G.V. Norton^*, J.C. Novarini^†

Molecular & Cellular Biomechanics, Vol.4, No.2, pp. 75-86, 2007, DOI:10.3970/mcb.2007.004.075

Abstract Ultrasonic imaging in medical applications involves propagation and scattering of acoustic waves within and by biological tissues that are intrinsically dispersive. Analytical approaches for modeling propagation and scattering in inhomogeneous media are difficult and often require extremely simplifying approximations in order to achieve a solution. To avoid such approximations, the direct numerical solution of the wave equation via the method of finite differences offers the most direct tool, which takes into account diffraction and refraction. It also allows for detailed modeling of the real anatomic structure and combination/layering of tissues. In all cases the correct inclusion of the dispersive properties… More >

X. Han^1,2,3, G. R. Liu^1,2, G. Y. Li ¹

CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 39-50, 2004, DOI:10.3970/cmc.2004.001.039

Abstract An efficient hybrid numerical method is presented for investigating transient response of cross-ply laminated axisymmetric cylinders subjected to an impact load. In this hybrid numerical method, the laminated cylinder is divided into layered cylindrical elements in the thickness direction. The Hamilton principle is used to develop governing equations of the structure. The displacement response is determined by employing the Fourier transformations and the modal analysis. Numerical examples for analyzing transient waves have been provided in axisymmetric laminated cylindrical structures, both for thin cylindrical shells and thick cylinders.
A computational inverse technique is also presented for reconstructing elastic constants of… More >

Chien-Ching Ma^1,2, Yi-Hsien Lin², Shih-Hao Lin²

CMC-Computers, Materials & Continua, Vol.31, No.1, pp. 37-64, 2012, DOI:10.3970/cmc.2012.031.037

Abstract In this article, the transient response in a functionally graded material (FGM) slab is analyzed by Laplace transform technique. The numerical Laplace inversion (Durbin's formula) is used to calculate the dynamic behavior of the FGM slab. The slab is subjected an uniform loading at the upper surface, and the lower surface are assumed to be traction-free or fixed conditions. The analytical solutions are presented in the transform domain and the numerical Laplace inversion is performed to obtain the transient response in time domain. To take the accuracy and computational efficiency in consideration, Durbin's method is suitable for calculating the long-time… More >

Y.J. Chen¹, N. Huber^1,2

CMC-Computers, Materials & Continua, Vol.29, No.1, pp. 1-14, 2012, DOI:10.3970/cmc.2012.029.001

Abstract Gear transmission is important in engineering due to its high efficiency in transferring both power and motion. As a surface phenomenon, wear may change the gear geometry, cause a non-uniform gear rate and increase dynamic effects, all of which can lead to reduced efficiency and even severe tooth failure. In numerical predictions of wear, the conventional method, where the contact pressure over the slip distance is integrated, will cause a computation bottle-neck. To obtain an accurate integration of the wear within the small, fast moving contact area, the finite element model needs to be meshed very finely, and the time… More >

De-Shin Liu¹, Zhen-Wei Zhuang¹, Shaw-Ruey Lyu^2,3, Cho-Liang Chung⁴, Pai-Chen Lin¹

CMC-Computers, Materials & Continua, Vol.26, No.2, pp. 111-136, 2011, DOI:10.3970/cmc.2011.026.111

Abstract This study proposes a two-dimensional heterogeneous hybrid moisture element method (HHMEM) for modeling transient moisture diffusion in permeable fiber-reinforced polymer composites.
The HHMEM scheme is based on a heterogeneous hybrid moisture element(HHME), with properties determined through an equivalent hybrid moisture capacitance/conductance matrix. This matrix was calculated using the conventional finite element formulation in space discretization as well as the θ-method in time discretization with similar mass/stiffness properties and matrix condensing operations. A coupled HHME-FE scheme was developed and implemented in computer code MATLAB in order to analyze the transient moisture diffusion characteristics of composite materials containing multiple permeable fibers. The… More >

Yonggang Duan¹, Ting Lu¹, Mingqiang Wei¹, Boming Yu², Zhelun Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.109-110, No.6, pp. 481-504, 2015, DOI:10.3970/cmes.2015.109.481

Abstract Analysis of Buckley-Leverett solution in fractal porous medium does prediction of water saturation profile a favor. On the approximation that porous medium consists of a bundle of tortuous capillaries, a physical conceptual Buckley- Leverett model of transient two-phase flow in fractal porous medium is developed based on the fractal characteristics of pore size distribution. The relationship between water saturation and distance is presented according to Buckley-Leverett solution, and the proposed Buckley-Leverett expression is the function of fractal structural parameters (such as pore fractal dimension, tortuosity fractal dimension, maximum and minimum diameters of capillaries) and fluid properties (such as viscosity, contact… More >

C.V. Nastos, T.C. Theodosiou, C.S. Rekatsinas, D.A. Saravanos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.5, pp. 379-409, 2015, DOI:10.3970/cmes.2015.107.379

Abstract A computationally efficient numerical method is developed for the prediction of transient response in orthotropic rod and beam structures. The method takes advantage of the outstanding properties of compactly supported Daubechies wavelet scaling functions for the spatial approximation of displacements in a finite domain of the structure, hence is termed Finite Wavelet Domain (FWD) method. The basic principles and advantages of the method are presented and the discretization of the equations of motion is formulated for one-dimensional structures. Numerical results for the simulation of propagating guided waves in rods and strips are presented and compared against traditional finite elements. More >

S. Masuri¹, K. K. Tamma²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 147-168, 2015, DOI:10.3970/cmes.2015.106.147

Abstract The objective in this paper is to extend the previously developed twoparameter GS4-1 (Generalized Single System Single Solve for 1st order transient systems) computational framework from parabolic to hyperbolic type of applications pertaining to first order linear transient systems. In particular, attention is paid to the selective control feature inherit in the framework, which is the new feature that enables different amounts of high frequency damping for the primary variable and its time derivative, allowing for physically accurate solutions of all variables in the system. This is in contrast to having only limited, often indiscriminate, control of the high frequency… More >

L. Godinho¹, D. Dias-da-Costa²

CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.5, pp. 293-316, 2013, DOI:10.3970/cmes.2013.096.293

Abstract Transient heat conduction problems can be dealt with using different numerical approaches. In some recent papers, a strategy to tackle these problems using a frequency domain formulation has been presented and successfully applied associated to methods such as the BEM. Here a formulation of the meshless local Petrov-Galerkin (MLPG) is developed and presented to allow the analysis of such problems. The proposed formulation makes use of the RBF-based version of the MLPG and employs the Heaviside step function as the test function, leading to the so-called MLPG(5). In addition, the method is associated with a visibility criterion to allow the… More >

D.S. Liu^1,2, Z.H. Fong¹, I.H. Lin¹, Z.W. Zhuang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.6, pp. 441-468, 2013, DOI:10.3970/cmes.2013.093.441

Abstract In this study, we proposed a novel numerical technique to simulate the transient moisture diffusion process and to apply it to heterogeneous composite resins. The method is based on a heterogeneous hybrid moisture element (HHME), with properties determined through an equivalent hybrid moisture capacitance/ conductance matrix that was calculated using the conventional finite element formulation in space discretization and the q-method in time discretization, with similar mass/stiffness properties and matrix condensing operations. A coupled HHME with finite element scheme was developed and implemented in the computer code by using the commercial software MATLAB to analyze the transient moisture diffusion process… More >