Buckling analysis of moderately thick composite conical shells using Galerkin and DQ methods (original) (raw)
Related papers
Archive of Applied Mechanics, 2016
This paper focuses on the buckling analysis of composite sandwich conical shells subjected to a uniform external lateral pressure based on the first-order shear deformation theory. Approximate analytical solutions are assumed to satisfy fully clamped boundary conditions and then Fourier decomposition and Galerkin method is applied to achieve closed-form relations of buckling loads. The closed analytical formula for the critical pressure has been verified by comparison with the finite-element solutions and a special case where the angle of the conical shell approaches zero, that is, a cylindrical shell. Based on this formula buckling analyses of sandwich conical shells with different types of core materials have been accomplished. The outcomes are achieved considering the effects of half-vertex cone angle, core thickness and indicating applicability, accuracy, and stability of the present method.
Journal of Mechanical Science and Technology, 2012
The objective of this research is determining the buckling load of composite truncated conical shells under external loading by theoretical and numerical methods. The boundary conditions are assumed to be clamped. At first, basic equations and stability relations of conical shells were derived. The analysis is carried out using Donnel-type stability equations for thin cross-ply conical shells. By applying Galerkin's method, these equations are converted to a system of ordinary time dependent differential equations. Ritz method is employed for finding the dynamic stability load. Finally, the critical static and dynamic buckling loads and the corresponding wave numbers have been found analytically. Then comparison of results is considered. Results of analytical calculations are compared with numerical results and with other researchers' analytical results. The effects of geometric parameters, the cone semi-vertex angle, number of layers and material of fibers on buckling loads are discussed.
2021
The object of this study is to determine the global buckling load of stiffened composite conical shells under axial compression. The conical shells are stiffened by stringers in longitudinal and rings in circumferential directions. The boundary conditions are assumed to be simply supported at both ends. At the first, the equilibrium equations are obtained using the first order shear deformation theory (FSDT) and principle of minimum potential energy. Effects of stiffeners ((longitudinal and circumferential directions) are considered using smearing technique. The resulting equations are solved using generalized differential quadrature method (GDQM) to obtain the critical buckling load. The acquired results are compared with the results of finite element method (FEM) and other researcher's results available in the literature, and good agreement is observed. The influence of number of stiffeners and rings, length, radius and semi-vertex angle of the cone on buckling behavior of the...
June 2019
A layerwise-differential quadrature method (LW-DQM) is developed for the vibration analysis of a stiffened laminated conical shell. The circumferential stiffeners (rings) and meridional stiffeners (stringers) are treated as discrete elements. The motion equations are derived by applying the Hamilton’s principle. In order to accurately account for the thickness effects and the displacement field of stiffeners, the layerwise theory is used to discretize the equations of motion and the related boundary conditions through the thickness. Then, the equations of motion as well as the boundary condition equations are transformed into a set of algebraic equations applying the DQM in the meridional direction. The advantage of the proposed model is its applicability to thin and thick unstiffened and stiffened shells with arbitrary boundary conditions. In addition, the axial load and external pressure is applied to the shell as a ratio of the global buckling load and pressure. This study demons...
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/buckling-analysis-of-laminated-composite-cylindrical-shells-subjected-to-axial-compressive-loads-using-finite-element-method https://www.ijert.org/research/buckling-analysis-of-laminated-composite-cylindrical-shells-subjected-to-axial-compressive-loads-using-finite-element-method-IJERTV2IS1370.pdf The Laminated cylindrical shells are being used in submarine, underground mines, aerospace applications and other civil engineering applications. Thin cylindrical shells and panels are more prone to fail in buckling rather than material failure. In this present study linear and non-linear buckling analysis of GFRP cylindrical shells under axial compression is carried out using general purpose finite element program (ANSYS). Non-linear buckling analysis involves the determination of the equilibrium path (or load-deflection curve) upto the limit point load by using the Newton-Raphson approach. Limit point loads evaluated for geometric imperfection magnitudes shows an excellent agreement with experimental reults [25]. The influence of composite cylindrical shell thickness, radius variation on buckling load and buckling mode has also investigated. Present study finds direct application to investigate the effect of geometric imperfections on other advanced grid-stiffened structures .
BUCKLING ANALYSIS OF SHELLS SUBJECTED TO COMBINTED LOADS
IAEME Publication, 2014
A semi-analytical isoparametric finite element with three nodes per element and five degrees of freedom per node has been used for the solution. Moderately thick shell theory has been used for the analysis. Second order strains with the in plane and transverse non-linear terms are used for the derivation of geometric matrix. Full Fourier expansion is used in the circumferential direction to overcome the coupling that arises due to material anisotropy and torque prestress. Comparison of the results obtained due to finite element is made with simplified solutions using two thin shell theories with and without shear deformation. The effects of combined load (axial compression and external pressure) on pre-buckling characteristics of composite circular cylindrical and conical shells of various geometric properties have been presented.
The Laminated cylindrical shells are being used in submarine, underground mines, aerospace applications and other civil engineering applications. Thin cylindrical shells and panels are more prone to fail in buckling rather than material failure. In this present study linear and non-linear buckling analysis of GFRP cylindrical shells under axial compression is carried out using general purpose finite element program (ANSYS). Non-linear buckling analysis involves the determination of the equilibrium path (or load-deflection curve) upto the limit point load by using the Newton-Raphson approach. Limit point loads evaluated for geometric imperfection magnitudes shows an excellent agreement with experimental reults [25]. The influence of composite cylindrical shell thickness, radius variation on buckling load and buckling mode has also investigated. Present study finds direct application to investigate the effect of geometric imperfections on other advanced grid-stiffened structures .
2019
In this research paper, an improved theory is used for buckling analysis of sandwich truncated conical shells with thick core and thin functionally graded material face sheets and homogeny core and with temperature-dependent properties. Section displacements of the conical core are assumed by cubic functions, and displacements of the functionally graded material face sheets are assumed by first-order shear displacements theory. The linear variations of temperature are assumed in the through thick. According to a power-law and exponential distribution the volume fractions of the constituents of the functionally graded material face sheets are assumed to be temp-dependent by a third-order and vary continuously through the thickness. In other words to get the strain components, the nonlinear Von-Karman method and his relation is used. The equilibrium equations are obtained via minimum potential energy method. Analytical solution for simply supported sandwich conical shells under axial compressive loads and thermal conditions is used by Galerkin’s solution method. Analysing the results show that the critical dimensionless axial loads are affected by the configurations of the constituent materials, compositional profile variations, thermal condition, semi-vertex angle and the variation of the sandwich geometry. Numerical modeling is made by ABAQUS finite element software. The comparisons show that the present results are in the good and better agreement with the results in the literature and the present finite element modelling.
International Journal of Mechanical and Materials Engineering, 2015
Background: Advanced lightweight laminated composite shells are increasingly being used in modern aerospace structures to enhance their structural efficiency and performance. Such thin-walled structures are susceptible to buckling when subjected to static and dynamic compressive stresses. This paper reports on the numerical (finite element method (FEM)) study on buckling of carbon fibre-reinforced plastic (CFRP) layered composite cylinders under displacement and load-controlled static axial compression. Methods: The effects of geometric properties, lamina lay-up, amplitudes of imperfection and parametric research of the shape (square, circular) and the dimensions (axial and circumferential sizes, diameter) of the opening on the strength of the cylinders under compression were studied. The measurement of imperfections on the cylindrical surface is achieved using the interpolation method and Fourier series. Results: The analysis indicates that the critical load is sensitive to the circumferential size of the opening. The function (critical load-circumferential size of the opening) is linear for large openings and independent of the geometrical imperfections of the shell. However, for small openings, it is necessary to take into account the coupling between the initial geometrical imperfections and the openings. Conclusions: The linear approach does not fit due to the importance of the evolution of the displacements near the openings. Also, it was shown that the buckling behaviour of thin composite cylindrical shells can be evaluated accurately via modelling to determine the imperfections and the material properties in FEM.
Buckling design of conical shells based on validated numerical models
Thin-Walled Structures, 1998
In most shell buckling codes, guidance on the design of conical shells is restricted to unstiffened cones and even in this case the clauses are based on the procedures for cylindrical shells. Virtually no guidance is offered on stiffened cones and the particular characteristics of conical shells are not treated in detail. In this paper, use is made of finite element analysis to quantify critical elastic response and imperfection sensitivity through numerical models, whose adequacy has been quantified through comparisons with test data. The finite element results obtained were aimed at validating existing design recommendations for unstiffened cones and at developing a design approach for stringer-stiffened cones under compression, with a philosophy and format compatible with the European Shell Buckling Recommendations (ECCS).