研究了复杂微细导线电容矩阵提取边界元法(boundary element method,BEM)的边界离散问题以及增强计算精度和数值稳定性的有效措施,分析了开阔边界尺寸、开阔边界离散、导线离散对计算精度的影响以及伪解、矩阵奇异性问题,提出了基于导...研究了复杂微细导线电容矩阵提取边界元法(boundary element method,BEM)的边界离散问题以及增强计算精度和数值稳定性的有效措施,分析了开阔边界尺寸、开阔边界离散、导线离散对计算精度的影响以及伪解、矩阵奇异性问题,提出了基于导线离散迭代和开阔边界迭代两阶段自动迭代边界元算法(automatic iterative boundary element method,AIBEM),并结合实例阐述了全域法和区域分解法两种多层介质问题系数矩阵生成方法。研究结果表明,边界环内生成的系数矩阵存在误差均衡协调问题,对复杂模型需合理选择各线段离散单元数及开阔边界尺寸,通过AIBEM可以获得经济的离散参数,有效避免矩阵奇异性,并提高收敛稳定性。将计算结果与有限元法、解析法、传输线法、矩量法进行了对比分析,证实了算法的可靠性。展开更多
隧道开挖后形成的复杂地质结构导致边坡内部应力场分布极不规则,尤其是近开挖面区域存在强烈的应力集中和近奇异现象,这使得传统的数值模拟方法难以准确捕捉和模拟这些区域的应力状态,进而无法精确预测边坡的变形行为。因此,提出扁平状...隧道开挖后形成的复杂地质结构导致边坡内部应力场分布极不规则,尤其是近开挖面区域存在强烈的应力集中和近奇异现象,这使得传统的数值模拟方法难以准确捕捉和模拟这些区域的应力状态,进而无法精确预测边坡的变形行为。因此,提出扁平状断面高速公路隧道边坡稳定性数值模拟方法。利用边界元法(Boundary Element Method,BEM)求解扁平状断面高速公路隧道边坡内部应力场,克服近奇异问题,确保边界条件的可靠性及初始应力状态的真实性。随后,将BEM数据融入有限元模型(Finite Element Model,FEM),通过精细网格与强大计算力,全面模拟边坡变形过程及其稳定性状态。最后,将FEM的模拟结果作为输入,运用遗传算法(Genetic Algorithm,GA)进行全局搜索,以识别出最危险的滑动面,从而实现对边坡稳定性的精准监测。实验结果表明,上述方法能够有效提升模拟精度,为工程设计加固提供坚实依据。展开更多
In this paper, a method of transforming volume integrals to boundary integrals is given for complicated loadings such as a i(y)x i and b i(x)y i . In the present method the volume in...In this paper, a method of transforming volume integrals to boundary integrals is given for complicated loadings such as a i(y)x i and b i(x)y i . In the present method the volume integrals are approximately transformed to boundary integrals.展开更多
For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a su...For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a surface-piercing body. The set of over-determined linear equations obtained from the method is modified into a normal set of linear equations by superposing a set of linear equations with zero solutions. Numerical experiments have also been carried out to find the optimum choice of the size of the auxiliary domain and the discretization on it.展开更多
Cavity resonance noise of passenger car tires is generated by interacting excitation between a tire structure and the fill gas (air), and generally lies in a frequency range of 200?250 Hz. As such, this noise is stron...Cavity resonance noise of passenger car tires is generated by interacting excitation between a tire structure and the fill gas (air), and generally lies in a frequency range of 200?250 Hz. As such, this noise is strongly perceived and may be a serious source of driver annoyance. Thus, many studies regarding the cavity noise mechanism and its reduction have already been conducted. In this work, a vibro-acoustic coupled analysis was conducted between a tire structure and air cavity. Using this analysis, we can more accurately simulate the tire noise performance in the region of the cavity resonance frequency. An analysis of the effects of variation of tire contour design factors was conducted, using design-of-experiments methods. Finally, a multi-objective optimization was performed using in-house codes to reduce the cavity noise level while minimizing the loss of other performances, such as diminished ride comfort and handling caused by the variations of contour. As a result of this optimization, an optimized contour shape was derived, which satisfied the multi-objective performances.展开更多
文摘研究了复杂微细导线电容矩阵提取边界元法(boundary element method,BEM)的边界离散问题以及增强计算精度和数值稳定性的有效措施,分析了开阔边界尺寸、开阔边界离散、导线离散对计算精度的影响以及伪解、矩阵奇异性问题,提出了基于导线离散迭代和开阔边界迭代两阶段自动迭代边界元算法(automatic iterative boundary element method,AIBEM),并结合实例阐述了全域法和区域分解法两种多层介质问题系数矩阵生成方法。研究结果表明,边界环内生成的系数矩阵存在误差均衡协调问题,对复杂模型需合理选择各线段离散单元数及开阔边界尺寸,通过AIBEM可以获得经济的离散参数,有效避免矩阵奇异性,并提高收敛稳定性。将计算结果与有限元法、解析法、传输线法、矩量法进行了对比分析,证实了算法的可靠性。
文摘隧道开挖后形成的复杂地质结构导致边坡内部应力场分布极不规则,尤其是近开挖面区域存在强烈的应力集中和近奇异现象,这使得传统的数值模拟方法难以准确捕捉和模拟这些区域的应力状态,进而无法精确预测边坡的变形行为。因此,提出扁平状断面高速公路隧道边坡稳定性数值模拟方法。利用边界元法(Boundary Element Method,BEM)求解扁平状断面高速公路隧道边坡内部应力场,克服近奇异问题,确保边界条件的可靠性及初始应力状态的真实性。随后,将BEM数据融入有限元模型(Finite Element Model,FEM),通过精细网格与强大计算力,全面模拟边坡变形过程及其稳定性状态。最后,将FEM的模拟结果作为输入,运用遗传算法(Genetic Algorithm,GA)进行全局搜索,以识别出最危险的滑动面,从而实现对边坡稳定性的精准监测。实验结果表明,上述方法能够有效提升模拟精度,为工程设计加固提供坚实依据。
文摘In this paper, a method of transforming volume integrals to boundary integrals is given for complicated loadings such as a i(y)x i and b i(x)y i . In the present method the volume integrals are approximately transformed to boundary integrals.
基金This work is a part of the research project financially supported by the National Natural Science Foundation of China
文摘For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a surface-piercing body. The set of over-determined linear equations obtained from the method is modified into a normal set of linear equations by superposing a set of linear equations with zero solutions. Numerical experiments have also been carried out to find the optimum choice of the size of the auxiliary domain and the discretization on it.
文摘Cavity resonance noise of passenger car tires is generated by interacting excitation between a tire structure and the fill gas (air), and generally lies in a frequency range of 200?250 Hz. As such, this noise is strongly perceived and may be a serious source of driver annoyance. Thus, many studies regarding the cavity noise mechanism and its reduction have already been conducted. In this work, a vibro-acoustic coupled analysis was conducted between a tire structure and air cavity. Using this analysis, we can more accurately simulate the tire noise performance in the region of the cavity resonance frequency. An analysis of the effects of variation of tire contour design factors was conducted, using design-of-experiments methods. Finally, a multi-objective optimization was performed using in-house codes to reduce the cavity noise level while minimizing the loss of other performances, such as diminished ride comfort and handling caused by the variations of contour. As a result of this optimization, an optimized contour shape was derived, which satisfied the multi-objective performances.
