Figure 5 - uploaded by Akbar Afaghi Khatibi
Content may be subject to copyright.
Buckling mode shapes of three types of shells. 

Buckling mode shapes of three types of shells. 

Source publication
Article
Full-text available
The results of an experimental study on the buckling behavior of thin-walled GFRP cylindrical shells are presented. The specimens were fabricated from continuous glass fiber using a specially-designed filament winding machine. The buckling behaviors of unstiffened shells and stiffened shells with lozenge, triangular and hexagonal grids were then st...

Context in source publication

Context 1
... this paper, only the axial load-displacement curves obtained from the experiments are presented. From the total of twenty specimens used, only 4 samples, namely one unstiffened shell, one with hexagonal grid and two specimens with triangular grids, were excluded from the study for different reasons including manufacturing processes failing, while other sixteen specimens showed a good turnover during the loading. Figure 5 represents the buckling mode shapes of the specimens under uniaxial compression load. Figures 6, 9 illustrate load- displacement curves of different specimens. Considering the consistency of the results in these figures, one can conclude that the manufacturing process was accurate and the results can be reproduced. Figure 6 shows the load-displacement behavior of the unstiffened shells. The Figure clearly shows that only one sample failed differently from the others, for this case, the corresponding average of maximum buckling load is 4887 N. Figure 7 shows the behavior of the stiffened shells with lozenge grids under axial loading, where the average of maximum buckling load is 5763 N. Figure 8 shows the load-displacement curves of the stiffened shells with hexagonal grids with the average of maximum buck- ling load is 7368 N. The load-displacement results for ...

Similar publications

Article
The results of an experimental study on the buckling behavior of thin-walled GFRP-stiffened cylindrical shells are presented. The buckling behavior of stiffened shells, with lozenge and triangular grids, and unstiffened shells were studied under quasi-static axial loading at room temperature. The effect of the number of helical ribs and grid shapes...

Citations

... Yazdani et al. [9] conducted an experimental study on the buckling behavior of thin-walled glass-fiber-reinforced polymer (GFRP) cylinders, which were fabricated from continuous glass fiber using a filament winding machine. Burlayenko and Sadowski [10] presented a FE model to study the material properties of the honeycomb cores filled with foams by employing the ABAQUS software. ...
Article
In this study, an analytical solution is presented to determine the buckling load of composite cylindrical shells with an auxetic honeycomb layer under a uniform axial load. The composite shell consists of three layers in which the core layer is made of the auxetic honeycomb structure with a negative Poisson’s ratio and the internal and external layers have been made of elastic and isotropic materials. The first-order shear deformation theory has been used as the displacement field. The equilibrium equations are determined by considering the von Kármán theory, and they are coupled nonlinear differential equations that are solved by employing the perturbation technique. The buckling load has been determined analytically by solving the stability equations, which are a system of coupled differential equations with variable coefficients. By conducting a parametric study, the effects of the honeycomb structure and the aspect ratios on the buckling load have been investigated. It is seen that by changing the geometrical parameters of the honeycomb structure, the Poisson ratio can be adjusted and the mechanical behavior of the composite shell has been modified. The results are compared with some other references and the finite element analysis.
... After drying the resin, the specimens are removed from the mould. Two simple supports at two opposite edges of the specimens are provided with silicone glue to avoid slipping and local boundary damages during loading [50,51]. The gypsum moulds, the specimens tested and their specifications are given in Table 4 and Figs. 8 and 9, respectively. ...
Article
Full-text available
The Finite Strip Method (FSM) was employed to study the buckling behavior of laminated glass fiber-reinforced polymer (GFRP) stiffened plates with different boundary conditions under axial compression. The theoretical formulation was established based on the first-order shear deformation theory (FSDT) for the thin plate and the stiffener. In this formulation, the stiffeners are not required to be placed on the nodal lines. This feature is considered useful in modeling the stiffened plates in which the stiffener elements are placed arbitrarily in complex planforms. Experimental, numerical and analytical studies were conducted to investigate the effects of the plate width-to-thickness ratio, the stiffener thickness-to-width ratio, dimensions, angle, eccentricity, torsional stiffness and geometric configuration of stiffeners on axial buckling capacity. Furthermore, the obtained results of the analytical method were compared with experimental results and ANSYS code to show its accuracy and convergence. The advantages of the present are that number of elements is much less and the mesh refinement process is much more convenient than commercial finite element software and traditional finite element method (FEM). Therefore, time consumed for analysis is less than the codes which work based on the finite element method.
... Limited experimental studies deal with the stability, strength, and buckling of the lattice cylindrical shells. Yazdani et al. [33] tested the specimens prepared by filament winding glass fibers in the form of hexagonal and triangular lattice reinforcements under axial compression and obtained the buckling loads. In a similar approach, Frulloni et al. [34] produced and tested carbon fiber composite rhombic grid lattice cylindrical shells under axial compression and obtained their buckling loads. ...
In this paper, we present an analytical method based on equivalent continuum homogenization for the global buckling analysis of the general grid lattice cylindrical structures. In the proposed scheme, grid structures with arbitrary cell geometries can be analyzed by obtaining their effective cell stiffness based on force and moment analysis of the struts. The grid structures are assumed to be composed of curvilinear axial, circumferential, and oblique unidirectional composite ribs. To evaluate the results of the presented analytical method, a parametric finite element code is derived to generate the desired geometry of the grid structures and their buckling loads are obtained and compared with the analytical method. The effects of various parameters, including the number of ribs, their thickness and elastic properties, and helical angle of the oblique ribs are studied for hexagonal, triangular, and mixed grid shells. The results are compared with the available data published in the literature with a good agreement.
... Nonlinear buckling analysis involves the determination of the equilibrium path (or load-deflection curve) upto the limit point load by using the Newton-Raphson approach. Limit point loads evaluated for geometric imperfection magnitudes shows an excellent agreement with experimental reults [25]. The influence of composite cylindrical shell thickness, radius variation on buckling load and buckling mode has also investigated. ...
... The mechanical properties of the Glass Fiber Reinforced Plastic (GFRP) [25] material are shown in Table 1. 0.25mm ply thickness and +45°/-45° ply orientation of the laminate is considered in linear and non-linear analysis. ...
... Nonlinear analysis is carried out by modeling first eigen buckled mode shapes as geometric irregularities on the non linear geometric model. Figure 3 shows the comparison of non-linear buckling load and the experimental results [25] for the GFRP laminated composite cylindrical shell. It is clearly observed that the load obtained in nonlinear analysis in present study and the experimental results carried out by the referenced. ...
Article
Full-text available
The Laminated cylindrical shells are being used in submarine, underground mines, aerospace applications and other civil engineering applications. Thin cylindrical shells and panels are more prone to fail in buckling rather than material failure. In this present study linear and non-linear buckling analysis of GFRP cylindrical shells under axial compression is carried out using general purpose finite element program (ANSYS). Non-linear buckling analysis involves the determination of the equilibrium path (or load-deflection curve) upto the limit point load by using the Newton-Raphson approach. Limit point loads evaluated for geometric imperfection magnitudes shows an excellent agreement with experimental reults [25]. The influence of composite cylindrical shell thickness, radius variation on buckling load and buckling mode has also investigated. Present study finds direct application to investigate the effect of geometric imperfections on other advanced grid-stiffened structures .
... One recently proposed rehabilitation method is the application of plastic fibre reinforcement or ring stiffener to strengthen the tank shells against buckling [9,10]. An experimental study on the buckling behaviour of unstiffened and stiffened cylindrical shells under quasi-axial loading showed an improvement in the buckling load with the addition of plastic fibres [11]. The addi tion of plastic fibre reinforcement to the tank shell has been investigated using both numerical and experimental methods. ...
Article
The current study proposes a new vertical seismic isolation of an aboveground liquid storage tank (AST) and theoretically and numerically evaluates its effectiveness for a comprehensive practical range of tank geometries. In the proposed system, the forces in the vertical direction caused by the overturning moment are isolated as an alternative to the common horizontal system used for shear base isolation of ASTs. The equations of motion for a liquid tank equipped in the proposed system were extracted using the mass-spring simplified model of contained liquid. A parametric study was performed by employing the non-linear solution of the governing equations and the effectiveness of the proposed system for all AST aspect ratios is discussed. The numerical results show that the overturning moment of the tanks equipped with the proposed isolation system decreased significantly with respect to the corresponding fully anchored tanks. The results of the parametric study on the tank aspect ratio and liquid height indicate that the proposed system is more efficient for slender tanks than for broad tanks.
... The application of fibre-reinforced plastics (FRP) to strengthen the tank shells against E buckling has been considered. An experimental study on the buckling behaviour of unstiffened and stiffened cylindrical shells under quasi-axial loading showed an increase in buckling load as a result of the plastic fibres [24]. The effects of adding FRP composite material to the tank shell has been investigated using numerical and experimental methods. ...
Article
Full-text available
In this paper, the relation between the steel cylindrical tank geometry and the governing critical damage mode of the tank shell is numerically determined for all practical ranges of liquid storage tanks (aspect ratio H/D = 0.2 to 2). In addition, the interaction between the seismic intensity, soil type, acceptable seismic risk and tank geometry along with the extra material demanded by the seismic loads is examined based on the provisions of major codes. The importance of seismic factors on the economics of the design of a liquid tank in zones with high seismic activity is comprehensively discussed. In this regard, an empirical relation to estimate the steel volume required for specific seismic conditions and tank geometries is proposed based on the results of analysis. © 2018 New Zealand Society for Earthquake Engineering. All rights reserved.
... From this point on, different researchers worked in this domain using composites: postbuckling of stiffener with ''I'' cross section, new components of AGS, effectiveness of rib geometry, i.e., rectangular, triangular and tapered, stability check for truss system replacing long columns in space vehicle, determination of optimal design using genetic algorithm are some of the prominent published works [9][10][11][12][13]. A number of researchers worked using composites, which included working on stability analysis of composite stiffened plates using hybrid element, post-buckling of composite Iso-grid using carbon-reinforced epoxy for Iso-grid cylinder and glass fiber-reinforced plastic-stiffened shells [14][15][16]. Others worked on curved orthotropic stiffener, closed form analytical tool for determining the stiffness of composite cylinders, damage tolerance using composite single stiffener, optimization on composite cylindrical shell, carbonreinforced skinless and double-sided designs and published their results [17][18][19][20][21][22]. ...
Article
Full-text available
Iso-grid structures provide high strength with reduced weights, which is an essential requirement for aerospace applications. Buckling of Ortho-grid structure is a phenomenon with complex interaction between skin, stiffeners and sub-stiffeners. Introduction of sub-stiffeners increases the load bearing capacity of the structures many folds as compared to the classical Iso-grid or Ortho-grid structure. In this work, a customized MATLAB® code is developed for computational analysis based on finite element (FE) analysis. In case of FE analysis, the degenerated shell element is used. In the first phase of the MATLAB® code development, an elasto-plastic analysis of a clamped quadratic-shell is performed and the results are verified with the published literature. In the next phase, the buckling analysis of thin-plate is performed and the results are again verified with the literature. After verification of developed code, FE analysis of the Ortho-grid-stiffened plates is successfully validated. The results attained from developed code are compared with analysis performed on ANSYS® software along with the published work. The results revalidate the fact that stiffeners increase buckling load by over fifty times, which stands the main motive for their use in aerospace industry.
... Yazdani et al. [32] investigated experimentally the buckling behavior of unstiffened and stiffened shells with hexagonal, triangular and lozenge grids manufactured by a special-designed filament winding machine. Based on their experimental results, the critical buckling load was higher for the shells with hexagonal and triangular grids while the unstiffened shells and stiffened shells with lozenge grids exhibited much lower critical buckling loads. ...
... In order to investigate the effect of loading condition on the deformation behavior and energy absorption capacity of the composite shells, Figs. 15 and 16 respectively show the load-displacement diagrams of the grid-stiffened and unstiffened composite shells. Based on the previous research on the grid-stiffened composite cylindrical shells [32], existence of the grid stiffeners negatively affected the specific buckling load of the structure. In contrast, based on the above figures, it can be obviously seen that existence of the grid stiffeners leads to a remarkable increase in the specific energy absorption. ...
... The problem of cylindrical shell buckling subjected to axial compressive loads has been investigated by many researchers [6][7][8][9][10] using approximate analytical methods as well as finite element methods. Theoretically evaluated classical buckling load is generally much higher than the actual buckling load of the cylindrical shell and a knockdown factor is introduced to evaluate a better approximation based on an extensive experimental investigation [11][12][13]. E.R. Lancaster [14] has investigated the effect on the buckling load of imperfections in the form of local initial stress, which are probably more typical of practice than purely geometric ones. Reza Akbari Alashti [15] has presented the buckling analysis of cylindrical shells with cutouts under axial loading. ...
Article
Full-text available
In this paper, the buckling analysis of thin walled composite cylindrical shells with and without cutouts is investigated by applying axial load on Glass Fiber Reinforced Plastic (GFRP) shell. The effect of cutout not only introduces stress concentration but also significantly reduces the buckling strength. The column is fixed at one end and load is applied at the other end. The Static and Eigenvalue buckling analysis is done on shell model. The circular, elliptical and rectangle cutouts are considered on cylindrical shell. The buckling analysis is repeated in each case. The compressive stress, buckling load factor and lateral strain of each case for cylindrical shell is obtained from ANSYS software. The buckling load decreases for shell with cutout when compared to the value of the shell without a cutout. Stress and lateral strain increases for shell with cutout when compared to the shell without a cutout. The buckling load value is maximum in circular cutout and minimum in the rectangular cutout.
... These kinds of structures have many advantages such as high strength and stiffness to weight ratios and damage tolerance and have been investigated widely [6,7]. Yazdani et al. [8] investigated the buckling behavior of unstiffened and stiffened shells with hexagonal, triangular and lozenge grids, experimentally. They observed that in very small skin thicknesses, when the specific buckling loads for all specimens were compared, the unstiffened shells showed the highest specific buckling load. ...
... As can be seen from the figure, the stiffened specimens can absorb more energy in comparison with the simple ones. Based on the previous research on the grid-stiffened composite cylindrical shells [8], existence of the grid stiffeners had negative effect on the specific buckling load of the structure while, based on the above figures, it can be obviously seen that existence of the grid stiffeners lead to increase the specific energy absorption significantly. Furthermore, it can be realized from the figures that, the effect of the stiffeners on the stiffness, contact force and energy absorption capacity of the structures is more significant in the elastic deformation stage of the compression process. ...
... The stiffness, contact force and consequently the energy absorption capacity of the grid-stiffened structures were compared with the unstiffened shells and showed a significant increase. Experimental data had been asserted that existence of the grid stiffeners led to increase the specific energy absorption of the composite cylindrical shells while, in the axial loading, the grid stiffeners showed a negative effect on the specific buckling load of the same structures [8,10]. ...
Conference Paper
In this article, three types of unstiffened, grid-stiffened and lattice composite cylindrical shells are experimentally investigated under quasi-static axial loading. The E-glass/Epoxy composite cylindrical shells are manufactured by filament winding technique. The main purpose of this paper is to investigate the effect of stiffener on the buckling behavior of unstiffened shell and also the interaction between the grid stiffener and the outer shell. Experimental results show that the lattice shell has a negligible buckling load in comparison with the unstiffened and grid-stiffened composite cylindrical shells. Meanwhile, it is worth to notice that using of grid stiffener leads to increase the buckling load of the unstiffened shell and decrease the buckling displacement as well. Based on the experimental data, the grid-stiffened shell has the highest buckling load, while the lattice stiffener has the lowest buckling load. Also, results from the literature and this paper reveal that the specific buckling load of the unstiffened shells is more than the stiffened shell, regardless of the geometry of the stiffener. Thus, it may be concluded that these kinds of structures are more efficient in non-moving applications such as tower structures, stationary fuel tanks and stationary energy absorbing structures.