Papers by Keyword: Cylindrical Shell

Abstract: This study analysed the buckling behaviour of thin-cylindrical shells under axial compression, addressing the persistent disparity between theoretical predictions and numerical simulations. The research investigated the influence of key parameters height, Young's modulus, and thickness on the critical buckling load. A Finite Element Analysis (FEA), specifically a Geometrically and Materially Non-Linear Analysis (GMNA), was performed using the software ABAQUS to model the shells. To bridge the gap between simulation and theory, a mathematical model for uncertainty analysis was developed in MATLAB, employing the Monte-Carlo Simulation (MCS) and referencing Rankine's theory. This study introduces a novel analytical framework that integrates Finite Element Analysis (FEA) and uncertainty analysis to resolve discrepancies in buckling predictions for thin cylindrical shells. The model's accuracy was validated with a maximum error of less than 13% compared to existing studies, and the uncertainty analysis demonstrated a robust standard deviation of 0.249 (less than 1%). The findings revealed that thickness is the most influential parameter; a 10% increase in thickness led to a 10.86% increase in the buckling load. Young's modulus had a moderate impact, with a 10% increase causing a 0.28% rise in the buckling load, while height was the least influential, with a 10% increase leading to only a 0.1% increase. This research provides valuable insights into the complexities of predicting critical buckling loads, highlighting the distinct impact of geometric and material properties on the structural behaviour of cylindrical shells.

Abstract: The paper outlines a method for comparative analysis of the load-bearing capacity and crack formation of reinforced concrete and fiber-reinforced concrete cylindrical shells based on experimental studies. To implement this task, the authors have developed a special stand. The results of tests of reinforced concrete and fiber-reinforced concrete cylindrical shells, which had the same geometric parameters, are presented. The fiber-reinforced concrete shell had additional dispersed reinforcement with steel fiber with curved ends, which was added at the stage of mixing the concrete mixture in an amount of 1% by volume of concrete. The shells were hinged at four points and loaded with a vertical distributed load applied along four strips, each 13 cm wide, and only along the body of the shell. The load-bearing capacity of the reinforced concrete shell was 101.6 kN, and the first crack appeared at a load of 64.5 kN, which is 63.48% of the load-bearing capacity. Before the loss of bearing capacity, 10 cracks with the same initial opening width of 0.05 mm had formed in the shell. The load-bearing capacity of the fiber-reinforced concrete shell was 149.9 kN, and the first crack appeared at a load of 74.9 kN, which is 49.97% of the load-bearing capacity. Before the loss of bearing capacity, 12 cracks with the same initial opening width of 0.05 mm had formed in the shell. The load-bearing capacity of the fiber-reinforced concrete shell turned out to be 1.48 times greater than that of the reinforced concrete shell.

Abstract: The methodology of experimental research of long cylindrical shells to determine their stress-strain state, carrying capacity and crack resistance is proposed. To implement the task, the authors have developed a special stand. Eight cylindrical shell models were made for testing - four of reinforced concrete and four of fiber concrete. Fibro-concrete specimens-shells had additional dispersed reinforcement by steel fiber with bent ends in an amount of 1% by volume of concrete. All specimens-shells had a constant length and cross-sectional radius, and varied the thickness of the shell and the size of the cross-sectional section of the board elements. The paper presents the results of tests of reinforced concrete cylindrical shell, which showed that the carrying capacity of the shell was 96.4 kN, and the first crack formed with a load of 42.9 kN, which is 44.5 % of the carrying capacity. Up to the moment of bearing capacity loss, 8 cracks with the same initial opening width of 0.05 mm and maximum final opening width of 0.8 mm had formed in the shell. Computer modeling of the shell and calculations with ANSYS 17.1 licensed software were performed. The bearing capacity determined in ANSYS was 93.0 kN, which is 3.6 % less than in the experiment. The test methodology and the developed stand are universal and will be used for further research.

Abstract: The paper proposes an analytical method for calculating a long cylindrical shell supported by two identical side elements and loaded with vertical load. The case when the shell is hinged on curvilinear edges is considered, and recommendations for taking into account other boundary conditions are given. No restrictions are imposed on the shape and dimensions of the cross-section of the side element. The proposed algorithm assumes the possibility of implementing two approaches - calculation according to the general semimoment theory and calculation with simplifying hypotheses for flat shells of medium length. In the presented work, the first approach is considered. Mathematically, the problem is reduced to a system of four linear equations. By solving this system, it is possible to determine the forces and displacements due to the action of additional boundary forces, and by adding them with the corresponding components of the momentless stress state, one can obtain the total forces and displacements in the cylindrical shell.

Abstract: Circular cylindrical shells, application of which is widely widespread in a space-rocket technique and aircraft building, often have cutouts on the surface on structural and technological terms. The feature of the stress-strain state, when a circular hole is introduced into the shell, is the appearance of stress concentration zones, in which stress can be increased in many times. The linear static analysis often used for determination of maximal stresses in such elements of constructions does not reflect character of stresses change with increasing of the external loading. The results of Finite-Elements nonlinear static analysis of the stresses concentration caused by the hole presence depending on the size of torsion moment increasing from zero to the maximal values are presented in this article. The parametric analysis for the wide range of shells lengths and hole radii is carried out, at which different combinations the dependences of stresses concentration factor (SCF) on the value of torsion moment on all range of loading are defined. It is shown that the stresses fields, unlike the linear model of deformation, transform in the loading process. SCF obtained by taking into account the geometrical nonlinearity of deformation depends not only on the geometrical parameters of the considered sample, but also on the level of loading. There are two types of behavior of SCF dependence on the loading level and on the structure parameters. The SCF increases continuously in the first half of loading range. In the second half in case of the small holes the monotonous growth proceeds to the maximal values, and for the large holes ‒ SCF can fall at load increasing, and sometimes has the repeated areas of intensive growth in the pre-ultimate state.

Abstract: At present the orthotropic pressurized metal structure is generally used as the isotropic one, ignoring the anisotropic characteristics of material caused during rolling process. At the same time, the elastic stress analysis design method is commonly used in pressure vessel, and the load capacity coming from plasticity of material has not been utilized. Therefore, elastic-plastic analysis of orthotropic pressurized structure is of great theoretical significance and engineering value. In present paper the limit load of orthotropic titanium cylindrical shell under internal pressure was studied. By finite element method with twice elastic slope criterion the variations of limit load for orthotropic and isotropic titanium cylindrical shells under different diameter-thickness ratios were investigated. The effect of orthotropic mechanical property on limit load of titanium cylindrical shell was discussed. At the same time, the difference of limit loads between orthotropic and isotropic titanium cylindrical shells was compared. The calculation results show that the limit loads of orthotropic and isotropic titanium cylindrical shell increase with the diameter-thickness ratio, and the limit load of orthotropic titanium cylindrical shell increases more obviously. Additionally, if the yield strength of isotropic cylindrical shell is the same as or close to the yield strength of circumferential direction for orthotropic titanium cylindrical shell, the difference of limit load is smaller. While the yield strength of isotropic cylindrical shell is much different from the yield strength of circumferential direction for orthotropic titanium cylindrical shell, the difference of the limit load is higher.

Abstract: The problem of static analysis of a circular cylindrical shell, which is located on elastic Winkler foundation and reinforced by the longitudinal edges are considered. There is rib stiffness of rectangular cross section. Exposure is represented evenly distributed along the longitudinal axis forces. The forces acting on the edges of the rigidity of the upper structure. Agreed that the ends of the envelope is flat, vertical walls, giving the contour of the absolute rigidity in the transverse direction and does not prevent the longitudinal displacement of points of the envelope. To solve the problem, the total moment theory of circular cylindrical shell was used. To implement the proposed algorithm is the calculation of computer program. With the help of the program is executed a number of examples of calculation. In these examples, analyze the impact of stress on the shell of such factors as the relative length and thickness, angle mortar shell, the value of the relative rigidity of airborne elements and other.

Abstract: The analytical method of residual strains determination on joints of layers of a glass-metal cylindrical shell arising in the course of its cooling description is provided in article. For the numerical implementation of the proposed model modern numerical and digital-analytical methods were used. In connection with the exponential change of the required functions close to butt ends of the shell numerical methods lead to instability of calculation. In order to overcome this obstacle, Godunov’s method of discrete orthogonalization was applied. It has significantly leveled disturbance peaks of strains on the surfaces conjunction of the composite shell layers.

Abstract: A technique is developed for fabrication of a shell from glass-metal composite based on the borate glass and aluminum alloy. The metal–glass interface was studied by the optical and atomic force microscopy, it was found the presence of a diffuse layer with thickness of about 1 micron. The diffuse layer composition was studied by the XPS.

Abstract: Considering the effect of stress wave, the dynamic buckling of circular cylindrical shells under an axial step load is discussed using the classical shell theories and the state-space technique in the paper. Based on the Hamilton’s principle, the dynamic buckling governing equations of shells are derived and solved with the Rayleigh-Ritz method. If the linear homogeneous equations have a non-trivial solution, the determinant of the coefficient matrix must be equal to zero, so the expression of the critical load on the dynamic buckling is got. The relationship between the critical load and length is obtained by using MATLAB software. The influences of boundary conditions, thickness, the number of circumferential waves and the number of axial waves on the dynamic buckling loads are discussed based on numerical computation.