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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...
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... 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 ...
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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
... Substituting Eqs. (27)- (30), (34), and (35) into Eq. (37), the potential energy of in-plane stresses of the strip during buckling can be expressed in the matrix form as: ...
... Those specimens are removed from the mold when the resin is dried. Two simple supports are generated at opposite edges of the specimens to prevent slipping and local boundary damage at their edges during loading using silicone glue [30,31]. Figure 7 and Table 3 show the specimens experimented with and their specifications, respectively. ...
... The plate and the stiffener are connected through the interface area between them. The parameters of the stiffener consist of the width (4, 8, 12, 16 and 20 mm) and height (20,25,30,35, 40, 45 and 50 mm) and the length is a function of the plate dimensions. The finite-element model of the plate and the stiffener is generated using the eight-node three-dimensional elements SOLID185. ...
The buckling behavior of moderately thick and thick stiffened composite plates with different stiffener layouts is formulated based on the higher-order shear deformation theory. This investigation is performed under axial compression using the Finite Strip Method and experiment. The effects of dimensions, orientation, eccentricity, torsional stiffness, position and geometric configuration of stiffeners on the buckling load coefficient are achieved by employing the principle of minimum potential energy. Six grid-stiffened composite plate specimens with ortho-grid, angle-grid, and orthotropic-grid stiffeners are tested. The results of the presented method show good outcomes with those of experimental tests and the finite element ANSYS code.
... Yazdani et al. [13][14][15] created and tested a tool for producing grid-stiffened composite shells under compressive axial load. They discovered that reinforced shells with triangular or hexagonal grid patterns were more resistant to buckling. ...
Grid‐stiffened composite cylinders are widely used in a variety of applications and are subjected to static, dynamic, and impact loads. In terms of buckling strength, these structures outperform simple layered and sandwich composites of the same weight, and the presence of unidirectional fiber ribs contributes to their delamination resistance. The purpose of this research is to look into the buckling behavior of grid‐stiffened composite cylinders under low‐velocity and high‐energy axial impacts. The tests were carried out at room temperature using a 35 kg impactor with an impactor fall height of about 2.75 m. This study builds on previous research and considers the samples' thin skin, indicating that skin buckling is the primary buckling mode in such scenarios. According to static loading research, three types of buckling can occur in grid‐stiffened composite cylinders: local shell buckling, local rib buckling, and general buckling, and each of these can be controlled by adjusting the geometric properties. But, based on the loading speed in the weight‐drop test, controlling the specific type of buckling that occurs during impact loading is difficult. Examining residual structural effects can help determine the type of buckling and damage sustained during impact events. According to the results, the forces that cause buckling in grid‐stiffened composite structures under impact loads are 1.5–2 times greater than static loading conditions. Notably, once the forces are removed, these structures can return to their original positions, however with less stiffness. As a result, they absorb a significant amount of impact energy.
Highlights
Composite cylinders with spiral ribs have higher static compression resistance.
Dynamic loading increases local buckling forces in grid‐stiffened structures.
Despite being damaged, grid‐stiffened cylinders bounce back quickly after impact.
Skin buckling is a common mode of failure for grid‐stiffened composite.
The global buckling force is greater than the local buckling force.
... Yazdani et al. conducted several experimental tests in order to study the buckling behavior of the grid-sti®ened composite cylindrical shells with di®erent sti®ening structures and helical ribs' number. [12][13][14] The number of studies carried out on the vibrational behavior investigation of grid-sti®ened cylindrical shells is not as much as those dealing with the buckling behavior. Perhaps for the¯rst time, Hemmatnezhad et al. 15 used an exact analytical approach based on the¯rst-order shear deformation theory (FSDT) in order to study the free vibrations of grid-sti®ened composite cylindrical shells taking the°exural behavior of the ribs into account. ...
This paper investigates the vibrational behavior of sandwich conical shells with geodesic lattice core and variable skin thicknesses using analytical and numerical approaches. The filament wound conical shell has been considered to have varying skin thickness along the longitudinal direction. The smeared stiffener approach has been used to obtain the equivalent stiffness parameters due to the geodesic lattice core via the force and moment analyses of a unit cell. Superimposing the stiffness contribution of the stiffeners with those due to the inner and outer skins, one can calculate the equivalent stiffness of the whole structure. The equations of motion have been formulated based on the first-order shear deformation theory. The power series method has been implemented for extracting the natural frequencies of vibration. To validate the analytical results, a 3-D finite element model has been provided which is then used to conduct an extensive parametric study. The comparisons indicate an acceptable agreement between the two approaches. Moreover, the effect of variable skin thickness on the natural frequency has been examined. Furthermore, the influences of skin lamination angle, semi-vertex angle of the cone and stiffeners orientation angle have been discussed. The obtained results can be used for future relevant researches.
... 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. ...
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. ...
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. ...
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. ...
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. ...
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]. ...
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.
