-
دسترسی آزاد مقاله
1 - Characterization of Stress Concentration in Thin Cylindrical Shells with Rectangular Cutout Under Axial Pressure
O. Sam Daliri M. FarahaniIn this paper, stress concentration in the thin cylindrical shell with rectangular cutout subjected to uniform axial pressure was investigated using a parametric finite element model. Design of experiments techniques and statistical analysis was used to provide a model چکیده کاملIn this paper, stress concentration in the thin cylindrical shell with rectangular cutout subjected to uniform axial pressure was investigated using a parametric finite element model. Design of experiments techniques and statistical analysis was used to provide a model for characterizing the critical stress in these components. The influences of the geometrical parameters and their combinations were studied in detail. It was observed that the length to width ratio of the cutout, the length and the radius to thickness ratio of the cylinder were significant parameters for describing the stress concentration around the cutout, respectively. By increasing the length to width ratio as a main effective geometrical factor in the stress concentration, the stress around the cutout was increased significantly. Based on the statistical analysis conducted in this study, a formula was derived which can predict the stress concentration around the cutout of the cylinder with the accuracy more than 84% (R2 = 88.7%, R2pred = 84.6%, R2adj= 86.7%). پرونده مقاله -
دسترسی آزاد مقاله
2 - Frequency Analysis of Ring-Stiffened Composite Cylindrical Shell using Experimental, Analytical and Finite Element Methods
Hadi Salimi Ali Davar Mohsen Heydari Beni Jafar Eskandari Jam Majid Eskandari ShahrakiIn this paper, free vibration of laminated composite cylindrical shells reinforced with circumferential rings, are investigated with experimental, analytical and finite element methods and natural frequencies are obtained. The analysis is carried out for clamp-free and چکیده کاملIn this paper, free vibration of laminated composite cylindrical shells reinforced with circumferential rings, are investigated with experimental, analytical and finite element methods and natural frequencies are obtained. The analysis is carried out for clamp-free and clamp-clamp boundary conditions and the results are compared with each other. To solve the problem, the equilibrium Equations of motions are written according to the classical shells theory and after simplification, the structural stiffness and mass matrices and the frequency Equation are derived using Galerkin method. The results obtained in this paper, are compared with the results available in the literatures, and the results of experimental and finite element methods and good agreement is observed. پرونده مقاله -
دسترسی آزاد مقاله
3 - Analysis of FGM Cylindrical Shell under Impact Loading of Explosion
reza azarafza puya pirali Ali JavadiDue to the increasing application of Functionally Graded Materials (FGM) shells, it seems necessary to investigate their behaviour under different loads. Therefore, in this paper, the dynamic response of functionally graded materials cylindrical shells under explosive l چکیده کاملDue to the increasing application of Functionally Graded Materials (FGM) shells, it seems necessary to investigate their behaviour under different loads. Therefore, in this paper, the dynamic response of functionally graded materials cylindrical shells under explosive load has been investigated with analytical and simulation methods. LS-DYNA software is used in the simulation method. In analytical solution, vibration of composite circular cylindrical shells is investigated based on the first-order deformation shell theory. The boundary conditions are assumed to be fully simply supported. The dynamic response of composite shells is studied under blast loading. The modal technique is used to develop the analytical solution of composite shell. The solution for the shell under the giving loading condition can be found using the convolution integral. Material properties are assumed to be graded in the thickness direction according to Reddy function. A FGM cylindrical shell is made up of a mixture of ceramic and metal. Results show that the effect of explosion is such that it has the greatest effect on the inner layer and with increasing thickness to the outside of the shell this effect decreases and when the maximum deflection occurs, the dynamic velocity is zero. Also, it was observed that with increasing length, the radial deflection increases due to increasing the distance from the support to the center of the shell. پرونده مقاله -
دسترسی آزاد مقاله
4 - Size-Dependent Vibration Problem of Two Vertically-Aligned Single-Walled Boron Nitride Nanotubes Conveying Fluid in Thermal Environment Via Nonlocal Strain Gradient Shell Model
P Roodgar Saffari M Fakhraie M. A RoudbariThe free vibration behavior of two fluid-conveying vertically-aligned single-walled boron nitride nanotubes are studied in the present paper via the nonlocal strain gradient piezoelectric theory in conjunction with the first-order shear deformation shell assumption in t چکیده کاملThe free vibration behavior of two fluid-conveying vertically-aligned single-walled boron nitride nanotubes are studied in the present paper via the nonlocal strain gradient piezoelectric theory in conjunction with the first-order shear deformation shell assumption in thermal environments. It is supposed that the two adjacent boron nitride nanotubes are coupled with each other in the context of linear deformation by van der Waals interaction according to Lennard–Jones potential function. To achieve a more accurate modeling for low-scale structures, both hardening and softening effects of materials are considered in the nonlocal strain gradient approach. Themotion equations and associated boundary conditions are derived by means of Hamilton’s variational principle, then solved utilizing differential quadrature method. Numerical studies are done to reveal the effect of different boundary conditions, size scale parameters, aspect ratio, inter-tube distance, and temperature change on the variations of dimensionless eigenfrequency and critical flow velocity. پرونده مقاله -
دسترسی آزاد مقاله
5 - Modelling of Random Geometrical Imperfections and Reliability Calculations for Thin Cylindrical Shell Subjected to Lateral Pressure
N Rathinam B PrabuIt is well known that it is very difficult to manufacture perfect thin cylindrical shell. Initial geometrical imperfections existing in the shell structure is one of the main determining factor for load bearing capacity of thin cylindrical shell under uniform lateral pr چکیده کاملIt is well known that it is very difficult to manufacture perfect thin cylindrical shell. Initial geometrical imperfections existing in the shell structure is one of the main determining factor for load bearing capacity of thin cylindrical shell under uniform lateral pressure. As these imperfections are random, the strength of same size cylindrical shell will also random and a statistical method can be preferred to find the allowable load of these shell structures and therefore a In this work the cylindrical shell of size R/t = 228, L/R = 2 and t=1mm is taken for study. The random geometrical imperfections are modeled by linearly adding the first 10 eigen mode shapes using 2kfullfactorial design matrix of DoE. By adopting this method 1024 FE random imperfect cylindrical shell models are generated with tolerance limit of ± 1 mm. Nonlinear static FE analysis of ANSYS is used to find the buckling strength of these 1024 models. FE results of 1024 models are used to predict the reliability based on MVFOSM method. پرونده مقاله -
دسترسی آزاد مقاله
6 - Non-Linear Response of Torsional Buckling Piezoelectric Cylindrical Shell Reinforced with DWBNNTs Under Combination of Electro-Thermo-Mechanical Loadings in Elastic Foundation
M Sarvandi M.M Najafizadeh H SeyyedhasaniNanocomposites provide new properties and exploit unique synergism between materials. Polyvinylidene fluoride (PVDF) is an ideal piezoelectric matrix applicable in nanocomposites in a broad range of industries from oil and gas to electronics and automotive. And boron ni چکیده کاملNanocomposites provide new properties and exploit unique synergism between materials. Polyvinylidene fluoride (PVDF) is an ideal piezoelectric matrix applicable in nanocomposites in a broad range of industries from oil and gas to electronics and automotive. And boron nitride nanotubes (BNNTs) show high mechanical, electrical and chemical properties. In this paper, the critical torsional load of a composite tube made of PVDF reinforced with double-walled BNNTs is investigated, under a combination of electro-thermo-mechanical loading. First, a nanocomposite smart tube is modeled as an isotropic cylindrical shell in an elastic foundation. Next, employing the classical shell theory, strain-displacement equations are derived so loads and moments are obtained. Then, the total energy equation is determined, consisting of strain energy of shell, energy due to external work, and energy due to elastic foundation. Additionally, equilibrium equations are derived in cylindrical coordinates as triply orthogonal, utilizing Euler equations; subsequently, stability equations are developed through the equivalent method in adjacent points. The developed equations are solved using the wave technique to achieve critical torsional torque. Results indicated that critical torsional buckling load occurred in axial half-wave number m = 24 and circumferential wave number n = 1, for the investigated cylindrical shell. The results also showed that with the increase in the length-to-radius ratio and in the radius-to-shell thickness ratio, the critical torsional buckling load increased and decreased, respectively. Lastly, results are compared in various states through a numerical method. Moreover, stability equations are validated via comparison with the shell and sheet equations in the literature. پرونده مقاله -
دسترسی آزاد مقاله
7 - Free Vibration Analysis of Composite Grid Stiffened Cylindrical Shells Using A Generalized Higher Order Theory
H Mohammad Panahiha A Davar M Heydari Beni J Eskandari JamThe present study analyzes the free vibration of multi-layered composite cylindrical shells and perforated composite cylindrical shells via a modified version of Reddy’s third-order shear deformation theory (TSDT) under simple support conditions. An advantage of t چکیده کاملThe present study analyzes the free vibration of multi-layered composite cylindrical shells and perforated composite cylindrical shells via a modified version of Reddy’s third-order shear deformation theory (TSDT) under simple support conditions. An advantage of the proposed theory over other high-order theories is the inclusion of the shell section trapezoidal form coefficient term in the displacement field and strain equations to improve the accuracy of results. The non-uniform stiffness and mass distributions across reinforcement ribs and the empty or filled bays between the ribs in perforated shells were addressed via a proper distribution function. For integrated perforated cylindrical shells, the results were validated by comparison to other studies and the numerical results obtained via ABAQUS. The proposed theory was in good consistency with numerical results and the results of previous studies. It should be noted that the proposed theory was more accurate than TSDT. پرونده مقاله -
دسترسی آزاد مقاله
8 - Free Vibration Analysis of Bidirectional Functionally Graded Conical/Cylindrical Shells and Annular Plates on Nonlinear Elastic Foundations, Based on a Unified Differential Transform Analytical Formulation
M Molla-Alipour M Shariyat M ShabanIn the present research, a unified formulation for free vibration analysis of the bidirectional functionally graded conical and cylindrical shells and annular plates on elastic foundations is developed. To cover more individual cases and optimally tailored material prop چکیده کاملIn the present research, a unified formulation for free vibration analysis of the bidirectional functionally graded conical and cylindrical shells and annular plates on elastic foundations is developed. To cover more individual cases and optimally tailored material properties, the material properties are assumed to vary in both the meridian/radial and transverse directions. The shell/plate is assumed to be supported by a non-uniform Winkler-type elastic foundation in addition to the edge constraints. Therefore, the considered problem contains some complexities that have not been considered together in the available researches. The proposed unified formulation is derived based on the principle of minimum total potential energy and solved using a differential transform analytical method whose center is located at the outer edge of the shell or plate; so that the resulting semi-analytical solution can be employed not only for truncated conical shells and annular plates, but also for complete conical shells and circular plates. Accuracy of results of the proposed unified formulation is verified by comparing the results with those of the three-dimensional theory of elasticity extracted from the ABAQUS finite element analysis code. A variety of the edge condition combinations are considered in the results section. A comprehensive parametric study including assessment of influences of the material properties indices, thickness to radius ratio, stiffness distribution of the elastic foundation, and various boundary conditions, is accomplished. Results reveal that influence of the meridian variations of the material properties on the natural frequencies is more remarkable than that of the transverse gradation. پرونده مقاله -
دسترسی آزاد مقاله
9 - Comparison of Various Shell Theories for Vibrating Functionally Graded Cylindrical Shells
M JavadinejadThe classical shell theory, first-order shear deformation theory, and third-order shear deformation theory are employed to study the natural frequencies of functionally graded cylindrical shells. The governing equations of motion describing the vibration behavior of fun چکیده کاملThe classical shell theory, first-order shear deformation theory, and third-order shear deformation theory are employed to study the natural frequencies of functionally graded cylindrical shells. The governing equations of motion describing the vibration behavior of functionally graded cylindrical shells are derived by Hamilton’s principle. Resulting equations are solved using the Navier-type solution method for a functionally graded cylindrical shell with simply supported edges. The effects of transverse shear deformation, geometric size, and configurations of the constituent materials on the natural frequencies of the shell are investigated. Validity of present formulation was checked by comparing the numerical results with the Love’s shell theory. پرونده مقاله -
دسترسی آزاد مقاله
10 - Electro-Thermo-Mechanical Vibration Analysis of a Foam-Core Smart Composite Cylindrical Shell Containing Fluid
A Ghorbanpour Arani R KolahchiIn this study, free vibration of a foam-core orthotropic smart composite cylindrical shell (SCCS) filled with a non-viscous compressible fluid, subjected to combined electro-thermo-mechanical loads is investigated. Piezoelectric polymeric cylindrical shell, is made from چکیده کاملIn this study, free vibration of a foam-core orthotropic smart composite cylindrical shell (SCCS) filled with a non-viscous compressible fluid, subjected to combined electro-thermo-mechanical loads is investigated. Piezoelectric polymeric cylindrical shell, is made from polyvinylidene fluoride (PVDF) and reinforced by armchair double walled boron nitride nanotubes (DWBNNTs). Characteristics of the equivalent composite are determined using micro-electro-mechanical models. The poly ethylene (PE) foam-core is modeled based on Winkler and Pasternak foundations. Employing the charge equation for coupling electrical and mechanical fields, the problem is turned into an eigenvalue one, for which analytical frequency equations are derived considering free electrical and simply supported mechanical boundary conditions at circular surfaces at either ends of the cylindrical shell. The influence of electric potential generated, filled-fluid, orientation angle of DWBNNTs, foam-core and a few other parameters on the resonance frequency of SCCS are investigated. Results show that SCCS and consequently the generated Φ improve sensor and actuator applications in several process industries, because it not only increases the vibration frequency, but also extends economic viability of the smart structure. پرونده مقاله -
دسترسی آزاد مقاله
11 - Finite Element Analysis of Buckling of Thin Cylindrical Shell Subjected to Uniform External Pressure
B Prabu N Rathinam R Srinivasan K.A.S NaarayenOne of the common failure modes of thin cylindrical shell subjected external pressure is buckling. The buckling pressure of these shell structures are dominantly affected by the geometrical imperfections present in the cylindrical shell which are very difficult to allev چکیده کاملOne of the common failure modes of thin cylindrical shell subjected external pressure is buckling. The buckling pressure of these shell structures are dominantly affected by the geometrical imperfections present in the cylindrical shell which are very difficult to alleviate during manufacturing process. In this work, only three types of geometrical imperfection patterns are considered namely (a) eigen affine mode imperfection pattern, (b) inward half lobe axisymmetric imperfection pattern extended throughout the height of the cylindrical shell and (c) local geometrical imperfection patterns such as inward dimple with varying wave lengths located at the mid-height of the cylindrical shell. ANSYS FE non-linear buckling analysis including both material and geometrical non-linearities is used to determine the critical buckling pressure. From the analysis it is found that when the maximum amplitude of imperfections is 1t, the eigen affine imperfection pattern gives out the lowest critical buckling pressure when compared to the other imperfection patterns considered. When the amplitude of imperfections is above 1t, the inner half lobe axisymmetric imperfection pattern gives out the lowest critical buckling pressure when compared to the other imperfection patterns considered. پرونده مقاله -
دسترسی آزاد مقاله
12 - Vibration Analysis of Functionally Graded Spinning Cylindrical Shells Using Higher Order Shear Deformation Theory
M MehrparvarIn this paper the vibration of a spinning cylindrical shell made of functional graded material is investigated. After a brief introduction of FG materials, by employing higher order theory for shell deformation, constitutive relationships are derived. Next, governing di چکیده کاملIn this paper the vibration of a spinning cylindrical shell made of functional graded material is investigated. After a brief introduction of FG materials, by employing higher order theory for shell deformation, constitutive relationships are derived. Next, governing differential equation of spinning cylindrical shell is obtained through utilizing energy method and Hamilton’s principle. Making use of the principle of minimum potential energy, the characteristic equation of natural frequencies is derived. After verification of the results, the effect of changing different parameters such as material grade, geometry of shell and spinning velocity on the natural frequency are examined. پرونده مقاله -
دسترسی آزاد مقاله
13 - Calculation of Natural Frequencies of Bi-Layered Rotating Functionally Graded Cylindrical Shells
I Fakhari GolpayeganiIn this paper, an exact analytical solution for free vibration of rotating bi-layered cylindrical shell composed of two independent functionally graded layers was presented. The thicknesses of the shell layers were assumed to be equal and constant. The material properti چکیده کاملIn this paper, an exact analytical solution for free vibration of rotating bi-layered cylindrical shell composed of two independent functionally graded layers was presented. The thicknesses of the shell layers were assumed to be equal and constant. The material properties of the constituents of bi-layered FGM cylindrical shell were graded in the thickness direction of the layers of the shell according to a volume fraction power-law distribution. In order to derive the equations of motion, the Sanders’ thin shell theory and Rayleigh-Ritz method were used. Also the results were extracted by considering Coriolis, centrifugal and initial hoop tension effects. Effects of rotating speed, geometrical parameters, and material distribution in the two functionally graded layers of the shell, circumferential and longitudinal wave number on the forward and backward natural frequencies were investigated. A comparison of the results was made with those available in the literature for the validity and accuracy of the present methodology. پرونده مقاله -
دسترسی آزاد مقاله
14 - Numerical and Experimental Study on Ratcheting Behavior of Steel Cylindrical Shells with/without Cutout Under Cyclic Combined and Axial Loading
M Shariati K Kolasangiani H.R Epakchi H ChavoshanRatcheting behavior of steel 304L cylindrical shell under cyclic combined and axial loading are investigated in this paper, numerically. Cylindrical shells were fixed oblique at angle of 20° and normal with respect to the longitudinal direction of the shell and subj چکیده کاملRatcheting behavior of steel 304L cylindrical shell under cyclic combined and axial loading are investigated in this paper, numerically. Cylindrical shells were fixed oblique at angle of 20° and normal with respect to the longitudinal direction of the shell and subjected to force-controlled cycling with non-zero mean force, which causes the accumulation of plastic deformation or ratcheting behavior. Numerical analysis was carried out by ABAQUS software using nonlinear isotropic/kinematic hardening model. Numerical results compared to experimental data that was performed by an INSTRON 8802 servo hydraulic machine. Simulations show good agreement between numerical and experimental results. Also, the effect of length, angle of cylindrical shell and existence of cutout are studied with finite element method. Seen, the bending moment plays a strong role in increase of plastic deformation. It is observed that there is more plastic deformation for cylindrical shell under combined loading in comparison to cylindrical shell under uniaxial loading. Ratcheting behavior is sensitive to cutout and showed that creating the cutout increases the plastic deformation. پرونده مقاله -
دسترسی آزاد مقاله
15 - Torsional Stability of Cylindrical Shells with Functionally Graded Middle Layer on the Winkler Elastic Foundation
A.H Sofiyev S AdiguzelIn this study, the torsional stability analysis is presented for thin cylindrical with the functionally graded (FG) middle layer resting on the Winker elastic foundation. The mechanical properties of functionally graded material (FGM) are assumed to be graded in the thi چکیده کاملIn this study, the torsional stability analysis is presented for thin cylindrical with the functionally graded (FG) middle layer resting on the Winker elastic foundation. The mechanical properties of functionally graded material (FGM) are assumed to be graded in the thickness direction according to a simple power law and exponential distributions in terms of volume fractions of the constituents. The fundamental relations and basic equations of three-layered cylindrical shells with a FG middle layer resting on the Winker elastic foundation under torsional load are derived. Governing equations are solved by using the Galerkin method. The numerical results reveal that variations of the shell thickness-to-FG layer thickness ratio, radius-to-shell thickness ratio, lengths-to-radius ratio, foundation stiffness and compositional profiles have significant effects on the critical torsional load of three-layered cylindrical shells with a FG middle layer. The results are verified by comparing the obtained values with those in the existing literature. پرونده مقاله -
دسترسی آزاد مقاله
16 - Evaluation of Buckling and Post Buckling of Variable Thickness Shell Subjected to External Hydrostatic Pressure
A.R Ghasemi M.H HajmohammadBuckling and post buckling of cylindrical shells under hydrostatic pressure is regarded as important issue in structure of submarines. These cylindrical shells have variable thickness due to construction process which effected by pressure of buckling and its destruction چکیده کاملBuckling and post buckling of cylindrical shells under hydrostatic pressure is regarded as important issue in structure of submarines. These cylindrical shells have variable thickness due to construction process which effected by pressure of buckling and its destruction. In this paper, effects of changing thickness on buckling and destruction pressure under external hydrostatic pressure of a shell are studied. Results of buckling pressure of cylindrical shell have been obtained with theoretical relations and finite element method. Then, using machining process a sample of cylindrical shell with variable thickness has been produced. Buckling pressure and post buckling of the constructed sample have been obtained with the reservoir under closed-ended hydrostatic pressure. Changes of the test sample size have been considered with closed-ended testing apparatuses which are used for new evaluation of buckling. In this research, results of the pressure have been obtained in terms of the volume change. At the end, results of the finite element method have been compared with results of the analytical solutions and experimental data. Results show that the shell with variable thickness has buckling pressure close to shell bucking pressure with mean thickness. پرونده مقاله -
دسترسی آزاد مقاله
17 - Nonlinear Dynamic Buckling of Viscous-Fluid-Conveying PNC Cylindrical Shells with Core Resting on Visco-Pasternak Medium
A Ghorbanpour Arani A.A Mosallaie Barzoki R KolahchiThe use of intelligent nanocomposites in sensing and actuation applications has become quite common over the past decade. In this article, electro-thermo-mechanical nonlinear dynamic buckling of an orthotropic piezoelectric nanocomposite (PNC) cylindrical shell conveyin چکیده کاملThe use of intelligent nanocomposites in sensing and actuation applications has become quite common over the past decade. In this article, electro-thermo-mechanical nonlinear dynamic buckling of an orthotropic piezoelectric nanocomposite (PNC) cylindrical shell conveying viscous fluid is investigated. The composite cylindrical shell is made from Polyvinylidene Fluoride (PVDF) and reinforced by zigzag boron nitride nanotubes (BNNTs) where characteristics of the equivalent PNC being determined using micro-mechanical model. The poly ethylene (PE) foam-core is modeled based on Pasternak foundation. Employing the charge equation, Donnell's theory and Hamilton's principle, the four coupled nonlinear differential equations containing displacement and electric potential terms are derived. Harmonic differential quadrature method (HDQM) is applied to obtain the critical dynamic buckling load. A detailed parametric study is conducted to elucidate the influences of the geometrical aspect ratio, in-fill ratio of core, viscoelastic medium coefficients, material types of the shell and temperature gradient on the dynamic buckling load of the PNC cylindrical shell. Results indicate that the dimensionless critical dynamic buckling load increases when piezoelectric effect is considered. پرونده مقاله -
دسترسی آزاد مقاله
18 - Buckling of Piezoelectric Composite Cylindrical Shell Under Electro-thermo-mechanical Loading
A Ghorbanpour Arani S Shams S Amir M.J MaboudiUsing principle of minimum total potential energy approach in conjunction with Rayleigh-Ritz method, the electro-thermo-mechanical axial buckling behavior of piezoelectric polymeric cylindrical shell reinforced with double-walled boron-nitride nanotube (DWBNNT) is inves چکیده کاملUsing principle of minimum total potential energy approach in conjunction with Rayleigh-Ritz method, the electro-thermo-mechanical axial buckling behavior of piezoelectric polymeric cylindrical shell reinforced with double-walled boron-nitride nanotube (DWBNNT) is investigated. Coupling between electrical and mechanical fields are considered according to a representative volume element (RVE)-based micromechanical model. This study indicates how buckling resistance of composite cylindrical shell may vary by applying thermal and electrical loads. Applying the reverse voltage or decreasing the temperature, also, increases the critical axial buckling load. This work showed that the piezoelectric BNNT generally enhances the buckling resistance of the composite cylindrical shell. پرونده مقاله -
دسترسی آزاد مقاله
19 - Elastic Buckling Analysis of Ring and Stringer-stiffened Cylindrical Shells under General Pressure and Axial Compression via the Ritz Method
A Ghorbanpour Arani A Loghman A.A Mosallaie Barzoki R KolahchiElastic stability of ring and stringer-stiffened cylindrical shells under axial, internal and external pressures is studied using Ritz method. The stiffeners are rings, stringers and their different arrangements at the inner and outer surfaces of the shell. Critical buc چکیده کاملElastic stability of ring and stringer-stiffened cylindrical shells under axial, internal and external pressures is studied using Ritz method. The stiffeners are rings, stringers and their different arrangements at the inner and outer surfaces of the shell. Critical buckling loads are obtained using Ritz method. It has been found that the cylindrical shells with outside rings are more stable than those with inside rings under axial compressive loading. The critical buckling load for inside rings is reducing by increasing the eccentricity of the rings, while for outside ring stiffeners the magnitude of eccentricity does not affect the critical buckling load. It has also been found that the shells with inside stringers are more stable than those with outside one. Moreover, the stability of cylindrical shells under internal and external pressures is almost the same for inside and outside arrangements of stringers. The results are verified by comparing with the results of Singer at the same loading and boundary conditions. پرونده مقاله -
دسترسی آزاد مقاله
20 - On the Magneto-Thermo-Elastic Behavior of a Functionally Graded Cylindrical Shell with Pyroelectric Layers Featuring Interlaminar Bonding Imperfections Rested in an Elastic Foundation
M Saadatfar M Aghaie-KhafriThe behavior of an exponentially graded hybrid cylindrical shell subjected to an axisymmetric thermo-electro-mechanical loading placed in a constant magnetic field is investigated. The hybrid shell is consisted of a functionally graded host layer embedded with pyroelect چکیده کاملThe behavior of an exponentially graded hybrid cylindrical shell subjected to an axisymmetric thermo-electro-mechanical loading placed in a constant magnetic field is investigated. The hybrid shell is consisted of a functionally graded host layer embedded with pyroelectric layers as sensor and/or actuator that can be imperfectly bonded to the inner and the outer surfaces of a shell. The shell is simply supported and could be rested on an elastic foundation. The material properties of the host layer are assumed to be exponentially graded in the radial direction. To solve governing differential equations, the Fourier series expansion method along the longitudinal direction and the differential quadrature method (DQM) across the thickness direction are used. Numerical examples are presented to discuss effective parameters influence on the response of the hybrid shell. پرونده مقاله -
دسترسی آزاد مقاله
21 - Third Order Formulation for Vibrating Non-Homogeneous Cylindrical Shells in Elastic Medium
M Gheisari H Molatefi S.S AhmadiThird order shear deformation theory of cylindrical shells is employed to investigate the vibration characteristics of non-homogeneous cylindrical shells surrounded by an elastic medium. The kinematic relations are obtained using the strain-displacement relations of Don چکیده کاملThird order shear deformation theory of cylindrical shells is employed to investigate the vibration characteristics of non-homogeneous cylindrical shells surrounded by an elastic medium. The kinematic relations are obtained using the strain-displacement relations of Donnell shell theory. The shell properties are considered to be dependent on both position and thermal environment. A suitable function through the thickness direction is assumed for the non-homogeneity property. The Winkler-Pasternak elastic foundation is used to model the elastic medium. Analytical solutions are presented for cylindrical shells with simply supported boundary conditions. From the numerical studies, it is revealed that, the natural frequencies are affected significantly by the elastic foundation coefficients and environmental temperature conditions. پرونده مقاله -
دسترسی آزاد مقاله
22 - Influence of the Elastic Foundation on the Free Vibration and Buckling of Thin-Walled Piezoelectric-Based FGM Cylindrical Shells Under Combined Loadings
M Mohammadimehr M Moradi A LoghmanIn this paper, the influence of the elastic foundation on the free vibration and buckling of thin-walled piezoelectric-based functionally graded materials (FGM) cylindrical shells under combined loadings is investigated. The equations of motion are obtained by using the چکیده کاملIn this paper, the influence of the elastic foundation on the free vibration and buckling of thin-walled piezoelectric-based functionally graded materials (FGM) cylindrical shells under combined loadings is investigated. The equations of motion are obtained by using the principle of Hamilton and Maxwell's equations and the Navier's type solution used to solve these equations. Material properties are changed according to power law in the direction of thickness. In this study, the effects of Pasternak elastic foundation coefficients and also the effects of material distribution, geometrical ratios and loading conditions on the natural frequencies are studied. It is observed that by increasing Pasternak elastic medium coefficients, the natural frequencies of functionally graded piezoelectric materials (FGPM) cylindrical shell always increases. The mode shapes of FGPM cylindrical shell has been shown in this research and the results show that the distribution of the radial displacements is more significant than circumferential and longitudinal displacements. پرونده مقاله -
دسترسی آزاد مقاله
23 - First-Order Formulation for Functionally Graded Stiffened Cylindrical Shells Under Axial Compression
A HasaniThe buckling analysis of stiffened cylindrical shells by rings and stringers made of functionally graded materials subjected to axial compression loading is presented. It is assumed that the material properties vary as a power form of the thickness coordinate variable. چکیده کاملThe buckling analysis of stiffened cylindrical shells by rings and stringers made of functionally graded materials subjected to axial compression loading is presented. It is assumed that the material properties vary as a power form of the thickness coordinate variable. The fundamental relations, the equilibrium and stability equations are derived using the first order shear deformation theory. Resulting equations are employed to obtain the critical buckling loads. The effects of the material properties and geometry of shell on the critical buckling loads are examined. Excellent agreement with the results in the literature indicates the correctness of the proposed closed form solution. پرونده مقاله -
دسترسی آزاد مقاله
24 - Free Vibration of Functionally Graded Cylindrical Shell Panel With and Without a Cutout
k.S Sai Ram K Pratyusha P KiranmayiThe free vibration analysis of the functionally graded cylindrical shell panels with and without cutout is carried out using the finite element method based on a higher-order shear deformation theory. A higher-order theory is used to properly account for transverse shea چکیده کاملThe free vibration analysis of the functionally graded cylindrical shell panels with and without cutout is carried out using the finite element method based on a higher-order shear deformation theory. A higher-order theory is used to properly account for transverse shear deformation. An eight noded degenerated isoparametric shell element with nine degrees of freedom at each node is considered. The stiffness and mass matrices are derived based on the principle of minimum potential energy. The stiffness and mass matrices of the element are evaluated by performing numerical integration using the Gaussian quadrature. The effect of volume fraction exponent on the fundamental natural frequency of simply supported and clamped functionally graded cylindrical shell panel without a cutout is studied for various aspect ratios and arc-length to thickness ratios. Results are presented for variation of the fundamental natural frequency of the cylindrical shell panel with cutout size for simply supported and clamped boundary conditions. پرونده مقاله -
دسترسی آزاد مقاله
25 - Coupled Vibration of Partially Fluid-Filled Laminated Composite Cylindrical Shells
M.R SavizIn this study, the free vibration of partially fluid-filled laminated composite circular cylindrical shell with arbitrary boundary conditions has been investigated by using Rayleigh-Ritz method. The analysis has been carried out with strain-displacement relations based چکیده کاملIn this study, the free vibration of partially fluid-filled laminated composite circular cylindrical shell with arbitrary boundary conditions has been investigated by using Rayleigh-Ritz method. The analysis has been carried out with strain-displacement relations based on Love’s thin shell theory and the contained fluid is assumed irrotational, incompressible and inviscid. After determining the kinetic and potential energies of fluid filled laminated composite shell, the eigenvalue problem has been obtained by means of Rayleigh-Ritz method. To demonstrate the validity and accuracy of the results, comparison has been made with the results of similar works for the empty and partially fluid-filled shells. Finally, an extensive parameter study on a typical composite tank is accomplished and some conclusions are drawn. پرونده مقاله -
دسترسی آزاد مقاله
26 - Non-Linear Analysis of Asymmetrical Eccentrically Stiffened FGM Cylindrical Shells with Non-Linear Elastic Foundation
A.R Shaterzadeh K ForoutanIn this paper, semi-analytical method for asymmetrical eccentrically stiffened FGM cylindrical shells under external pressure and surrounded by a linear and non-linear elastic foundation is presented. The proposed linear model is based on two parameter elastic foundatio چکیده کاملIn this paper, semi-analytical method for asymmetrical eccentrically stiffened FGM cylindrical shells under external pressure and surrounded by a linear and non-linear elastic foundation is presented. The proposed linear model is based on two parameter elastic foundation Winkler and Pasternak. According to the von Karman nonlinear equations and the classical plate theory of shells, strain-displacement relations are obtained. The smeared stiffeners technique and Galerkin method, used for solving nonlinear problem. To finding the nonlinear dynamic response of fourth order Runge-Kutta method is used. The effect of parameters asymmetrical eccentrically stiffened on the nonlinear dynamic buckling response of FGM cylindrical shells have been investigated. پرونده مقاله -
دسترسی آزاد مقاله
27 - Buckling of Stiffened Thin-Walled Cylindrical Shells under Axial Compression with Symmetrical Imperfections
Armin A.NobakhtNaminThis study aimed to investigate the effects of stiffeners on buckling of thin cylindrical shells under uniform axial compression. To this end, more than 300 finite element models of stiffened cylindrical shells were prepared. The variables considered are shell thickness چکیده کاملThis study aimed to investigate the effects of stiffeners on buckling of thin cylindrical shells under uniform axial compression. To this end, more than 300 finite element models of stiffened cylindrical shells were prepared. The variables considered are shell thickness, number, dimension and the location of the vertical and horizontal stiffeners as well as circular symmetrical imperfections. Results show that the stiffeners can increase buckling of the stiffened cylindrical shells under axial compression. It is also shown that buckling of the cylindrical shells is susceptible to some circular imperfection patterns. In this context, buckling graph of the models are compared with each other; obviously, the stiffened shells with more stiffeners have upper buckling graph in force - displacement curves. پرونده مقاله -
دسترسی آزاد مقاله
28 - Buckling of Cylindrical Steel Shells with Random Imperfections due to Global Shear
Nima Rahmani Mehran S. Razzaghi Mahmoud HosseiniThis study aims to investigate the effects of geometric imperfections on buckling of thin cylindrical shells due to global shear. To this end, more than 320 finite element models of cylindrical shells with different diameter to thickness ratios were prepared. Random imp چکیده کاملThis study aims to investigate the effects of geometric imperfections on buckling of thin cylindrical shells due to global shear. To this end, more than 320 finite element models of cylindrical shells with different diameter to thickness ratios were prepared. Random imperfections with different amplitudes were applied to numerical models. The results revealed that global buckling of cylindrical shells are susceptible to imperfection patterns. It was also shown that Yamaki’s expression can be considered as upper band for plastic shear buckling of thin cylindrical shells. پرونده مقاله -
دسترسی آزاد مقاله
29 - Nonlinear bucking analysis of Polystyrene, Polyvinyl chloride, and Polypropylene cylindrical nano-composite shells reinforced by carbon nanotubes based on micro-mechanics and finite element methods
Reza Hosseini-Ara Mohsen AkbariIn this paper, we present nonlinear buckling instability analysis of Polystyrene, Polyvinyl chloride, and Polypropylene nano-composite shell-structures reinforced by carbon nanotubes (CNTs) under uni-axial compressive load to obtain a more conservative buckling response چکیده کاملIn this paper, we present nonlinear buckling instability analysis of Polystyrene, Polyvinyl chloride, and Polypropylene nano-composite shell-structures reinforced by carbon nanotubes (CNTs) under uni-axial compressive load to obtain a more conservative buckling response as compared with linear analysis. For this end, the Mori-Tanaka method is firstly utilized to estimate the effective elastic modulus of composites having aligned oriented straight CNTs. Then, a novel model based on micro-mechanics and finite element method is developed for buckling analysis of a cylindrical nano-composite shell reinforced by CNTs and various effects of different types of polymer matrices (Polystyrene, Polyvinyl chloride, and Polypropylene), CNTs volume fraction, CNTs orientation angle, aspect ratio of cylinder, and different boundary conditions (simply supported and clamped ends) on critical buckling load of cylindrical nano-composite shells are discussed. The proposed model is based on Mori-Tanaka micro-mechanics which is developed in ABAQUS finite element package. Herein, numerical results show different behavior from shell-type buckling to beam-type buckling in L/R =8 due to change of the cylinder’s aspect ratios. Moreover, the developed finite element code and numerical results are compared and validated with Mori-Tanaka analytical model in available literature and shown a good agreement. پرونده مقاله -
دسترسی آزاد مقاله
30 - Effect of Material Gradient on Stresses of FGM Rotating Thick-Walled Cylindrical Pressure Vessel with Longitudinal Variation of Properties under Non-uniform Internal and External Pressure
Mehdi Jabbari Mohammad Zamani Nejad Mehdi GhannadThe present paper provides a semi-analytical solution to obtain the displacements and stresses in a functionally graded material (FGM) rotating thick cylindrical shell with clamped ends under non-uniform pressure. Material properties of cylinder are assumed to change al چکیده کاملThe present paper provides a semi-analytical solution to obtain the displacements and stresses in a functionally graded material (FGM) rotating thick cylindrical shell with clamped ends under non-uniform pressure. Material properties of cylinder are assumed to change along the axial direction according to a power law form. It is also assumed that the Poisson’s ratio is constant. Given the existence of shear stress in the thick cylindrical shell due to material and pressure changes along the axial direction, the governing equations are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations with variable coefficients. Given that the FG cylinder is divided into n homogenous disks, n sets of differential equations with constant coefficients are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. The problem was also solved, using the finite element method (FEM), the results of which were compared with those of the multi-layered method (MLM). Finally, some numerical results are presented to study the effects of applied pressure, non-homogeneity index, and power law index of FGM on the mechanical behavior of the cylindrical shell. پرونده مقاله -
دسترسی آزاد مقاله
31 - Effects of Power-Law Distribution and Exponential with Uniform Pressures on Vibration Behavior of Reinforced Cylindrical Shell Made of Functionally Graded Materials under Symmetric Boundary Conditions
Mohammad Reza IsvandzibaeiIn this paper, the influence of the constituent volume fractions by changing the values of the power-law exponent with uniform pressure on the vibration frequencies of reinforced functionally graded cylindrical shells is studied. The FGM shell with ring is developed in چکیده کاملIn this paper, the influence of the constituent volume fractions by changing the values of the power-law exponent with uniform pressure on the vibration frequencies of reinforced functionally graded cylindrical shells is studied. The FGM shell with ring is developed in accordance to the volume fraction law from two constituents namely stainless steel and nickel. These constituents are graded through the thickness direction, from one surface of the shell to the other and are controlled by power-law volume fraction distribution. The reinforced FGM shell equations with ring and uniform pressure are established based on first order shear deformation theory. The governing equations of motion were employed, using energy functional and by applying Ritz method. The boundary conditions represented by end conditions of the FGM cylindrical shell are simply supported-simply supported, clamped-clamped and free-free. Effects of the different values of the power-law exponent, uniform pressure, reinforced ring and different symmetric boundary conditions on natural frequencies characteristics are studied. To check the validity of the present study, the results obtained are compared with those available in the literature. پرونده مقاله -
دسترسی آزاد مقاله
32 - Influence of Power Law Distribution with Pressure on the Frequencies of Supported Functionally Graded Material Cylindrical Shell with C-SL and F-SS Boundary Conditions
Mohammad Reza IsvandzibaeiIn this paper, influence power-law distribution with pressure on frequencies of the supported functionally graded cylindrical shell is studied. This shell is constructed from a functionally graded material (FGM) with two constituent materials. FGMs are graded through th چکیده کاملIn this paper, influence power-law distribution with pressure on frequencies of the supported functionally graded cylindrical shell is studied. This shell is constructed from a functionally graded material (FGM) with two constituent materials. FGMs are graded through the thickness direction, from one surface of the shell to the next. The supported FGM shell equations are created based on FSDT. The governing equations of the movement were utilized by the Ritz method. The boundary conditions are clamp-sliding and free-simply support. The influence of the various values of the power-law distribution with pressure supported and different conditions on the frequencies characteristics are studied. This study shows that the frequencies decreased with the increase in the amounts of the power-law distribution with pressure. Thus, the constituent power-law distribution with pressure effects on the frequencies. The results show the frequencies with different power-law distribution under pressures are various for different conditions. پرونده مقاله -
دسترسی آزاد مقاله
33 - Experimental and FEM Analysis of Ribs Defects on Composite Lattice Cylindrical Shells
Amin Kolahdooz Seyyed Ali Latifi RostamiIn this study, the behavior of a composite lattice cylindrical shell is investigated in the buckling deforming. Also, the distribution of shell buckling response and the stress field is studied after making some defects on the ribs.Therefore using ANSYS software, a 3D f چکیده کاملIn this study, the behavior of a composite lattice cylindrical shell is investigated in the buckling deforming. Also, the distribution of shell buckling response and the stress field is studied after making some defects on the ribs.Therefore using ANSYS software, a 3D finite element model of the shell has been created for the analysis. Material properties and geometrical data of the shell are obtained from the some experimental tests. In fact, these parameters have been extracted from the prototypesthat made with filament winding method. The parameters studied in this study include of the kind of ribs defects on buckling response and the geometrical ratios. Composite shells have been tested under axial force and obtained results are compared with the results of FEM. Based on the parametric study, the structural strength-to-weight ratio is increased around %50 by increasing the thickness of the outer shell. It is observed that in each consecutive buckling test, the buckling load is reduced; however the failed sample had reasonably good resistance to the applied load. پرونده مقاله -
دسترسی آزاد مقاله
34 - Numerical Analysis of Delamination Buckling in Composite Cylindrical Shell under Uniform External Pressure: Cohesive Element Method
Sayed Ali Sajjady Saeed Rahnama Mohammad Lotfi Reza NosouhiNowadays, due to high ratio of strength to weight, composite cylindrical shells are extensively used in a great variety of different industrial applications and under different cases of loads. In this study, the buckling of composite cylindrical shells was examined unde چکیده کاملNowadays, due to high ratio of strength to weight, composite cylindrical shells are extensively used in a great variety of different industrial applications and under different cases of loads. In this study, the buckling of composite cylindrical shells was examined under uniform external pressure. The buckling analysis of composite cylindrical shells was first done by using theoretical relationships. Doing this, Donnell and improved Donnell equations were employed. Then finite element analysis of composite cylindrical shells was done considering inter-layers delamination. Since delamination is a predominant reason for damage in composite materials, considering different models, the effect of delamination and the factors affecting it (such as the ratio of cylinder length to its cross-section perimeter, delamination size, delamination depth location, and delamination shape) on critical buckling load will be examined. Finally, in the section related to delamination growth, its growth direction and also the effect of embedded delamination shape and size upon delamination growth were examined. The analysis of variance of finite element results show that the area and the depth of delamination with the effectiveness of % 31.92 and % 28.85 have respectively the most effects on critical buckling load. In this study, the 3D modeling of delamination and its growth by using cohesive elements is carried out in ABAQUS software which is the main novelty of this work. پرونده مقاله -
دسترسی آزاد مقاله
35 - Resolution composite shell with a layer of piezoelectric vibration analysis
اکبر علی بیگلو عبدالمجید کنیIn this paper, the vibration of composite cylindrical shell with piezoelectric layers in the interior and exterior surfaces is investigated. The composite shell without piezoelectric layers can be studied and compared the results with the results of other researchers, t چکیده کاملIn this paper, the vibration of composite cylindrical shell with piezoelectric layers in the interior and exterior surfaces is investigated. The composite shell without piezoelectric layers can be studied and compared the results with the results of other researchers, the cylindrical shell laminated with layers of piezoelectric vibration checked. The result is a three-dimensional elasticity equations relationships because they do not apply any approximate gain are quite analytical. Shells intended, is closed and has restricted the mainstays in the end it was simple, and the results for the ratio of the radius and the radius of the different thickness are obtained پرونده مقاله -
دسترسی آزاد مقاله
36 - Free Vibration Analysis of FGM Cylindrical Shell with Supported Ring Based on Reddy Model under Clamped Boundary Condition
محمد رضا عیسوند زیبائی مهدی سلمان زاده رسول موسویفرIn this paper a study on the vibration of thin cylindrical shells with ring supports and made of functionally graded materials (FGMs) composed of stainless steel and nickel is presented. The properties are graded in the thickness direction according to a volume fraction چکیده کاملIn this paper a study on the vibration of thin cylindrical shells with ring supports and made of functionally graded materials (FGMs) composed of stainless steel and nickel is presented. The properties are graded in the thickness direction according to a volume fraction power-law distribution.The cylindrical shells with ring supports which are arbitrarily placed along the shell and impose zero lateral deflections. The study is carried out based on third order shear deformation shell theory (T.S.D.T). The analysis is carried out using Hamilton’s principle. The governing equations of motion of FGM cylindrical shells are derived based on shear deformation theory. Results are presented on the frequency characteristics, influence of ring support position and the influence of clamed-clamped boundary conditions. پرونده مقاله -
دسترسی آزاد مقاله
37 - Investigation of Axial to Lateral Load ratio on the Buckling of Thin Orthotropic Cylindrical Shells
مسیب اسماعیل دخت رضا اکبری آلاشتی محمدحسن قاسمی مرتضی دردلBuckling analysis of thin cylindrical shells is very important due to their production process. Usually longitudinal and transversal stiffeners are used to increase the buckling stiffness. In this paper, considering a thin cylindrical shell with longitudinal and transve چکیده کاملBuckling analysis of thin cylindrical shells is very important due to their production process. Usually longitudinal and transversal stiffeners are used to increase the buckling stiffness. In this paper, considering a thin cylindrical shell with longitudinal and transversal ribs subjected to axial force and lateral pressure, the influence of different aspect of axial force to lateral pressure on buckling load is investigated for different ratios such as thickness to radius and length to radius. The analytical results based on Donnell’s classical linear stability equations for anisotropic cylindrical shells are compared with FEM results of ANSYS software. The results show that the analytical method of Donnell can be used for special aspect ratios. Furthermore, by increasing the axial to lateral load ratio, the axial buckling load is increased for most of the aspect ratios, while the lateral buckling load decreases. پرونده مقاله -
دسترسی آزاد مقاله
38 - Severe Impact on the Behavior of Energy Absorbing Cylindrical Base in Frontal Impact
عبدالمجید کنی اکبر علی بیگلوIn this paper, the vibration characteristics of multi-layer shell that internal and external surfaces with a layer of piezoelectric sensor and actuator is investigated. The backrest shell laminated with simple analytical method to evaluate and the results were compared چکیده کاملIn this paper, the vibration characteristics of multi-layer shell that internal and external surfaces with a layer of piezoelectric sensor and actuator is investigated. The backrest shell laminated with simple analytical method to evaluate and the results were compared with results obtained by other researchers. The numerical solution methods (GDQ) for shells with piezoelectric layers and plain bearings, compared with analytical solution and then a variety of boundary conditions is studied. Using the equations of motion, the fundamental equations and relations Krnsh- displacement, State-space equations derived the equations using approximate separate layer, State-space equations with constant coefficients will become. These equations can be solved using natural frequencies in the backrest shell simple to obtain. If the abutments are not simple, solving equations differentials State-space analysis is not possible and should be used numerical methods. A fourth difference method numerical method common with the small number of sample points can be exact to achieve. By dq, State-space differential equations are solved and the non-traction conditions by applying high and low levels, can be found at the natural frequency. The direct and inverse piezoelectric effect, piezoelectric layer and composite layer thickness ratio of the radius of the middle of a thick crust on the vibrational behavior is studied پرونده مقاله -
دسترسی آزاد مقاله
39 - Buckling Analysis of Cylindrical Grooved Shell under Axial Load Discs
امین رحمت نژاد محمد مهدی نجفی زاده حمید محسنی منفردIn this paper, buckling of cylindrical grooved shells under axial load has been examined by theoretical and experimental methods. The shell is made of USA/API – X42 5L steel standards. This material is one of the most common materials used in gas, oil and petroche چکیده کاملIn this paper, buckling of cylindrical grooved shells under axial load has been examined by theoretical and experimental methods. The shell is made of USA/API – X42 5L steel standards. This material is one of the most common materials used in gas, oil and petrochemical industries. The effect of spiral grooves on cylindrical shell was analyzed, and the results obtained from the Abaqus software were compared with experimental results. Theoretical and experimental results were in good agreement. Hence, the numerical results can be used as well. It was also found that the number of grooves on the critical buckling load has an important role so that the critical buckling load decreases with an increase in critical load groove. پرونده مقاله
سکوی نشر دانش
سند یا سکوی نشر دانش ،سامانه ای جهت مدیریت حوزه علمی و پژوهشی نشریات دانشگاه آزاد می باشد
پیوندهای سایت
مراکز مرتبط
پشتیبانی
صفحات رسمی
حقوق این وبسایت متعلق به سامانه مدیریت نشریات دانشگاه آزاد اسلامی است.
حق نشر © 1403-1400