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建立了多元件谐振腔本征模的有限元传输矩阵模型。提出了模式计算相对误差概念及相应表达式,该表达式在数值上不受菲涅耳数的影响,能够很好反映有限单元划分方案对不同菲涅耳数的谐振腔的模式计算精度的影响。提出了有限单元划分精细度的概念和相应表达式,用以表征有限单元划分的精细程度。该表达式以菲涅耳数作为有限元传输矩阵法对腔镜单元格数划分的相对要求,用镜面实际划分的单元格数与菲涅耳数的比值来表征有限单元划分的精细程度。分析了不同谐振腔参数变化时模式计算相对误差与有限单元划分精细度的关系,建立了3种不同函数形式的经验表达式,并通过比较拟合残差选择了拟合效果较好的表达式。 相似文献
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由于Green应变具有单元翻转不变性,在大变形的仿真中有可能会出现单元的逆转,破坏模型网格的拓扑结构,导致仿真失败,因此提出一个新的有限单元模型,在采用Green应变度量变形同时把单元体积变化率和单元内压强关系引入到本构方程中,解决单元逆转问题;同时,模型导出的单元弹性势能是单元结点位移的多项式函数,有效地简化了共轭梯度法的求解,效率显著提高.实验结果表明,该模型可以应用于软组织大变形的实时仿真中. 相似文献
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用单块电子俘获器件,以一种新方法一时域编码方法,实现了所有16种布尔逻辑运算.根据电子俘获材料的存贮和可擦除特性,按特定顺序进行一系列单元操作,可测到每种布尔逻辑函数,同一般光学逻辑处理器相比,这种处理器具有新的自由度一时域自由度,文末给出了实验结果. 相似文献
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为提高计算生成集成成像实时交互显示性能和灵活性,构建与集成成像再现系统结构一致的集成光场视见模型,通过该模型为单元图像阵列中每个像素生成一条逆向追踪的光线,使用光线追踪技术并行渲染光线为单元图像阵列像素着色.实验结果表明,顶点数为565 880的点云模型、面数为977 308的含纹理网格模型在透镜数为22×13、视点数为175×175的4K显示系统上显示帧率40fps以上,并实现了缩放、移动、旋转、显示微调等交互功能.该方法摆脱了虚拟相机模型,降低了算法复杂度,利于实现实时交互,能够应用于基于不同分布形式透镜阵列的集成成像显示系统. 相似文献
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提出一种改进型HOPFIELD神经网络模型。通过对存贮模式进行互补扩展,消除了存贮模式中0和1个数不等问题。利用扩展模式互补性和由扩展模式所形成的连接权的镜象对称性,在不增加神经元个数和连接权矩阵维数的情况下,提高了网络的存贮能力和容错能力。在此基础上设计了全正光学连接权矩阵,在单通道内实现了双极寻址,降低了光学系统的复杂性。 相似文献
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采用磁性液体边界元数值模型分析了磁性粒子微结构磁化状态及相互作用,并与相应的有限元数值结果进行比较.结果表明:虽然粒子边界层附近的磁场分布出现了一定的模糊,且变化幅度明显高于有限元结果,但在粒子边界层以外的其它区域两种数值解法具有高度一致性;当粒子边界元节点数较小时,磁力相互作用边界元结果与有限元结果相差较大,且很不稳定;随着节点数增加,边界元结果逐渐趋近于有限元虚功原理的磁力数值结果,并达到一个较稳定的量值.结果清晰地反映出边界元数值方法在磁性液体多体动力学模拟研究中的一些基本特征。 相似文献
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New approaches are presented to discretize an arbitrarily supported linear structure carrying various lumped attachments. Specifically, the exact eigendata, i.e., the exact natural frequencies and mode shapes, of the linear structure without the lumped attachments are first used to modify its finite element mass and stiffness matrix so that the eigensolutions of the discretized system coincide with the exact modes of vibration. This is achieved by identifying a set of minimum changes in the finite element system matrices and enforcing certain constraint conditions. Once the updated matrices for the linear structure are found, the finite element assembling technique is then used to include the lumped attachments by adding their parameters to the appropriate elements in the modified mass and stiffness matrices. Numerical experiments show that for the same number of elements, the proposed scheme returns higher natural frequencies that are substantially more accurate than those given by the finite element model. Alternatively, the proposed discretization scheme allows one to efficiently and accurately determine the higher natural frequencies of a combined system without increasing the number of elements in the finite element model. 相似文献
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A multiresolution hexahedron element is presented with a new multiresolution analysis(MRA)framework.The MRA framework is formulated out of a mutually nesting displacement subspace sequence,whose basis functions are constructed of scaling and shifting on element domain of a basic node shape function.The basic node shape function is constructed from shifting to other seven quadrants around a specific node of a basic isoparametric element in one quadrant and joining the corresponding node shape functions of eight elements at the specific node.The MRA endows the proposed element with the resolution level(RL)to adjust structural analysis accuracy.As a result,the traditional 8-node hexahedron element is a monoresolution one and also a special case of the proposed element.The meshing for the monoresolution finite element model is based on the empiricism while the RL adjusting for the multiresolution is laid on the solid mathematical basis.The simplicity and clarity of shape function construction with the Kronecker delta property and the rational MRA enable the proposed element method to be more rational,easier and efficient in its implementation than the conventional mono-resolution solid element method or other MRA methods.The multiresolution hexahedron element method is more adapted to dealing with the accurate computation of structural problems. 相似文献
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A finite element model used to simulate the dynamics with continuum and discontinuum is presented. This new approach is conducted
by constructing the general contact model. The conventional discrete element is treated as a standard finite element with
one node in this new method. The one-node element has the same features as other finite elements, such as element stress and
strain. Thus, a general finite element model that is consistent with the existed finite element model is set up. This new
model is simple in mathematical concept and is straightforward to be combined into the existing standard finite element code.
Numerical example demonstrates that this new approach is more effective to perform the dynamic process analysis in which the
interactions among a large number of discrete bodies and continuum objects are included. 相似文献
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精确控制施加于驱动元件上的预应力,对换能器的设计及其工作过程都有重要意义,特别对于稀土磁致伸缩换能器来说,有助于发挥其最大潜能.利用有限元方法,计算了VII型水声弯张换能器壳体给驱动元件施加一定预应力时,壳体所需的装配位移的大小,并通过实验作了验证;弯张换能器随入水深度的不同, 驱动元件两端所受到的总的预应力是不同的.利用有限元方法,计算了换能器入水深度与预应力的关系.本文方法可适合于其他任何类型的换能器.
关键词:
弯张换能器
装配位移
预应力
入水深度 相似文献
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Designers often want to analyze more and more sophisticated structures, thus leading to very large finite element models (typically 10 00 000 degrees of freedom for a body car, for example). These models being too costly for the early stages of design and optimization can be reduced by a substructure analysis or a mesh simplification of the components. A methodology is proposed in this paper for simplifying finite triangular plate element models leading to a dramatic reduction in the number of degrees of freedom while preserving the dynamical properties of the initial system. In particular, the proposed method is developed for models composed of the plate element STIFF63 generated by the software ANSYS. The principle consists in determining the parameters (thickness, Young's modulus, density) of the triangular elements of a coarse model which replaces a large set of elements of the refined model. The simplified mesh must satisfy one of two criteria. The first requires that the mass and stiffness matrices of the simplified model be as close as possible to the Guyan condensed matrices of the refined model on the reduced node set, whilst the second requires that the dynamical properties of the global structure be preserved. The application of these approaches is illustrated on two test structures using the gradient method to solve the resulting optimization problem. The second approach is shown to give the best results. Typically, the size of the models can be reduced by a factor of 20 whilst preserving the dynamical properties of the structure at low frequencies. 相似文献
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A new finite element method for the efficient discretization of elliptic homogenization problems is proposed. These problems, characterized by data varying over a wide range of scales cannot be easily solved by classical numerical methods that need mesh resolution down to the finest scales and multiscale methods capable of capturing the large scale components of the solution on macroscopic meshes are needed. Recently, the finite element heterogeneous multiscale method (FE-HMM) has been proposed for such problems, based on a macroscopic solver with effective data recovered from the solution of micro problems on sampling domains at quadrature points of a macroscopic mesh. Departing from the approach used in the FE-HMM, we show that interpolation techniques based on the reduced basis methodology (an offline-online strategy) allow one to design an efficient numerical method relying only on a small number of accurately computed micro solutions. This new method, called the reduced basis finite element heterogeneous multiscale method (RB-FE-HMM) is significantly more efficient than the FE-HMM for high order macroscopic discretizations and for three-dimensional problems, when the repeated computation of micro problems over the whole computational domain is expensive. A priori error estimates of the RB-FE-HMM are derived. Numerical computations for two and three dimensional problems illustrate the applicability and efficiency of the numerical method. 相似文献
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以建立高效的动态分析方法为出发点,以边单元作为求解点,改进传统的格林元方法,减少未知数和求解矩阵维度;并提出基于改进格林元的加密网格加密方法,保证考虑复杂裂缝网络的压裂水平井动态模拟的早期精度.退化模型与半解析解、数值模拟结果进行对比,验证本文基于加密网格的改进格林元方法的准确性和动态分析的高效性.最后进行动态响应的敏感性分析,结果表明:①格林元方法是一种高精度的动态模拟方法,将求解节点设置在网格的边上可以提高压裂水平井动态模拟的速度;②改进格林元方法的加密基于叠加原理,不需要通过插值近似,其求解精度高.在相同加密网格条件下,基于本文改进格林元方法的加密效果比有限差分加密效果更佳;③复杂裂缝导流能力、改造区渗透率提高倍数、改造区大小等参数对压裂水平井动态特征影响较大,在动态分析和参数反演时,应着重考虑这些因素的影响. 相似文献