Chun-Ying Wu^1,3, Xue-Yan Liu², A. Scarpas², Xiu-Run Ge³

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.2, pp. 149-158, 2006, DOI:10.3970/cmes.2006.012.149

Abstract For the spectral analysis of the three-dimensional multi-layered pavement, 3D layer spectral element method is presented to solve the problems of bounded layer system subjected to a transient load pulse. In spectral element, each layer is treated as one spectral element. The wave propagation inside each layer element is achieved by the superposition of the incident wave and the reflection wave. Fast Fourier transformation is used to transform FWD datum from time domain to frequency domain. The accuracy and efficiency of 3D layer spectral element approach were verified by analyzing the Falling weight deflectometer(FWD) testing More >

R. Ahrem¹, A. Beckert², H. Wendland³

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.2, pp. 121-136, 2006, DOI:10.3970/cmes.2006.012.121

Abstract We present a new efficient scheme for loose coupling in fluid-structure-interaction problems as they typically appear in the context of aircraft design. This coupling scheme is based upon a multivariate scattered data interpolation approach, based on radial basis functions and partition of unity methods. It allows us to couple arbitrary meshes on fluid and structure side. It conserves virtual work and forces. It is designed for large scale problems and allows the coupling of entire aircraft meshes. More >

Jeng-Tzong Chen¹, Wen-Cheng Shen², Po-Yuan Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.2, pp. 109-119, 2006, DOI:10.3970/cmes.2006.012.109

Abstract In this paper, we derive the null-field integral equation for a circular bar weakened by circular cavities with arbitrary radii and positions under torque. To fully capture the circular geometries, separate forms of fundamental solution in the polar coordinate and Fourier series for boundary densities are adopted. The solution is formulated in a manner of a semi-analytical form since error purely attributes to the truncation of Fourier series. Torsion problems are revisited to demonstrate the validity of our method. Torsional rigidities for different number of holes are also discussed. More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.2, pp. 83-108, 2006, DOI:10.3970/cmes.2006.012.083

Abstract The system we consider consists of two parts: a purely algebraic system describing the manifold of constraints and a differential part describing the dynamics on this manifold. For the constrained dynamical problem in its engineering application, it is utmost important to developing numerical methods that can preserve the constraints. We embed the nonlinear dynamical system with dimensions n and with k constraints into a mathematically equivalent n + k-dimensional nonlinear system, which including k integrating factors. Each subsystem of the k independent sets constitutes a Lie type system of X^˙_i = A_iX_i with A_i ∈ so(n_i,1) and n₁ +···+n_k = n.… More >

C.-S. Liu¹, C.-W. Chang², J.-R. Chang²

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.1, pp. 67-82, 2006, DOI:10.3970/cmes.2006.012.067

Abstract In this paper we are concerned with the backward problems governed by differential equations. It is a first time that we can construct a backward time dynamics on the past cone, such that an augmented dynamical system of the Lie type X^˙ = B(X,t)X with t ∈ R⁻, X ∈ Mⁿ⁺¹ lying on the past cone and B ∈ so(n,1), was derived for the backward differential equations system x^· =f(x,t), t ∈ R⁻, x ∈ Rⁿ. These two differential equations systems are mathematically equivalent. Then we apply the backward group preserving scheme (BGPS), which is an explicit single-step algorithm… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.1, pp. 55-66, 2006, DOI:10.3970/cmes.2006.012.055

Abstract In this paper we are concerned with the numerical integration of Burgers equation backward in time. We construct a one-step backward group preserving scheme (BGPS) for the semi-discretization of Burgers equation. The one-step BGPS is very effectively to calculate the solution at an initial time t = 0 from a given final data at t = T, which with a time stepsize equal to T and with a suitable grid length produces a highly accurate solution never seen before. Under noisy final data the BGPS is also robust to against the disturbance. When the solution appears steep gradient, More >

A. P. S. Selvadurai¹, Wenjun Dong

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.1, pp. 41-54, 2006, DOI:10.3970/cmes.2006.012.041

Abstract A Fourier analysis conducted on both the spatial and the temporal discretizations of the governing partial differential equation shows that the Courant number as well as the time marching scheme have significant influences on the numerical behaviour of a Modified Least Squares (MLS) method for the solution of the advection equation. The variations of the amplification factor and the relative phase velocity with the Courant number and the dimensionless wave number indicate that when Courant number is equal to unity, the MLS method with the specified time-weighting and upwind function gives accurate results. This conclusion… More >

H. Kawai¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.3, pp. 111-120, 2006, DOI:10.3970/cmes.2006.011.111

Abstract ADVENTURE AutoGL (pronounced as ‘Ote- ga-lu’) is a graphics and GUI library, dedicated for simulation-based research and development. It is designed for the simulation users to develop their own data viewers and editors. Currently, the library is used among many researchers and simulation users, mainly in universities and national research centers. Its functionalities and supported platforms are explained. AutoGL applications of various kinds of simulation methods are demonstrated also. More >

G.P. Nikishkov¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 81-90, 2006, DOI:10.3970/cmes.2006.011.081

Abstract This paper presents the object oriented approach to programming the finite element method using the Java language. The developed finite element code consists of ten Java packages. Three main methods are related to generation of finite element models, solution of elastic and elastic-plastic boundary value problems, and visualization of models and solution results. Object-oriented model of the code is described. It is demonstrated that Java 1.5 new features are useful in development of the finite element code. Java 3D is used for visualization of models and results. More >

M. Perl¹, C. Levy ², V. Rallabhandy ²

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 37-48, 2006, DOI:10.3970/cmes.2006.011.037

Abstract The Bauschinger Effect (BE) impact on K_IN– the combined, Mode I, 3-D Stress Intensity Factor (SIF) distributions for arrays of radial, internal, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. A in-depth comparison between the combined SIFs for a “realistic” - Bauschinger Effect Dependent Autofrettage (BEDA) and those for an “ideal” - Bauschinger Effect Independent Autofrettage (BEIA) is performed. The 3- D finite element (FE) analysis is performed employing the submodeling technique and singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are… More >