Walled Cylindrical Shells Research Articles

Finite element analysis of a generalized rotating FGM vessel subjected to thermo-mechanical loadings: Effect of Poisson ratio and inhomogeneity parameters

Cylinders and thick walled cylindrical shells are commonly utilized in several industries to transport and store fluids under certain pressure and temperature conditions. In the present paper, a numerical solution is developed in order to investigate displacement, temperature and stress fields in a rotating pressure vessel made of generalized functionally graded material (FGM) subjected to different thermo-mechanical boundary conditions. The aim is to investigate the effect of Poisson ratio, internal pressure and temperature and inhomogeneity parameters on the stress and deformation distributions of the rotating pressure vessel. The material is considered isotropic nonhomogeneous and linearly elastic with its properties varying along the radial direction. Additionally, certain conditions, such as exterior or interior problems where r → ∞ or r → 0, respectively, are impossible to resolve using the variation of attributes as a power-law distribution. An approach to the spatial Young modulus distribution that is more broad has been suggested in the literature which can be applied to such physical challenges. The rotation of the pressure vessel is considered in the analysis, and the temperature distribution is assumed to be non-uniform. Since an analytical solution to the differential equation is not accessible, the conventional Galerkin discretization approach of the Finite Element Method (FEM) is applied, nowadays is considered one of the main numerical tools for solving Boundary Value Problems (BVP). It is addressed how stress, strain, and displacement are affected by the inhomogeneity parameter, rotation speed, pressure, temperature, and Poisson ratio. The examination of the various findings indicates that changes in the temperature profile, rotation, and inhomogeneity parameter on the thermoelastic field have a substantial impact on the stress and strain in the FGM cylinder. The findings indicate that the Poisson ratio and inhomogeneity parameters have a significant impact on the stress and deformation distributions. According to the results, the above-mentioned parameters can be adapted to control the thermoelastic filed in a FGM cylinder. The present research offers significant perspectives on the development and enhancement of rotating FGM pressure vessels intended for high-temperature applications.

Effects of composite material layering on the buckling mode of a cylindrical shell

Introduction. At present, composite materials are widely used in building structures and their components. The relevance of the work is determined by the buckling study of a shell structure made of a carbon fiber reinforced polymer. Despite the available experience in creating geometric models of finite element grids and studying the buckling of shell structures, the task of analyzing the mechanical behavior of shell layers remains insufficiently investigated. Therefore, research into the effects caused by polymer layering variations on a buckling mode appears to be urgent for regulating the layering process at various angle combinations due to a lack of sufficient data.Aim. The study was aimed at identifying a layering pattern, under which maximum and minimum critical forces operate.Materials and methods. The object of the study involves a cylindrical shell with a radius of 300 mm, a height of 600 mm, and a wall thickness of 1.56 mm made of eight variously-oriented carbon fiber layers impregnated with epoxy resin. The design modeling was performed using the finite element method. The cylindrical shell walls were modeled in terms of Laminate type flat elements, taking into account the composite layers. At the lower end, the cylinder was rigidly fixed and 100 kN axial compressive force was applied to the upper end of the cylinder. Using a software package, the variants of buckling modes were obtained for further analysis.Results. The data, describing the buckling of a cylindrical shell, including the critical load coefficient at the first buckling mode were obtained by the finite element method. In addition, the dependence of a critical force on layering patterns was determined. Depending on the critical force value and the buckling mode, the most and least favorable patterns of layering in a package of a composite material were selected.Conclusions. The orientation of layers in a composite material package affects the buckling mode and the value of critical force. An optimal selection of the layer orientation increases the critical force value by 2.25 times based on the information about the conditions of structural loading and fastening.

Reliability evaluation of critical local buckling load on the thin walled cylindrical shell made of composite material

The goal of this research is to evaluate the variability of the buckling load in thin orthotropic cylindrical shells due to the deviation with respect to the nominal values, for both the geometrical and material properties. In this research also the fiber orientation i.e the alignment with respect to the cylinder axis was considered. The research is developed by comparing the results obtained through analytical formulas and numerical results (f.e.m.) for isotropic and orthotropic materials. The coefficient of variation for critical buckling load (for symmetrical and non-symmetrical deformation), assumed for comparing the standard deviation values, is linear with the variation of material and geometrical parameters. The standard deviation on critical buckling load considering both the material and geometrical variations and fiber orientation can be very well described by a surface. From these surfaces it is important to underline that to quantify the dispersion values on the critical buckling load, the material properties assume the fundamental role with respect to the fiber orientation. The main implications of these results are correlated to the fact that, for example, during the manufacturing process, the geometrical and material variability is more important than the fiber orientation in order to have a reliability component.

Effect of Hydrochloric Acid Corrosion and CFRP Coating on the Buckling Behavior of Cylindrical Shells Under External Pressure

Thin walled cylindrical shells are being widely used as silos, liquid tanks, marine structures, and industrial chemical plants. In such applications, the shells are mostly exposed to liquids. When shells filled with low-pH-liquids, corrosion occurs at the surface. Corroded material loss, causes the thickness of the shells to decrease, and it reduces the buckling capacity of shells. The purpose of this study is to investigate the effects of corrosion on the buckling capacity of thin walled cylindrical shells subjected to uniform external pressure. The model shells were half or full filled with 5% and 10% HCl (Hydrochloric Acid) solutions for corrosion. To tolerate the negative effects of corrosion, the cylinders were coated with varying sizes of CFRP sheet. Totally 12 models were investigated throughout this research, with the dimensions of 800x400x0.45 mm (with and without CFRP). The perfect non-corroded models were used to compare the behavior of all the models. Results show that corrosion causes a significant decrease on the buckling capacity of thin walled cylindrical shells. Acid ratio, filling rate and surface area coated with CFRP fabrics affects the buckling capacity of cylinders. Coating the cylinders with one layer of CFRP resulted with tolerating the buckling capacity loss.

Thermo-elasto-plastic analysis of thick-walled cylinder made of functionally graded materials using successive approximation method

In this paper, the thermo-elasto-plastic behavior of a thick walled cylindrical shell made of a Functionally Graded Material (FGM) is analyzed by Successive Approximation Method (SAM). The FGM ingredients include Aluminum and Silicon Carbide in which the effective material properties are estimated using the Modified Rule of Mixture. The shell is subjected to a combination of internal pressure and temperature gradient. After application of equilibrium equations for derivation of governing equations, the Differential Quadrature Method (DQM) is used for numerical solution. It is assumed that the two ends of the cylinder are closed and the plane strain conditions are established. The distribution of elastoplastic stresses and strains along the cylinder's thickness is presented in terms of characteristics of material composition and thermo-mechanical loadings such as volume fraction, in-homogeneous index, internal pressure and thermal loadings. Trueness and accuracy of the present problem is justified through comparison with available results in literature. The results show that by enhancement of ceramic particles percentage in the outer layers of cylinder's wall, amount of plastic strains is reduced at that layers, but at the same time, the amount of plastic strains and range of plastic region, increases at inner layers of thickness.

Noninvasive Acoustic Measurements in Cylindrical Shell Containers.

Acoustic time-of-flight (ToF) measurements enable noninvasive material characterization, acoustic imaging, and defect detection and are commonly used in industrial process control, biomedical devices, and national security. When characterizing a fluid contained in a cylinder or pipe, ToF measurements are hampered by guided waves, which propagate around the cylindrical shell walls and obscure the waves propagating through the interrogated fluid. We present a technique for overcoming this limitation based on a broadband linear chirp excitation and cross correlation detection. By using broadband excitation, we exploit the dispersion of the guided waves, wherein different frequencies propagate at different velocities, thus distorting the guided wave signal while leaving the bulk wave signal in the fluid unperturbed. We demonstrate the measurement technique experimentally and using numerical simulation. We characterize the technique performance in terms of measurement error, signal-to-noise-ratio, and resolution as a function of the linear chirp center frequency and bandwidth. We discuss the physical phenomena behind the guided bulk wave interactions and how to utilize these phenomena to optimize the measurements in the fluid.

Formation of converging cylindrical detonation front

Purpose. To develop a laser method for initiating a converging cylindrical front of a detonation wave and a method for calculating the kinematic parameters of the cylindrical shell walls, accelerated by the pressure of the detonation products of an external explosive charge. Methodology. An experimental technology for the manufacture of a photosensitive explosive composite and an experimental technique for igniting the surface of its layer with an extended laser beam without the use of a fiber-optic cable are used. The results of simulation modeling the Monte Carlo method were used to study the effect of illumination on the process of ignition of explosives by laser pulsed radiation. For the selected type of photosensitive explosive composite, its explosive and optical characteristics, the distance from the surface of the explosive charge to the lens scattering the laser beam, and taking into account the total area of the expanded beam, the regularities of the distribution of the radiation energy density over the vertical and horizontal sections of the laser beam were studied. Findings. The analysis of the scientific and technical level of methods of shock-wave processing of materials in the region of ultrahigh pressures from the point of view of the fundamental value of the cumulation of energy in the waves of a converging cylindrical detonation and shock front is carried out. Physicomathematical modeling was carried out and the regularities of pressure increase in the wave front were established in the process of approaching the shell walls to the axis. The scientific results of modeling converging cylindrical shells under the influence of the pressure of the explosion products have been analyzed. A method for laser initiation of a converging cylindrical front of a detonation wave has been developed, and a method for calculating the kinematic parameters of the converging walls of a cylindrical shell has been proposed. Originality. A technique has been developed for determining the energy characteristics of an expanded laser beam, calculating the laser radiation energy required to initiate detonation simultaneously on the entire lateral cylindrical surface of a photosensitive explosive composite. The idea of technical implementation of the cumulation of converging cylindrical detonation and shock waves was developed further. A technique has been developed for the numerical determination of the change in the internal average compression rate of the shell during the movement of its walls towards the axis for various ratios of its external radius to the wall thickness and taking into account the increase in pressure in the converging detonation front. Practical value. For the first time, a method for laser initiation of a converging cylindrical front of a detonation wave was developed and a device was tested that forms a converging cylindrical front of a detonation wave and a corresponding shock front in the material under study by the impact of a metal shell converging to the axis. The core of the device is a laser explosive initiation system that uses light-sensitive explosive composites to initiate an explosive charge.

An experimental vibration-buckling investigation on classical and variable angle tow composite shells under axial compression

Two laminated composite shells, one with a conventional straight fiber laminate denoted the classical laminated shell and the second one with a variable angle tow reinforced composite, had been excited and their natural frequencies and mode shapes had been measured and monitored as a function of the axial compression load. Then, the in-situ buckling loads of the two tested specimens were predicted using the Vibration Correlation Technique (VCT) and compared with actual experimental buckling loads and Finite Element buckling predictions, yielding matching, consistent and repeatable results. It was shown that the VCT predicts the actual in-situ buckling loads of laminated composite thin walled cylindrical shells with a high accuracy, yielding 96% and 98.6% of the experimental buckling load, for the classical and variable angle tow composite shells, respectively. These results, although based on only two specimens, join the relatively small data base published in the literature, proving the nondestructive nature of the VCT approach, making it an adequate method for application on thin-walled structures, like shells. In addition, some testing recommendations are presented, to effectively enable the successful application of the VCT for in-situ buckling prediction of the buckling sensitive structures, like composite cylindrical shells.

USING THE SEMIBENDING THEORIES IN SOLVING THIN WALLED CYLINDRICAL SHELL CONSTRUCTIONS.

The semibending theories of thin walled cylindrical shell construction neglect the increment in curvature of the shell in the axial direction. The basic differential equations of the shells using the semibending theories are derived for three different cases and are named as simpli-fied semibending, semibending theory with incompressible middle surface and semibending theory with compressible middle surface. The differen-ces between these theories depend on the values of the circumferential normal strain and the shear strain. The derived differential equations are solved and applied to the prnblems of influence lines of stresses and deformations for different loading conditions on a long shells.

Characteristics of wave propagation, vibration transmission and acoustic emission in fluid-filled coaxial periodic shells

The wave propagation, vibration transmission and acoustic emission characteristics in the two coaxial shells containing fluid are studied. A finite element method (FEM) is utilized to conduct the investigation. Elastic band gaps (BGs) are generated in this coaxial shell system with either light or heavy fluid loading if the cylindrical shell walls are design to be periodic structure. For light fluid loading, BGs of the fluid-filled coaxial shell system are almost the same as those for the inner and outer shells in vacuum. Because the coupling effect of the annular light fluid is so weak that it can be neglected; thus, the inner and outer shell may behave independently. In terms of heavy fluid loading, the confined annular fluid region acts as an effective energy transmission medium that links the two shell motion together. The “hydrodynamic” mass induced by the annular-fluid can be far larger than its actual mass when the annular gap is sufficient narrow. As a result, the fluid inertial loading on the other shell can be quite enormous, rendering the central frequencies of BGs for the coaxial periodic shell system notably decreased. The BG formation mechanism may be attributed to (i) phenomenon of interference of waves reflected by these repeated “periodicity cells”, (ii) cut-off frequencies and (iii) hybrid vibration motion modes of different shell sections, according to various circumferential modes and frequency ranges. The acoustic pressure in the narrow annular region is extremely high, if the filling fluid is dense. However, when the harmonic frequency is located at the BG, the acoustic pressure becomes weaker and weaker along the axial direction of the shell; in contrast, if frequency is in the wave pass bands, the acoustic pressure levels will remain as strong as at the front end of the shell throughout the shell.

Application of ring beam stiffness criterion for discretely supported shells under global shear and bending

Silos in the form of a cylindrical metal shell are commonly elevated to provide access to the space beneath. In general, a few discrete column supports at evenly spaced intervals are commonly utilized. The presence of discrete supports results in circumferential non-uniformity in the axial compressive stress above the support. Depending on the size of the structure, several different support arrangements may be chosen. A stiff ring beam is utilized in larger silos to transfer and evenly distribute the discrete forces from the supports into the cylindrical shell wall. A stiffness criterion was developed by Rotter to assess the degree of non-uniformity in axial compressive stresses around the circumference. The stiffness criterion is based on the relative stiffnesses of the ring beam and the cylindrical shell and was verified for loading conditions that produce circumferentially uniform axial stresses around the circumference. A study has been undertaken to investigate the applicability of the stiffness criterion to cylindrical shells under global shear and bending. Pursuant to this goal, extensive finite element analyses were conducted where different ring beam and cylindrical shell combinations are subjected to global shearing and bending actions. The results revealed that the stiffness criterion can be extended to shells under this loading condition. The degree of non-uniformity in axial stresses is quantified and presented as simple formulas that can be readily adopted by design standards.

Wear Resistance of Piston Sleeve Made of Layered Material Structure: MMC A356R, Anti-Abrasion Layer and FGM Interface

Abstract The aim of this paper is the numerical analysis of the one of main part of car engine – piston sleeve. The first example is for piston sleeve made of metal matrix composite (MMC) A356R. The second improved material structure is layered. Both of them are comparison to the classical structure of piston sleeve made of Cr-Ni stainless steel. The layered material structure contains the anti-abrasion layer at the inner surface of piston sleeve, where the contact and friction is highest, FGM (functionally graded material) interface and the layer of virgin material on the outer surface made of A356R. The complex thermo-elastic model with Archard's condition as a wear law is proposed. The piston sleeve is modelling as a thin walled cylindrical axisymmetric shell. The coupled between the formulation of thermo-elasticity of cylindrical axisymmetric shell and the Archard’s law with functionally changes of local hardness is proposed.

ASPECT RATIO FACTOR FOR FINITE ELEMENT METHOD ANALYSIS OF AXIALLY SYMMETRIC CYLINDRICAL SHELL WALLS

Finite Element Method (FEM) is one of the most commonly used numerical analysis method for the structural analysis. The axially symmetric cylindrical shell walls analysis can be made by using FEM or similarity of beams on elastic foundation. The Superposition Method (SPM) is a method developed for the analysis of beams and can be employed in the analysis of cylindrical shell walls. In the analyses using FEM, there are some assumptions and boundaries for preparing mathematical models. One of these boundaries for shell walls is aspect ratio. In this study, it is investigated, the aspect ratio factor for FEM analysis of axially symmetric cylindrical shell walls. For that reason the FEM analysis results are compared with the Superposition Method (SPM). In order to obtain exact solution of cylindrical shell walls, the effects of loadings is calculated and defined to the computer program, which is developed for SPM analysis by using Visual Basic programming language. According to analysis results, aspect ratio has a significantly effect on analysis results. Also, it is occurred minor difference in the FEM analysis results even if in case of obeying the rules.

Comparison of theoretical approaches to account for geometrical imperfections of unstiffened isotropic thin walled cylindrical shell structures under axial compression

Thin walled circular cylindrical shell structures are prone to buckle and very sensitive towards geometrical imperfections. The influence of imperfections on the load carrying capacity of shell structures, as they are applied in launcher vehicles is considered by reducing theoretical buckling loads with empirical knock down factors. In general, these knock down factors may lead to a conservative estimate of the load carrying capacity since a worst case scenario is considered. In order to exploit the lightweight design potential of a structure, theoretical approaches to account for geometrical imperfections may lead to more adequate buckling load predictions. Within this contribution different theoretical approaches to account for geometrical imperfections of isotropic shell structures subjected to axial compression are investigated, and the influence of these approaches on the buckling load obtained is studied.

Free vibration of anti-symmetric angle-ply cylindrical shell walls using first-order shear deformation theory

In the present study, free vibration of anti-symmetric angle-ply cylindrical shell walls is investigated under first-order shear deformation theory using the spline method. Assuming the displacement components in a separable form, a system of coupled equations on three displacement and two rotational functions are obtained. A generalized eigenvalue problem is obtained using the collocation procedure and applying the spline function approximation for displacement and rotational function. The resulting eigenvalue problem is solved for the frequency parameters to get as many eigenvalues as required starting from the least. The eigenvectors are the spline coefficients from which the mode shapes can be constructed. The parametric study showed the effect of length parameter, circumferential node number, ply angles, number of lay-ups, lamination materials and different boundary conditions on the shell frequency.

Dynamic responses and damages of water-filled cylindrical shell subjected to explosion impact laterally

An account is given of some principal observations made from a series of experiments in which metal cylindrical shells were subjected to lateral explosion impact by different TNT charge mass and stand-off distance. These cylindrical shells were filled with water in order to identify the main effects produced by the fluid-structure interaction. In comparison, the explosion impact experiments of the empty cylindrical shells were also carried out. The effects of TNT charge mass, stand-off distance, cylindrical shell wall thickness and filled fluid (water) on perforation and deformation of metal cylindrical shells were discussed, which indicated that water increased the wall strength of the cylindrical shells under explosion impact loading, and the buckling deformation and perforation of the cylindrical shell was significantly influenced by the presence of the water; blast-resistant property of the tube under explosive impact loading of 200g TNT charge was much excellent; deformation and damage of empty cylindrical shell were more sensitive to stand-off distance changed. ALE finite element method was employed to simulate the deformations and damages of empty and water-filled cylindrical shells under explosion impact loading. The experimental and computational results are in agreement, showing the validity of the computational scheme in complex fluid-structure interaction problems involving metal materials subjected to explosion impact. The results show that internal pressure of water will increase when subjecting to impact loading, the anti-blast ability of tube structure is significantly enhanced.

An experimental investigation on interactive behavior of thin walled cylindrical shells

AbstractCylindrical shells are widely used in many kinds of applications under different cases of load combination. Nevertheless, only a small number of researches have been executed on cylindrical shells under pure bending in combination with external pressure. The present experimental research studies the buckling behavior of long cylindrical steel shells under combined pure bending and peripheral pressure. This study shows that initial sectional deformation developed by preloading considerably affects the buckling capacity of such shells. Moreover, it was found that primary load appreciably expedites the initiation of the buckling by activating the possible geometrical imperfections once shells are exposed to secondary load.

Contributions to member stresses due to overall wind-induced behaviors of thin-walled cylindrical shell

The exterior walls of thin-walled cylindrical shells cannot be clearly identified as structural frames or cladding/components according to the current wind loading codes. Wind loading effects on such members depend not only on the overall wind-induced behavior of the cylinder, but also on imposed local wind pressures. In this paper, we identify the contributions of the largest wind loading effects on the overall behaviors of a structure. Fluctuating wind pressures measured from a 1:250 scaled cylinder model were investigated by the proper orthogonal decomposition (POD) method and used to generalize wind loads for analysis. The finite element model and an equivalent lumped-mass model corresponding to the prototype of the scaled model were built as analysis models. Expanded wind pressures were applied directly to the finite element model to calculate the wind loading effects, focusing on structural member stresses. Dynamic displacements obtained from the lumped-mass model were used to analyze the loading effects due to the overall behavior only. The contributions to the largest loading effects due to overall behaviors were identified and are presented in this paper.

An Experiential Optimization Design Method for Orthogonal Rib-Stiffened Thin Walled Cylindrical Shells under Axial Loading

Parametric structural FEA (Finite Element Analysis) models of the orthogonal rib-stiffened thin walled cylindrical shells are established using APDL (ANSYS Parametric Design Language). An experiential optimization design method is then developed based on conclusions of series numerical analysis investigating the effects of parameters’ modification upon buckling loads and modes of the structure. The effects of single design parameter modification under both variational and fixed volume (mass) constraints upon the buckling loads and modes indicate that, only one design scheme is able to obtain maximum buckling load when deployment of the strengthening ribs and volume (mass) parameter were settled previously, and minimum mass would be obtained while this maximum buckling load equals to the required design load. Optimization calculations for aluminum alloy material and layered C/E (Carbon/Epoxy) composite material shells with three layering styles are implemented and discussed, and some useful conclusions are obtained. Method and approach developed in this paper provide certain reference value for the optimal design of such structures.

Ring Beam Stiffness Criterion for Column-Supported Metal Silos

Cylindrical metal silos are commonly elevated to provide access space beneath to directly discharge the contained materials into transportation systems. Evenly spaced column supports are commonly utilized. In larger silos, the discrete forces from supports are more evenly transferred and distributed into the cylindrical shell wall by using a ring beam. A fundamental assumption in the design of the silo shell is that the meridional compressive stresses are relatively uniformly distributed around the circumference. This assumption can easily be violated if the ring beam is flexible, so it is necessary to determine the ring stiffness needed to achieve a particular degree of uniformity of support. Current methods of assessing this stiffness rely on onerous finite-element analysis, which only provides information for the specific design being checked. In this paper, a criterion is developed to identify the required ring beam stiffness to achieve a particular degree of uniformity in the shell stresses. It is ba...