C.V. Nastos, T.C. Theodosiou, C.S. Rekatsinas, D.A. Saravanos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.5, pp. 379-409, 2015, DOI:10.3970/cmes.2015.107.379

Abstract A computationally efficient numerical method is developed for the prediction of transient response in orthotropic rod and beam structures. The method takes advantage of the outstanding properties of compactly supported Daubechies wavelet scaling functions for the spatial approximation of displacements in a finite domain of the structure, hence is termed Finite Wavelet Domain (FWD) method. The basic principles and advantages of the method are presented and the discretization of the equations of motion is formulated for one-dimensional structures. Numerical results for the simulation of propagating guided waves in rods and strips are presented and compared More >

A. Tadeu¹, P. Stanak², J. Antonio¹, J. Sladek², V. Sladek²

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.5, pp. 345-378, 2015, DOI:10.3970/cmes.2015.107.345

Abstract This paper implements a numerical method based on the mutual coupling of the boundary element method (BEM) and the meshless local Petrov-Galerkin (MLPG) method to simulate elastic wave propagation in fluid-filled boreholes. The fluid-solid interaction is solved in the frequency domain assuming longitudinally invariant geometry in the axial direction (2.5D formulation).
This model is used to assess the influence of the non-homogeneous material properties of a borehole wall that can be caused by a damaged zone, construction process or the ageing of material. The BEM is used to model propagation within the unbounded homogeneous domain… More >

T. Gortsas¹, S.V. Tsinopoulos², D. Polyzos^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.4, pp. 321-343, 2015, DOI:10.3970/cmes.2015.107.321

Abstract An advanced Boundary Element method (BEM) accelerated via Adaptive Cross Approximation (ACA) and Hierarchical Matrices (HM) techniques is presented for the solution of large-scale elastostatic problems with multi-connected domains like in fiber reinforced composite materials. Although the proposed ACA/ BEM is demonstrated for two-dimensional (2D) problems, it is quite general and it can be used for 3D problems. Different forms of ACA technique are employed for exploring their efficiency when they combined with a BEM code. More precisely, the fully and partially pivoted ACA with and without recompression are utilized, while the solution of the More >

Da-guo Wang^1,2, Bin Hu¹, Qing-xiang Shui¹

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.4, pp. 297-320, 2015, DOI:10.3970/cmes.2015.107.297

Abstract A numerical large eddy simulation (LES) method combined with the characteristic-based operator-splitting finite element method is proposed. The subgrid eddy viscosity model is used to calculate sub-grid stress in LES. In each time step, the governing equations are split into diffusive and convective parts. The convective part is first discretized by using the characteristic Galerkin method and then solved explicitly. The backward-facing step flow and the flow past a single cylinder are adopted to validate the model. Results agree with existing numerical results or experimental data. The flow past two cylinders in tandem arrangement is More >

J. Useche¹, H. Alvarez¹

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.4, pp. 277-296, 2015, DOI:10.3970/cmes.2015.107.277

Abstract Dynamic stress analysis of laminated composites plates represents a relevant task in designing of aerospace, shipbuilding and automotive components where impulsive loads can lead to sudden structural failure. The mechanical complexity inherent to these kind of components makes the numerical modeling an essential engineering analysis tool. This work deals with dynamic analysis of stresses and deformations in laminated composites thick plates using a new Boundary Element Method formulation. Composite laminated plates were modeled using the Reissner’s plate theory. We propose a direct time-domain formulation based on elastostatic fundamental solution for symmetrical laminated thick plates. Formulation More >

L.L. Chen¹, H.B. Chen^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.3, pp. 249-276, 2015, DOI:10.3970/cmes.2015.107.249

Abstract Engineers have started to develop ways to decrease noise radiation. Structural-acoustic design sensitivity analysis can provide information on how changes in design variable affect the radiated acoustic performance. As such, it is an important step in the structural-acoustic design and in optimization processes. For thin structures immersed in water, a full interaction between the structural domain and the fluid domain needs to be taken into account. In this work, the finite element method is used to model the structure parts and the boundary element method is applied to the exterior acoustic problem. The formula of More >

Delfim Soares Jr.¹

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.3, pp. 223-247, 2015, DOI:10.3970/cmes.2015.107.223

Abstract In this work, an explicit time marching procedure, with solution-adaptive time integration parameters, is introduced for the analysis of hyperbolic models. The proposed technique is conditionally-stable, second-order accurate and it has controllable algorithm dissipation, which locally adapts at each time step, according to the computed solution. Thus, spurious modes can be more effectively dissipated and accuracy is improved. Since this is an explicit time integration technique, the new procedure is very efficient, requiring no system of equations to be dealt with at each time-step. Moreover, the technique is simple and easy to implement, being based More >

K. Naveen Kumar¹, K. Srinivasa Rao², Y. Srinivas³, Ch. Satyanarayana⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.3, pp. 201-221, 2015, DOI:10.3970/cmes.2015.107.201

Abstract Texture Analysis is one of the prime considerations for image analysis and processing. Texture segmentation gained lot of importance due to its ready applicability in automation of scene identification and computer vision. Several texture segmentation methods have been developed and analysed with the assumption that the feature vector associated with the texture of the image region is modelled as Gaussian mixture model. Due to the limitations of the Gaussian model being meso kurtic, it may not characterise the texture of all image regions accurately. Hence in this paper, a texture segmentation algorithm is developed and… More >

Taku Itoh¹, Susumu Nakata²

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.3, pp. 187-199, 2015, DOI:10.3970/cmes.2015.107.187

Abstract To speed up generating a scalar field g(x) based on a piecewise polynomial, a new method for determining field values that are indispensable to generate g(x) has been proposed. In the proposed method, an intermediate for generating g(x) does not required, i.e., the field values can directly be determined from given point data. Numerical experiments show that the computation time for determining the field values by the proposed method is about 10.4–12.7 times less than that of the conventional method. In addition, on the given points, the accuracy of g(x) obtained by using the proposed More >

Qifeng Fan¹, Yaping Zhang², Leiting Dong^1,3, Shu Li¹, Satya N. Atluri⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.2, pp. 155-186, 2015, DOI:10.3970/cmes.2015.107.155

Abstract Although “higher-order” and layer-wise “higher-order” plate and shell theories for composite laminates are widely popularized in the current literature, they involve (1) postulating very complex assumptions of plate/shell kinematics in the thickness direction, (2) defining generalized variables of displacements, strains, and stresses, and (3) developing very complex governing equilibrium, compatibility, and constitutive equations in terms of newly-defined generalized kinemaic and generalized kinetic variables. Their industrial applications are thus hindered by their inherent complexity, and the fact that it is difficult for end-users (front-line structural engineers) to completely understand all the newly-defined FEM DOFs in higher-order… More >