共查询到18条相似文献,搜索用时 93 毫秒
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本文在采用边界元方法计算无限域中任意形状结构声辐射的基础上,通过重新推导适用于半无限域问题的Green函数,对存在反射面时结构的声辐射情况进行了研究并编制了相应的计算机程序;在此基础上,对放置在刚性反射面上的均匀脉动球的辐射声场进行了计算,与相应的解析解进行了比较并对计算误差作了分析。 相似文献
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结构振动辐射声场的预估——边界积分方程中奇异积分的间接处理 总被引:4,自引:0,他引:4
本文讨论了利用边界积分方程和边界元技术计算结构的稳态外辐射声场的方法,同时,对边界元方法所固有的奇异数值积分提出了一种简单方便的间接处理方法。计算实例证明所编计算程序和奇异积分处理方法是成功的。利用该程序在已知结构表面振速分布的条件下,可以求出该结构在自由声场中的声功率、表面辐射效率以及声场中任意点的声压值和相位。对一个实际钢质空心封闭圆筒作了计算与实测的比较,结果显示了该方法可应用于实际结构或机器的前景。 相似文献
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本文从半无限域结构体声辐射的理论公式──半无限域Helmhothtz积分方程入手,采用边界元法(简称BEM法)离散积分方程,通过变压器壳体表面振动速度场来计算变压器向外辐射的噪声场。文中讨论了计算变压器辐射噪声场的数值计算模型,变压器体表面振动速度的测试,并将BEM法计算结果与实测结果进行了比较,两者基本吻合,最后简要分析了造成误差的原因。 相似文献
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用样条边界元计算振动体的三维稳态声辐射 总被引:1,自引:0,他引:1
本文采用三次B样条边界单元计算振动体的三维稳态声辐射。实际计算表明:采用样条边界元可获得较好的数值计算结果。此外,本文在计算声场内点声压的Helmholtz边界积分公式的基础上,导出了计算声场内点质点振速和声强的边界积分公式。文中还给出了应用本文方法计算的算例结果。 相似文献
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Helmholtz声学边界积分方程中奇异积分的计算 总被引:5,自引:0,他引:5
提出了一种非等参单元的四边形坐标变换,它将积分的曲面单元映射为另一四边形单元,通过两次坐标变换引入的雅可比行列式可以消除Helmholtz声学边界积分方程中的弱奇异型O(1/r))积分.而且利用δr/δn以及坐标变换可以同时消除坐标变换无法消除的Cauchy型(O(1/r^2))奇异积分,并给出了消除奇异性的详细证明.该方法给Helmholtz声学边界积分方程中的弱奇异积分与Cauchy奇异积分的计算以及编程提供了极大便利。 相似文献
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结构声辐射有限元/边界元法声学-结构灵敏度研究 总被引:12,自引:1,他引:12
声学-结构灵敏度用于预测结构辐射声压随结构设计变量的变化,该值对结构降噪设计有重要意义。提出了基于有限元法、边界元法的声学-结构灵敏度计算方法。基于有限元法计算结构动力学响应及响应速度灵敏度,基于边界元法计算结构辐射声压及声压对振动速度灵敏度。将两个灵敏度联合,得到声学-结构设计灵敏度。以中空六面体为研究实例,给出了激励频率为1~100 H z时,外场声压对壳厚度的灵敏度,并分析了灵敏度随激励频率、设计变量的变化规律。结果表明,基于有限元法、边界元法的声学-结构灵敏度是有效和正确的。 相似文献
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利用边界元法中的全特解场方法计算结构振动声辐射 总被引:6,自引:0,他引:6
本文通过利用边界元法中的全特解场方法,对结构振动声辐射的计算进行了研究,并以脉动球为算例,将计算结果与解析解进行比较,结果表明:该方法与一般边界元法相比,在边界剖分相同的情况下,能够在相当宽的振动范围内,给出满意的计算结果。 相似文献
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Letizia Scuderi 《International journal for numerical methods in engineering》2008,74(11):1733-1770
In this paper, we propose an efficient strategy to compute nearly singular integrals over planar triangles in R 3 arising in boundary element method collocation. The strategy is based on a proper use of various non‐linear transformations, which smooth or move away or quite eliminate all the singularities close to the domain of integration. We will deal with near singularities of the form 1/r, 1/r2 and 1/r3, r=∥ x ? y ∥ being the distance between a fixed near observation point x and a generic point y of a triangular element. Extensive numerical tests and comparisons with some already existing methods show that the approach proposed here is highly efficient and competitive. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Sundararajan Natarajan Chongmin Song 《International journal for numerical methods in engineering》2013,96(13):813-841
In this paper, we replace the asymptotic enrichments around the crack tip in the extended finite element method (XFEM) with the semi‐analytical solution obtained by the scaled boundary finite element method (SBFEM). The proposed method does not require special numerical integration technique to compute the stiffness matrix, and it improves the capability of the XFEM to model cracks in homogeneous and/or heterogeneous materials without a priori knowledge of the asymptotic solutions. A Heaviside enrichment is used to represent the jump across the discontinuity surface. We call the method as the extended SBFEM. Numerical results presented for a few benchmark problems in the context of linear elastic fracture mechanics show that the proposed method yields accurate results with improved condition number. A simple code is annexed to compute the terms in the stiffness matrix, which can easily be integrated in any existing FEM/XFEM code. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Bruce A. Ammons Madhukar Vable 《International journal for numerical methods in engineering》1998,41(4):639-650
The discretization of the boundary in boundary element method generates integrals over elements that can be evaluated using numerical quadrature that approximate the integrands or semi-analytical schemes that approximate the integration path. In semi-analytical integration schemes, the integration path is usually created using straight-line segments. Corners formed by the straight-line segments do not affect the accuracy in the interior significantly, but as the field point approaches these corners large errors may be introduced in the integration. In this paper, the boundary is described by a cubic spline on which an integration path of straight-line segments is dynamically created when the field point approaches the boundary. The algorithm described improves the accuracy in semi-analytical integration schemes by orders of magnitude at insignificant increase in the total solution time by the boundary element method. Results from two indirect BEM and a direct BEM formulation in which the unknowns are approximated by linear and quadratic Lagrange polynomial and a cubic Hermite polynomial demonstrate the versatility of the described algorithm. © 1998 John Wiley & Sons, Ltd. 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1466-1487
In this paper, the coupling of the improved interpolating element‐free Galerkin (IIEFG) method and the variable‐order infinite acoustic wave envelope element (WEE) method is studied. A coupled IIEFG‐WEE method for computing sound radiation is proposed to make use of their advantages while evading their disadvantages. The coupling is achieved by constructing the hybrid shape function of continuity and compatibility on the interface between the IIEFG and WEE domains. In the IIEFG domain, the improved interpolating moving least‐squares (IIMLS) method is used to form the shape functions satisfying the Kronecker delta condition while nonsingular weight functions can be used. The impacts of the size of the influence domain and the shape parameter on the performance of this coupled method are investigated. The numerical results show that the coupled IIEFG‐WEE method can take full advantage of both the IIEFG and WEE methods and that it not only can achieve higher accuracy but also has a faster convergence speed than the conventional method of the finite element coupled with the WEE. The experimental results show that the method is very flexible for acoustic radiation prediction in the infinite domain. 相似文献
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Yan Gu Wen Chen Hongwei Gao Chuanzeng Zhang 《International journal for numerical methods in engineering》2016,107(2):109-126
This study documents the first attempt to extend the singular boundary method, a novel meshless boundary collocation method, for the solution of 3D elasticity problems. The singular boundary method involves a coupling between the regularized BEM and the method of fundamental solutions. The main idea here is to fully inherit the dimensionality and stability advantages of the former and the meshless and integration‐free attributes of the later. This makes it particularly attractive for problems in complex geometries and three dimensions. Four benchmark 3D problems in linear elasticity are well studied to demonstrate the feasibility and accuracy of the proposed method. The advantages, disadvantages, and potential applications of the proposed method, as compared with the FEM, BEM, and method of fundamental solutions, are also examined and discussed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Analytic formulations for calculating nearly singular integrals in two-dimensional BEM 总被引:1,自引:0,他引:1
Zhongrong Niu Changzheng Cheng Huanlin Zhou Zongjun Hu 《Engineering Analysis with Boundary Elements》2007,31(12):949-964
There exist the nearly singular integrals in the boundary integral equations when a source point is close to an integration element but not on the element, such as the field problems with thin domains. In this paper, the analytic formulations are achieved to calculate the nearly weakly singular, strongly singular and hyper-singular integrals on the straight elements for the two-dimensional (2D) boundary element methods (BEM). The algorithm is performed after the BIE are discretized by a set of boundary elements. The singular factor, which is expressed by the minimum relative distance from the source point to the closer element, is separated from the nearly singular integrands by the use of integration by parts. Thus, it results in exact integrations of the nearly singular integrals for the straight elements, instead of the numerical integration. The analytic algorithm is also used to calculate nearly singular integrals on the curved element by subdividing it into several linear or sub-parametric elements only when the nearly singular integrals need to be determined. The approach can achieve high accuracy in cases of the curved elements without increasing other computational efforts. As an application, the technique is employed to analyze the 2D elasticity problems, including the thin-walled structures. Some numerical results demonstrate the accuracy and effectiveness of the algorithm. 相似文献
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Peter R. Johnston 《International journal for numerical methods in engineering》1999,45(10):1333-1348
Accurate numerical determination of line integrals is fundamental to reliable implementation of the boundary element method. For a source point distant from a particular element, standard Gaussian quadrature is adequate, as well as being the technique of choice. However, when the integrals are weakly singular or nearly singular (source point near the element) this technique is no longer adequate. Here a co‐ordinate transformation technique, based on sigmoidal transformations, is introduced to evaluate weakly singular and near‐singular integrals. A sigmoidal transformation has the effect of clustering the integration points towards the endpoints of the interval of integration. The degree of clustering is governed by the order of the transformation. Comparison of this new method with existing co‐ordinate transformation techniques shows that more accurate evaluation of these integrals can be obtained. Based on observations of several integrals considered, guidelines are suggested for the order of the sigmoidal transformations. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献