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Based on domain decomposition, a semi-analytical method (SAM) is applied to analyze the free vibration of double-curved shells of revolution with a general curvature radius made from graphene nanoplatelet (GPL)-reinforced porous composites. The mechanical properties of the GPL-reinforced composition are assessed with the Halpin–Tsai model. The double-curvature shell of revolution is broken down into segments along its axis in accordance with first-order shear deformation theory (FSDT) and the multi-segment partitioning technique, to derive the shell’s functional energy. At the same time, interfacial potential is used to ensure the continuity of the contact surface between neighboring segments. By applying the least-squares weighted residual method (LWRM) and modified variational principle (MVP) to relax and achieve interface compatibility conditions, a theoretical framework for analyzing vibrations is developed. The displacements and rotations are described through Fourier series and Chebyshev polynomials, accordingly, converting a two-dimensional issue into a suite of decoupled one-dimensional problems. The obtained solutions are contrasted with those achieved using the finite element method (FEM) and other existing results, and the current formulation’s validity and precision are confirmed. Example cases are presented to demonstrate the free vibration of GPL-reinforced porous composite double-curved paraboloidal, elliptical, and hyperbolical shells of revolution. The findings demonstrate that the natural frequency of the shell is related to pore coefficients, porosity, the mass fraction of the GPLs, and the distribution patterns of the GPLs.

This paper describes the free and forced vibration of the doubly curved shells of revolution made of functionally graded (FG) material and constrained by various boundary conditions using a convenient and efficient method based on the Jacobi–Ritz method. The theoretical formulation is established on the basis of the multi-segment partitioning technique and first-order shear deformation theory (FSDT). It is assumed that the material properties of the shell vary smoothly and gradually in the thickness direction according to a typical four-parameter power-law function. At both end positions of the shell, the artificial spring technique is introduced to model the corresponding boundary conditions. Similarly, the connective spring parameters are used to model the continuity conditions between the divided shells. The displacements and rotations of any point of the FG doubly curved shell of revolution including the boundary and connection positions are expanded in form of Jacobi orthogonal polynomials in the meridional direction and Fourier series in the circumferential direction. Then, the dynamic characteristics including natural frequency are easily obtained by the Ritz method. The accuracy and credibility of the present method for free and forced vibration analysis are evidenced through comparison with previous literature and the results of the finite element method (FEM). In addition, through numerical examples, some interesting results about the dynamic behaviors of FG doubly curved shells of revolution with various boundary conditions are investigated, which may be provided as reference data for future study.

Purpose The purpose of this work is to apply the Fourier–Ritz method to study the vibration behavior of the moderately thick functionally graded (FG) parabolic and circular panels and shells of revolution with general boundary conditions. Design/methodology/approach The modified Fourier series is chosen as the basis function of the admissible functions of the structure to eliminate all the relevant discontinuities of the displacements and their derivatives at the edges, and the vibration behavior is solved by means of the Ritz method. The complete shells of revolution can be achieved by using the coupling spring technique to imitate the kinematic compatibility and physical compatibility conditions of FG parabolic and circular panels at the common meridian of θ = 0 and 2π. The convergence and accuracy of the present method are verified by other contributors. Findings Some new results of FG panels and shells with elastic restraints, as well as different geometric and material parameters, are presented and the effects of the elastic restraint parameters, power-law exponent, circumference angle and power-law distributions on the free vibration characteristic of the panels are also presented, which can be served as benchmark data for the designers and engineers to avoid the unpleasant, inefficient and structurally damaging resonant. Originality/value The paper could provide the reference for the research about the moderately thick FG parabolic and circular panels and shells of revolution with general boundary conditions. In addition, the change of the boundary conditions can be easily achieved by just varying the stiffness of the boundary restraining springs along all the edges of panels without making any changes in the solution procedure.

We solve the forward and inverse problems associated with the transformation of flat sheets with circularly symmetric director fields to surfaces of revolution with non-trivial topography, including Gaussian curvature, without a stretch elastic cost. We deal with systems slender enough to have a small bend energy cost. Shape change is induced by light or heat causing contraction along a non-uniform director field in the plane of an initially flat nematic sheet. The forward problem is, given a director distribution, what shape is induced? Along the way, we determine the Gaussian curvature and the evolution with induced mechanical deformation of the director field and of material curves in the surface (proto-radii) that will become radii in the final surface. The inverse problem is, given a target shape, what director field does one need to specify? Analytic examples of director fields are fully calculated that will, for specific deformations, yield catenoids and paraboloids of revolution. The general prescription is given in terms of an integral equation and yields a method that is generally applicable to surfaces of revolution.

Here, higher order models of elastic shells of revolution are developed using the variational principle of virtual power for 3-D equations of the linear theory of elasticity and generalized series in the coordinates of the shell thickness. Following the Unified Carrera Formula (CUF), the stress and strain tensors, as well as the displacement vector, are expanded into series in terms of the coordinates of the shell thickness. As a result, all the equations of the theory of elasticity are transformed into the corresponding equations for the expansion coefficients in a series in terms of the coordinates of the shell thickness. All equations for shells of revolution of higher order are developed and presented here for cases whose middle surfaces can be represented analytically. The resulting equations can be used for theoretical analysis and calculation of the stress–strain state, as well as for modeling thin-walled structures used in science, engineering, and technology.

Here, we present a Navier close form solution method for some type of the higher-order theories for elastic shells of revolution developed using the CUF approach. The higher-order models of elastic shells of revolution are developed using the variational principle of virtual power for 3-D equations of the linear theory of elasticity and generalized series in the coordinates of the shell thickness. The higher-order cylindrical supported on the edges and axisymmetric shells, as well as the shallow spherical shells with rectangular planform, are considered. Numerical calculations were performed using the computer algebra software Mathematica. The resulting equations can be used for theoretical analysis and calculation of the stress–strain state, as well as for modeling thin-walled structures used in science, engineering, and technology. The numerical results can be used as benchmark examples for finite element analysis of the higher-order elastic shells.

We consider shallow elastic shells with a given circular boundary and seek an axisymmetric shell shape minimizing the weight at a given fundamental frequency of shell vibrations. Using the resulting formula for the linear part of the increment of the frequency functional, the multiplicity of the minimum natural frequency of vibrations of the shell is estimated. The Fréchet differentiability of the frequency functional is also established, and optimal conditions for minimizing the weight of the shell at a given fundamental vibration frequency are obtained.

The present research develops a general formulation for thermo-elastic analysis of a functionally graded thick shell of revolution with arbitrary curvature and variable thickness subjected to thermo-mechanical loading by using higher-order shear deformation theory. Mechanical properties except Poisson’s ratio are assumed to vary along a two-dimensional coordinate system with arbitrary functional distribution. Given that the thick shell is divided into some virtual disks and replacing various variable terms by their constant values, a set of differential equations for constant thickness are obtained for each virtual disk. By applying continuity conditions between the virtual disks, the general solution of the thick shell is obtained. The final relations are derived in general state for every arbitrary structure and material property distributions. Although previous publications presented a general formulation for thick shells of revolution, to the best of the authors’ knowledge, a closed-form solution is not provided.

This paper investigates the dynamic behavior of shell structures presenting variable-angle tow laminations. The choice of placing fibers along curvilinear patterns allows for a broader structural design space, which is advantageous in several engineering contexts, provided that more complex numerical analyses are managed. In this regard, Carrera’s unified formulation has been widely used for studying variable-angle tow plates and shells. This article aims to expand this formulation through the derivation of the complete formulation for a generic shell reference surface. The principle of virtual displacements is used as a variational statement for obtaining, in a weak sense, the stiffness and mass matrices within the finite element solution method. The free vibration problem of singly and doubly curved variable-angle tow shells is then addressed. The proposed approach is compared to Abaqus three-dimensional reference solutions and classical theories to investigate the effectiveness of the developed models in predicting the vibrational frequencies and modes. The results demonstrate a good agreement between the proposed approach and reference solutions.

New applications introduced capsule designs with features that have not been fully analysed in the literature. In this study, thin shells of revolution are used to model drug delivery capsules both with closed and open designs including perforations. The effects of internal boundary layers and sensitivity on frequency response are discussed in the special case with symmetric concentrated load. The simulations are carried out using high-order finite element method and the frequency response is computed with a very accurate low-rank approximation. Due to the propagation of the singularities induced by the concentrated loads, the most energetic responses do not necessarily include a pinch-through at the point of action. In sensitive configurations, the presence of regions with elliptic curvature leads to strong oscillations at lower frequencies. The amplitudes of these oscillations decay as the frequencies increase. For efficient and reliable analysis of such structures, it is necessary to understand the intricate interplay of loading types and geometry, including the effects of the chosen shell models.