Jiawei Xiang¹, Toshiro Matsumoto², Yanxue Wang³, Zhansi Jiang⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 269-294, 2011, DOI:10.3970/cmes.2011.081.269

Abstract Damages occurred in a structure will lead to changes in modal parameters (natural frequencies and modal shapes). The relationship between modal parameters and damage parameters (locations and depths) is very complicated. Single detection method using natural frequencies or modal shapes can not obtain robust damage detection results from the inevitably noise-contaminated modal parameters. To eliminate the complexity, a hybrid approach using both of wavelets on the interval (interval wavelets) method and wavelet finite element model-based method is proposed to detect damage locations and depths. To avoid the boundary distortion phenomenon, Interval wavelets are employed to… More >

C.B. Du^1,2, S.Y Jiang², W. Qin³, Y.M. Zhang²

CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 229-248, 2011, DOI:10.3970/cmes.2011.081.229

Abstract A numerical analysis of concrete composites at the mesoscale based on three-dimensional (3D) reconstruction technology of X-ray computed tomography (CT) images is presented in this paper. For X-ray CT images of concrete, morphology processing was used to recover complete image information, including borders, and the median filtering method was applied to eliminate potential impurities in the images. The final X-ray CT images obtained after processing for a concrete section were composed of three-value pixels that indicated aggregate particles, mortar matrix and air voids, and the 3D structure of the concrete specimen was reconstructed using the More >

F.Z. Wang ^1,2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.80, No.3&4, pp. 201-218, 2011, DOI:10.3970/cmes.2011.080.201

Abstract In this paper, we consider the boundary particle method (BPM) which is excellent in solving inhomogeneous partial differential equations in terms of solution accuracy and simplicity. In order to investigate the applicability of the BPM, we examine the relationship between its solution accuracy and the effective condition number. We show that the effective condition number, which estimates system stability with the right-hand side vector taken into account, is inversely proportional to the root mean square error in the numerical approximation. Moreover, for noisy-boundary cases, we find that the BPM can not yield reasonable results, for More >

N. Mai-Duy¹, T. Tran-Cong¹, N. Phan-Thien²

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 223-236, 2011, DOI:10.3970/cmes.2011.079.223

Abstract This paper presents a new numerical technique for solving the evolution equations in molecular dynamics (MD). The variation of the MD system is represented by radial-basis-function (RBF) equations which are constructed using integrated multiquadric basis functions and point collocation. The proposed technique requires the evaluation of forces once per time step. Several examples are given to demonstrate the attractiveness of the present implementation. More >

A. Brancati¹, M. H. Aliabadi¹, A. Milazzo²

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.1, pp. 1-24, 2011, DOI:10.3970/cmes.2011.078.001

Abstract This paper presents an improved adaptive cross approximation (ACA) approach developed in conjunction with the Hierarchical format matrix and the GMRES solver. A novel scheme to generate the cluster tree (based upon preliminary considerations of the prescribed boundary conditions) and an improved ACA algorithm (approximating the system matrix for mixed Robin conditions) are described. The asymptotic smoothness property of a kernel generated by a linear combination of two asymptotic smooth kernels is demonstrated. Numerical results show the new approach to be up to 50% faster than the conventional ACA approach. More >

Yi W. Wan¹, Huan J. Keh²

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.2, pp. 109-138, 2011, DOI:10.3970/cmes.2011.074.109

Abstract The steady rotation of an axially symmetric particle about its axis of revolution normal to two plane walls at an arbitrary position between them in a viscous fluid is studied theoretically in the limit of small Reynolds number. The fluid is allowed to slip at the surface of the particle. A method of distribution of a set of spherical singularities along the axis of revolution inside a prolate particle or on the fundamental disk within an oblate particle is used to find the general solution for the fluid velocity distribution that satisfies the boundary conditions… More >

Jiawei Xiang^1,2, Ming Liang^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.3, pp. 267-298, 2011, DOI:10.3970/cmes.2011.073.267

Abstract The importance of damage detection in structures has been widely recognized in mechanical and civil engineering. A new method is proposed to detect multiple damages based on frequency measurement. According to linear fracture mechanics theory, the damages are modeled by rotational springs. The first problem of interest is concerned with the construction of multi-scaling wavelet finite element model using Hermite cubic spline wavelet on the interval (HCSWI) in the forward problem analysis to obtain damages detection database. The second problem is the inverse problem analysis to determine the number of damages, their locations and depths More >

A. Gakwaya¹, H. Sharifi², M. Guillot¹, M. Souli³, F. Erchiqui⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.3, pp. 209-266, 2011, DOI:10.3970/cmes.2011.073.209

Abstract A mechanical computer aided design and engineering system can be used to reduce the design-to-manufacture cycle time in metal forming process. Such a system could be built upon a solid modeling geometry engine and an efficient finite element (FE) solver. The maintenance of a high-quality mesh throughout the analysis is an essential feature of an efficient finite element simulation of large strain metal forming problems. In this paper, a mesh adaptation technique employing the Arbitrary Lagrangian-Eulerian formulation (ALE) is applied to some industrial metal forming problems. An ACIS boundary representation of the solid model is… More >

K. Wang¹, S.J. Zhou^2,3, Z.F. Nie⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.1, pp. 77-102, 2011, DOI:10.3970/cmes.2011.073.077

Abstract The natural neighbour Galerkin method is tailored to solve boundary value problems of the couple-stress elasticity to model the size dependent behaviour of materials. This method is based on the displacement-based Galerkin approach, and the calculation of the global stiffness matrix is performed using gradient smoothing technique combined with the non-Sibsonian partition of unity approximation scheme. This method possesses the following properties: the complex C1-continuous approximation scheme is avoided without using either Lagrange multipliers or penalty parameters; no domain integrals involved in the assembly of the global stiffness matrix; and the imposition of essential boundary More >

D.-A. An-Vo¹, N. Mai-Duy¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.4, pp. 299-336, 2011, DOI:10.3970/cmes.2011.072.299

Abstract This paper presents a new control-volume discretisation method, based on Cartesian grids and integrated-radial-basis-function elements (IRBFEs), for the solution of second-order elliptic problems in one and two dimensions. The governing equation is discretised by means of the control-volume formulation and the division of the problem domain into non-overlapping control volumes is based on a Cartesian grid. Salient features of the present method include (i) an element is defined by two adjacent nodes on a grid line, (ii) the IRBF approximations on each element are constructed using only two RBF centres (a smallest RBF set) associated… More >