furthermore, the effects of magnetic and electric fields are remarkable on the mechanical responses of the system and cannot be neglected.

• Journal of the Society of Naval Architects of Korea
• /
• v.28 no.2
• /
• pp.307-317
• /
• 1991

A displacement-based finite element method is presented for the geometrically nonlinear analysis of eccentrically stiffened plates. The nonlinear degenerated shell and eccentric isobeam(isoparametric beam) elements are formulated on the basis of total Lagrangian and updated Lagrangian descriptions. To describe the stiffener's local plate buckling mode, some additional local degrees of freedom are used in the eccentric isobeam element. The eccentric isobeam element can be affectively employed to model the eccentric stiffener just like the case of the degenerated shell element. A detailed nonlinear analysis including the effects of stiffener's eccentricity is performed to estimate the critical load and the post buckling behaviour of an eccentrically stiffened plate. The critical buckling loads are found higher than analytic plate buckling load but lower than Euler buckling load which are the buckling strength requirements of classification society.

• Structural Engineering and Mechanics
• /
• v.40 no.6
• /
• pp.783-800
• /
• 2011

This paper addresses the finite strip formulations for the stability analysis of viscoelastic composite plates with variable thickness in the transverse direction, which are subjected to in-plane forces. While the finite strip method is fairly well-known in the buckling analysis, hitherto its direct application to the buckling of viscoelastic composite plates with variable thickness has not been investigated. The equations governing the stiffness and the geometry matrices of the composite plate are solved in the time domain using both the higher-order shear deformation theory and the method of effective moduli. These matrices are then assembled so that the global stiffness and geometry matrices of a moderately thick rectangular plate are formed which lead to an eigenvalue problem that is solved to determine the magnitude of critical buckling load for the viscoelastic plate. The accuracy of the proposed model is verified against the results which have been reported elsewhere whilst a comprehensive parametric study is presented to show the effects of viscoelasticity parameters, boundary conditions as well as combined bending and compression loads on the critical buckling load of thin and moderately thick viscoelastic composite plates.