Dan Zhao^1,*, Qiong Wu¹, Minyao Gan², Ke Li¹, Wenhong Ma¹, Qun Wu¹, Liqiang Dong¹, Shaogang Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.134, No.3, pp. 2041-2055, 2023, DOI:10.32604/cmes.2022.021026

Abstract To reduce the vibration and sound radiation of underwater cylindrical shells, a skin composed of micro floating raft arrays and a compliant wall is proposed in this paper. A vibroacoustic coupling model of a finite cylindrical shell covered with this skin for the case of turbulence excitation is established based on the shell theories of Donnell. The model is solved with the modal superposition method to investigate the effects of the structural parameters of micro floating raft elements on the performance of reducing vibration and sound radiation of the cylindrical shell of this skin. The results indicate that increasing the… More >

Mahmoud M. Selim^1,2,*, Khaled A. Gepreel³

CMC-Computers, Materials & Continua, Vol.70, No.2, pp. 3021-3030, 2022, DOI:10.32604/cmc.2022.019579

Abstract The dispersion relation of torsional wave in a dissipative, incompressible cylindrical shell of infinite length incorporating initial stresses effects is investigated. The governing equation and closed form solutions are derived with the aid of Biot's principle. Phase velocity and damping of torsional wave are obtained analytically and the influences of dissipation and initial stresses are studied in details. We proposed a new method for obtaining the phase and damping velocities of torsional wave in a complex form. Numerical results analyzing the torsional wave propagation incorporating initial stress effects are analyzed and presented in graphs. The analytical and numerical solutions reveal… More >

Siyang Piao¹, Huajiang Ouyang^{1, 2}, Yahui Zhang^{1, *}

CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.2, pp. 571-591, 2020, DOI: 10.32604/cmes.2020.08789

Abstract A beam approximation method for dynamic analysis of launch vehicles modelled as stiffened cylindrical shells is proposed. Firstly, an initial beam model of the stiffened cylindrical shell is established based on the cross-sectional area equivalence principle that represents the shell skin and its longitudinal ribs as a beam with annular cross-section, and the circumferential ribs as lumped masses at the nodes of the beam elements. Then, a fine finite element model (FE model) of the stiffened cylindrical shell is constructed and a modal analysis is carried out. Finally, the initial beam model is improved through model updating against the natural… More >

Hai Qian^1,*, Sai-Huen Lo², Ding Zhou³, Yang Yang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.121, No.1, pp. 215-247, 2019, DOI:10.32604/cmes.2019.07922

Abstract The temperature and the stress distribution in simply-supported laminated cylindrical shells undergo thermal loads on the surface have been investigated. Exact solutions of physical quantities including temperature, heat flux, thermal displacement and stress are developed for the cylindrical laminated shell. Cylindrical shells are partitioned into more thin layers. In cylindrical coordinate, analytical expressions for physical quantities inside each layer are derived. Taking into account the compatibility of physical quantities at the interfaces, the relations between the outer and the inner layer of the laminated shell can be described with a transfer matrix. The undetermined parameters from the solutions of each… More >

Takaya Kobayashi, Yasuko Mihara, Fumio Fujii

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.1, pp. 27-28, 2011, DOI:10.3970/icces.2011.019.027

Abstract In designing a modern lightweight structure, the determination of the critical buckling load in an ideal condition is not sufficient. Clarifying the postbuckling behavior is also required. One reason is to estimate the effect of practically unavoidable imperfections on the critical load and another reason is to evaluate the ultimate load-carrying capacity of the structure. For the buckling problem of circular cylindrical shells under axial compression, experimental results showed that after the primary buckling, the secondary buckling occurred accompanied by successive reductions in the number of the circumferential waves at every path-jumping. In this paper, we traced this successive buckling… More >

Chih-Ping Wu¹, Yen-Wei Chi¹

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 337-352, 2004, DOI:10.3970/cmc.2004.001.337

Abstract Within the framework of the three-dimensional (3D) nonlinear elasticity, a refined asymptotic theory is developed for the nonlinear analysis of laminated circular cylindrical shells. In the present formulation, the basic equations including the nonlinear relations between the finite strains (Green strains) and displacements, the nonlinear equilibrium equations in terms of the Kirchhoff stress components and the generalized Hooke's law for a monoclinic elastic material are considered. After using proper nondimensionalization, asymptotic expansion, successive integration and then bringing the effects of transverse shear deformation into the leading-order level, we obtain recursive sets of the governing equations for various orders. It is… More >

B. Kriegesmann¹, R. Rolfes¹, E. L. Jansen¹, I. Elishakoff², C. Hühne³, A. Kling³

CMC-Computers, Materials & Continua, Vol.32, No.3, pp. 177-200, 2012, DOI:10.3970/cmc.2012.032.177

Abstract Four different approaches for the design of axially compressed cylindrical shells are presented, namely (1) the knockdown factor (KDF) concept, (2) the single perturbation load approach, (3) a probabilistic design procedure and (4) the convex anti-optimization approach. The different design approaches take the imperfection sensitivity and the scatter of input parameters into account differently. In this paper, the design of a composite cylinder is optimized considering the ply angles as design variables. The KDF concept provides a very conservative design load and in addition an imperfection sensitive design, whereas the other approaches lead to a significantly less conservative design load… More >

M. V. Kunte¹, Venkata R. Sonti¹

CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.2, pp. 119-156, 2011, DOI:10.3970/cmes.2011.081.119

Abstract Analytical expressions are found for the wavenumbers in an infinite flexible in vacuo / fluid-filled circular cylindrical shell based on different shell-theories using asymptotic methods. Donnell-Mushtari theory (the simplest shell theory) and four higher order theories, namely Love-Timoshenko, Goldenveizer-Novozhilov, Flügge and Kennard-simplified are considered. Initially, in vacuo and fluid-coupled wavenumber expressions are presented using the Donnell-Mushtari theory. Subsequently, the wavenumbers using the higher order theories are presented as perturbations on the Donnell-Mushtari wavenumbers. Similarly, expressions for the resonance frequencies in a finite shell are also presented, using each shell theory. The basic differences between the theories being what they are,… More >

F. Guarracino ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.3, pp. 167-184, 2011, DOI:10.3970/cmes.2011.072.167

Abstract The design of many engineering problems requires accurate test results and interpretation in order to evaluate the carrying capacity of circular cylindrical shells subjected to various loads including bending. Apparently anomalous values of axial tensile and compressive strains from recent test results have been lately investigated and explained using Finite Element modeling. As a complement to numerical analyses, in the present paper a simple analytical formula for the estimation of the effects of local conditions in tubes testing and design is provided on the basis of an extended Ritz's approach and of the general linear theory of shells. The findings… More >

Abhijit Sarkar¹, Venkata R. Sonti¹

CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.3, pp. 193-208, 2007, DOI:10.3970/cmes.2007.021.193

Abstract The coupled wavenumbers of a fluid-filled flexible cylindrical shell vibrating in the axisymmetric mode are studied. The coupled dispersion equation of the system is rewritten in the form of the uncoupled dispersion equation of the structure and the acoustic fluid, with an added fluid-loading term involving a parameter$\epsilon$ due to the coupling. Using the smallness of Poisson's ratio$(\nu )$, a double-asymptotic expansion involving$\epsilon$ and$\nu ^2$ is substituted in this equation. Analytical expressions are derived for the coupled wavenumbers (for large and small values of$\epsilon$). Different asymptotic expansions are used for different frequency ranges with continuous transitions occurring between them. The… More >