S. D. Akbarov^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.92, No.4, pp. 387-421, 2013, DOI:10.3970/cmes.2013.092.387

Abstract Flexural wave dispersion in finitely pre-stretched (or pre-compressed) solid and hollow, circular cylinders is investigated with the use of the threedimensional linearized theory of elastic waves in initially stressed bodies. It is assumed that the initial strains in the cylinders are homogeneous and correspond to the uniaxial tension, or compression, along their central axes. The elasticity relations of the cylinders’ materials are described by the harmonic potential. The analytical solution of the corresponding field equations is presented and, using these solutions, the dispersion equations for the cases under consideration are obtained. The dispersion equations are solved numerically and based on… More >

Chih-Ping Wu^1,2, Jian-Sin Wang², Yung-Ming Wang²

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.1, pp. 1-38, 2009, DOI:10.3970/cmes.2009.052.001

Abstract A meshless collocation method based on the differential reproducing kernel (DRK) interpolation is developed for the three-dimensional (3D) coupled analysis of simply-supported, functionally graded (FG) piezoelectric hollow cylinders. The material properties of FG hollow cylinders are regarded as heterogeneous through the thickness coordinate, and then specified to obey an exponent-law dependent on this. In the present formulation, the shape function for the reproducing kernel (RK) interpolation function at each sampling node is separated into a primitive function possessing Kronecker delta properties and an enrichment function constituting reproducing conditions. By means of this DRK interpolation, the essential boundary conditions can be… More >

S.-Y. Leu¹, J.T. Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.14, No.2, pp. 129-140, 2006, DOI:10.3970/cmes.2006.014.129

Abstract Plastic limit angular velocity of rotating hollow cylinders made of the von Mises materials with nonlinear isotropic hardening is investigated numerically and analytically in the paper. The paper applies sequential limit analysis to deal with the rotating problems involving hardening material property and weakening behavior resulted from the widening deformation. By sequential limit analysis, the paper treats the plasticity problems as a sequence of limit analysis problems stated in the upper bound formulation. Rigorous upper bounds are acquired iteratively through a computational optimization procedure with the angular velocity factor as the objective function. Especially, rigorous validation was conducted by numerical… More >

S.M. Moussavinezhad¹, Farzad Shahabian¹, Seyed Mahmoud Hosseini^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.3, pp. 177-204, 2013, DOI:10.3970/cmes.2013.091.177

Abstract In this article, the propagation of elastic wave is studied in two dimensional functionally graded thick hollow cylinder with finite length subjected to mechanical shock loading, considering two dimensional variations for mechanical properties. The meshless local Petrov-Galerkin (MLPG) method is developed to solve the boundary value problem. The Newmark finite difference method is used to treat the time dependence of the variables for transient problems. The FG cylinder is considered to be under axisymmetric conditions. The mechanical properties of FG cylinder are assumed to vary across thickness and length of FG cylinder in terms of two dimensional volume fractions as… More >

Subhankar Sen¹, Sanjay Mittal², Gautam Biswas¹

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.1, pp. 1-28, 2012, DOI:10.3970/cmes.2012.086.001

Abstract The steady flow around elliptic cylinders is investigated using a stabilized finite-element method. The Reynolds number, Re, is based on cylinder major axis and free-stream speed. Results are presented for Re ≤ 40 and 0° ≤ α ≤ 90°, where α is angle of attack. Cylinder aspect ratios, AR considered are 0.2 (thin), 0.5, 0.8 (thick) and 1.0. Results for the laminar separation Reynolds number, Re_s available in the literature are only for thin cylinder and exhibit large scatter. Also, very limited information is available for separation angle. The present study attempts to provide this data. In addition, issues concerning… More >

Seyed Mahmoud Hosseini¹, Farzad Shahabian²,Jan Sladek³, Vladimir Sladek³

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.1, pp. 39-66, 2011, DOI:10.3970/cmes.2011.071.039

Abstract The thermo-elastic wave propagation based on Green-Naghdi (GN) coupled thermo-elasticity (without energy dissipation) is studied in a functionally graded thick hollow cylinder considering uncertainty in constitutive mechanical properties under thermal shock loading. The meshless local Petrov-Galerkin method accompanied with Monte-Carlo simulation is developed to solve the stochastic boundary value problem. In the presented method, the mechanical properties of FGM are considered to be as random variables with Gaussian distribution and mean values equal to deterministic values reported in previous works, which are generated using Monte-Carlo simulation with various coefficients of variations (COVs). The time evolution for transient problems is treated… More >

Surkay D. Akbarov^1,2,3, Mugan S. Guliev⁴, Ramazan Tekercioglu⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.1, pp. 1-32, 2010, DOI:10.3970/cmes.2010.055.001

Abstract Dispersion relations of axisymmetric longitudinal wave propagation in a finite pre-strained compound (bi-material) cylinder made from high elastic incompressible materials are investigated within the scope of a piecewise homogeneous body model utilizing three-dimensional linearized theory wave propagation in the initially stressed body. The materials of the inner and outer cylinders are assumed to be neo-Hookean. The numerical results regarding the influence of the initial strains in the inner and outer cylinders on the wave dispersion are presented and discussed. These results are obtained for the case where the material of the inner solid cylinder is stiffer than that of the… More >

A.R. da Silva¹, A. Silveira-Neto^2,3, D.A. Rade^2,4, R.Francis⁴, E.A. Santos⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.3, pp. 285-304, 2009, DOI:10.3970/cmes.2009.050.285

Abstract In the context of computational fluid dynamics a numerical investigation of incompressible flow around fixed pairs of rigid circular cylinders was carried out. The two-dimensional filtered Navier-Stokes equations with the Smagorinsky sub-grid scale model were solved using a Cartesian non-uniform grid. The immersed Boundary Method with the Virtual Physical Model was used in order to model the presence of two circular cylinders embedded in the flow. The fractional time step method was used to couple pressure and velocity fields. The simulations were carried out for Reynolds number equal to 72,000 for pitch ratio equal to 2 and different arrangements regarding… More >

Q. Ma¹, C. Levy², M. Perl³

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.2, pp. 95-110, 2008, DOI:10.3970/cmes.2008.029.095

Abstract Networks of radial and longitudinally-coplanar, internal, surface cracks are typical in rifled, autofrettaged, gun barrels. In two previous papers, the separate effects of large arrays of either radial or longitudinally-coplanar semi-elliptical, internal, surface cracks in a thick-walled, cylindrical, pressure vessel under both ideal and realistic autofrettage were studied. When pressure is considered solely, radial crack density and longitudinal crack spacing were found to have opposing effects on the prevailing stress intensity factor, K_IP. Furthermore, the addition of the negative stress intensity factor (SIF), K_IA, resulting from the residual stress field due to autofrettage, whether ideal or realistic, tended to decrease… More >

M. Perl¹, C. Levy ², V. Rallabhandy ²

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 37-48, 2006, DOI:10.3970/cmes.2006.011.037

Abstract The Bauschinger Effect (BE) impact on K_IN– the combined, Mode I, 3-D Stress Intensity Factor (SIF) distributions for arrays of radial, internal, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. A in-depth comparison between the combined SIFs for a “realistic” - Bauschinger Effect Dependent Autofrettage (BEDA) and those for an “ideal” - Bauschinger Effect Independent Autofrettage (BEIA) is performed. The 3- D finite element (FE) analysis is performed employing the submodeling technique and singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are simulated using an equivalent… More >