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  Subjects -> ENGINEERING (Total: 2269 journals)
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ENGINEERING (1203 journals)            First | 1 2 3 4 5 6 7 | Last

Showing 401 - 600 of 1205 Journals sorted alphabetically
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 13)
IET Optoelectronics     Hybrid Journal   (Followers: 1)
IET Radar, Sonar & Navigation     Hybrid Journal   (Followers: 24)
IET Renewable Power Generation     Hybrid Journal   (Followers: 9)
IET Science, Measurement & Technology     Hybrid Journal   (Followers: 2)
IET Signal Processing     Hybrid Journal   (Followers: 15)
IETE Journal of Research     Open Access   (Followers: 8)
IETE Technical Review     Open Access   (Followers: 9)
IIE Transactions     Hybrid Journal   (Followers: 2)
Implementation Science     Open Access   (Followers: 14)
Indian Journal of Biotechnology (IJBT)     Open Access   (Followers: 2)
Indonesian Journal of Science and Technology     Open Access  
Industrial Data     Open Access   (Followers: 1)
Industrie et Technologies     Full-text available via subscription   (Followers: 15)
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Ingeniare : Revista Chilena de Ingenieria     Open Access  
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Ingenius : Revista de Ciencia y Tecnología     Open Access  
Innovare : Revista de ciencia y tecnología     Open Access  
Instrumentation Science & Technology     Hybrid Journal   (Followers: 7)
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Intelligent Control and Automation     Open Access   (Followers: 6)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 8)
Interface Science and Technology     Full-text available via subscription  
Intermetallics     Hybrid Journal   (Followers: 21)
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International conference KNOWLEDGE-BASED ORGANIZATION     Open Access  
International Heat Treatment and Surface Engineering     Hybrid Journal   (Followers: 3)
International Journal for Numerical Methods in Engineering     Hybrid Journal   (Followers: 29)
International Journal for Numerical Methods in Fluids     Hybrid Journal   (Followers: 19)
International Journal for Simulation and Multidisciplinary Design Optimization     Open Access   (Followers: 3)
International Journal for the History of Engineering & Technology     Hybrid Journal   (Followers: 8)
International Journal of Abrasive Technology     Hybrid Journal   (Followers: 2)
International Journal of Adaptive Control and Signal Processing     Hybrid Journal   (Followers: 2)
International Journal of Adhesion and Adhesives     Hybrid Journal   (Followers: 16)
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International Journal of Advances in Applied Sciences     Open Access   (Followers: 4)
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International Journal of Advances in Engineering Sciences and Applied Mathematics     Hybrid Journal   (Followers: 1)
International Journal of Advances in Engineering, Science and Technology     Open Access   (Followers: 4)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 17)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 17)
International Journal of Air-Conditioning and Refrigeration     Hybrid Journal   (Followers: 7)
International Journal of Antennas and Propagation     Open Access   (Followers: 9)
International Journal of Applied Ceramic Technology     Hybrid Journal   (Followers: 7)
International Journal of Applied Power Engineering     Open Access   (Followers: 4)
International Journal of Architectural Computing     Full-text available via subscription   (Followers: 5)
International Journal of Automation and Control Engineering     Open Access   (Followers: 2)
International Journal of Automotive Technology and Management     Hybrid Journal   (Followers: 5)
International Journal of Autonomic Computing     Hybrid Journal   (Followers: 1)
International Journal of Autonomous and Adaptive Communications Systems     Hybrid Journal   (Followers: 4)
International Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
International Journal of Bifurcation and Chaos     Hybrid Journal   (Followers: 2)
International Journal of Biomedical and Clinical Engineering     Full-text available via subscription   (Followers: 4)
International Journal of Biomedical Imaging     Open Access   (Followers: 5)
International Journal of Cast Metals Research     Hybrid Journal  
International Journal of Circuit Theory and Applications     Hybrid Journal   (Followers: 2)
International Journal of Coal Science & Technology     Open Access   (Followers: 1)
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International Journal of Communication Systems     Hybrid Journal   (Followers: 2)
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International Journal of Control Science and Engineering     Open Access   (Followers: 5)
International Journal of Control, Automation and Systems     Hybrid Journal   (Followers: 12)
International Journal of Corrosion     Open Access   (Followers: 10)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 7)
International Journal of Design Engineering     Hybrid Journal   (Followers: 14)
International Journal of Digital Multimedia Broadcasting     Open Access   (Followers: 5)
International Journal of Education and Management Engineering     Open Access   (Followers: 2)
International Journal of Education Economics and Development     Hybrid Journal   (Followers: 3)
International Journal of Embedded Systems     Hybrid Journal   (Followers: 5)
International Journal of Emerging Multidisciplinary Fluid Sciences     Full-text available via subscription   (Followers: 2)
International Journal of Energy Optimization and Engineering     Hybrid Journal   (Followers: 3)
International Journal of Engine Research     Hybrid Journal   (Followers: 1)
International Journal of Engineering & Technology     Open Access   (Followers: 4)
International Journal of Engineering and Manufacturing     Open Access   (Followers: 1)
International Journal of Engineering and Technologies     Open Access  
International Journal of Engineering Business Management     Open Access  
International Journal of Engineering Education     Full-text available via subscription   (Followers: 6)
International Journal of Engineering Management and Economics     Hybrid Journal   (Followers: 3)
International Journal of Engineering Mathematics     Open Access   (Followers: 2)
International Journal of Engineering Pedagogy     Open Access  
International Journal of Engineering Practical Research     Open Access  
International Journal of Engineering Research in Africa     Full-text available via subscription   (Followers: 2)
International Journal of Engineering Science     Hybrid Journal   (Followers: 6)
International Journal of Engineering Systems Modelling and Simulation     Hybrid Journal   (Followers: 9)
International Journal of Engineering, Science and Technology     Open Access  
International Journal of Engineering, Social Justice, and Peace     Open Access   (Followers: 4)
International Journal of Environmental Engineering     Hybrid Journal   (Followers: 6)
International Journal of Experimental Design and Process Optimisation     Hybrid Journal   (Followers: 5)
International Journal of Fatigue     Hybrid Journal   (Followers: 33)
International Journal of Flow Control     Full-text available via subscription   (Followers: 5)
International Journal of Foresight and Innovation Policy     Hybrid Journal   (Followers: 7)
International Journal of Fracture     Hybrid Journal   (Followers: 11)
International Journal of Geo-Engineering     Open Access   (Followers: 1)
International Journal of Geotechnical Engineering     Hybrid Journal   (Followers: 5)
International Journal of Grid and Utility Computing     Hybrid Journal  
International Journal of Heat and Fluid Flow     Hybrid Journal   (Followers: 31)
International Journal of Heat and Mass Transfer     Hybrid Journal   (Followers: 148)
International Journal of Heavy Vehicle Systems     Hybrid Journal   (Followers: 6)
International Journal of Hypersonics     Full-text available via subscription   (Followers: 4)
International Journal of Imaging Systems and Technology     Hybrid Journal   (Followers: 1)
International Journal of Impact Engineering     Hybrid Journal   (Followers: 9)
International Journal of Information Acquisition     Hybrid Journal   (Followers: 1)
International Journal of Innovation and Applied Studies     Open Access   (Followers: 5)
International Journal of Innovation Science     Hybrid Journal   (Followers: 9)
International Journal of Innovative Technology and Research     Open Access   (Followers: 1)
International Journal of Integrated Engineering     Open Access  
International Journal of Intelligent Engineering Informatics     Hybrid Journal  
International Journal of Intelligent Systems and Applications in Engineering     Open Access   (Followers: 3)
International Journal of Lifecycle Performance Engineering     Hybrid Journal   (Followers: 1)
International Journal of Machine Tools and Manufacture     Hybrid Journal   (Followers: 6)
International Journal of Manufacturing Research     Hybrid Journal   (Followers: 6)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 8)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 5)
International Journal of Mathematical Education in Science and Technology     Hybrid Journal   (Followers: 8)
International Journal of Mathematics in Operational Research     Hybrid Journal  
International Journal of Medical Engineering and Informatics     Hybrid Journal   (Followers: 4)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 7)
International Journal of Microwave Science and Technology     Open Access   (Followers: 4)
International Journal of Mobile Network Design and Innovation     Hybrid Journal   (Followers: 1)
International Journal of Multiphase Flow     Hybrid Journal   (Followers: 4)
International Journal of Nanomanufacturing     Hybrid Journal  
International Journal of Nanoscience     Hybrid Journal   (Followers: 2)
International Journal of Nanotechnology     Hybrid Journal   (Followers: 6)
International Journal of Nanotechnology and Molecular Computation     Full-text available via subscription   (Followers: 2)
International Journal of Navigation and Observation     Open Access   (Followers: 19)
International Journal of Network Management     Hybrid Journal   (Followers: 1)
International Journal of Nonlinear Sciences and Numerical Simulation     Hybrid Journal  
International Journal of Numerical Methods for Heat & Fluid Flow     Hybrid Journal   (Followers: 9)
International Journal of Optics     Open Access   (Followers: 6)
International Journal of Organisational Design and Engineering     Hybrid Journal   (Followers: 6)
International Journal of Pattern Recognition and Artificial Intelligence     Hybrid Journal   (Followers: 6)
International Journal of Pavement Engineering     Hybrid Journal   (Followers: 6)
International Journal of Physical Modelling in Geotechnics     Hybrid Journal   (Followers: 4)
International Journal of Plasticity     Hybrid Journal   (Followers: 6)
International Journal of Plastics Technology     Hybrid Journal   (Followers: 1)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 6)
International Journal of Polymer Science     Open Access   (Followers: 22)
International Journal of Precision Engineering and Manufacturing     Hybrid Journal   (Followers: 8)
International Journal of Precision Engineering and Manufacturing-Green Technology     Hybrid Journal  
International Journal of Precision Technology     Hybrid Journal  
International Journal of Pressure Vessels and Piping     Hybrid Journal   (Followers: 17)
International Journal of Production Economics     Hybrid Journal   (Followers: 13)
International Journal of Quality and Innovation     Hybrid Journal   (Followers: 5)
International Journal of Quality Assurance in Engineering and Technology Education     Full-text available via subscription   (Followers: 3)
International Journal of Quality Engineering and Technology     Hybrid Journal   (Followers: 2)
International Journal of Quantum Information     Hybrid Journal   (Followers: 2)
International Journal of Rapid Manufacturing     Hybrid Journal   (Followers: 4)
International Journal of Recent Contributions from Engineering, Science & IT     Open Access   (Followers: 1)
International Journal of Reliability, Quality and Safety Engineering     Hybrid Journal   (Followers: 12)
International Journal of Renewable Energy Technology     Hybrid Journal   (Followers: 9)
International Journal of Robust and Nonlinear Control     Hybrid Journal   (Followers: 4)
International Journal of Science Engineering and Advance Technology     Open Access  
International Journal of Sediment Research     Full-text available via subscription   (Followers: 3)
International Journal of Self-Propagating High-Temperature Synthesis     Hybrid Journal   (Followers: 2)
International Journal of Service Science, Management, Engineering, and Technology     Full-text available via subscription   (Followers: 1)
International Journal of Signal and Imaging Systems Engineering     Hybrid Journal  
International Journal of Six Sigma and Competitive Advantage     Hybrid Journal   (Followers: 2)
International Journal of Social Robotics     Hybrid Journal   (Followers: 2)
International Journal of Software Engineering and Knowledge Engineering     Hybrid Journal   (Followers: 4)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 4)
International Journal of Speech Technology     Hybrid Journal   (Followers: 8)
International Journal of Spray and Combustion Dynamics     Hybrid Journal   (Followers: 12)
International Journal of Surface Engineering and Interdisciplinary Materials Science     Full-text available via subscription   (Followers: 1)
International Journal of Surface Science and Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Manufacturing     Hybrid Journal   (Followers: 5)
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International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 4)
International Journal of Technoethics     Full-text available via subscription   (Followers: 1)
International Journal of Technology Management and Sustainable Development     Hybrid Journal   (Followers: 1)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 6)
International Journal of Telemedicine and Applications     Open Access   (Followers: 3)
International Journal of Thermal Sciences     Hybrid Journal   (Followers: 14)
International Journal of Thermodynamics     Open Access   (Followers: 8)
International Journal of Turbo & Jet-Engines     Hybrid Journal   (Followers: 3)
International Journal of Ultra Wideband Communications and Systems     Hybrid Journal  
International Journal of Vehicle Autonomous Systems     Hybrid Journal  
International Journal of Vehicle Design     Hybrid Journal   (Followers: 6)
International Journal of Vehicle Information and Communication Systems     Hybrid Journal   (Followers: 2)
International Journal of Vehicle Noise and Vibration     Hybrid Journal   (Followers: 4)
International Journal of Vehicle Safety     Hybrid Journal   (Followers: 6)
International Journal of Vehicular Technology     Open Access   (Followers: 4)
International Journal of Virtual Technology and Multimedia     Hybrid Journal   (Followers: 3)
International Journal of Wavelets, Multiresolution and Information Processing     Hybrid Journal   (Followers: 1)
International Journal on Artificial Intelligence Tools     Hybrid Journal   (Followers: 6)

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Journal Cover Engineering Analysis with Boundary Elements
  [SJR: 1.251]   [H-I: 52]   [1 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0955-7997
   Published by Elsevier Homepage  [3040 journals]
  • Dynamic fracture analysis of the soil-structure interaction system using
           the scaled boundary finite element method
    • Abstract: Publication date: April 2017
      Source:Engineering Analysis with Boundary Elements, Volume 77
      Author(s): Denghong Chen, Shangqiu Dai
      Dynamic fracture analysis of the soil-structure interaction system by using the scaled boundary finite element method is presented in this paper. The polygon scaled boundary finite elements, which have some salient features to model any star convex polygons, are employed for modelling the near-field bounded domains. A procedure for coupling the bounded domains with an improved continued-fraction-based high-order transmitting boundary is established. The formulations of the soil-structure interaction system are coupled via the interaction force vector at the interface. The dynamic stress intensity factors and T-stress are extracted according to the definition of the generalized stress intensity factors. The dynamic stress intensity factors of the coupled system are evaluated accurately and efficiently. Two numerical examples are demonstrated to validate the developed method.

      PubDate: 2017-01-18T12:31:45Z
       
  • An element-free based IMLS-Ritz method for buckling analysis of
           nanocomposite plates of polygonal planform
    • Abstract: Publication date: April 2017
      Source:Engineering Analysis with Boundary Elements, Volume 77
      Author(s): L.W. Zhang
      The buckling behavior of nanocomposite plates of polygonal planform under in-plane loads is examined. The plate under consideration is reinforced by single-walled carbon nanotubes (CNTs). The governing eigenvalue equation to this problem is derived based on the first-order shear deformation plate theory (FSDT) with a set of element-free shape functions in approximating the two-dimensional displacement fields. To solve this eigenvalue equation, the element-free IMLS-Ritz method is employed to furnish the buckling solution. The convergence of the solution for the CNT-reinforced composite plates is examined. Comparison study is further carried out to validate the accuracy of the solution. A parametric study is performed by varying the CNT volume fraction, CNT distribution, plate thickness-to-apothem ratio and boundary conditions. This first known buckling solution may serve as benchmarks for future research.

      PubDate: 2017-01-18T12:31:45Z
       
  • Numerical study of flow-excited noise of a submarine with full appendages
           
    • Abstract: Publication date: April 2017
      Source:Engineering Analysis with Boundary Elements, Volume 77
      Author(s): Huilan Yao, Huaixin Zhang, Hutao Liu, Wencheng Jiang
      Large eddy simulation (LES) is applied to simulate the flow field around a submarine with full appendages. The predicted ship resistance, velocity distributions and surface pressures are validated by experimental data. Dynamic velocity responses of the structure are obtained by solving the fluid-solid coupling equations. The flow noise and flow-excited noise of the submarine are predicted using the boundary element method (BEM). Flow noise predicted by the BEM and the Ffowcs Williams-Hawkings (FW-H) equations are compared and discussed. The spectra of flow-excited noise are different from those of flow noise, and the sound pressure level of flow-excited noise is larger than that of flow noise, especially when structural resonance occurs. Flow-excited noise rapidly decreases in the near-field and maintains a slow attenuation rate in the far-field. The influence of ship speed on flow-excited noise is investigated, and results show that the spectral characteristics of flow-excited noise of the submarine change greatly with different sailing speeds. To achieve noise reduction, different shell thicknesses and different numbers of longitudinal girders are investigated. It is found that increasing the shell thickness and the number of longitudinal girders can indeed reduce noise emission. It should be noted that the noise reduction effect might differ.

      PubDate: 2017-01-18T12:31:45Z
       
  • Fundamental solutions of a multi-layered transversely isotropic saturated
           half-space subjected to moving point forces and pore pressure
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): Zhenning Ba, Jianwen Liang
      The steady-state dynamic response of a multi-layered transversely isotropic (TI) saturated half-space due to point forces and pore pressure moving with a constant speed is investigated in this paper. To solve this problem, the dynamic stiffness method combined with the inverse Fourier transform is employed. First, the governing equations in terms of the displacement components and pore fluid pressure are solved in the transformed domain by employing the Fourier transform. Next, the exact three-dimensional (3D) dynamic stiffness matrices for the TI saturated layer, as well as the TI saturated half-space, are constructed, and the global dynamic matrix of the problem is formulated by assembling the dynamic matrices of the discrete layers and the underlying half-space. Finally, solutions in the frequency-wavenumber domain of the displacement, pore pressure and stress are obtained through the dynamic stiffness method. The result in the time-space domain is recovered by the Fourier synthesis of the frequency responses which, in turn, are obtained by numerical integration over on one horizontal wavenumber. The accuracy of the developed formulations is confirmed by comparison with existing solutions for an isotropic and saturated medium that is a special case of the more general problem addressed. Numerical results for both low and high source velocities are presented, and the effects of moving speed, material anisotropy, permeability, surface drainage condition and TI saturated layer on the dynamic response are analyzed. It is observed that the dynamic responses reach their peak values when the source velocity is equal to or approaches the phase velocities of SH-, qP1-, qP2- and qSV- in the horizontal direction and the phase velocity of qRayleigh waves. Material anisotropy is very important for the accurate assessment of the dynamic response due to the moving point forces and pore pressure in a TI saturated medium.

      PubDate: 2017-01-10T11:45:22Z
       
  • Modelling of acoustic and elastic wave propagation from underground
           structures using a 2.5D BEM-FEM approach
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): A. Romero, P. Galvín, J. António, J. Domínguez, A. Tadeu
      This paper presents a numerical method based on a two-and-a-half dimensional (2.5D) boundary element-finite element (BEM-FEM) coupled formulation to study noise and vibration from underground structures. The proposed model properly represents the soil-structure interaction problem and the radiated noise and vibration. The soil is modelled with the boundary element method, and the Green's function for a fluid-solid formation is taken as the fundamental solution to represent a solid half-space flattened by a fluid medium, which represents the soil and the air above the ground surface. The finite element method is used to represent structures and enclosed air volumes. The problem representation is limited to a soil-structure interface and the ground surface does not need to be discretised. Radiated noise and vibration are determined after the soil-structure interaction problem has been solved. We verify the proposed method by comparing the solution with an analytical solution for the wave propagation in a fluid-solid medium. Three examples are given to illustrate the noise and vibration radiated by tunnels. The results show that the soil-structure interaction influences the sound pressure field above the ground surface.

      PubDate: 2017-01-10T11:45:22Z
       
  • Three-dimensional dynamic ring load and point load Green's functions for
           
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): Saeed Cheshmehkani, Morteza Eskandari-Ghadi
      An analytical formulation is presented for three-dimensional Green's functions of continuously inhomogeneous linear viscoelastic transversely isotropic half-space subjected to either ring load or point load. It is assumed that the elastic moduli of the half-space vary in terms of depth as bounded exponentially functions, while the mass density is constant. The method of potential functions is used to partially decouple the governing equations, after which Fourier series expansion followed by Hankel integral transforms is applied to transform the partial differential equations to ordinary differential equations (ODEs) with variable coefficients. Then, Frobenius series method is employed to determine the potential functions and then the displacements and stresses in the transformed domain, which are used to evaluate these functions in physical domain. The validity of the formulations and numerical process is shown for several simplified cases comparing with the known solutions in the literature. Finally, the displacement and stress Green's functions are presented for several physical cases due to either unit ring load or unit point load. The results show that if the shear waves are produced in the interested direction, both inhomogeneity parameters and material damping may change the dynamic response of the half-space significantly, especially in high frequencies.

      PubDate: 2017-01-10T11:45:22Z
       
  • Why dual boundary element method is necessary?
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): Jeng-Tzong Chen, Ching-Yun Yueh, Yu-Lung Chang, Chun-Chiang Wen
      Dual boundary integral equation (BIE) was developed for problems containing degenerate boundaries in 1988 by Hong and Chen [Journal of Engineering Mechanics-ASCE, 114, 6, 1988] and was termed the dual boundary element method (BEM) in 1992 by Portela et al. [International Journal for Numerical Methods in Engineering, 33, 6, 1992]. After near 30 years, the dual BIE/BEM for the problem containing a zero-thickness barrier was revisited mathematically to study the rank deficiency from the viewpoint of the updating term and the updating document of singular value decomposition (SVD) [Journal of Mechanics, 31, 5, 2015]. In this paper, we revisit the dual BEM from the physical point of view. Although there is no zero-thickness barrier in the real world, it is always required to simulate a finite-thickness degenerate boundary to be zero-thickness in comparison with sea, air or earth scale. For example, a sheet pile, a screen, a crack problem, a thin airfoil and a breakwater were modeled by the geometry of zero-thickness. The role of the dual BEM is evident since Lafe et al. [Journal of the Hydraulics Division-ASCE, 106, 6, 1980] used the conventional BEM to model the finite-thickness pile wall to geometrically approximate zero-thickness barrier but numerically yielding divergent solution. On the contrary, we physically model the finite-thickness breakwater as a zero-thickness barrier. The breakwater is employed as an illustrative case to demonstrate that the dual BEM simulated by a zero-thickness barrier can yield more acceptable results to match the experiment data in comparison with those of the finite thickness using the conventional BEM. Finally, a single horizontal plate and two dual horizontal plates in vertical direction and in horizontal direction are three illustrative cases to tell you why the dual BEM is necessary not only in mathematics but also in physics.

      PubDate: 2017-01-10T11:45:22Z
       
  • A modification on strictly positive definite RBF-DQ method based on matrix
           decomposition
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): Saeed Kazem, Ali Hatam
      The infinitely smooth RBF methods are theoretically spectrally accurate for applying on scattered data interpolation, and also partial differential equations, but the interpolation matrices of them are extremely ill-conditioned especially for strictly positive definite ones. Therefore, an efficient technique to recover this problem is too important. In this article, a general matrix decomposition method for strictly positive definite RBFs interpolation matrix has been investigated. In the current decomposition the RBFs interpolation matrix is obtained as multiplication of some well-conditioned matrices. This decomposition has been applied to RBF-DQ method and its results more accurate weight coefficients when we involve solving PDEs.

      PubDate: 2017-01-10T11:45:22Z
       
  • Numerical simulation of three-dimensional double-diffusive natural
           convection in porous media by boundary element method
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): J. Kramer Stajnko, J. Ravnik, R. Jecl
      The paper presents numerical results for three-dimensional double-diffusive natural convection in a cubic enclosure fully filled with fluid saturated porous media. Two opposite vertical walls of the enclosure are subjected to different values of temperature and concentration, which causes buoyant and diffusive flow in the porous media domain. Mathematical model is based on the Brinkman-extended Darcy formulation as a governing momentum equation, which is coupled with the energy and species equations. The three-dimensional boundary element method based solver was used to solve the obtained set of partial differential equations. The existing numerical algorithm primarily derived for the pure fluid flow simulations was adopted to simulate transport phenomena in porous media. It is based on the combination of single and subdomain boundary element method, which solves the velocity-vorticity formulation of the governing equations. In the paper the influence of some governing parameters, specially the Rayleigh number, Darcy number and buoyancy coefficient are investigated in order to analyze the heat and mass transfer through porous enclosure. The numerical code is verified by comparison of the results with available previous numerical data found in the literature.

      PubDate: 2017-01-10T11:45:22Z
       
  • Elastodynamic analysis of regular polygonal CNT-reinforced composite
           plates via FSDT element-free method
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): L.W. Zhang, W.H. Liu, L.N. Xiao
      A comprehensive study on elastodynamic behavior of regular polygonal carbon nanotube (CNT) reinforced functionally graded composite plates subjected to a sudden transverse dynamic load is presented in this paper. This analysis uses as its base the first-order shear deformation theory (FSDT) and the element-free IMLS-Ritz method, to conduct a numerical simulation. A numerical time integration for the dynamic problems is performed using the Newmark-β method. Convergence studies are carried out for an isotropic square plate with different support sizes and different numbers of nodes. Parametric studies are further carried out to investigate the effect of four special regular polygons with different CNT volume fractions, CNT distribution types, plate apothem-to-thickness ratios and boundary conditions on the dynamic behaviors of regular polygonal CNT-reinforced composite plates.

      PubDate: 2017-01-10T11:45:22Z
       
  • Strategies using boundary integral equations for solving exterior
           anisotropic conduction problems outside long cylinders
    • Abstract: Publication date: March 2017
      Source:Engineering Analysis with Boundary Elements, Volume 76
      Author(s): A. Corfdir, G. Bonnet
      2D approximations can greatly alleviate the computing effort required to solve anisotropic conduction problems outside long 3D cylindrical domain using boundary integral methods. Two strategies can be used to this aim: either transform the anisotropic conduction problem into an isotropic one, or deal with the anisotropic 2D Green's function. In the first case, it is necessary to provide not only the new features of the transformed domain, but also the new expressions of the boundary conditions over the domain. Conversely, the anisotropic 2D Green's function is defined upto a constant which depends on the length of the cylindrical domain, as shown in the isotropic case. In addition, the use of anisotropic Green's function cannot avoid the occurrence in some cases of degenerate scales, which is well known in the isotropic case. The paper addresses these different points: construction of the anisotropic 2D Green's function and its relation with line sources, description of the transformation leading to an equivalent isotropic problem and finally study of the boundary integral solution of the equivalent 2D problem, including the occurence of degenerate scales.

      PubDate: 2016-12-30T11:03:48Z
       
  • The birth of the boundary element method from conception to application
    • Abstract: Publication date: Available online 27 December 2016
      Source:Engineering Analysis with Boundary Elements
      Author(s): Carlos A. Brebbia
      The Boundary Element Method (BEM) has now become a well established numerical technique with a number of computer programmes to its credit oriented towards industrial applications. They are reliable and robust tools which stress its unique features versus finite elements, ie reduced dimensionality which makes it easier to interface it to CAD codes; better accuracy, the elegant way in which moving boundaries are dealt with and the possibility of taking into consideration infinite domains without the need of introducing artificial boundaries. An excellent paper on the early work that led to the development of boundary elements has been given by A&D Cheng [1] and from which many of the illustrations depicting famous scientists were taken. The present contribution aims to explain further how the methodology developed and consolidated towards the end of the 1970s, beginning of the 1980s.

      PubDate: 2016-12-30T11:03:48Z
       
  • DRBEM formulation for transient Stokes flow with slip boundary condition
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): S. Gümgüm, Luiz C. Wrobel
      In this study, the effect of linear and nonlinear slip boundary conditions on the flow of a slow viscous fluid is investigated numerically. The boundary integral representation of the transient Stokes equations is given in primitive variables form. The fundamental solution to the steady Stokes equations is employed in the boundary element method (BEM) formulation. The time derivative is taken to the boundary with the dual reciprocity method and approximated by the finite difference method (FDM) until a steady-state is achieved. It is assumed that the fluid is capable of slip, with the slip velocity expressed as a function of shear rate at the wall. In the numerical tests, the fluid is initially assumed to be stationary; at each time step, the velocity boundary conditions along the walls are updated as the shear forces vary with time.

      PubDate: 2016-12-23T10:07:21Z
       
  • A meshfree approach for homogenization of mechanical properties of
           heterogeneous materials
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): Siavash Rastkar, Maryam Zahedi, Igor Korolev, Arvind Agarwal
      In this paper, asymptotic homogenization and meshfree Solution Structure Method (SSM) are combined to develop a hybrid homogenization technique. This hybrid method makes it possible to capture accurate geometric information of material microstructure, directly from micrographs or Computed Tomography (CT) scans, and offers a completely automated numerical procedure. Homogenization methods often employ FEA to incorporate realistic geometry of the material's microstructure. However, generating a finite element mesh from images or 3D voxel data could be tedious, error-prone, and expensive. Also, in many practical situations, considerable manual modifications are often required. On the other hand, the SSM uses implicit mathematical functions to represent the geometric model. It could be implemented using different types of basis functions, either on a non-conforming structural grid or cloud of points. Adaptive numerical and geometric algorithms assure good geometric flexibility of SSM in handling complex structures. Furthermore, to accommodate material homogenization equations, the SSM is extended so it can provide the exact satisfaction of periodic boundary conditions without using any spatial meshes. To validate the developed method, the architecture of a computer software package is designed that provides an automated computational pipeline for material homogenization. Numerical examples are provided to evaluate the developed platform against other methods and previously published data.

      PubDate: 2016-12-23T10:07:21Z
       
  • A non-singular method of fundamental solutions for two-dimensional
           steady-state isotropic thermoelasticity problems
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): Q.G. Liu, B. Šarler
      We consider a boundary meshless numerical solution for two-dimensional linear static thermoelastic problems. The formulation of the problem is based on the approach of Marin and Karageorghis, where the Laplace equation for the temperature field is solved first, followed by a particular solution of the non-homogenous term in the Navier-Lamé system for the displacement, the solution of the homogenous equilibrium equations, and finally the application of the superposition principle. The solution of the problem is based on the method of fundamental solutions (MFS) with source points on the boundary. This is, by complying with the Dirichlet boundary conditions, achieved by the replacement of the concentrated point sources with distributed sources over the disk around the singularity, and for complying with the Neumann boundary conditions by assuming a balance of the heat fluxes and the forces. The derived non-singular MFS is assessed by a comparison with analytical solutions and the MFS for problems that can include different materials in thermal and mechanical contact. The method is easy to code, accurate, efficient and represents a pioneering attempt to solve thermoelastic problems with a MFS-type method without an artificial boundary. The procedure makes it possible to solve a broad spectra of thermomechanical problems.

      PubDate: 2016-12-23T10:07:21Z
       
  • Publisher's Note
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73


      PubDate: 2016-12-16T09:39:01Z
       
  • A note on the use of the Companion Solution (Dirichlet Green's function)
           on meshless boundary element methods
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): H. Power, N. Caruso, M. Portapila
      Most implementations of meshless BEMs use a circular integration contours (spherical in 3D) embedded into a local interpolation stencil with the so-called Companion Solution (CS) as a kernel, in order to eliminate the contribution of the single layer potential. However, the Dirichlet Green's Function (DGF) is the unique Fundamental Solution that is identically zero at any given close surface and therefore eliminates the single layer potential. One of the main objectives of this work is to show that the CS is nothing else than the DGF for a circle collocated at its origin. The use of the DGF allows the collocation at more than one point, permitting the implementation of a P-adaptive scheme in order to improve the accuracy of the solution without increasing the number of subregions. In our numerical simulations, the boundary conditions are imposed at the interpolation stencils in contact with the problem boundary instead of at the corresponding integration surfaces, permitting always the use of circular integration contours, even in regions near or in contact with the problem domain where the densities of the integrals are reconstructed from the interpolation formulae that already included the problem boundary conditions.

      PubDate: 2016-12-16T09:39:01Z
       
  • An examination of evaluation algorithms for the RBF method
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): Scott A. Sarra, Samuel Cogar
      Radial Basis Function (RBF) methods are important tools for scattered data interpolation and for the solution of PDEs in complexly shaped domains. Several approaches for the evaluation of RBF methods are known. To date, the most noteworthy methods are solving a linear system in the standard RBF basis using both double and extended precision floating point arithmetic and two approaches that make a change of basis for the purpose of obtaining a better conditioned linear system. In this work the approaches are compared and contrasted for the purpose of illustrating the strengths and weakness of each method as well as to give insight into the application of each approach.

      PubDate: 2016-12-09T08:49:41Z
       
  • Thermal shock analysis of 2D cracked solids using the numerical manifold
           method and precise time integration
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): H.H. Zhang, G.W. Ma, L.F. Fan
      The numerical manifold method (NMM), combined with the precise time integration method (PTIM), is proposed for thermal shock fracture analysis. The temperature and displacement discontinuity across crack faces is naturally portrayed attributing to the cover systems in the NMM. The crack tip singularities are characterized through the use of asymptotic bases in the approximations. The discrete equations for transient thermal analysis are firstly solved with the PTIM and then the thermoelastic study is performed. With the interaction integral, the stress intensity factors are computed. Several examples are tested and the nice consistency between the present and existing results is found.

      PubDate: 2016-12-09T08:49:41Z
       
  • Evaluation of nearly singular integrals in isogeometric boundary element
           method
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): Y.P. Gong, C.Y. Dong, Y. Bai
      Isogeometric boundary element method (IGBEM) is a new numerical method that has received a lot of attentions in recent years. However, nearly singular integrals in the IGBEM have not yet received more attention when the IGBEM is used to study thin-body/coating structures. In this paper, the exponential transformation method based on the idea of diminishing the difference of the orders or the scale of change of addition factors in the denominator of the kernels is used to remove or weaken the near singularities of nearly singular integrals appearing in 2D/3D potential problems. Numerical results show that the present method is effective, stable and competitive. We believe that this work clearly presents the power of the IGBEM and provides an efficient approach to investigate the boundary layer effect appearing in thin-body/coating structures.

      PubDate: 2016-11-26T12:03:15Z
       
  • Studying normal perforation of monolithic and layered steel targets by
           conical projectiles with SPH simulation and analytical method
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): Yihua Xiao, Huanghuang Dong, Jianmin Zhou, Jungang Wang
      The normal perforation of monolithic and layered Weldox 460 E steel targets by conical projectiles is investigated with smoothed particle hydrodynamics (SPH) simulation and analytical method. A series of SPH simulations are performed for the perforation of monolithic targets with different thicknesses and layered targets with different total thicknesses and layering schemes. According to the simulated results, an empirical relation between ballistic limit velocity and target thickness is determined for monolithic target, and the variation of ballistic resistance with number of layers, total thickness and thickness configuration is revealed for layered target. Based on the established empirical relation for monolithic target, an analytical method is used to analyze the ballistic resistance of layered targets with different total thicknesses and layering schemes. The analytical results are compared with SPH simulation results, and the applicability and accuracy of the analytical method for the present problems are discussed.

      PubDate: 2016-11-20T00:21:44Z
       
  • Line integration method for treatment of domain integrals in 3D boundary
           element method for potential and elasticity problems
    • Abstract: Publication date: February 2017
      Source:Engineering Analysis with Boundary Elements, Volume 75
      Author(s): Qiao Wang, Wei Zhou, Yonggang Cheng, Gang Ma, Xiaolin Chang
      A line integration method is presented in this paper for evaluation of domain integrals in 3D problems. The method is a boundary-only discretization method and the domain integrals can be computed by sum of integrals on one-dimensional straight lines. Divergence theorem is used to transform the domain integrals into boundary integrals with one-dimensional integrals. The boundary integrals can be evaluated by boundary elements with integral points. Each integral point can be used to construct an integral line, and the domain integrals can be finally computed by line integrals on integral lines. Only the boundary discretization is needed and background cells are used to cut the integral lines into sub-lines to obtain the desired accuracy. The method is proved and applied in boundary element method for 3D potential and elasticity problems. Numerical examples have demonstrated the accuracy of the proposed method.

      PubDate: 2016-11-20T00:21:44Z
       
  • Compact approximation stencils based on integrated flat radial basis
           functions
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): N. Mai-Duy, T.T.V. Le, C.M.T. Tien, D. Ngo-Cong, T. Tran-Cong
      This paper presents improved ways of constructing compact integrated radial basis function (CIRBF) stencils, based on extended precision, definite integrals, higher-order IRBFs and minimum number of derivative equations, to enhance their performance over large values of the RBF width. The proposed approaches are numerically verified through second-order linear differential equations in one and two variables. Significant improvements in the matrix condition number, solution accuracy and convergence rate with grid refinement over the usual approaches are achieved.

      PubDate: 2016-11-12T23:48:09Z
       
  • Global error analysis of two-dimensional panel methods for dirichlet
           formulation
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): José M. Ezquerro, Ana Laverón-Simavilla, Victoria Lapuerta, Jeff Porter
      A rigorous analytical study of the global error of panel methods is presented. The analysis is performed for a wide variety of body shapes and different panel geometries to fully understand their effect on the convergence of the method. In particular, we study the global error associated with panel methods applied to thin or thick bodies with purely convex parts or with both convex and concave parts, and with smooth or non-smooth boundaries. Most previous studies focused on the analysis of local error, considering only the influence of the nearest panels and excluding the rest. The difference is shown to be appreciable in many configurations. Generally, there is a lack of consensus concerning the order of magnitude of the error for panel methods even in the simplest case with flat panels and a constant distribution of doublets along them. This paper clarifies apparently different or inconsistent results obtained by other authors.

      PubDate: 2016-11-12T23:48:09Z
       
  • Boundary element analysis of bar silencers using the scattering matrix
           with two-dimensional finite element modes
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): L. Yang, P. Wang, T.W. Wu
      Bar silencers used in industry may consist of a large array of rectangular or round bars packed in a rectangular lattice arrangement. Due to the size of the lattice, normally only a single unit that represents a building block for the lattice is isolated for analysis purposes. Even with one isolated unit, the inlet and the outlet are still quite large, and the plane-wave cutoff frequency can be very low. Therefore, higher-order modes must be considered at the inlet and outlet in order to calculate the transmission loss. This paper uses the recently developed “impedance-to-scattering matrix method” to convert the element-based impedance matrix into the mode-based scattering matrix for transmission loss calculation. Depending on the shape of the inlet and outlet, it may not always be possible to find an analytical expression of the modes needed for the modal expansion. In this paper, the two-dimensional finite element method is used to extract the eigenvalues and the eigenvectors of the inlet/outlet cross section. The eigenvectors are then used in the modal expansion to convert the impedance matrix into the scattering matrix. Test cases include several commonly used inlet and outlet configurations, such as rectangular, circular and triangular cross sections.

      PubDate: 2016-11-12T23:48:09Z
       
  • Domain decomposition scheme with equivalence spheres for the analysis of
           aircraft arrays in a large-scale range
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Ting Su, Mengmeng Li, Rushan Chen
      we propose a domain decomposition scheme for solving scattering problem from multi-objects distribution in a large-scale range. Each sub-object is enclosed by an equivalence sphere. The scheme is composed of the equivalence process and translation process. In the equivalence process, the scattering fields from the sub-object are produced by the equivalence mode currents on the equivalence sphere. The equivalence mode currents are the current expansion of the body of revolution (BoR) basis functions, which are transformed from the current expansion of the Rao–Wilton-Glisson (RWG) basis functions. The multilevel fast multipole algorithm (MLFMA) is employed to accelerate the equivalence process. In the translation process, the mode translation matrices are obtained based on the BoR basis functions and the coordinate conversion method for computing the interactions among the equivalence spheres. The adaptive cross algorithm (ACA) is used to accelerate the evaluation of mode translation matrices. The proposed approach is very efficient for analysis of the objects distributed in a large-scale range. Numerical results demonstrate that the approach provides significant improvements in terms of memory requirements.

      PubDate: 2016-11-06T23:18:28Z
       
  • Three-dimensional BEM analysis of stress state near a crack-borehole
           system
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Dmitry V. Nikolskiy, Mattia Zammarchi, Sofia G. Mogilevskaya, Alberto Salvadori
      The paper presents a numerical study of the three-dimensional problem of cracks interacting with a cylindrical uniformly pressurized borehole. The theoretical developments describe general case in which the axis of the borehole can be inclined to the vertical direction, the cracks are either located outside of the borehole or emanate from it, and the in-situ stresses are uniform with major principal stress acting in vertical direction. The tractions are prescribed at the cracks surfaces that includes two limiting cases of traction-free cracks (“fast pressurization”) or cracks subjected to uniform load equal to that applied at the surface of the borehole (“slow pressurization”). The study is based on the complex integral representations for the three-dimensional fields around the borehole-crack system. The boundary surfaces are approximated using triangular mesh and quadratic polynomials are employed for approximating the boundary unknowns. The prescribed boundary conditions are met using “limit after discretization” procedure. The linear algebraic system to find the unknowns is set up by the collocation method. Two numerical benchmarks are presented.

      PubDate: 2016-11-06T23:18:28Z
       
  • Dynamic pressure distributions of semi-submersible
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Ke Wang, Xiaowei Gao, Xiaoming Cheng
      In the hydrodynamic study of Semi-submersibles, the wave pressure distribution on the wetted surface is critical input for structure analysis. Based on wave radiation and diffraction theory, a higher-order boundary element method (HOBEM) was applied to calculate the wave pressure distribution for a semi-submersible under specified wave direction and frequency. An integral system containing the FEM modeling of the semi-submersible, numerical calculation of hydrodynamic motion coefficients and data extraction and export for BEM analysis was established in the current study. A newly developed multiple and double nodes relocation method coupled with FEM-BEM model transformation is applied to remove the singularities along the sharp edges and corners of the semi-submersible. The numerical results confirm that the above algorithm significantly improves the numerical accuracy of wave pressure analysis for the semi-submersible.

      PubDate: 2016-11-06T23:18:28Z
       
  • A piecewise partitioning Scaled Boundary Finite Element algorithm to solve
           viscoelastic problems with cyclic symmetry
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Chongshuai Wang, Yiqian He, Haitian Yang
      Scaled Boundary Finite Element Method (SBFEM) and a temporally adaptive algorithm are combined to solve viscoelastic problems. By expanding variables at a discretized time interval, a spatially and temporally coupled viscoelastic problem is decoupled into a series of recursive spatial problems, which are solved by SBFEM, the computing accuracy in the time domain is controlled via a self-adaptive process. For the cyclic symmetric structures, the cyclic symmetry is exploited to reduce the computational expense of SBFEM, both the eigenvalue and system equations of SBFEM are partitioned into a number of smaller independent problems, which are solved by a partitioning algorithm. Two numerical examples are given to verify and illustrate the proposed approach.

      PubDate: 2016-11-06T23:18:28Z
       
  • Flows in slip-patterned micro-channels using boundary element methods
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Chandra Shekhar Nishad, Anirban Chandra, G.P. Raja Sekhar
      In this study we investigate steady, pressure-driven, two-dimensional flow of Newtonian fluid through slip-patterned, rectangular channels in the low Reynolds number limit. The slip flow regime is modeled using the Navier's slip boundary condition. In this work, we present only in-phase patterned slip. Subsequently, based on the characteristic length of the patterning, we have considered two subcases, namely large and fine patterned slip. Boundary element method (BEM) is used to numerically solve Stokes equation and obtain the streamline profiles. Streamlines, velocity profiles, pressure gradients, and shear stresses are analyzed to gain a proper understanding of the flow mechanics.

      PubDate: 2016-11-06T23:18:28Z
       
  • A generalized beta finite element method with coupled smoothing techniques
           for solid mechanics
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): W. Zeng, G.R. Liu, C. Jiang, T. Nguyen-Thoi, Y. Jiang
      This paper presents a generalized smoothing techniques based beta finite element method (βFEM) to improve the performance of standard FEM and the existing smoothed finite element methods (S-FEM) in solid mechanics. As we know, the edge-based (for 2D) or face-based (for 3D) strain smoothing techniques can bring much more accurate solutions than standard FEM, and offer lower bounds for force driven problems. The node-based smoothing technique with “overly-soft” feature, on the other hand has a unique property of producing upper bound solutions. This work proposes a novel generalized S-FEM with the smoothing domains generated based on both edges/faces and nodes. An adjustable parameter β is introduced to control the ratio of the area of edge/face-based and node-based smoothing domains. It is found that nearly exact solutions in strain energy can be obtained by tuning the parameter, making use of the important property that the exact solution is bonded by the solutions of NS-FEM and ES/FS-FEM. Standard patch tests are likewise satisfied. A number of numerical examples (static, dynamic, linear and nonlinear) have shown that the present βFEM method is found to be ultra-accurate, insensitive to mesh quality, temporal stable, capable of modeling complex geometry, immune from volumetric locking, etc.

      PubDate: 2016-11-06T23:18:28Z
       
  • Heat conduction analysis by adaptive iterative BEM-FEM coupling procedures
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): D. Soares, L. Godinho
      This work explores the application of coupled numerical models in thermal conduction analysis, taking into account frequency domain formulations. For this purpose, iterative coupling techniques between the Boundary Element Method (BEM) and the Finite Element Method (FEM) are discussed, also considering adaptive discretization procedures. Two coupling approaches are studied here, both using optimal relaxation parameters to ensure and/or to speed up the convergence of the iterative analysis. Non-matching discretizations on the common interfaces of the different subdomains of the model are allowed, and a single iterative cycle is adopted, incorporating both the adaptive and the coupling processes simultaneously. The methodology is quite flexible, and the possibility of using independent discretizations on each subdomain greatly facilitates the use of enhanced adaptive remeshing; in this context, specialized adaptive techniques for each subdomain/methodology may be applied. The adoption of a single iterative loop also renders a very efficient methodology, avoiding the excessive computational costs of sequentially chained iterative cycles. Numerical examples are presented in the end of the paper, illustrating the good performance of the proposed techniques, as well as their potentialities in engineering applications.

      PubDate: 2016-11-06T23:18:28Z
       
  • Automated hybrid singularity superposition and anchored grid pattern BEM
           algorithm for the solution of inverse geometric problems
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Marcus W. Ni, Alain J. Kassab, Eduardo Divo
      A method for solving an inverse geometric problem is presented by reconstructing the unknown subsurface cavity geometry with the boundary element method (BEM) and a genetic algorithm in combination with the Nelder-Mead non-linear simplex optimization method. The heat conduction problem is solved by the BEM which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a first step, clusters of singularities are utilized to solve the inverse problem and to identify the location of the centroid(s) of the subsurface cavity(ies)/flaw(s). In a second step, the reconstruction of the estimated cavity(ies)/flaw(s) geometry(ies) is accomplished by utilizing an anchored grid pattern upon which cubic spline knots are restricted to move in the search for the unknown geometry. The solution is achieved using a genetic algorithm accelerated with the Nelder-Mead non-linear simplex method. The automated algorithm successfully reconstructs single and multiple subsurface cavities within two dimensional mediums. The cavity detection was enhanced by applying multiple boundary condition sets (MBCS) to the same geometry. This extra information supplied on the boundary made the subsurface cavity easily detectable despite its low heat signature effect on the boundaries.

      PubDate: 2016-11-06T23:18:28Z
       
  • A new dual reciprocity hybrid boundary node method based on Shepard and
           Taylor interpolation method and Chebyshev polynomials
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Fei Yan, Xia-Ting Feng, Jia-He Lv, Peng-Zhi Pan, Shao-Jun Li
      A new dual reciprocity hybrid boundary node method (DHBNM) is proposed in this paper, in which the Shepard and Taylor interpolation method (STIM) and Chebyshev polynomials interpolation are proposed. Firstly, the Shepard interpolation is used to construct zero level shape function, and the high-power shape functions are constructed through the Taylor expansion, and through those two methods, no inversion is needed in the whole process of the shape function construction. Besides, Chebyshev polynomials are used as the basis functions for particular solution interpolation instead of the conical function, radial basis functions, and the analytical solutions of the basic form of particular solutions related to Chebyshev polynomials for elasticity are obtained, by means of this method, no internal node is needed, and interpolation coefficients can be given as explicit functions, so no inversion is needed for particular solution interpolation, which costs a large amount of computational expense for the traditional method. Based on those two methods, a new dual reciprocity hybrid boundary node method is developed, compared to the traditional DHBNM, no inversion is needed for both shape function construction and particular solution interpolation, which greatly improves the computational efficiency, and no internal node is needed for particular solution interpolation. Numerical examples are given to illustrate that the present method is accurate and effective.

      PubDate: 2016-11-06T23:18:28Z
       
  • Mixed miscible-immiscible fluid flow modelling with incompressible SPH
           framework
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Gourabananda Pahar, Anirban Dhar
      A divergence-free Incompressible Smoothed Particle Hydrodynamics (ISPH) framework is developed for modelling multifluid immiscible/miscible flows. The numerical model considers Navier-Stokes equation along with scalar-transport equation to represent flow characteristics. Pure divergence free ISPH algorithm is used to solve Navier-Stokes momentum equation. Scalar transport equation is solved based on the nature of the fluid particles represented in terms of colour indicator (ϕ). Fixed ghost particles are utilized for simulating slip boundary. Proposed model is validated against three analytical/experimental results: (a) immiscible Rayleigh-Taylor Instability (b) lock-exchange non-Boussinesq flow (c) miscible gravity current with low density ratio. The model can capture Kelvin-Helmholtz instabilities generated at the interface. the framework is capable of capturing density-dependent flow with low to high density ratio alike. The capability of the developed model in general multifluid system is demonstrated for two cases (a) miscible multimode Rayleigh-Taylor Instability and (b) mixed miscible-immiscible fluid flow simulation.

      PubDate: 2016-11-06T23:18:28Z
       
  • On deterministic-stochastic time domain study of dipole antenna for GPR
           applications
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): D. Poljak, S. Antonijevic, S. Sesnic, S. Lallechere, K. El Khamlichi Drissi
      A deterministic-stochastic transient study of Ground Penetrating Radar (GPR) dipole antenna radiating in a presence of a two-media configuration is carried out in the paper. A deterministic direct time domain formulation is based on the corresponding space-time Hallen integral equation. The numerical solution is carried out via the improved space-time variant of the Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM). The Stochastic-Collocation (SC) method is then applied to determine accurate confidence intervals due to the random variations of GPR input parameters. Once obtaining the current along the dipole antenna, it is possible to calculate other parameters of interest for GPR dipole antenna behavior, such as the field reflected from the interface of two media, or the field transmitted into a lower half-space. Some illustrative numerical results for the transient current along the dipole antenna and transient electric field transmitted into the lower half-space are given.

      PubDate: 2016-11-06T23:18:28Z
       
  • Using the Gaussian function to simulate constant potential anodes in
           multiobjective optimization of cathodic protection systems
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): W.J. Santos, J.A.F. Santiago, J.C.F. Telles
      The purpose of this work is to numerically find the optimum location of constant potential anodes to ensure complete structure surface protection using a cathodic protection technique. The existence of sacrificial anodes is originally introduced through the boundary conditions of the corresponding boundary value problem (BVP). However, if constant potential galvanic regions are introduced through its boundaries, then finding their optimal location is not an easy task due to the necessity of redefining boundary geometric nodes and the arrangement of virtual sources for the standard method of fundamental solutions (MFS) formulation. Therefore, in this work, the galvanic anodes are introduced as source terms using a Gaussian function. Hence, the boundary remains the same for different anode positions. The optimization process includes the identification of the following parameters characterizing the Gaussian function: the optimum coordinates of the centre of the anode, a factor that involves the inherent potential of the electrode and a proportionality factor for the electrode diameter. The MFS methodology coupled with a genetic algorithm presented good results for this multiobjective optimization procedure. This fact can be seen in the several results of applications that are discussed in this paper, considering numerical simulations in finite regions in R 2.

      PubDate: 2016-11-06T23:18:28Z
       
  • Direct meshless local Petrov–Galerkin method for the two-dimensional
           Klein–Gordon equation
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): Mohammadreza Ahmadi Darani
      In this paper we apply the direct meshless local Petrov–Galerkin (DMLPG) method to solve the two dimensional Klein–Gordon equations in both strong and weak forms. Low computational cost is the main property of this method compared with the original MLPG technique. The reason lies behind the approach of generalized moving least squares approximation where the discretized functionals, obtained from the PDE problem, are directly approximated from nodal values. This shifts the integration over polynomials rather than the MLS shape functions, leading to an extremely faster scheme. We will see that this method can successfully solve the problem with a reasonable accuracy.

      PubDate: 2016-11-06T23:18:28Z
       
  • Analysis of the inherent instability of the interpolating moving least
           squares method when using improper polynomial bases
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Xiaolin Li, Qingqing Wang
      This paper first discusses the inherent instability of the interpolating moving least squares (IMLS) method. In the original IMLS method, non-scaled polynomial bases are used. Theoretical and numerical results indicate that the stability of the original IMLS method decreases as the separation distance decreases. Then, using shifted and scaled polynomial bases, a stabilized algorithm of the IMLS method is proposed and analyzed. As an application, the stabilized IMLS method is finally introduced into the meshless Galerkin boundary node method (GBNM) to produce a stabilized GBNM for potential problems and Stokes problems. Numerical examples are given to demonstrate the stability and convergence of the presented stabilized algorithms.

      PubDate: 2016-11-06T23:18:28Z
       
  • A linear complementarity formulation of meshfree method for elastoplastic
           analysis of gradient-dependent plasticity
    • Abstract: Publication date: December 2016
      Source:Engineering Analysis with Boundary Elements, Volume 73
      Author(s): Guiyong Zhang, Yong Li, Haiying Wang, Zhi Zong
      This work presents a linear complementarity formulation for elastoplastic analysis of the gradient-dependent plasticity including large deformation problems. The formulation is based on the meshfree smoothed radial point interpolation method, where the parametric variational principle (PVP) is used in the form of linear complementarity and the gradient-dependent plasticity is represented by the linearization of yield criterion. The yield stress is linearly evolved through equivalent plastic strain as well as its Laplacian (namely second gradient). The global discretized system equations are transformed into a standard linear complementarity problem (LCP), which can be solved readily using the Lemke method. The proposed approach is capable of simulating material hardening/softening and strain localization. An extensive numerical study is performed to validate the proposed method and to investigate the effects of various parameters. The numerical results demonstrate that the proposed approach is accurate and stable for the elastoplastic analysis of 2D solids with gradient-dependent plasticity on strain localization.

      PubDate: 2016-11-06T23:18:28Z
       
  • Boundary element analysis of 3D cracks in anisotropic
           thermomagnetoelectroelastic solids
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): Iaroslav Pasternak, Roman Pasternak, Viktoriya Pasternak, Heorhiy Sulym
      The paper presents a general boundary element approach for analysis of 3D cracks in anisotropic thermomagnetoelectroelastic solids. Dual boundary integral equations are derived, which kernels are explicitly written. These equations do not contain volume integrals in the absence of distributed body heat and extended body forces, which is advantageous comparing to the existing approaches. The issues on the boundary element solution of these equations are discussed in details. The efficient numerical evaluation of kernels based on the trapezoid rule is proposed. Modified Kutt's quadrature with Chebyshev nodes is derived for integration of singular and hypersingular integrals. Nonlinear polynomial mappings are adopted for smoothing the integrand at the crack front, which is advantageous for accurate evaluation of field intensity factors. Special shape functions are introduced, which account for a square-root singularity of extended stress and heat flux at the crack front. The issues on numerical determination of field intensity factors are discussed. Several numerical examples are presented, which show the efficiency (low computational time and high precision) of the proposed boundary element formulation.

      PubDate: 2016-11-06T23:18:28Z
       
  • Boundary element analyses on the adhesive contact between an elastic
           sphere and a rigid half-space
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): Jiunn-Jong Wu, Yu Ju Lin
      Boundary element method is used to analyze the adhesive contact between an elastic sphere and a rigid half-space. Lennard-Jones potential is used for the surface traction. In the past, the simulation for the adhesive contact between spheres usually used paraboloid approximation for sphere surface. In this paper, the adhesive contact is investigated using exact sphere. A new algorithm for boundary element method is proposed. The S-shaped load-approach curve and the whole solution can be obtained. The result is compared with the adhesive contact between a rigid paraboloid and an elastic half-space, and that between an elastic paraboloid and a rigid half-space. It is found that the Tabor parameter and the radius of sphere affect the adhesive contact. As the Tabor parameter is larger, the effect of the radius is larger. As the radius is smaller, the pull-off force and the pull-off distance for fixed-grips device are smaller. The adhesive contact for rigid paraboloid/elastic half-space can approximate that for elastic paraboloid/rigid half-space and that for elastic sphere/rigid half-space with small Tabor parameter and large radius. Finally, an approximate equation for the pull-off force vs. Tabor parameter is proposed.

      PubDate: 2016-11-06T23:18:28Z
       
  • Quantification of cohesive fracture parameters based on the coupling of
           Bayesian updating and the boundary element method
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): Sergio Gustavo Ferreira Cordeiro, Edson Denner Leonel, Pierre Beaurepaire
      The fracture process in concrete involves nonlinear mechanical phenomena, which are accurately represented via the cohesive crack model. Due to the inherent randomness of this process, large scatter is observed in the experimental results. Therefore, significant uncertainties control the parameters that govern the theoretical approaches for concrete fracture modelling. In this study, a stochastic procedure for the parameter quantification of concrete nonlinear fracture models is presented. The Boundary Element Method is coupled to the cohesive model to model the nonlinear fracture phenomena. The Bayesian updating approach is subsequently applied to quantify the parameters that govern the cohesive laws based on the results of experimental analyses. The stochastic procedure enables the use of different cohesive laws to identify the law that provides the best agreement between numerical responses and experimental responses. A three-point bending notched test regarding different concrete mixtures is used to demonstrate the relevance of the proposed scheme.

      PubDate: 2016-11-06T23:18:28Z
       
  • GPU acceleration of the boundary element method for shear-deformable
           bending of plates
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): Ahmed A. Torky, Youssef F. Rashed
      This paper presents a novel implementation of GPU computing for boundary element method (BEM) formulation of plates. The new GPU code written in CUDA Fortran alters three kernels: the calculation of influence matrices, the solution of equations, and the computation of internal values. Comparisons for computation time and different GPU architecture are presented. The formulation is implemented for both constant and quadratic elements. The efficiency of the parallel quadratic code is demonstrated via analysis of practical building slabs. The benefits of parallel computing of the solution of the system of equations and of points inside the domain are discussed.

      PubDate: 2016-11-06T23:18:28Z
       
  • BEM numerical simulation of coupled heat, air and moisture flow through a
           multilayered porous solid
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): L. Škerget, A. Tadeu, J. Ravnik
      The problem of unsteady coupled moisture, air and heat energy transport through a porous solid is studied numerically using singular boundary integral representation of the governing equations. The governing transport equations are written and solved for the continuous driving potentials, i.e. relative humidity, temperature and air pressure. The boundary and interface conditions are discussed. The integral equations are discretized using mixed-boundary elements and a multidomain method also known as the macro-elements technique. The numerical model uses quadratic approximation over space and linear approximation over time for all field functions, which provides highly accurate numerical results. Three test benchmark examples (moisture uptake in a semi-infinite region, air transfer through a lightweight wall, and moisture redistribution inside a multilayered wall with capillary-active interior insulation), were analyzed to show the applicability and accuracy of the simulation model developed.

      PubDate: 2016-11-06T23:18:28Z
       
  • The combination of the boundary element method and the numerical manifold
           method for potential problems
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): Fei Tan, Yu-Yong Jiao
      In this study, a boundary element method coupled with numerical manifold method is developed for solving potential problems in two dimension. This approach combines an equivalent variational form of a boundary integral equation with the finite cover approximations for generating the trial and test functions of the variational formulation. This method exploits the reduced dimensionality advantages of the BEM, and is especially suited for the problems with an unbounded domain. Since the local cover function can be chosen in the covers arbitrarily, the method provides flexibility to use different cover functions for different covers and increases the solution accuracy without any local mesh refinement, and the p-adaptive analysis can also be performed conveniently. The validity and efficiency of the present method are demonstrated by some numerical examples of potential problems.

      PubDate: 2016-11-06T23:18:28Z
       
  • A regularization scheme applied to the direct interpolation boundary
           element technique with radial basis functions for solving eigenvalue
           problem
    • Abstract: Publication date: January 2017
      Source:Engineering Analysis with Boundary Elements, Volume 74
      Author(s): Carlos Friedrich Loeffler, Webe João Mansur
      This paper shows a regularization scheme applied to the recently developed Direct Interpolation Technique with Radial Basis Functions (DIBEM) for elimination of the singularity that exists in the kernel of the domain integral. As a simple interpolation, the kernel is approximated directly in DIBEM; however, it is composed of the fundamental solution, distinct positions between the source points and the field points being thus required. Through the proposed regularization scheme, both sets of source points and field points, as well as base points used for interpolation with radial functions may have the same coordinates. This facilitates the data entry and also the implementation of several operational steps of the DIBEM formulation. Solution of eigenvalue problem, generated by the Helmholtz Equation, is here chosen to exemplify the efficacy of the regularization procedure, but many other problems can thus be addressed, particularly the diffusive-advective problem, that has higher level of singularity in the interpolated kernel.

      PubDate: 2016-11-06T23:18:28Z
       
 
 
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