scholarly journals Buckling Test of Composite Cylindrical Shells with Large Radius Thickness Ratio

2021 ◽  
Vol 11 (2) ◽  
pp. 854
Author(s):  
Atsushi Takano ◽  
Ryuta Kitamura ◽  
Takuma Masai ◽  
Jingxuan Bao
Keyword(s):  
Cylindrical Shells ◽  
Design Criterion ◽  
Thickness Ratio ◽  
Buckling Load ◽  
Large Radius ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Buckling Test ◽  
Composite Cylinders ◽  
Composite Cylindrical Shells

A buckling test of composite cylindrical shells with a radius–thickness ratio (r/t) = 893 under axial compression was conducted to investigate the effects of the radius–thickness ratio (r/t). It is known that the buckling load of cylinders shows large differences and scatter between theory and experiment. The ratio of the experimental buckling load and theoretical buckling load is called the knockdown factor (KDF). Many investigations have been conducted to find the cause of the degradation and scatter in the KDF, but as yet, no cause has been found. In 1968, NASA’s buckling design criterion, NASA SP-8007, gave an empirical KDF curve that decreased with the increasing r/t (up to 2000) for metal cylinders. The same curve has been applied to composite cylinders. Recently, Takano derived a flat lower-bound KDF in terms of A- and B-basis values (99% and 90% probability with a 95% confidence level) through a statistical analysis of experimental buckling loads. The result, however, based on experimental results up to r/t = 500 and, thus, the dependency on a large range of r/t, is not clear. Thus, the authors focused on a larger range of r/t. Cylindrical shells made from carbon fiber-reinforced plastic (CFRP) were tested. The nominal radius, thickness, and length were r = 100.118 mm, t = 0.118 mm, and L = 200 mm and, thus, the r/t = 848 and length-to-radius ratio (L/r) = 2.0. Shape imperfections were also measured by using in-house laser displacement equipment. The buckling load was slightly affected by the r/t, but the reduction in the KDF was insignificant.

Optimization and Antioptimization of Buckling Load for Composite Cylindrical Shells Under Uncertainties

AIAA Journal ◽  
2012 ◽  
Vol 50 (7) ◽  
pp. 1513-1524 ◽  
Author(s):  
Isaac Elishakoff ◽  
Benedikt Kriegesmann ◽  
Raimund Rolfes ◽  
Christian Hühne ◽  
Alexander Kling
Keyword(s):  
Cylindrical Shells ◽  
Buckling Load ◽  
Composite Cylindrical Shells

Buckling Analysis of Advanced Grid Stiffened Composite Cylinders

2014 ◽  
Vol 875-877 ◽  
pp. 755-762 ◽  
Author(s):  
Kang Hee Lim ◽  
He Wei ◽  
Zhi Dong Guan
Keyword(s):  
Cylindrical Shells ◽  
Computational Cost ◽  
Structure Design ◽  
Grid Structure ◽  
Constant Weight ◽  
Buckling Loads ◽  
Design Variables ◽  
Weight Design ◽  
Composite Cylinders ◽  
Composite Cylindrical Shells

Advanced Grid Stiffened(AGS) composite cylindrical shells are widely used in aerospace industry. This study analyzes the buckling loads for various types of grid structures of AGS composite cylindrical shells. The grid structures are classified as Angle-grid, Iso-grid, Kagome-grid, Ortho-grid, Orthotropic-grid and the characteristics had been analyzed for each grid type. In this study, the various types of grid structure were designed that weight of the whole structure keeps a constant. Under the condition of constant-weight, design variables such as grid angle, number of the grid, h/t ratio of the grid were controlled, and buckling loads of the grid structures were analyzed. The results were analyzed for each type of grid and each design variable of the structures. This study was performed through finite element method and the accuracy of the analysis was verified by previous studies. Finally, buckling modes were analyzed with the thickness of the skin. The selection for the most appropriate design variables had been verified for each grid type and the result can be applied to the optimization of grid structure design, and is also very helpful for reducing the computational cost and obtaining optimization values more accurately.

scholarly journals Stability of Filament-Wound Composite Cylinders Subjected to Hydrostatic Pressure

2018 ◽  
Vol 36 (5) ◽  
pp. 839-847
Author(s):  
Kechun Shen ◽  
Guang Pan ◽  
Jun Jiang ◽  
Qiaogao Huang ◽  
Yao Shi
Keyword(s):  
Hydrostatic Pressure ◽  
Cylindrical Shells ◽  
Filament Winding ◽  
Filament Wound ◽  
Filament Wound Composite ◽  
Critical Buckling Pressure ◽  
Winding Angle ◽  
Composite Cylinders ◽  
Wound Composite ◽  
Composite Cylindrical Shells

In order to know the mechanical properties of filament-wound composite cylindrical shells subjected to hydrostatic pressure, solve the buckling problem of pressure hull in deep sea and provide reference for engineering design, it is necessary to research the stability of filament-wound composite cylindrical shells. Based on the theory of thin shells, the governing equations were derived. Stability of composite cylindrical shells was researched by employing Galerkin method to solve the eigenvalue equation. The critical buckling pressure was calculated for cross filament-wound, metal-filament-wound and angle filament-wound composite cylinders under hydrostatic pressure. Compared to the test results, the numerical solution was illustrated to be feasibility. On this basis, the numerical method was interacted with genetic algorithm to search optimum stacking sequence and filament winding angle. Three types of winding pattern [(±θ)12], [(±θ1)x/(±θ2)12-x] and [(±θ1)4/(±θ2)4/(±θ3)4] were investigated, . Further, the effects of winding angle and the corresponding layer number on the critical buckling pressure were evaluated. It was shown that winding angle variation affected the critical buckling pressure significantly. Stability was greatly improved by numerical optimization, and the maximum critical buckling loads are increased by 31.31%, 43.25% and 57.51% compared with the base line, respectively. As the number of design variable increased, the carrying capacity was improved markedly. The optimal critical buckling pressure was increased by 57.17%.

Buckling of the Composite Cracked Cylindrical Shells Subjected to Axial Load

2003 ◽  
Author(s):  
A. Vaziri ◽  
H. Nayeb-Hashemi ◽  
H. E. Estekanchi
Keyword(s):  
Crack Length ◽  
Cylindrical Shells ◽  
Critical Length ◽  
Pressure Vessels ◽  
Buckling Load ◽  
Mode Shapes ◽  
Buckling Mode ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Composite Cylindrical Shells

Cylindrical shells constitute the main structural components in pressure vessels and pipelines. Cylindrical shells made of fiber-reinforced composites are now being considered in the design of many components due to their high specific strength and stiffness. Buckling is one of the main failure considerations, when designing the cylindrical shells. The buckling behavior of the composite cylindrical shells can severely the compromised by introducing defect in the structure, due to high stress field generated around these defects. Defects could be generated during service due to cyclic loading or during manufacturing. A reliable operation of these structures require to understand the effects of these defects on the bucking of cylindrical shells. Finite Element Analyses are performed to study the buckling behaviour of composite cylindrical shells with and without a crack, under an axial compressive loading. The effects of the plies angle on the buckling loads and buckling mode shapes of the composite cylindrical shells are studied. Furthermore, the effects of the crack length and its orientation on the buckling loads of the composite cylindrical shells are investigated. The results indicate that the global buckling loads and mode shapes of the cracked composite shells are not significantly sensitive to the presence of the defect, for shells with a crack length less than a critical length. This critical crack length depends on the crack orientation, composite ply angles, ply sequence and the cylinder geometry. For shells with a crack longer than the critical length, the buckling load reduces and the local buckling mode at the crack tip prevail the buckling behavior of the composite cylindrical shell. The optimum ply angle for attaining the maximum buckling load is specified.

Preliminary Analysis of Grid Stiffened Composite Cylinders

2002 ◽  
Author(s):  
Samuel Kidane ◽  
Eyassu Woldesenbet ◽  
Guoqiang Li ◽  
Jack Helms ◽  
Brett H. Smith
Keyword(s):  
Buckling Load ◽  
Analytical Models ◽  
Matrix Stiffness ◽  
Composite Cylinder ◽  
Aerospace Structure ◽  
Design Variables ◽  
Moment Interaction ◽  
Buckling Test ◽  
Important Design ◽  
Composite Cylinders

Stiffened cylindrical shells are major components of Aerospace structure application. Two models were developed for assessing the universal buckling load of a generally cross and horizontal stiffened composite cylinder. The first model uses a simple conservation of volume and direction of stiffener orientation, while the second model analyzes the force and moment interaction of the stiffeners and the shell. Based on these models the A, B and D matrix stiffness parameters were determined for the overall cylinder panel. The buckling load was solved for a particular stiffener configuration by using the energy method. Buckling test was also performed on a stiffened composite cylinder and compared with buckling load results of both analytical models, and conclusions were drawn on the degree of reliability of the models developed. Finally, parametric analysis of some of the important design variables was performed based on the ‘Force Smearing’ model.

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