Analysis Of Composite Cylindrical Shells Research Articles

Data-driven approach for uncertainty quantification and risk analysis of composite cylindrical shells for underwater vehicles

Designing underwater vehicles considering uncertainties in mechanical properties of composites is computationally expensive. In this paper, inexpensive-to-evaluate sparse polynomial chaos expansion (PCE) based on small data is employed to alleviate computational burden arising in uncertainty analysis. Experiments and finite element analysis for buckling are performed. Relative contribution of mechanical properties to critical buckling pressure is quantified. Distribution function histogram and risk of structral failure are obtained by performing Monte Carlo simulation (MCS) on inexpensive-to-evaluate sparse PCE. Mean of critical buckling pressure is 8.27 MPa, with coefficient of variation 8.59%. 95% confidence interval is 6.86 MPa–9.65 MPa.

Free Vibration Analysis of Composite Cylindrical Shell Reinforced with Silicon Nano-Particles: Analytical and FEM Approach

Previous research presented the effect of nanomaterials on the mechanical properties of composite materials with various volume fraction effects; in addition, their research presented the effect of nanomaterials on the same mechanical characteristics for a composite plate structure, such as vibration and thermal buckling behavior. Therefore, since the use of shell structures is for large applications, it is necessary to investigate the modification of the vibration characteristics of its design with the effect of nanomaterials and study the influence of other reinforced nanoparticle types on its features. Therefore, in this work, silicon nanoparticles were selected to investigate their effect on the vibration behavior of a shell structure. As a result, this work included studying the vibration behavior by testing the shell structure with a vibration test machine. In addition, after manufacturing the composite material shell with various silicon volume fractions, the mechanical properties were evaluated. In addition, the finite element technique with the Ansys program was used to assess and compare the vibration behavior of the shell structure using the numerical technique. The comparison of the results gave an acceptable percentage error not exceeding 10.93%. Finally, the results evaluated showed that the modification with silicon nanomaterials gave very good results since the nanomaterials improved about 65% of the shell's mechanical properties and vibration characteristics.

A semi-analytical approach for instability analysis of composite cylindrical shells subjected to harmonic axial loading

In this article, nonlinear vibration and dynamic stability analyses of simply supported laminated composite circular cylindrical shells subjected to periodic edge loading are carried out. A third-order shear deformation shell theory that considers all the nonlinear terms in all five kinematic parameters and rotary inertia is used to develop the present mathematical model so that the model is also valid for thick cylindrical shells. Hamilton’s principle, an energy-based approach, is used to obtain the governing partial differential equations (PDEs) of motion of the cylindrical shell. Further, these equations are reduced into ordinary differential equations by employing Galerkin’s method. The incremental harmonic balance (IHB) method in conjunction with the pseudo-arc-length method is used to obtain the frequency-amplitude response of the system. For obtaining the zone of instability regions, Bolotin’s method is adopted. For more practical significance, analysis of results is also extended by considering damping into account for the composite cylindrical shells. Time history response and phase portrait are plotted by adopting Newmark-beta method. The effects of the static load factor, dynamic load factor, modal damping coefficient, and stacking sequence on nonlinear vibration, instability regions and time history responses are also examined.

A closed-form solution for asymmetric free vibration analysis of composite cylindrical shells with metamaterial honeycomb core layer based on shear deformation theory

Asymmetric free vibration analysis of composite cylindrical shells with a honeycomb core layer and adjustable Poisson’s ratio is performed analytically in this study. The equations of motion which are a system of coupled partial differential equations are extracted using Hamilton’s principle by employing the first-order shear deformation theory and they are solved analytically. To study the sensitivity of the results to the different parameters of the honeycomb structure, geometrical parameters, and boundary conditions, a parametric study is presented. It is concluded that for the auxetic composite shell with a negative Poisson’s ratio, by decreasing the Poisson ratio, the frequency decreases. Also, it is shown that by employing the composite shells the weight decreases significantly, while the asymmetric frequency will not change remarkably. By adjusting the Poisson ratio, the frequency variations are studied for a composite shell with a honeycomb core layer. The results are compared with the finite element method and some other references.

Stress state analysis of laminated shells with piezoelectric layers based on the refined theory

This paper presents stress state analysis of composite cylindrical shells bonded piezoelectric layers in the top and bottom surfaces. The laminated smart shell is subjected to electric potential and mechanical loading. The mathematical model of electroelasticity behaviour is based on the refined theory and virtual work principle. The governing differential equations are reduced to ordinary differential equations by means of trigonometric function expansion for displacement and electric potential. Operative method is used to solution of boundary problem. Stress-strain state of smart cylinder for electromechanical loads with clamped support is provided. Numerical results are presented showing the effect of boundary layer at clamped edges and comparison between the obtained results to the classical theory of the Kirchhoff-Love type is accurate.

Buckling Analysis of Composite Cylindrical Shell with Cutout Section

In the construction of aerospace structures the use of cylindrical shell-type components with cut-out sections are unavoidable. The fact is prominent because the structural failure of these components commonly occurs at the cut-out because of high stress concentrations that begin to the cracks formation. Therefore, a cu-tout can cause a local failure at a load level which is less than the global failure load of a similar type shell without a cut-out section. Because of which the design sizing of a cylindrical shell with a cut-out is often based on the value of the stress near the cut-out. For the development of safe and reliable designs an accurate assessment of the stress concentrations in a given shell which is subjected to different kinds of loading is analysed.The objective of the present paper is to determine the stress and deformation values in a thin laminated composite cylindrical shell with an elliptical cut-out by buckling and static analysis. The cylindrical shell considered in this is effect of cut out in pressure vessels. The modeling of the cylindrical shell is done in Pro-E and analysis is carried out in ANSYS using solid and shell element. As Fiber-reinforced composite materials are more efficient and reliable structures for this application because of their high strength and specific modulus compared to other metallic materials. Therefore, materials used are Steel, S2 Glass Epoxy and Kevlar. 5 and 11 layers are used as layer stacking for composite materials S2 Glass and Kevlar.

Nonlinear Forced Vibration Analysis of FG-CNTRC Cylindrical Shells Under Thermal Loading Using a Numerical Strategy

Employing an efficient numerical strategy, the nonlinear forced vibration analysis of composite cylindrical shells reinforced with single-walled carbon nanotubes (CNTs) is carried out. It is assumed that the distribution of CNTs along the thickness direction of the shell is uniform or functionally graded and the temperature dependency of the material properties is accounted. The governing equations are presented based on the first-order shear deformation theory along with von-Karman nonlinear strain-displacement relations. The vectorized form of energy functional is derived and directly discretized using numerical differential and integral operators. By the use of variational differential quadrature (VDQ) method, discretized nonlinear governing equations are obtained. Then, the time periodic differential operators are applied to perform the discretization procedure in time domain. Finally, the pseudo-arc length continuation method is employed to solve the nonlinear governing equations and trace the frequency response curve of the nanocomposite cylindrical shell. A comparison study is first presented to verify the efficiency and validity of the proposed numerical method. Comprehensive numerical results are then given to investigate the effects of the involved factors on the nonlinear forced vibration characteristics of the structure. The results show that the changes of fundamental vibrational mode shape have considerable effects on the frequency response curves of composite cylindrical shells reinforced with CNTs.

Nonlinear Bending Analysis of Composite Cylindrical Shells Reinforced by Functionally Graded Carbon Nanotube in Circumferential Direction

Nonlinear Bending Analysis of Composite Cylindrical Shells Reinforced by Functionally Graded Carbon Nanotube in Circumferential Direction

Imperfection sensitivity analysis of composite cylindrical shells using Koiter’s method

ABSTRACTThe novel methodology for imperfection sensitivity analysis, presented in Barbero et al. [1], is here applied for the evaluation of limit load of composite cylindrical shells. Koiter’s perturbation method is used to calculate the imperfection paths emanating from mode interaction bifurcations, and the Monte Carlo method is used to test a large number of modes and all possible interactions among them. The computational cost is low because of the efficiency of Koiter’s method. The demands of Koiter’s method for accurate evaluations of higher order derivatives of the potential energy are met by a mixed, corotational element.

Finite Element Buckling Analysis of Composite Cylindrical Shell with Cutouts Subjected to Axial Compression

Finite Element Buckling Analysis of Composite Cylindrical Shell with Cutouts Subjected to Axial Compression

Free vibration analysis of composite cylindrical shells with non-uniform thickness walls

The paper proposes to characterize the free vibration behaviour of non-uniform cylindrical shells using spline approximation under first order shear deformation theory. The system of coupled differential equations in terms of displacement and rotational functions are obtained. These functions are approximated by cubic splines. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector which are spline coefficients. Four and two layered cylindrical shells consisting of two different lamination materials and plies comprising of same as well as different materials under two different boundary conditions are analyzed. The effect of length parameter, circumferential node number, material properties, ply orientation, number of lay ups, and coefficients of thickness variations on the frequency parameter is investigated.

Forced vibration analysis of composite cylindrical shells using spline finite strip method

In this study, forced vibration behavior of thin-walled composite circular cylindrical shells is investigated using the spline finite strip method (spline FSM). Spline FSM is one of the versions of finite element method (FEM) employing a special element called finite strip. The shells considered in this study are assumed to be thin; therefore, the classical bending theory of shells and Sanders–Koiter's strain–displacement relation are used in the theoretical formulation of developed method. Time-history response of shells concerning arbitrary type of forces, boundary conditions and damping effects are obtained using developed spline FSM. To check the validity of results a comparison has been performed with the results obtained by conventional finite element method using ANSYS software. As far as the time history response of cylindrical shells is available the natural frequencies are extracted using Fast Fourier Transform (FFT) approach. The evaluated natural frequencies of composite shells are then compared with those obtained from an eigenvalue analysis. The comparison of results revealed the fact that developed spline FSM is an accurate tool that can be used in transient and harmonic analyses of composite laminated cylindrical shells.

Improved stochastic methods for modelling imperfections for buckling analysis of composite cylindrical shells

Imperfection sensitive CFRP cylindrical shells are used in a variety of civil and aerospace applications and feature a large scatter in buckling load levels induced from imperfections introduced from their manufacture. Currently, there are no complete methods that can realistically simulate cylinders with a full spectrum of imperfection types for a complete diagnosis of possible buckling loads. This forces shell designers to utilise an outdated, inefficient and conservative design philosophy that is unsuitable for modern manufacturing methods and materials. Stochastic analyses can optimise and improve the robust design and reliability of such cylinders through accurate prediction of the range of conceivable buckling loads by realistic simulation of structural imperfections. Such imperfections include initial shell-wall geometric, thickness and material imperfections and non-uniform applied end-loads. A procedure which aims to improve the stochastic modelling of thickness and material imperfections in imperfection sensitive composite cylindrical shells is proposed. Monte-Carlo simulations of axially compressed cylinders are performed to show that the stochastic methods described here are able to capture the scatter introduced from the imperfections. The results show that the axial buckling load of the specific cylinder analysed here can be reduced to 29.5kN and increased to over 40kN from a perfect load of 38.2kN from material and thickness imperfections alone.

Buckling Analysis of Composite Cylindrical Shells Reinforced by Carbon Nanotubes

In this paper, the authors investigate a cylindrical shell reinforced by carbon nanotubes. The critical buckling load is calculated using analytical method when it is subjected to compressive axial load. The Mori-Tanaka method is firstly utilized to estimate the effective elastic modulus of composites having aligned oriented straight CNTs. The eigenvalues of the problem are obtained by means of an analytical approach based on the optimized Rayleigh-Ritz method. There is presented a study on the effects of CNTs volume fraction, thickness and aspect ratio of the shell, CNTs orientation angle, and the type of supports on the buckling load of cylindrical shells. Furthermore the effect of CNTs agglomeration is investigated when CNTs are dispersed none uniformly in the polymer matrix. It is shown that when the CNTs are arranged in 90_ direction, the highest critical buckling load appears. Also, the results are plotted for different longitudinal and circumferential mode numbers. There is a specific value for aspect ratio of the cylinder that minimizes the buckling load. The results reveal that for very low CNTs volume fractions, the volume fraction of inclusions has no important effect on the critical buckling load.

Finite Element Analysis of Composite Cylindrical Shells with and without Cutouts

Finite Element Analysis of Composite Cylindrical Shells with and without Cutouts

Geometrically Non-Linear Analysis of Composite Cylindrical Shells and Shallow Sphere Shell

At present, the plate shell structure is broadly used in the engineering field, and the finite element method is the main method to analysis of the structural design. Because many variables are used in the finite element method and the computation is complex, this paper used Bezier surface patches as the admissible displacement fields to represent the shell’s middle surface displacement and rotation components, the deformation of the composite material cylindrical shell and shallow sphere shell under the loads are studied with a Semi-analytical procedure. The results show that semi-analytical and analytical procedure are in good agreement with the results of the analysis, it can be applied in the project.

Dynamic buckling analysis of composite cylindrical shells using a finite element based perturbation method

In this paper a finite element formulation of a reduction method for dynamic buckling analysis of imperfection-sensitive shell structures is presented. The reduction method makes use of a perturbation approach, initially developed for static buckling and later extended to dynamic buckling analysis. The implementation of a single-mode dynamic buckling analysis in a general purpose finite element code is described. The effectiveness of the approach is illustrated by application to the dynamic buckling of composite cylindrical shells under axial and radial step loads. Results of the reduction method are compared with results available in the literature. The results are also compared with full model finite element explicit dynamic analysis, and a reasonable agreement is obtained.

Efficient modeling of imperfections for buckling analysis of composite cylindrical shells

Unstiffened composite cylindrical shells show a large scatter in the load levels that the structure can withstand before buckling occurs. Such scatter is greatly influenced by the unavoidable imperfections of the structure, introduced during the fabrication phase. It is thus of key importance to be able to accurately model such imperfections in a numerical computation, in order to recreate and predict the scatter shown in experimental buckling tests. The imperfections can be analyzed by means of random fields, inferring their statistical properties from available measurements. In this manuscript, evolutionary spectra are used to derive random fields of surface and material imperfections of cylindrical shells. A procedure based on a moving window averaging technique is proposed in order to accurately capture the variation of material properties due to imperfect thickness and laminate manufacturing. Finally, Monte Carlo simulations of compression and torsional buckling of cylinders are carried out to show the combined effect of surface and thickness imperfections in the scatter of the buckling limit load.

Stress analysis of composite cylindrical shells with an elliptical cutout

Stress analysis of composite cylindrical shells with an elliptical cutout

The effect of filament-winding mosaic patterns on the strength of thin-walled composite shells

The paper deals with the modelling and stress analysis of filament-wound composite shells. Existing approaches to the structural analysis of composite shells are usually based on the implementation of mechanics of composite laminates. However, there are some manufacturing effects, specific for the filament-winding process, which could significantly affect the stress and strain fields in the thin-walled composite shells. One of such effects is related to the filament-winding mosaic pattern of the composite layer and usually is not considered in the general stress analysis procedures, including existing finite element software packages. The paper presents results of the modelling and analysis of composite cylindrical shells with different types of filament-winding mosaic patterns. The differences in the numerically predicted stress values caused by the mosaic pattern effect are demonstrated using particular examples. As shown, the actual level of stresses in the thin-walled filament wound composite shells could be underestimated in some cases by the stress analysis based on the conventional mechanics of laminated structures.