Xiaomin An¹, Min Xu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.6, pp. 601-629, 2014, DOI:10.3970/cmes.2014.098.601

Abstract Nonlinear aeroelasticity, caused by the interaction between nonlinear fluid and geometrically nonlinear structure, is studied by an improved CFD and CSD coupled program. An AUSMpw+ flux splitting scheme, combined with an implicit time marching technology and geometric conservation law, is utilized to solve unsteady aerodynamic pressure; The finite element co-rotational theory is applied to model geometrically nonlinear two-dimensional and three-dimensional panels, and a predictor-corrector program with an approximately energy conservation is developed to obtain nonlinear structure response. The two solvers are connected by Farhat’s second order loosely coupled method and the aerodynamic loads and structural displacements are transferred by boundary… More >

X. X. Cui¹, X. Zhang^1,2, X. Zhou³, Y. Liu¹, F. Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.6, pp. 565-599, 2014, DOI:10.3970/cmes.2014.098.565

Abstract The material point method (MPM) discretizes the material domain by a set of particles, and has showed advantages over the mesh-based methods for many challenging problems associated with large deformation. However, at the same time, it requires more computational resource and has difficulties to construct high order scheme when simulating the fluid in high explosive (HE) explosion problems. A coupled finite difference material point (CFDMP) method is proposed through a bridge region to combine the advantages of the finite difference method (FDM) and MPM. It solves a 3D HE explosion and its interaction with the surrounding structures by dividing the… More >

T.A. Elgohary¹, L. Dong², J.L. Junkins³, S.N. Atluri⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.6, pp. 543-563, 2014, DOI:10.3970/cmes.2014.098.543

Abstract In this study, the Scalar Homotopy Methods are applied to the solution of post-buckling and limit load problems of solids and structures, as exemplified by simple plane elastic frames, considering only geometrical nonlinearities. Explicitly derived tangent stiffness matrices and nodal forces of large-deformation planar beam elements, with two translational and one rotational degrees of freedom at each node, are adopted following the work of [Kondoh and Atluri (1986)]. By using the Scalar Homotopy Methods, the displacements of the equilibrium state are iteratively solved for, without inverting the Jacobian (tangent stiffness) matrix. It is well-known that, the simple Newton’s method (and… More >

Cheng-Yu Ku ^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.5, pp. 509-541, 2014, DOI:10.3970/cmes.2014.098.509

Abstract This paper proposes the numerical solution of three-dimensional Laplacian problems in a multiply connected domain using the collocation Trefftz method with multiple source points. A numerical solution for three-dimensional Laplacian problems was approximated by superpositioning T-complete functions formulated from 36 independent functions satisfying the governing equation in the cylindrical coordinate system. To deal with complicated problems for multiply connected domain, we adopted the generalized multiple source point boundary collocation Trefftz method which allows many source points in the Trefftz formulation without using the decomposition of the problem domain. In addition, to mitigate a severely ill-conditioned system of linear equations, this… More >

Guangyao Li¹, Shuaiping Guo¹, Jianming Zhang^1,2, Baiping Fei¹, Yuan Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.5, pp. 487-508, 2014, DOI:10.3970/cmes.2014.098.487

Abstract In this paper, we will propose a new concept, namely the Complete Solid Buckling Analysis, in which the deformation assumptions for rods, beams and plates are all discarded, and the entire structure, including all its local smallsized features, is modeled as a three-dimensional (3D) solid according to its real shape and dimensions. Firstly, we derive a new control equation, in which physical variables in three directions are considered. Then, an equivalent Boundary Integral Equation (BIE) is derived from the control equation. In the numerical implementation, the Boundary Face Method is employed, by which analyses can be performed directly on the… More >

M. Toujani¹, R. Djebali², L. Hassini¹, S. Azzouz¹, A. Belghith¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.5, pp. 469-485, 2014, DOI:10.3970/cmes.2014.098.469

Abstract In the present work we aim to simulate unsteady two-dimensional evolution of the moisture content, temperature and mechanical stress in a parallelepiped apple sample during convective drying. The model is based on the heat and mass transfer equations and the mechanical equilibrium equation under the assumptions of plane deformation, viscoelasticity and isotropic hydric shrinkage. The Finite Elements COMSOL Multiphysics solver is used to solve the developed model. The hydro-thermal model was validated on experimental data drawn in our laboratory for moisture and temperature internal profiles of the product. Excellent agreement has been obtained between numerical and measured data for different… More >

C. Jiang^1,2, S. Yu¹, H.C. Xie¹, B.C. Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.4, pp. 443-467, 2014, DOI:10.3970/cmes.2014.098.443

Abstract Based on the interval analysis method, this paper proposes an uncertain optimization model for the ride comfort in vehicles and achieves the optimal design of vehicle ride comfort under the condition of complicated uncertainty. The spring stiffness and shock absorber damping of suspension is regarded as the design parameters, while the root mean square (RMS) of the vehicle body acceleration is treated as the design objective and the corresponding constraints are composed of suspension stiffness, natural frequency and RMS of suspension dynamic deflection. Moreover, the uncertainties of key parameters, such as sprung mass, tire stiffness, vehicle speed and road roughness,… More >

Zichun Yang^1,2, Maolin Peng^1,3,4, Yueyun Cao¹, Lei Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.4, pp. 409-442, 2014, DOI:10.3970/cmes.2014.098.409

Abstract A new multi-objective reliability-based robust design optimization (M ORBRDO) model is proposed which integrats the multi-objective robustness, the reliability sensitivity robustness and the six sigma robustness design idea. The pure-quadratic polynomial functions are adopted to fit the performance objective functions (POF) and the ultimate limited state functions (ULSF) of the structure. Based on the ULSF and the checking point method, the equations of the first order reliability index are calculated. The mapping transformation method is employed when the non-normal distribution variables are included. According to the POF and the Taylor series expansion method, the equations of mean value and standard… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.4, pp. 375-407, 2014, DOI:10.3970/cmes.2014.098.375

Abstract In this paper we study the nonlinear dynamical system x^·=f(x,t) from a newly developed theory, viewing the time-varying function of sign(||f||²||x||²− 2(f·x)²) = −sign(cos 2θ) as a key factor, where θ is the intersection angle between x and f. It together with sign(cos θ) can reveal the complexity of nonlinear Duffing oscillator and a quadratic ship rolling oscillator. The barcode is formed by plotting sign(||f||²||x||²− 2(f·x)²) with respect to time. We analyze the barcode to point out the bifurcation of subharmonic motions and the range of chaos in the parameter space. The bifurcation diagram obtained by plotting the percentage… More >

É. Budyn¹, A. Bilagi², V. Subramanian³, A.A. Espinoza Orías⁴, N. Inoue⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.3, pp. 341-374, 2014, DOI:10.32604/cmes.2014.098.341

Abstract Focal damage such as cartilaginous defects, erosions, micro-fractures, Schmorl nodes and thinning in the human vertebral endplate are thought to contribute to intervertebral disc degeneration by compromising the nutrition transport between the vertebral bone marrow and the disc nucleus pulposus. However, microfractures in the endplate are currently not detectable by conventional clinical radiographic methods. Nonetheless high quality visualisation of the human endplate is possible by means of advanced light microscopy and appropriate staining. The objective of this study focuses on efficient and inexpensive multi-scale protocols to prepare the surfaces of human endplate specimens for morphometric characterisations at the tissue and… More >