Weidong Lei¹, Hai Zhou^1,*, Hongjun Li², Rui Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 577-597, 2021, DOI:10.32604/cmes.2021.011857 - 21 January 2021

Abstract In order to simulate the propagation process of subway vibration of parallel tunnels in semi-infinite rocks or soils, time domain boundary element method (TD-BEM) formulation for analyzing the dynamic response of twin-parallel circular tunnels in an elastic semi-infinite medium is developed in this paper. The time domain boundary integral equations of displacement and stress for the elastodynamic problem are presented based on Betti’s reciprocal work theorem, ignoring contributions from initial conditions and body forces. In the process of establishing time domain boundary integral equations, some virtual boundaries are constructed between finite boundaries and the free… More >

Leilei Chen¹, Kunpeng Li¹, Xuan Peng², Haojie Lian^3,4,*, Xiao Lin⁵, Zhuojia Fu⁶

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.1, pp. 125-146, 2021, DOI:10.32604/cmes.2021.012821 - 22 December 2020

Abstract This paper presents an isogeometric boundary element method (IGABEM) for transient heat conduction analysis. The Non-Uniform Rational B-spline (NURBS) basis functions, which are used to construct the geometry of the structures, are employed to discretize the physical unknowns in the boundary integral formulations of the governing equations. B´ezier extraction technique is employed to accelerate the evaluation of NURBS basis functions. We adopt a radial integration method to address the additional domain integrals. The numerical examples demonstrate the advantage of IGABEM in dimension reduction and the seamless connection between CAD and numerical analysis. More >

Mohamed Abdelsabour Fahmy^1,2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.1, pp. 175-199, 2021, DOI:10.32604/cmes.2021.012218 - 22 December 2020

Abstract The main aim of this paper is to propose a new memory dependent derivative (MDD) theory which called threetemperature nonlinear generalized anisotropic micropolar-thermoelasticity. The system of governing equations of the problems associated with the proposed theory is extremely difficult or impossible to solve analytically due to nonlinearity, MDD diffusion, multi-variable nature, multi-stage processing and anisotropic properties of the considered material. Therefore, we propose a novel boundary element method (BEM) formulation for modeling and simulation of such system. The computational performance of the proposed technique has been investigated. The numerical results illustrate the effects of time More >

Hongyin Yang^1,2, Jiwei Zhong^1,*, Ying Wang³, Xingquan Chen², Xiaoya Bian²

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.3, pp. 807-824, 2020, DOI:10.32604/cmes.2020.010936 - 21 August 2020

Abstract In this paper, general interpolating isogeometric boundary node method (IIBNM) and isogeometric boundary element method (IBEM) based on parameter space are proposed for 2D elasticity problems. In both methods, the integral cells and elements are defined in parameter space, which can reproduce the geometry exactly at all the stages. In IIBNM, the improved interpolating moving leastsquare method (IIMLS) is applied for field approximation and the shape functions have the delta function property. The Lagrangian basis functions are used for field approximation in IBEM. Thus, the boundary conditions can be imposed directly in both methods. The More >

Shige Wang¹, Zhongwang Wang¹, Leilei Chen¹, Haojie Lian^2,3,*, Xuan Peng⁴, Haibo Chen⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.2, pp. 585-604, 2020, DOI:10.32604/cmes.2020.09904 - 20 July 2020

Abstract The paper applied the isogeometric boundary element method (IGABEM) to thermoelastic problems. The Non-Uniform Rational B-splines (NURBS) used to construct geometric models are employed to discretize the boundary integral formulation of the governing equation. Due to the existence of thermal stress, the domain integral term appears in the boundary integral equation. We resolve this problem by incorporating radial integration method into IGABEM which converts the domain integral to the boundary integral. In this way, IGABEM can maintain its advantages in dimensionality reduction and more importantly, seamless integration of CAD and numerical analysis based on boundary More >

Yui-Chuin Shiah^{1, *}, Sheng-Chi Huang¹, M. R. Hematiyan²

CMC-Computers, Materials & Continua, Vol.64, No.2, pp. 701-727, 2020, DOI:10.32604/cmc.2020.010417 - 10 June 2020

Abstract In engineering practice, analysis of interfacial thermal stresses in composites is a crucial task for assuring structural integrity when sever environmental temperature changes under operations. In this article, the directly transformed boundary integrals presented previously for treating generally anisotropic thermoelasticity in two-dimension are fully regularized by a semi-analytical approach for modeling thin multi-layers of anisotropic/isotropic composites, subjected to general thermal loads with boundary conditions prescribed. In this process, an additional difficulty, not reported in the literature, arises due to rapid fluctuation of an integrand in the directly transformed boundary integral equation. In conventional analysis, thin… More >

Weihua Fang¹, Zhilin An², Tiantang Yu^{2, *}, Tinh Quoc Bui^{3, 4, *}

CMC-Computers, Materials & Continua, Vol.62, No.2, pp. 929-962, 2020, DOI:10.32604/cmc.2020.05022

Abstract Numerical analysis of unsteady heat transfer problems with complex geometries by the isogeometric boundary element method (IGABEM) is presented. The IGABEM possesses many desirable merits and features, for instance, (a) exactly represented arbitrarily complex geometries, and higher-order continuity due to nonuniform rational B-splines (NURBS) shape functions; (b) using NURBS for both field approximation and geometric description; (c) directly utilizing geometry data from computer-aided design (CAD); and (d) only boundary discretization. The formulation of IGABEM for unsteady heat transfer is derived. The domain discretization in terms of IGABEM for unsteady heat transfer is required as that More >

Ney Augusto Dumont

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.4, pp. 192-192, 2019, DOI:10.32604/icces.2019.05284

Abstract The use of boundary integral equations as an attempt to solve general problems of elasticity and potential has largely preceded the use of domain-related developments, which only became feasible (and conceivable) with the advent of powerful computational devices. On the other hand, the present-day matrix, computational-ready outline of the boundary element method (including its nowadays prevalent name) has borrowed – in part correctly and in part wrongly – much from the finite element concepts and formulation. We propose a revisit of the method, including, as for elasticity problems: a) conceptual reformulation in terms of weighted… More >

Godwin Kakuba^1,∗, John M. Mango¹, Martijn J.H. Anthonissen²

CMES-Computer Modeling in Engineering & Sciences, Vol.119, No.1, pp. 207-225, 2019, DOI:10.32604/cmes.2019.04269

Abstract Sometimes boundary value problems have isolated regions where the solution changes rapidly. Therefore, when solving numerically, one needs a fine grid to capture the high activity. The fine grid can be implemented as a composite coarse-fine grid or as a global fine grid. One cheaper way of obtaining the composite grid solution is the use of the local defect correction technique. The technique is an algorithm that combines a global coarse grid solution and a local fine grid solution in an iterative way to estimate the solution on the corresponding composite grid. The algorithm is… More >

Xu Liu¹, Guojian Shao¹, Xingxing Yue^2,*, Qingbin Yang³, Jingbo Su⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.2, pp. 189-211, 2018, DOI:10.31614/cmes.2018.03947

Abstract This paper aims to apply a virtual boundary element method (VBEM) to solve the inverse problems of three-dimensional heat conduction in orthotropic media. This method avoids the singular integrations in the conventional boundary element method, and can be treated as a potential approach for solving the inverse problems of the heat conduction owing to the boundary-only discretization and semi-analytical algorithm. When the VBEM is applied to the inverse problems, the numerical instability may occur if a virtual boundary is not properly chosen. The method encounters a highly ill-conditioned matrix for the larger distance between the… More >