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41.
为研究机械激励下声呐导流罩壳内噪声预报问题,采用数值计算(有限元法-边界元法)结合实验的方法对一导流罩模型的壳内声场进行研究。首先依据实际导流罩模型建模,并加载机械激励进行数值计算,得到壳内声场的均方声压,然后进行湖内实验测量,最后对比了数值计算和实验的结果。研究表明:有限元法加间接边界元法是分析导流罩内声场这种封闭结构流-固-声耦合问题的有效方法;导流罩壳内声场的数值计算结果与实验测量结果吻合较好;声场均方声压与结构均方振速之比反映了罩壳结构内平均声场特性,可用来对比分析数值计算和实验的结果。 相似文献
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Federico C. Buroni Jhonny E. Ortiz Andrés Sáez 《International journal for numerical methods in engineering》2011,86(9):1125-1143
In this paper we develop an alternative boundary element method (BEM) formulation for the analysis of anisotropic three‐dimensional (3D) elastic solids. Our implementation is based on the derivation of explicit expressions for the fundamental solution displacements and tractions, of general validity for any class of anisotropic materials, by means of Stroh formalism and Cauchy's residue theory. The resulting fundamental solution remains valid for mathematical degenerate cases when Stroh's eigenvalues are coincident, meanwhile it does not exhibit numerical instabilities for quasi‐degenerate cases when Stroh's eigenvalues are nearly equal. A multiple pole residue approach is followed, leading to general explicit expressions to evaluate the traction fundamental solution for poles of m‐multiplicity. Despite the existence of general displacement solutions in the literature, and for the sake of completeness, the same approach as for the traction solution is considered to derive the displacement fundamental solution as well. Based on these solutions, an explicit BEM approach for the numerical solution of 3D linear elastic problems for solids with general anisotropic behavior is presented. The analysis of cracked anisotropic solids is also considered. Details on the numerical implementation and its validation for degenerate cases are discussed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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本文用的复变函数理论,导出了含裂板弯曲问题的基本解。该基本解满足自由裂纹的边界条件。将其引入直接或间接积分方程中,只要对板的外边界进行离散,就可计算有限尺寸裂纹板的弯曲问题。算例表明,本文所得到的基本解用以求解裂纹板弯曲问题划分的单元较少,精度较高。本文的方法还可用以求解含有形状比较复杂的裂纹或孔洞板弯曲问题的基本解。 相似文献
47.
Non-destructive evaluation for corrosion of reinforcement is performed limitedly by the half-cell potential measurement. To compensate the measured potentials for reasonable corrosion estimation, theory of the half-cell potential is clarified and a modified boundary element method (BEM) analysis was developed. An applicability of the proposed procedure was examined by electrolytic tests of reinforced concrete slabs. By the modified BEM, the potentials at rebars were computed from the potentials measured at the concrete surface. The ASTM criterion for the potential values was applied to the estimation of corrosion. Good agreement was observed between the predicted corrosive region of the rebars and actually corroded region. In the case of the specimen with a cavity, it was found that the half-cell potential measurement misleads to more negative potentials than those of no cavity. It was noted that software development is so simple as to be readily implemented in a microcomputer. 相似文献
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鱼雷电机-艉轴系统振动与声辐射特性分析 总被引:1,自引:0,他引:1
采用结构有限元软件ANSYS和声学边界元软件SYSNOSIE,对鱼雷电机一艉轴系统振动与声学特性数值计算问题进行了研究,建立了带有电机和轴系装置的鱼雷部分舱段的FEM/BEN数学模型。计算了在电机支撑架为刚性支撑和弹性支撑2种情况下,流固耦合模型结构的振动模态以及基于模拟电机激励下的频响分析。获得了鱼雷结构振动响应特征参数。以振动频响分析计算结果作为声学边界条件,比较了2种情况下结构噪声向外辐射的能力。最后考虑了电机空气动力噪声和敷设吸声材料,采用直接边界元法,对鱼雷近场声学特性进行了计算,计算结果表明,用AN- SYS和SYSNOSIE软件能合理地对鱼雷振动及声学特性进行分析,为工程设计提供了有效的工具。 相似文献
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Sang Soon Lee R. A. Westmann 《International journal for numerical methods in engineering》1995,38(4):607-629
This paper presents an accurate and efficient method for the treatment of time integrals in time-domain boundary integral equations for viscoelastic problems. First, the integral equations in space and time are derived for linear viscoelastic and thermo-viscoelastic problems. Then various quadrature rules are discussed for the computation of time integrals. A modified Simpson's rule is proposed as an effective integration scheme. The proposed procedure requires a small computational effort and it is applicable even in time-domain boundary element analysis of many different problems. Numerical results of example problems show the accuracy and effectiveness of the proposed method. 相似文献
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A formal error analysis of the order of approximation of a potential based boundary element method (BEM) for two-dimensional flows is performed in order to derive consistent approximations for the potential integrals. Two higher-order approaches satisfying consistency requirements to attain second and third order convergence in the potential are selected for numerical implementation. From the formal local expansions of the potential integrals the influence coefficients are derived and evaluated analytically. In order to assess the methods accuracy, the low and higher-order methods are applied to two-dimensional steady flows around analytical foils. A numerical error analysis is done and a comparison between their theoretical and numerical asymptotic order of accuracy performed.
The first author acknowledges the financial support granted by Fundação para a Ciência e a Tecnologia, Ph.D. grant PRAXISXXI/BD/2226/99. This work was done under the project PRAXIS/2/2.1/MAR/1723/95. 相似文献