• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.119-130
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• 1999

This paper deals buckling behavior of laminated composite cylindrical shells subjected to combination of axial compression and torison. Linear and nonlinear finite element analysis are carried out . the influence of load type, load ratio, fiber orientation angle, stacking sequence, and intial imperfect on buckling behavior is discussed.

• Steel and Composite Structures
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• v.30 no.4
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• pp.305-313
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• 2019

Creating different cutout shapes in order to make doors and windows, reduce the structural weight or implement various mechanisms increases the likelihood of buckling in thin-walled structures. In this study, the effect of cutout shape and geometric imperfection (GI) is simultaneously investigated on the critical buckling load and knock-down factor (KDF) of composite cylindrical shells. The GI is modeled using single perturbation load approach (SPLA). First, in order to assess the finite element model, the critical buckling load of a composite shell without cutout obtained by SPLA is compared with the experimental results available in the literature. Then, the effect of different shapes of cutout such as circular, elliptic and square, and perturbation load imperfection (PLI) is investigated on the buckling behavior of cylindrical shells. Results show that the critical buckling load of a shell without cutout decreases by increasing the PLI, whereas increasing the PLI does not have a great impact on the critical buckling load in the presence of cutout imperfection. Increasing the cutout area reduces the effect of the PLI, which results in an increase in the KDF.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.5
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• pp.807-819
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• 1989

Buckling and vibration of laminated non-circular cylindrical shells with constant thickness and simply supported boundary condition is considered. Governing equations are derived based on the Donnell and Flugge shell theory and Galerkin method is applied for the numerical analysis. Comparisons are made between present results and others. Variations of frequency parameter and buckling load parameter on the change of stacking angle, eccentricity parameter and shell theories are investigated. Conclusion of this study is as follows: (1) General solutions of buckling and vibration of laminated non-circular cylindrical shell are obtained. (2) Frequency parameter is decreased as the initial axial load is increased. (3) In general, frequency and buckling load parameter of laminated non-circular cylindrical shells are decreased as increasing of eccentricity parameter and stacking angle.

• Advances in nano research
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• v.10 no.5
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• pp.423-435
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• 2021

This paper examines the thermal post-buckling behaviors of graphene-reinforced metal matrix composite (GRMMC) laminated cylindrical panels which possess in-plane negative Poisson's ratio (NPR) and rest on an elastic foundation. A panel consists of GRMMC layers of piece-wise varying graphene volume fractions to obtain functionally graded (FG) patterns. Based on the MD simulation results, the GRMMCs exhibit in-plane NPR as well as temperature-dependent material properties. The governing equations for the thermal post-buckling of panels are based on the Reddy's third order shear deformation shell theory. The von Karman nonlinear strain-displacement relationship and the elastic foundation are also included. The nonlinear partial differential equations for GRMMC laminated cylindrical panels are solved by means of a singular perturbation technique in associate with a two-step perturbation approach and in the solution process the boundary layer effect is considered. The results of numerical investigations reveal that the thermal post-buckling strength for (0/90)_5T GRMMC laminated cylindrical panels can be enhanced with an FG-X pattern. The thermal post-buckling load-deflection curve of 6-layer (0/90/0)_S and (0/90)_3T panels of FG-X pattern are higher than those of 10-layer (0/90/0/90/0)_S and (0/90)_5T panels of FG-X pattern.

• Steel and Composite Structures
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• v.5 no.1
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• pp.1-15
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• 2005

Important characteristics of the previously proposed reduced stiffness method and a summery of its design curves for the buckling of the axially loaded sandwich cylindrical shells is presented. Comparison of the lower bound obtained with FEM analysis with that from the reduced stiffness analysis shows that the proposed reduced stiffness method can provide safe lower bounds for the buckling of geometrically imperfect, axially loaded sandwich cylindrical shells. One of the attractive features of the reduced stiffness elastic lower bound analysis is that it provides safe estimates of buckling loads that do not depend on the specification of the precise magnitude of the imperfection spectra. As a result, designers can readily apply this method without being worried about possible geometrical imperfections that might be generated during fabrication and construction of sandwich cylindrical shells.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.89-95
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• 2014

We analyze the buckling of a thin elastic plate due to intrinsic stresses in thin films attached to the surfaces of the plate. In the case of cylindrical buckling, it is shown that for a plate with clamped edges compressive intrinsic film stresses can cause flexural buckling of the plate, while tensile intrinsic film stresses cannot. For a plate with free edges, film intrinsic stresses, compressive or tensile, cannot cause buckling.

• Steel and Composite Structures
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• v.29 no.4
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• pp.557-567
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• 2018

Cylindrical shell structures buckle at service loads which are much lower than their associated theoretical buckling loads. The main source of this discrepancy is the presence of various imperfections which are created on the cylinder body during different processes as manufacturing, handling, assembling and machining. Many cylindrical shell structures are still designed against buckling based on the experimental data introduced by NASA SP-8007 as conservative lower bound curves. This study employed the numerical based Linear Buckling mode shape Imperfection (LBMI) method and modified it using a stochastic method to assess the effect of geometrical imperfections in more details on the buckling of cylindrical shells with and without the cutout. The comparison of results with those obtained from the numerical Simcple Perturbation Load Imperfection (SPLI) method for cylinders with and without cutout revealed a good correlation. The effect of two parameters of size and number of cutouts on the buckling load was investigated using the linear buckling and Modified LBMI methods. Results confirmed that in cylinders with a small cutout inserting geometrical imperfection using either SPLI or modified LBMI methods significantly reduced the value of the predicted buckling load. However, in cylinders with larger cutouts, the effect of the cutout is dominant, thus considering geometrical imperfection had a minor effect on the buckling loads predicted by both SPLI and modified LBMI methods. Furthermore, the modified LBMI method was employed to evaluate the combination effect of cutout numbers and size on the buckling load. It is shown that in small cutouts, an increasing in the cutout size up to a certain value resulted in a remarkable reduction of the buckling load, and beyond that limit, the buckling loads were constant against D/R ratios. In addition, the cutout number shows a more significant effect on decreasing the buckling load at small D/R ratios than large D/R ratios.

• Structural Engineering and Mechanics
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• v.55 no.2
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• pp.399-411
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• 2015

The buckling equations of filament wound composite cylindrical shell are established. The coefficients $K_{ij}$ and $L_{ij}$ of the buckling equations are determined by solving the equations. The geometric analysis and the effective stiffness calculation for the fiber crossover and undulation region are respectively accomplished. Using the effective stiffness of the undulation region, the specific formulas of the coefficients ${K^{\prime}}_{ij}$ and ${L^{\prime}}_{ij}$ of the buckling equations are determined. Numerical examples of the buckling critical loads have been performed for the different winding angles and stacking sequences cylindrical shell designs. It can be concluded that the fiber undulation results in the less effect on the buckling critical loads $P_{cr}$. $P_{cr}$ increases with the thickness-radius ratio. The effect on $P_{cr}$ due to the fiber undulation is more obvious with the thickness-radius ratio. $P_{cr}$ decreases with the length-radius ratio. The effect on $P_{cr}$ due to the fiber undulation can be neglected when the ratio is large.

• Advances in nano research
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• v.10 no.1
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• pp.43-57
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• 2021

In this study, thermally induced bifurcation buckling of shallow composite cylindrical panels reinforced with aligned single-walled carbon nanotubes is investigated. Distribution of carbon nanotubes across the thickness of the cylindrical panel as reinforcements may be either uniform or functionally graded. Thermo-mechanical properties of the matrix and reinforcements are considered to be temperature dependent. Properties of the cylindrical panel are obtained using a refined micromechanical approach which introduces the auxiliary parameters into the rule of mixtures. The governing equations are obtained by using the static version of the Hamilton principle based on the first-order shear deformation theory and considering the linear strain-displacement relation. An energy-based Ritz method and an iterative process are used to obtain the critical buckling temperature of composite cylindrical panel with temperature dependent material properties. In addition, the effect of various parameters such as the boundary conditions, different geometrical conditions, distribution pattern of CNTs across the thickness and their volume fraction are studied on the critical buckling temperature and buckled pattern of cylindrical panels. It is shown that FG-X type of CNT dispersion is the most influential type in thermal stability.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.630-648
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• 1992

The minimum weight design for simply-supported isotropic or symmetrically laminated stiffened cylindrical shells subjected to various loads (axial compression or combined loads) is studied by a nonlinear mathematical search algorithm. The minimum weight design in accomplished with the CONMIN optimizer by Vanderplaats. Several types of buckling modes with maximum allowable stresses and strains are included as constraints in the minimum weight design process, such as general buckling, panel buckling with either stingers or rings smeared out, local skin buckling, local crippling of stiffener segments, and general, panel and local skin buckling including stiffener rolling. The approach allows the consideration of various shapes of stiffening members. Rectangular, I, or T type stringers and rectangular rings are used for stiffened cylindrical shells. Several design examples are analyzed and compared with those in the previous literatures. The unstiffened glass/epoxy, graphite/epoxy(T300/5208), and graphite/epoxy aluminum honeycomb cylindrical shells and stiffened graphite/epoxy cyindrical shells under axial compression are analyzed through the present approach.