J. Sladek¹, V. Sladek¹, P. Solek²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.1, pp. 35-36, 2009, DOI:10.3970/icces.2009.012.035

Abstract Functionally graded materials are multi-phase materials with the phase volume fractions varying gradually in space, in a pre-determined profile. This results in continuously graded mechanical properties at the (macroscopic) structural scale. Often, these spatial gradients in material behaviour render FGMs as superior to conventional composites. FGMs possess some advantages over conventional composites because of their continuously graded structures and properties. Due to the high mathematical complexity of the initial-boundary value problems, analytical approaches for elastic analyses of FGMs are restricted to simple geometries and boundary conditions. The elastic analysis in FGM demands an accurate and efficient numerical method.
In spite… More >

S. S. Chen¹, Y. H. Liu^1,2, Z. Z. Cen¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.3, pp. 63-64, 2009, DOI:10.3970/icces.2009.011.063

Abstract In most engineering applications, solutions derived from the lower-bound theorem of plastic limit analysis are particularly valuable because they provide a safe estimate of the load that will cause plastic collapse. A solution procedure based on the meshless local Petrov-Galerkin (MLPG) method is proposed for lower-bound limit analysis. This is the first work for lower-bound limit analysis by this meshless local weak form method. In the construction of trial functions, the natural neighbour interpolation (NNI) is employed to simplify the treatment of the essential boundary conditions. The discretized limit analysis problem is solved numerically with the reduced-basis technique. The self-equilibrium… More >

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.2, pp. 101-106, 2008, DOI:10.3970/icces.2008.007.101

Abstract A nonliear meshless local Petrov-Galerkin (NMLPG) method for solving nonlinear boundary value problems, based on the nonlinear regular local boundary integral equation (NRLBIE) and the moving least squares approximation, is proposed in the present paper. No special integration scheme is needed to evaluate the volume and boundary integrals. The integrals in the present method are evaluated only over regularly-shaped sub-domains and their boundaries. This flexibility in choosing the size and the shape of the local sub-domain will lead to a more convenient formulation in dealing with the nonlinear problems. Compared to the original meshless local Petrov-Galerkin (MLPG) method that has… More >

K. Y. Liu^1,2, S. Y. Long^1,2,3, G. Y. Li¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.5, No.2, pp. 99-120, 2008, DOI:10.3970/icces.2008.005.099

Abstract A meshless local Petrov-Galerkin method (MLPG)^[1] for the analysis of cracks in isotropic functionally graded materials is presented. The meshless method uses the moving least squares (MLS) to approximate the field unknowns. The shape function has not the Kronecker Delta properties for the trial-function-interpolation, and a direct interpolation method is adopted to impose essential boundary conditions. The MLPG method does not involve any domain and singular integrals to generate the global effective stiffness matrix if body force is ignored; it only involves a regular boundary integral. The material properties are smooth functions of spatial coordinates and two interaction integrals^[2,3] are… More >

Zhenhan Yao¹,Zhangfei Zhang¹, Xi Zhang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.3, pp. 133-138, 2007, DOI:10.3970/icces.2007.003.133

Abstract The Meshless Local Petrov-Galerkin (MLPG) Method is applied to solve large deformation problems of elasto-plastic materials. In order to avoid re-computation of the shape functions, the supports of MLS approximation functions cover the same sets of nodes during the deformation; fundamental variables are represented in spatial configuration, while the numerical quadrature is conducted in the material configuration; the derivation of shape function to spatial coordinate is pushed back to material coordinate by tensor transformation. For simulating both large strain and large rotation, the multiplicative hyperelasto-plastic constitutive model is adopted for path-dependent material. Numerical results indicate that the MLPG method can… More >

J. Sladek¹, V. Sladek¹, Ch. Zhang², C.L. Tan³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.2, pp. 87-92, 2007, DOI:10.3970/icces.2007.003.087

Abstract In this paper, the Meshless Local Petrov-Galerkin (MLPG) method for two-dimensional (2-d), linear and transient coupled thermoelastic analysis in orthotropic solids is presented. To eliminate the time-dependence in the governing equations, the Laplace-transform technique is used. Local integral equations are derived for small circular sub-domains which surround nodal points distributed over the analyzed domain. As for the spatial variations of the displacements and temperature, they are approximated by the Moving Least-Squares (MLS) scheme. More >

R. Schaback¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.2, pp. 81-86, 2007, DOI:10.3970/icces.2007.003.081

Abstract This is a short summary of recent mathematical results on error bounds and convergence of certain unsymmetric methods, including variations of Kansa's collocation technique and Atluri's MLPG method. The presentation is kept as simple as possible in order to address a larger community working on applications in Science and Engineering. More >

S. N. Atluri¹, Shengping Shen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.3, pp. 241-268, 2005, DOI:10.3970/cmes.2005.007.241

Abstract Various MLPG methods, with the MLS approximation for the trial function, in the solution of a 4$^{th}$ order ordinary differential equation are illustrated. Both the primal MLPG methods and the mixed MLPG methods are used. All the possible local weak forms for a 4$^{th}$ order ordinary differential equation are presented. In the first kind of mixed MLPG methods, both the displacement and its second derivative are interpolated independently through the MLS interpolation scheme. In the second kind of mixed MLPG methods, the displacement, its first derivative, second derivative and third derivative are interpolated independently through the MLS interpolation scheme. The… More >

Shengping Shen¹, S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 49-68, 2005, DOI:10.3970/cmes.2005.007.049

Abstract The main objective of this paper is to develop a multiscale method for the static analysis of a nano-system, based on a combination of molecular mechanics and MLPG methods. The tangent-stiffness formulations are given for this multiscale method, as well as a pure molecular mechanics method. This method is also shown to naturally link the continuum local balance equation with molecular mechanics, directly, based on the stress or force. Numerical results show that this multiscale method quite accurate. The tangent-stiffness MLPG method is very effective and stable in multiscale simulations. This multiscale method dramatically reduces the computational cost, but it… More >

E. J. Sellountos¹, V. Vavourakis², D. Polyzos³

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 35-48, 2005, DOI:10.3970/cmes.2005.007.035

Abstract A new meshless local Petrov-Galerkin (MLPG) type method based on local boundary integral equation (LBIE) considerations is proposed for the solution of elastostatic problems. It is called singular/hypersingular MLPG (LBIE) method since the representation of the displacement field at the internal points of the considered structure is accomplished with the aid of the displacement local boundary integral equation, while for the boundary nodes both the displacement and the corresponding traction local boundary integral equations are employed. Nodal points spread over the analyzed domain are considered and the moving least squares (MLS) interpolation scheme for the approximation of the interior and… More >