Papers by Keyword: Boundary Element Method (BEM)

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Authors: Ulrich Groh, Meinhard Kuna
91
Authors: Lih Jier Young, Pau Lo Hsu, Syh Shiuh Yeh, Yu Fang Cheng
Abstract: Circular ring is the most popular specimen in industry. The location of a crack in a circular ring can strongly affect the sequence of plastic hinge development which in turn affects stability of a circular ring which has been obtained theoretically in Young [1] but not any numerically. Boundary element method is employed to investigate these effects. In fact, the ring will collapse if the number of plastic hinges is up to four. The results show the potential application of the boundary element method in this project.
4476
Authors: Yi Liu, Yang Shi, Ya Ning Zhang
Abstract: The boundary element method was introduced to calculate the thermal resistance between pipe outside surface and the borehole inner surface of vertical U-shaped pipe underground heat exchanger. The effects of U-tube diameter, borehole diameter and tube spacing on the thermal resistance were also discussed. The results showed that it took only 10 min to complete a simulation of an underground heat pump running continually for 1000 h, which took least 3 h to complete the same cycle through finite volume method. When the thermal conductivity λ of the backfill material was 1.8 W/m2·K, the thermal resistance of the U-shaped pipe decreased with the increase in the tube spacing, it decreased with the increase in the U-tube diameter, however, it increased when the borehole diameter increased.
705
Authors: Jian Hua Wu, Shao Hua Xing, Cheng Hao Liang, Yong Gui Yan
Abstract: The corrosion related electro-magnetic signature is easily detected by modern sensor deployed in mine and other signal measurement system, so the importance of reducing is rapidly growing today. The eliminating effect of shaft frequency signature by shaft insulating technique, passive grounding technique and active grounding technique was comparatively studied by physical scale model (PSM), and their influence on static electromagnetic signature was also studied by boundary element method (BEM). Simulation results suggested that active shaft grounding technique was the best way for eliminating shaft frequency signature, but static electromagnetic signature was stronger than that when the shaft was insulated from hull.
450
Authors: Ivano Benedetti, M.H. Aliabadi
Abstract: A 3D grain boundary formulation is presented for the analysis of polycrystalline microstructures. The formulation is expressed in terms of intergranular displacements and tractions, that play an important role in polycrystalline micromechanics, micro-damage and micro-cracking. The artificial morphology is generated by Hardcore Voronoi tessellation, which embodies the main statistical features of polycrystalline microstructures. Each crystal is modeled as an anisotropic elastic region and the integrity of the aggregate is restored by enforcing interface continuity and equilibrium between contiguous grains. The developed technique has been applied to the numerical homogenization of cubic polycrystals and the obtained results agree well with available data.
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Authors: Z.L. Li, F.L. Zhan, S.H. Du
91
Authors: Hiroshi Okada, Yasuyoshi Fukui, Noriyoshi Kumazawa
511
Authors: Ivano Benedetti, M.H. Aliabadi
Abstract: A two-scale three-dimensional approach for degradation and failure in polycrystalline materials is presented. The method involves the component level and the grain scale. The damage-induced softening at the macroscale is modelled employing an initial stress boundary element approach. The microscopic degradation is explicitly modelled associating Representative Volume Elements (RVEs) to relevant points of the macro continuum and employing a cohesive-frictional 3D grain-boundary formulation to simulate intergranular degradation and failure in the Voronoi morphology. Macro-strains are downscaled as RVEs' periodic boundary conditions, while overall macro-stresses are obtained upscaling the micro-stress field via volume averages. The comparison between effective macro-stresses for the damaged and undamaged RVEs allows to define a macroscopic measure of local material degradation. Some attention is devoted to avoiding pathological damage localization at the macro-scale. The multiscale processing algorithm is described and some preliminary results are illustrated.
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Authors: Hong Wei Li, Yong Jie Pang, Guo Cheng Zhang
Abstract: The theory of 2D wave generation with active wave absorption is outlined. A new control method of active absorption wave-maker is established based on the S plane control (SPC) algorithm in this paper. Using SPC, a piston-type 2D numerical wave flume (NWF) simulation program for simultaneous wave generation and active wave absorption is developed with Boundary Element Method (BEM) and Mixed Eulerian-Lagrangian (MEL). The absorbing wave-making contrast simulation tests for regular wave are also carried out in NWF. Simulation results verify that the controller is robust and well effect for absorbing re-reflected wave is obtained in low reflect condition. Meanwhile, stable wave profile can be output by the absorbing wave-maker in a long time when acute reflected waves appear in the terminal of NWF.
1748
Authors: Tore Lucht, M.H. Aliabadi
Abstract: In an incremental crack extension analysis each crack increment is in general modelled with a straight extension. In order to avoid introduction of an error when the local crack growth criterion is used with an incremental formulation, each straight crack extension would have to be infinitesimal as the crack growth direction changes when the crack grows. A correction procedure to correct the extension direction of the increment can however be applied to ensure that a unique crack path is achieved with different analyses of the same problem performed with different size of the crack-extension increments. A proposed correction procedure and an reference correction procedure are demonstrated by solving a computational crack growth example. The demonstration shows that analyses of the crack path performed with big crack extensions and the proposed crack correction procedure are in excellent agreement with analyses of the crack path performed with very small crack extensions. Furthermore it is shown that the reference correction procedure has a tendency to overcorrect the crack growth direction if the stop criterion for the iterative correction procedure is not specified for each new crack growth analysis.
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