Dynamic Behavior of a Stiffened Laminated Conical Shell under Hygrothermal Loads (original) (raw)
Related papers
Governing equations of a stiffened laminated inhomogeneous conical shell
AIAA Journal, 1996
This study presents the dynamic equations of a stiffened composite laminated conical thin shell under the influence of initial stresses. The governing equations of a truncated conical shell are based on the Donnell-Mushtari theory of thin shells including the transverse shear deformation and rotary inertia. The extension-bending coupling is considered in the derivation. The composite laminated conical shell is also reinforced at uniform intervals by elastic rings and/or stringers. The stiffening elements are relatively closely spaced, and therefore the stiffeners are smeared out along the conical shell. The inhomogeneity of material properties because of temperature, moisture, or manufacturing processes is taken into account in the constitutive equations. A generalized variational theorem is derived so as to describe the complete set of the fundamental equations of the conical shell. Next, the uniqueness is examined in solutions of the dynamic equations of the conical shell, and the boundary and initial conditions are shown to be sufficient for the uniqueness in solutions. The equations of the laminated composite conical shell are solved by the use of the finite difference method as an illustrative example. The accuracy of results is tested by certain earlier results, and a good agreement is found.
International Journal of Solids and Structures
The eect of hygrothermal conditions on the buckling and postbuckling of shear deformable laminated cylindrical shells subjected to combined loading of axial compression and external pressure is investigated using a micro-to-macromechanical analytical model. The material properties of the composite are aected by the variation of temperature and moisture, and are based on a micro-mechanical model of a laminate. The governing equations are based on Reddy's higher order shear deformation shell theory with von K arm an±Donnell-type of kinematic nonlinearity and including hygrothermal eects. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A boundary layer theory of shell buckling is extended to the case of shear deformable laminated cylindrical shells under hygrothermal environments and a singular perturbation technique is employed to determine the interactive buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behaviour of perfect and imperfect, moderately thick, cross-ply laminated cylindrical shells under dierent sets of environmental conditions. The results show that the hygrothermal environment has a signi®cant eect on the interactive buckling load as well as postbuckling response of the shell. In contrast, it has a small eect on the imperfection sensitivity of the shell with a very small geometric imperfection.
Vibration Characteristics of a Stiffened Conical Shell
Journal of Sound and Vibration, 1996
This paper is concerned with the free vibrations of a stiffened conical thin shell within the context of Donnell-Mushtari theory. A truncated cone with simply supported ends is reinforced by relatively closely spaced elastic stringers and/or rings. The tapered stringers are used to obtain an efficient stiffening. Change in the stringer spacing in the meridional direction is taken into account in the formulation. The stiffening elements are ''smeared out'' along the conical shell to yield a single equivalent orthotropic shell. The resulting orthotropic shell has a kind of inhomogeneity due to the tapered stringers. The equations of motion for the free vibrations of the stiffened conical shell are derived by the use of Hamilton's principle. The differential equations of the stiffened truncated conical shell, together with the boundary conditions, are solved by the use of the collocation method. Solutions are presented to show the influence of geometrical parameters and material properties on the vibration characteristics. The numerical results are compared with certain earlier results.
Journal of Solid Mechanics, 2017
In this paper, thermo-elastic analysis of a rotating thick truncated conical shell subjected to the temperature gradient, internal pressure and external pressure is presented. Given the existence of shear stress in the conical shell due to thickness change along the axial direction, the governing equations are obtained based on first-order shear deformation theory (FSDT). These equations are solved by using multi-layer method (MLM). The model has been verified with the results of finite element method (FEM). Finally, some numerical results are presented to study the effects of thermal and mechanical loading, geometry parameters of truncated conical shell.
Hygrothermal effects on the postbuckling of composite laminated cylindrical shells
Composites Science and Technology, 2000
The in¯uence of hygrothermal eects on the buckling and post-buckling of composite laminated cylindrical shells subjected to combined loading of external pressure and axial compression has been investigated by using a micro-to-macro-mechanical analytical model. The material properties of the composite are aected by the variation of temperature and moisture, and are based on a micro-mechanical model of a laminate. The governing equations are based on the classical laminated-shell theory, including hygrothermal eects. The non-linear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A boundary layer theory of shell buckling is extended to the case of laminated cylindrical shells under hygrothermal environments and a singular perturbation technique is employed to determine the interactive buckling loads and post-buckling equilibrium paths. The numerical illustrations concern the post-buckling behaviour of perfect and imperfect, cross-ply laminated cylindrical shells under dierent sets of environmental conditions. The results show that the hygrothermal environment has a sig-ni®cant eect on the interactive buckling load as well as post-buckling response of the shell. In contrast, it has a small eect on the imperfection sensitivity.
Numerical Investigation Of Stiffened Composite Cylindrical Shell Subjected To External Pressure
2013
Abstract— The present study is devoted for the development of a mathematical model to predict the structural behavior and critical pressure of composite cylindrical shell under external pressure using finite element analysis. The composites can be tailored to match the external loading. The effect of fibre orientation angle along with stacking sequence of the composites on the loading carrying capacity of the structure is assessed. A quantitative assessment of the effects of discrete stiffeners on the local and global behaviour of shells stiffened by rings is carried out for understanding the response of structure. The study captures the local effects of the stiffener spacing and highlights the effect of eccentricity of stiffeners on the strength of shells. The response of the composite shells has been investigated for different values of the shell thickness.
Buckling and postbuckling of laminated thin cylindrical shells under hygrothermal environments
Applied Mathematics and Mechanics, 2001
The influence of hygrothermal effects on the buckling and postbuckling of composite laminated cylindrical shells subjected to axial compression is investigated using a micro-to-macro-mechanical analytical model. The material properties of the composite are affected by the variation of temperature and moisture, and are based on a micromechanical model of a laminate. The governing equations are based on the classical laminated shell theory, and including hygrothermal effects. The nonlinear prebuckling deformations and initial geometric imperfections of the shell were both taken into account. A boundary layer theory of shell buckling was exlended to the case of laminated cylindrical shells under hygrothermal environments, and a singular perturbation technique was employed to determine buckling loads and postbuckling equilibrium paths. The numerical iUustrations concern the postbuckting behavior of perfect and imperfect, cross-ply laminated cylindrical shells under different sets of environmental conditions. The influences played by temperature rise, the degree of moisture concentration, fiber volume fraction, shell geometric parameter, total number of plies, stacking sequences and initial geometric imperfections are studied.
Hygrothermoelastic Analysis of Orthotropic Cylindrical Shells
Latin American Journal of Solids and Structures, 2016
In this work, the combined effect of moisture and temperature on the bending behavior of simply supported orthotropic cylindrical shells has been investigated. Initially three dimensional equilibrium equations of thermoelasticity, simplified to the case of generalized plane strain deformations in the axial direction are solved analytically for an orthotropic cylindrical shell strip under thermal loading. Based on the realistic variation of displacements from the elasticity approach, a new higher order shear deformation theory was proposed for the analysis of an orthotropic cylindrical shell strip under hygrothermal and mechanical loading. The zigzag form of the displacement is incorporated via the Murakami zigzag function. Results are presented for mechanical and thermal loading for various layups and they are validated against the derived elasticity solution. The significance of retaining various higher-order terms in the present model, in evaluating the stresses and deflection for composite laminates is brought out clearly through parametric study. Useful results for combined hygrothermal loading are presented in tabular and graphical form. It is expected that the numerical results presented herein will serve as bench mark in future.
In this article, stability of composite conical shells subjected to dynamic external pressure is investigated by numerical and experimental methods. In experimental tests, cross-ply glass woven fabrics were selected for manufacturing of specimens. Hand-layup method was employed for fabricating the glass-epoxy composite shells. A test-setup that includes pressure vessel and data acquisition system was designed. Also, numerical analyses are performed. In these analyses, effect of actual geometrical imperfections of experimental specimens on the numerical results is investigated. For introducing the imperfections to the numerical models, linear eigen-value buckling analyses were employed. The buckling modes are multiplied by very small numbers that are derived from measurement of actual specimens. Finally, results are compared together while a good agreement between results of imperfect numerical analyses and experimental tests is observed.
On Stability Of Stiffened Cylindrical Shells With Varying Material Properties
2009
The static stability analysis of stiffened functionally graded cylindrical shells by isotropic rings and stringers subjected to axial compression is presented in this paper. The Young's modulus of the shell is taken to be function of the thickness coordinate. The fundamental relations, the equilibrium and stability equations are derived using the Sander's assumption. Resulting equations are employed to obtain the closed-form solution for the critical axial loads. The effects of material properties, geometric size and different material coefficient on the critical axial loads are examined. The analytical results are compared and validated using the finite element model.