Annamaria Mazzia¹, Giorgio Pini¹, Flavio Sartoretto²

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.4, pp. 239-262, 2015, DOI:10.3970/cmes.2015.108.239

Abstract Meshless Local Petrov Galerkin (MLPG) methods are pure meshless techniques for solving Partial Differential Equations (PDE). MLPG techniques are nowadays used for solving a huge number of complex, real–life problems. While MLPG aims to approximate the solution of a given differential problem, its “dual” Direct MLPG (DMLPG) technique relies upon approximating linear functionals. Assume adaptive methods are to be implemented. When using a mesh–based method, inserting and/or deleting a node implies complex adjustment of connections. Meshless methods are more apt to implement adaptivity, since they does not require such adjustments. Nevertheless, ad–hoc insertion and/or deletion… More >

X.S. He¹, Q.X. Liu¹, X.C. Huang², Y.M. Chen^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.3, pp. 159-169, 2015, DOI:10.3970/cmes.2015.108.159

Abstract This paper presented dynamic response analysis for an MEMS viscometer. The responses are governed by a set of differential equations containing fractional derivatives. The memory-free Yuan-Agrawal’s approach was extended to solve fractional differential equations containing arbitrary fractional order derivative and then a simple yet efficient numerical scheme was constructed. Numerical examples show that the proposed method can provide very accurate results and computational efforts can be significantly saved. Moreover, the numerical scheme was extended to solve problems with a nonlinear spring. The influences of the nonlinear parameters on the dynamic responses were also efficiently analyzed. More >

Mohammad Hossein Ghadiri Rad¹, Farzad Shahabian^1,2, Seyed Mahmoud Hosseini³

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.3, pp. 135-157, 2015, DOI:10.3970/cmes.2015.108.135

Abstract A meshless method based on the local Petrov-Galerkin approach is developed for elasto-dynamic analysis of geometrically nonlinear two dimensional (2D) problems in hyper-elastic functionally graded materials. The radial point interpolation method (RPIM) is utilized to build the shape functions and the Heaviside step function is used as the test function. The mechanical properties of functionally graded material are considered to continuously vary in a certain direction and are simulated using a nonlinear power function in volume fraction form. Considering the large deformations, it is assumed that the domain be made of large deformable neo-Hookean hyperelastic… More >

Surkay D. Akbarov^1,2,3, Panakh G. Panakhlı⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.2, pp. 89-112, 2015, DOI:10.3970/cmes.2015.108.089

Abstract The discrete-analytical solution method is proposed for the solution to problems related to the dynamics of the hydro-elastic system consisting of an axially-moving pre-stressed plate, compressible viscous fluid and rigid wall. The fluid flow caused by the axial movement of the plate and the pre-stresses in the plate are taken into consideration as the initial state of the system under consideration. It is assumed that the additional lineally-located time-harmonic forces act on the plate and these forces cause additional flow field in the fluid and an additional stress-strain state in the plate. The additional stress-strain… More >

I. Kvasnica¹, P. Kvasnica²

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.6, pp. 447-462, 2015, DOI:10.3970/cmes.2015.107.447

Abstract The issue of simulation of decentralized mathematical models is discussed in the paper. The authors’ knowledge is based on a theory of design of decentralized computer control systems. Their knowledge is gained in the process of designing mathematical models that are simulated. A decomposed control system is required to meet the conditions of observation and control. The methodology of a multi-model design is based on main principles of object orientation such as abstraction, hierarchy, and modularity. Modelling on a parallel architecture has an impact on a simulator system. The system is defined by the equations More >

Xiaojing Liu^1,2, Jizeng Wang¹, Youhe Zhou¹

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.6, pp. 433-446, 2015, DOI:10.3970/cmes.2015.107.433

Abstract Based on the approximation scheme for a L²-function defined on a three-dimensional bounded space by combining techniques of boundary extension and Coiflet-type wavelet expansion, a modified wavelet Galerkin method is proposed for solving three-dimensional Poisson problems with various boundary conditions. Such a wavelet-based solution procedure has been justified by solving five test examples. Numerical results demonstrate that the present wavelet method has an excellent numerical accuracy, a fast convergence rate, and a very good capability in handling complex boundary conditions. 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 >

Marcin Kamiński², Jacek Szafran³

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.1, pp. 27-57, 2015, DOI:10.3970/cmes.2015.107.027

Abstract Basic probabilistic characteristics and reliability indices of critical forces for high steel skeletal towers are numerically modeled by using the Stochastic, perturbation-based Finite Element Method. It is implemented together with the Weighted Least Squares Method and compared with the Monte-Carlo simulation as well as with the semi-analytical Probabilistic FEM. The Finite Element Method solution to the stability problem for a full 3D model of a tower accounts for both first and second order effects known from the engineering codes as the so-called P-delta effect. Two different Gaussian input random variables are adopted here – Young More >

Jan Sladek¹, Vladimir Sladek¹, Peter Stanak¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.4, pp. 229-262, 2015, DOI:10.3970/cmes.2015.106.229

Abstract The scaled boundary finite element method (SBFEM) is presented to study thermoelastic problems in materials with voids. The SBFEM combines the main advantages of the finite element method (FEM) and the boundary element method (BEM). In this method, only the boundary is discretized with elements leading to a reduction of spatial dimension by one. It reduces computational efforts in mesh generation and CPU. In contrast to the BEM, no fundamental solution is required, which permits to analyze general boundary value problems, where the conventional BEM cannot be applied due to missing fundamental solution. The computational More >

K. Kuramoto¹, M. Furuichi², K. Kakuda²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 169-186, 2015, DOI:10.3970/cmes.2015.106.169

Abstract This paper describes a scheme to improve efficiency of multi-agent simulation system (MAS) on single computer that has multiple processor cores. Simulation technology is applied for broad usage in the world, and MAS gathers attention from the fields that treat complicated and non-numeric issues such as traffic analysis, analyzing evacuation from a building, and defense training. Since the requirements of simulation scale and fidelity are growing, the importance of their performance is also increasing. However, CPU clock speedup is slowing, and improvement of computer performance has come to depend on the number of processors, cores,… More >