Buckling Of Cylindrical Shells Research Articles

Comparison accurate calculate and Numerical solution of buckling thin Cylindrical shape memory alloy shell under Uniform load with d.q.m

The shape memory alloy has found too much significance among engineers and researchers due to their mechanical features behaviours and these alloys features are changed by temperature and tension. Also in correspondence to great mechanical strain made due to none linear and geometric features emerged in structure, encounter the equations solution with difficulty. In this research the numerical number has been presented based on the DQM basis to axisymmetric buckling of cylindrical shells made of shape memory alloys. First the solution incorporation presented then the numerical results are compared with exact solutions

Nonlinear static and dynamic hygrothermal buckling analysis of imperfect functionally graded porous cylindrical shells

• The material distributions of cylindrical shell are considered to functionally graded porous (FGP). • Increasing the porosity coefficients leads to decreasing the static hygrothermal buckling response. • Increasing the porosity coefficients leads to increasing the critical nonlinear dynamic hygrothermal buckling response. • The nonlinear hygrothermal buckling analysis FGP cylindrical shells has been not investigated, yet. This paper investigates the analytical and semi-analytical approaches for the nonlinear dynamic and static hygrothermal buckling analysis of imperfect functionally graded porous (FGP) cylindrical shells under hygrothermal loading. Effect of the von Kármán strain-displacement kinematic nonlinearity is included in the constitutive laws of the shell. Utilizing the Galerkin method, the nonlinear vibration problem has been solved. The fourth-order Runge–Kutta method is used to find the nonlinear dynamic hygrothermal buckling responses. To validate the results, comparisons are made with the available solutions for both nonlinear dynamic and static hygrothermal buckling of cylindrical shells. The effect of material parameters and various geometrical characteristics on the nonlinear dynamic and static hygrothermal buckling behavior of the system is investigated.

Dynamic Buckling of a Cylindrical Shell with a General Boundary Condition under an Axial Impact

The dynamic buckling of an elastic cylindrical shell with a general boundary condition (composed of stiffness and damping) under an axial impact by a rigid body is considered. A dynamic equation is derived to obtain the axial stress and radial displacement of the shell. Then, by substituting the results into the energy equation, the critical condition for the dynamic buckling of the shell is obtained. The influence of the general boundary condition on the critical velocity of the impactor is analyzed. The results reveal that the boundary condition exerts no effect on the dynamic buckling of the shell before the stress wave becomes reflected from the fixed end face of the shell. After reflection, the critical velocity decreases with increasing impactor mass and stiffness, but increases with increasing damping. At times smaller than the instant when the stress wave reaches the fixed end face of the shell, the dynamic buckling occurs earlier at greater values of damping and stiffness. After stress wave reflection, the earlier dynamic buckling is observed at smaller values of damping and stiffness.

Elastic buckling of cylindrical shell under pressure load evaluated on surface

Elastic buckling of cylindrical shell under pressure load evaluated on surface

The ‘panel analysis’ technique in the computational study of axisymmetric thin-walled shell systems

Thin-walled shells of revolution under circumferentially uniform pre-buckling stress states are important fundamental systems, often serving as reference ‘base cases’ to which the behaviour of more complex unsymmetrical systems can be related. However, the same simplicity that often permits closed-form algebraic expressions for the critical buckling load is also often responsible for a lack of localisation and significant ambiguity in the critical buckling mode. The computation of the linear or nonlinear buckling loads requires the systematic trial of many potential buckling modes to identify the one which minimises the necessary strain energy. In times when researchers used custom-written tools usually based on circumferential Fourier series expansions, this operation was relatively straightforward. However, today's analysts using ‘general’ commercial 3D finite element packages must apply careful safeguards to correctly identify the correct buckling load and associated mode in axisymmetric shell systems.This paper presents a detailed computational strategy to accurately and efficiently investigate the correct buckling load and mode number of axisymmetric shell systems using the technique of a ‘panel analysis’. This is implemented in the ABAQUS finite element solver controlled by the SIMULIA™ Isight automation software and the Python object-oriented programming language. The methodology is illustrated on three classical benchmark problems from the scientific literature on the buckling of cylindrical shells under meridional compression, with special attention given to meshing considerations.

Axisymmetric Buckling of Cylindrical Shells with Nonuniform Thickness and Initial Imperfection

In this article, the axial buckling load of an axisymmetric cylindrical shell with nonuniform thickness is determined analytically with the initial imperfection by using the first order shear deformation theory. The imperfection is considered as an axisymmetric continuous radial displacement. The strain–displacement relations are defined using the nonlinear von-Karman formulas. The constitutive equations obey Hooke’s law. The equilibrium equations are nonlinear ordinary differential equations with variable coefficients. The stability equations are determined from them. The stability equations are a system of coupled linear ordinary differential equations with variable coefficients. The results are compared with the finite element method and some other references.

Thermal buckling of cylindrical shell with temperature-dependent material properties: Conventional theoretical solution and new numerical method

Even though the thermal buckling behavior of shells has been investigated for many years, until now the thermal buckling problem with temperature-dependent material properties still cannot be solved by the existing commercial finite element codes. Therefore, the conventional theoretical solution of the critical temperature rise of cylindrical shell with the temperature-dependent material properties is first derived in this work. Then, an innovative numerical approach is developed by introducing the bisection method and a user subroutine of ANSYS to overcome the shortcoming of existing finite element codes. The results prove that the temperature-dependent material properties have a great negative influence on the ability of the thermal buckling resistance of the cylindrical shell. As a result, the subroutine of ANSYS developed in this work provides a convenient design method for engineers to avoid the complicated theoretical calculation.

Occurrence of Local Cylindrical Shell Buckling during Ultimate Strength Test of a Full-scale Transmission Tower, and Consideration Concerning Local Buckling Strength based on Reproduction Analyses

Occurrence of Local Cylindrical Shell Buckling during Ultimate Strength Test of a Full-scale Transmission Tower, and Consideration Concerning Local Buckling Strength based on Reproduction Analyses

Thermal buckling analysis of cylindrical shells of carbon nanotubes reinforced composites

The purpose of this study is to investigate the thermal buckling analysis of cylindrical shells of carbon nanotubes reinforced composites (CNTRC). In this study, a hybrid laminate composite plate consisting of N layers which are of thickness t is designed. N is the number of layers and the thickness of each functionally graded carbon nanotube reinforced composite (CNTR-FG) layer is h, and three types of the distribution of carbon nanotubes (CNT) are considered for each layer. CNTR-FG are multi-layered plates which have the length "a", width "b", thickness "t", and an arbitrary combination of boundary conditions along the four edges of the layer. The distribution of carbon nanotubes along the thickness of each layer of CNTR-FG is considered to be given. Implementation is done by using Abaqus software. In the investigation of the thermal buckling of cylindrical shells of CNTRC, in three different types of distribution of carbon nanotubes, the behavior of buckling of a cylindrical shell is investigated. In each case, the amount of buckling generated in the shell is calculated and analyzed. The results show that the behaviors of these three types of distributions are close, and the nanotubes with uniform distribution against thermal buckling loads perform better than the other two distributions.

Investigation of Buckling Behavior for Thin-Walled Bearing Aircraft Structural Elements with Cutouts by Means of Numerical Simulation

In this paper, we develop the consistent mathematical models and appropriate lowconsuming numerical methods for investigating the nonlinear strain and buckling behavior of statically loaded thin-walled structures with cutouts. The numerical simulation allowed us to study the effects of the dimensions of rectangular cutouts on the buckling of cylindrical shells loaded by the external pressure.

Investigation of imperfect effect on thermal buckling of cylindrical shell with FGM coating

Abstract The shell with functionally graded material (FGM) thermal barrier coating is a novel high temperature resistant structure, which has been increasingly applied in the aerospace, nuclear, turbo machinery and other engineering fields. However, there are some defects for the practical structures due to the limitation of manufacturing technique. But relevant theoretical research on the thermal buckling behavior of the imperfect cylindrical shell is limited in most open literature. Therefore, this work proposed to establish the theoretical solution of the critical temperature of buckling for the cylindrical shell with an axisymmetric imperfect and FGM coating based on the Donnell shell theory, Koiter model and Galerkin method. The theoretical solution deduced in this work agrees well with the existing literature. In addition, the influences of the profile of the axisymmetric imperfection, the volume fraction of the ceramic phase and the types of the thermal loading on the thermal buckling behavior of the coated imperfect cylindrical are further analyzed. The study provides a scientific solution and better understanding for the thermal buckling problem of the coated imperfect cylindrical shells.

Buckling of axially compressed composite cylinders with geometric imperfections

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.

Recovery of capacity lost due to openings in cylindrical shells under compression

Cylindrical shell structures such as silos and wind turbine towers often feature openings for internal access, and these may have a significant detrimental effect on the buckling load. This paper numerically investigates the buckling of cylindrical shells with cutouts near the cylinder end using nonlinear finite element analysis. The finite element (FE) model was validated against published experiments on the axial compression of moderately thin-walled cylinders with cutouts of various sizes and shapes. The results indicate excellent qualitative and quantitative agreements for loads, deflections, and buckled mode shapes. Using the validated FE model, it was found that the opening width is the most critical geometric parameter in terms of loss of carrying capacity. The model was then extended to explore a variety of stiffener configurations aimed at recovering the capacity lost due to the opening. These configurations included a frame ring, as well as the simpler option of straight ribs on either side of and above the hole. Thickness and protrusion were also considered in the analysis. It was found that the frame ring achieved full recovery of the lost capacity, while the straight stiffeners were effective where only up to 67% recovery was required. The results also indicated that the optimum placement of stiffeners was immediately adjacent to the cutout. This study demonstrates that the optimum stiffener is a fully enclosed ring immediately adjacent to the cutout edge, and that full load recovery can be achieved with an appropriate design.

Design of steel pipe-jacking based on buckling analysis by finite strip method

In practice, the steel pipe-jacking can be regarded as a thin-walled cylindrical shell mainly subjected to jacking force in the axial direction and surrounded by the soil which is usually simplified and modeled as an elastic foundation. In this paper, the elastic buckling behavior of steel jacking pipes primarily under axial compression and with the Pasternak foundation is analyzed by the finite strip method (FSM). The elastic foundation is considered in the stiffness matrix through the strain energy, and the deformation in the longitudinal direction is simulated by the series functions in FSM. A parametric study is conducted to analyze buckling of cylindrical shells embedded in different elastic foundations. It indicates that the Pasternak foundation is more conducive to prevent buckling of cylindrical shells under axial compression. The critical length and the lower bound of buckling loads are obtained, and they offer the basis for optimal design of steel pipe-jacking. Finally, the case study combined with the buckling accident in the steel pipe-jacking event is presented. The present buckling analysis of soil-embedded cylindrical shells under axial compression provides design guidance for steel pipe-jacking construction.

Buckling of Cylindrical Shells with Arbitrary Circumferential Thickness Variations Under External Pressure

AbstractThis paper presents an analytical study on the buckling of cylindrical shells with arbitrary circumferential thickness variations under external pressure. Firstly, based on the thin shell theory and separation of variables, corresponding ordinary differential equations of laterally pressured cylinders are obtained. Secondly, the general asymptotic formula of buckling load, which is in terms of thickness variation parameter up to arbitrary order, is derived by combining the perturbation method and Fourier series expansion. Thirdly, the effects of uniform and circumferential modal thickness variations on the buckling of cylindrical shells under external pressure are investigated, respectively, and the results agree well with those available in literature. Particularly, the buckling load reduction of cylinders with circumferential modal thickness variation obtained by the proposed method coincides with the numerical results presented by Gusic et al. This analytical method is applicable for evaluating the stability of laterally pressured cylindrical shells with arbitrary circumferential thickness variations, once the thickness variation is known.

Effect of stiffeners on nonlinear buckling of cylindrical shells with functionally graded coatings under torsional load

Stiffened cylindrical shells are widely used in modern engineering structures, especially in aircraft, oil-transmitting pipeline, spacecraft industry and ocean engineering. Due to the increasing demands for high structures performances, this paper presents the effect of stiffeners on the nonlinear buckling of cylindrical shells with functionally graded (FG) coatings under torsional load. The cylindrical shell is reinforced with external axial stiffeners. The material properties are assumed to vary continuously through the thickness direction. Equilibrium and stability equations for cylindrical shells are derived by using the classical shell theory (CST) with von-Karman nonlinear kinematic relations. Using analytical approach, Galerkin procedure, and the Airy stress function, the resulting equations are employed to obtain the closed-form expression for the critical buckling loads and load–deflection relation. The influences of the number of stiffeners, volume fraction exponent, the thickness of the metal layer, and geometric parameters on the nonlinear buckling behavior of the cylindrical shell with FG coatings are examined in details.

Analytical study on the buckling of cylindrical shells with stepwise variable thickness subjected to uniform external pressure

ABSTRACTThis article focuses on the buckling of cylindrical shells with stepwise variable thickness subjected to uniform external pressure. First, combining the method of separation of variables, perturbation method, and Fourier series expansion, an analytical method for the buckling analysis of cylindrical shells with axisymmetric thickness variation subjected to external pressure is established. The method is verified by comparing with the previous results. Then, the stepwise variable thickness of cylindrical shells is described exactly by the arc tangent function. Finally, using the presented method, a general formula for the critical buckling load of cylindrical shells with stepwise variable thickness subjected to uniform external pressure is derived. This general formula is compared and discussed with some empirical formulae in the current design standards. This study lays a theoretical foundation for the calculation of the buckling load of cylindrical shells with stepwise variable thickness subjected to uniform external pressure. Moreover, it provides a reference and guidance for the further revision of related standards.

A Theoretical and Experimental Analysis of Critical Buckling Force of Short and Long Cylindrical Shells with a Welded Seam Using Argon

In this paper, seaming and seamless as well as short and long cylindrical shell buckling of aluminum 6063 which is under axial loading is taken into account. The used parts have equal mass and thickness and the seam is filled with argon method. An experimental test has been done bySANTAM-STM-250 device. Numerical analysis has been conducted by Abaqus Software, and precision of these models is measured by experimental results.

Experimental and Numerical Investigation of Elephant Foot Buckling and Retrofitting of Cylindrical Shells by FRP

AbstractLarge and small cylindrical shells have long been used as tanks and silos to store materials such as oil and its derivatives. The radius-to-thickness ratio of these shells is 500∶2000; as a result, buckling collapse of these thin-walled structures is of major concern for designers. The present study examined inelastic buckling behavior of cylindrical shells near the base, known as elephant foot buckling. This form of buckling occurs under high internal pressure exerted simultaneously with axial compression. The buckling of cylindrical shells subjected to combined axial loads and internal pressure was experimentally studied and tested and a new method of strengthening steel cylindrical shells using fiber-reinforced polymer (FRP) composite materials is presented. The proposed method was studied by numerical methods using a nonlinear algorithm, and the results were evaluated for resistance to buckling of cylindrical shells. The results provide effective and useful information for use in retrofitting ...

Analytical and Numerical Investigations on Buckling of an Axially Compressed Cylindrical Panel with Specific Boundary Condition

In this paper, the stability of cylindrical panels with circular cross section in elastic form is estimated using both analytical and Numerical methods. The Donnell equations for linear buckling of cylindrical shells are assumed and finally the equations are resulted to numerical values with the use of Galerkin method. Boundary condition in this case is such that the two curved edges are simply supported and two straight edges are free. The effects of geometrical parameters such as thickness, radius, length and central angle on buckling of cylindrical shells have been investigated both numerically and analytically. Also, the results of both methods are presented in figures.