E. Tonti¹, F. Zarantonello¹

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.3, pp. 201-236, 2009, DOI:10.3970/cmes.2009.039.201

Abstract The theory of elasticity is usually formulated using differential calculus. We will show that it is possible to give an algebraic or discrete or finite formulation, by starting directly from experimental laws, i.e. by avoiding any discretization process of the differential equations. This direct formulation can be immediately used for numerical solution in elasticity problems and, from a theoretical point of view, it shows some interesting features which are hidden in the differential formulation or are not considered at all. More >

Chun-Lang Yeh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.2, pp. 179-200, 2009, DOI:10.3970/cmes.2009.039.179

Abstract In this research, the atomization process of a nanojet is investigated by molecular dynamics simulation. Liquid argon nanojet made of 44000 Lennard-Jones molecules is examined under various simulation parameters to study their influence on the nanojet atomization process. Snapshots of the molecules, evolution of the density field, and evolution of the intermolecular force are analyzed. The present simulation results can provide insight into the fundamental mechanism of the atomization process and will be helpful for the design of nanojet devices such as nano-printer or nano-sprayer. More >

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

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.2, pp. 155-178, 2009, DOI:10.3970/cmes.2009.039.155

Abstract The axisymmetric longitudinal wave propagation in a finite pre-strained compound (composite) cylinder is investigated within the scope of a piecewise homogeneous body model utilizing three-dimensional linearized theory wave propagation in an initially stressed body. The materials of the inner and outer cylinder are assumed to be compressible. The elasticity relations for those are given through the harmonic potential. The algorithm for constructing of the computer programmes and obtaining numerical results is discussed. The numerical results regarding the influences of the initial strains in the inner and outer cylinders on the wave dispersion are presented and More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.2, pp. 125-154, 2009, DOI:10.3970/cmes.2009.039.125

Abstract We propose a new numerical method for solving the boundary value problems of ordinary differential equations (ODEs) under multipoint boundary conditions specified at t = T_i, i = 1,...,m, where T₁ < ... < T_m. The finite difference scheme is used to approximate the ODEs, which together with the m-point boundary conditions constitute a system of nonlinear algebraic equations (NAEs). Then a Fictitious Time Integration Method (FTIM) is used to solve these NAEs. Numerical examples confirm that the new approach is highly accurate and efficient with a fast convergence. The FTIM can also be used to find More >

Shang Ma¹, Xiong Zhang^1,2, Yanping Lian¹, Xu Zhou³

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.2, pp. 101-124, 2009, DOI:10.3970/cmes.2009.039.101

Abstract Numerical simulation of high explosive explosion problems is a big challenge to traditional numerical methods because explosion usually involves extremely large deformation and multi-material interaction of different phases. Recently developed meshfree methods show much advantages over mesh-based method for problems associated with very large deformation. Some of them have been successfully applied to impact and explosion problems, such as smoothed particle hydrodynamics (SPH). Similar to SPH, material point method (MPM) is an efficient meshfree particle method solving continuum problems. With combination of the advantages of Eulerian and Lagrangian methods, MPM is a promising numerical tool… More >

Raju Sethuraman¹, N.R.Rajesh²

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.1, pp. 67-100, 2009, DOI:10.3970/cmes.2009.039.067

Abstract This paper presents a methodology based on Partition of Unity Finite Element Method (PUFEM) and Pseudo Elastic Analysis for solving material non-linear fracture problems within the scope of total deformation theory of plasticity. Local enrichment base functions are used to represent the asymptotic field near the crack tip and discontinuous field across the crack faces. An iterative linear elastic analysis using PUFEM is carried out for the determination of elastic-plastic crack tip stress fields by treating effective material properties as spatial field variables. The effective material parameters are defined using deformation theory and are updated… More >

Fuping Zhou¹, Suresh G. Advani², Eric D. Wetzel³

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.1, pp. 49-66, 2009, DOI:10.3970/cmes.2009.039.049

Abstract Slow drag of a cylinder through a confined, pressurized bed of granules is studied using two-dimensional discrete element method (DEM) simulations. The time-dependent total drag force experienced by the circular cylinder is calculated from the normal and tangential contact forces between the surfaces. To evaluate the role of the granule shape and the aspect ratio on the drag force, the simulation is performed for cylindrical granules, dumbbell-shaped granules, and elliptical granules of three different aspect ratios. Simulation results show that the drag in dumbbell-shaped granules is higher than that in cylindrical granules. In contrast, the More >

D. S. Liu¹, C.Y. Tsai¹

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.1, pp. 29-48, 2009, DOI:10.3970/cmes.2009.039.029

Abstract Utilizing a thin copper substrate for illustration purposes, this study presents a novel numerical method for extracting the thermo-mechanical properties of a thin-film. In the proposed approach, molecular dynamics (MD) simulations are performed to establish the load-displacement response of a thin copper substrate nanoindented at temperatures ranging from 300~1400 K. The load data are then input to an artificial neural network (ANN), trained using a finite element model (FEM), in order to extract the material constants of the copper substrate. The material constants are then used to construct the corresponding stress-strain curve, from which the… More >

F. Daghia¹, W. Hasan¹, L. Nobile¹, E. Viola^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.1, pp. 1-28, 2009, DOI:10.3970/cmes.2009.039.001

Abstract In this paper, a finite element model has been developed for analysing the flexural vibrations of a uniform Timoshenko beam-column on a two-parameter elastic foundation. The beam was discretized into a number of finite elements having four degrees of freedom each. The effect of end springs was incorporated in order to identify the end constraints. \newline The procedure for identifying geometric and mechanical parameters as well as the end restraints of a beam on two-parameter elastic foundation is based on experimentally measured natural frequencies from dynamic tests on the structure itself. \newline An iterative statistical More >

R. Prosser¹

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 411-424, 2009, DOI:10.3970/fdmp.2009.005.411

Abstract A novel wavelet-based method for the simulation of reacting flows on adaptive meshes is presented. The method is based on a subtraction algorithm, wherein the wavelet coefficients are calculated from the low resolution up (as opposed to the standard top-down approach). The advantage of this new method is that it allows the calculation of wavelet coefficients on sparse grids, and thus lends itself more readily to adaptive computational meshes than does the traditional wavelet algorithm. The approach is used to simulate a one-dimensional laminar pre-mixed flame with different Lewis numbers. The computational grid is adapted More >