Shueei-Muh Lin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.1, pp. 73-90, 2009, DOI:10.3970/cmes.2009.043.073

Abstract In this study, the mathematical model of a moving beam is established. This model is composed of a governing differential equation and three homogenous boundary conditions and one non-homogenous boundary condition including a time-dependent inertia force and a nonlinear active control force. Obviously, a moving mass problem with nonlinear and time dependent boundary condition is very complicated. One solution method is here developed to derive the exact solution for this system. By taking a change of dependent variable with a shifting function the original system is transformed to be a system composed of one non-homogeneous governing differential equation and four… More >

E. Majchrzak¹, B. Mochnacki², A. L. Greer³, J. S. Suchy⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.41, No.2, pp. 131-146, 2009, DOI:10.3970/cmes.2009.041.131

Abstract Multi-layered thin metal film subjected to a short-pulse laser heating is considered. Mathematical description of the process discussed bases on the equation in which there appear the relaxation time and the thermalization time (dual-phase-lag-model). In this study we develop a three level implicit finite difference scheme for numerical modelling of heat transfer in non-homogeneous metal film. At the interfaces an ideal contact between successive layers is assumed. At the stage of computations a solution of only one three-diagonal linear system corresponds to transition from time t to t + Δt. The mathematical model, numerical algorithm and examples of computations are… More >

I-L. Chang¹, M.-S. Yeh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.41, No.2, pp. 95-106, 2009, DOI:10.3970/cmes.2009.041.095

Abstract One-dimensional copper nanospring with elliptic cross section was studied using molecular statics method based on minimum energy consideration. Various geometric sizes (wire semi-axis length, radius, pitch) and crystal orientations of nanosprings were systematically modeled to investigate the size dependence of elastic properties for both normal and binormal nanosprings. It was observed that as the wire semi-axis increases, and the radius and pitch decrease, the nanospring stiffness would increase irrespective to the crystal orientations. Moreover, it was noticed that the normal nanosprings always behave stiffer than the binormal ones for the same radius, pitch and cross-sectional geometry in our study. More >

Cha’o-Kuang Chen^1,2, Hsin-Yi Lai¹, Chin-Chia Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.40, No.2, pp. 155-174, 2009, DOI:10.3970/cmes.2009.040.155

Abstract Electrostatically-actuated micro circular plates are used in many micro-electro-mechanical systems (MEMS) devices nowadays such as micro pumps and optical switches. However, the dynamic behavior of these circular plates is not easily analyzed using traditional analytic methods due to the complexity of the interactions between the electrostatic coupling effects. Accordingly, this study develops an efficient computational scheme in which the nonlinear governing equation of the coupled electrostatic force acting on the micro circular plate is solved using a hybrid differential transformation / finite difference approximation method. In deriving the dynamic equation of motion of the micro plate, explicit account is taken… More >

H.K. Mebatsion^1,2, P. Verboven¹, P. T. Jancsók¹, Q.T. Ho¹, B.E. Verlinden³, B.M. Nicolaï^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.3, pp. 137-150, 2008, DOI:10.3970/cmes.2008.029.137

Abstract Transport processes of gas and moisture are among the most important physiological processes in plant tissue. Microscale transport models based on Navier-Stokes equations provide insight into such processes at the microscopic scale. Due to microscopic complexity, numerical solutions based on the finite element or finite volume methods are mandatory. Therefore, a 3D geometric model of the tissue is essential. In this article, a novel algorithm for geometric reconstruction of 2D slices of synchrotron tomographic images is presented. The boundaries of 2D cells on individual slices were digitized to establish a set of boundary coordinates and the slice index of individual… More >

Yongjie Zhang¹, Boyle C. Cheng², Changho Oh¹, Jessica L. Spehar², James Burgess³

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.2, pp. 55-62, 2008, DOI:10.3970/cmes.2008.029.055

Abstract The spinal column plays a vital biomechanical role in the human body by providing structural support and facilitating motion. As degenerative changes occur in the spine, surgical treatment may be necessary in certain instances. Such treatments seek to address pain, frequently through the restriction of spinal motion. Traditional spinal implant devices are designed to restrict the motion of a functional spinal unit (FSU) but newer device designs allow for semi-constrained motion such as spinal arthroplasty devices. In this study, a sequence of fluoroscopic imaging data was recorded during the flexibility protocol with an interspinous process spacer device placed at L2-L3.… More >

N.Kringos¹, A.Scarpas¹, A.P.S. Selvadurai²

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 147-160, 2008, DOI:10.3970/cmes.2008.028.147

Abstract This paper presents a numerical approach for the modeling of water flow induced mastic erosion from a permeable asphalt mix and is part of an ongoing effort to model moisture-induced damage in asphalt mixes. Due to the complex composite structure of asphalt mixtures, moisture can infiltrate in various ways into the components and have an adverse effect on its mechanical performance. Depending on the gradation of the asphalt aggregates and the mixing procedure, asphalt structures with a variable permeability may result. Open-graded asphalt mixes are designed with a high interconnected air void content to serve as a drainage layer on… More >

Chun Yang¹, Dalin Tang², Chun Yuan³, William Kerwin², Fei Liu³, Gador Canton³, Thomas S. Hatsukami^3,4, Satya Atluri⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.2, pp. 95-108, 2008, DOI:10.3970/cmes.2008.028.095

Abstract Atherosclerotic plaque rupture and progression have been the focus of intensive investigations in recent years. Plaque rupture is closely related to most severe cardiovascular syndromes such as heart attack and stroke. A computational procedure based on meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Participating patients were scanned three times (T₁,T₂, and T₃, at intervals of about 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes were used as the measure for plaque progression. Since there was insufficient… More >

B. Yang^1,2, S.-C. Wong³, S. Qu³

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 81-94, 2008, DOI:10.3970/cmes.2008.024.081

Abstract In the modeling of overall property of composites, the effect of particle interaction has been either numerically taken into account within a (representative) volume element of a small number of particles or neglected/ignored in order for efficient solution to a large system of particles. In this study, we apply the point-defect Green's function (GF) to take into account the effect of particle interaction. It is applicable to small volume fractions of particles (within 10 %). The high efficiency of the method enables a simulation of a large system of particles with generally elastic anisotropy, arbitrary shape and composition, and arbitrary… More >

Chany Lee¹, Chang-Hwan Im², Hyun-Kyo Jung³, Hong-Kyu Kim⁴, Do Wan Kim⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.20, No.1, pp. 35-42, 2007, DOI:10.3970/cmes.2007.020.035

Abstract In the present study, a residual-based a posteriori error estimation for a kind of meshless method, called fast moving least square reproducing kernel (FMLSRK) method is proposed. The proposed error estimation technique does not require any integration cells in evaluating error norm but recovers the exact solutions in a virtual area defined by a dilation parameter of FMLSRK and node density. The proposed technique was tested on typical electrostatic problems with gird or random node sets and the simulation results show that the proposed error estimation technique can be applied to adaptive node refinement process for more efficient meshless analysis… More >