查询词典 fem

The major content of this thesis are as follows:1 Performed FEM analysis before strengthening, and to find out the reason for the cracking and present a strengthening scheme;2 Performed nonlinear FEM analysis before and after strengthening, and to get the varying rule of the relative displacement between the on-site cast concrete side wall and that between the precast concrete arch and the floor, as well as the stress distribution of the gallery;3 Performed on-site observation experiments on the 7~th gallery, and to get the varying rule of the relative displacement between the on-site cast concrete side wall, as well as that between the precast concrete arch and the floor.4 The results of the computation were compared with those of experiments, which verified the effect of the strengthening.

本文的主要工作有： 1 对加固之前的廊道结构进行有限元计算，找出廊道底板开裂的原因，提出加固方案； 2 对加固前后廊道结构进行非线性有限元计算，得到加固前后廊道两现浇边墙相对位移、拱顶与底板相对位移随水库水位变化的规律和廊道结构的应力分布情况； 3 进行廊道加固前后现场观测试验，得到廊道两现浇边墙相对位移以及拱顶与底板相对位移随水库水位变化的规律； 4 对比分析加固前后现场观测试验与非线性有限元计算所得结果，论证加固方案的合理性，验证加固效果。

Using fluid dynamics FEM (two dimensional, three dimensional andaxisymmetric) and three dimensional acoustic FEM in meticulous analysis ofexpansion muffler structure, this paper studies the influences of each mufflercomponents' position, dimension, form and quantity on the fluid dynamic andacoustic performances;therefore the paper indicates that the end of the intruding tubeis the linchpin of the fluid dynamic performance of the whole muffler structure, thespringhead of muffler fluid dynamic performance is the smoothness of air current, themain factor which affects the acoustic attenuation value of expansion chamber muffleris the grade of saltation of the section of air conducting access, and the attenuationvalue of specific frequency can be dramatically enhanced by carefully designing thelength of expansion chamber.

本文通过流体力学有限元方法和三维声学有限元方法对扩张腔消声结构的参数化模型进行了细致的分析，研究了这种结构的各个组成部份的位置、大小、形状和数量对其流体力学与声学性能的影响，指出插入管端口是影响整个结构流体力学性能的关键，消声结构流体力学性能的根源是气流通过时的平稳程度；影响扩张腔消声量的主要因素为声波传播通路截面突变的程度，并可以通过精细的设计扩张腔轴向长度获得宽频或指定频率消声量的大幅度提高。

The nitriding process of a large-scale crank shaft made from 35CrMo steel is simulated using non-linear FEM for the different supporting situations based on the above-stated visco-elastic mathematical model and measured data.

由于大型曲轴形状非常复杂，本文针对四种不同的支撑方式，用三维非线性有限元法结合上述粘弹性数学模型和实测数据模拟计算了35CrMo大型曲轴气体渗氮过程变形情况。

Through 3D FEM numerical simulation analysis of construction of the adit and main tunnel intersection structure with different intersection angles, this paper draws the conclusions that the smaller the intersection angle, the higher the concentration degree of the surrounding rock stresses and the larger the adit lining stresses.

本文采用三维有限元数值模拟主隧道与横通道组成不同交角的空间复杂受力交叉结构的施工过程，得出交叉角越小，围岩应力集中程度越高、横通道衬砌结构受力越大的结论。

The main factors affecting the soil-structure interface behaviors were found experimentally and theoretically, including: 1 the thickness of the interface that is five to six times the average grain size of the soil; 2 the aeolotropy of interface, which is responsible for anisotropic response of the stress-strain response of the interface; 3 two physical states, including crashing and compression of the soil near the structure surface, which govern the stress-strain response of the interface strongly; 4 two shear deformation components due to sliding and constraint of the structure surface relative to the soil respectively, which forms the deformation of the interface; 5 the volumetric strain due to dilatancy, which is found to be composed of a reversible dilatancy component and an irreversible dilatancy component. 4. A unified constitutive model of the interface, based on new elasto-plasticity damage theory, was developed. It was confirmed to be effective for the conditions considering monotonic and cyclic shearing, coupling effect of shear and volumetric strains, evolution of physical state, micro-structure aeolotropy of the soil and the resulting aeolotropy of the interface as well as the three normal boundary conditions stated above. 5. 2D and 3D finite element formulations of the present model were derived and incorporated into the FEM codes. They were applied to the evaluation of practical engineering problems with different typical interfaces between soil and structure. The new model was shown to be reasonable and effective.

确定了粗粒土与结构接触面厚度约为5～6倍的平均粒径，首次揭示了接触面的细观结构异向性以及由此所引起的宏观剪切异向性，发现了在单调和往返剪切荷载作用下土颗粒破碎和剪切压密两种物态变化机制共同支配着接触面力学性质的变化，通过细观分析证实了接触面的变形可分解为一般同时发生的土与结构交界面上的滑移变形以及结构面位移约束范围之内土体本身的剪切变形两部分，观测到接触面受剪时表现出明显的相对法向位移，并可分解为可逆性和不可逆性两个分量；(4)建立了第一个能够统一地描述单调与往返剪切特性、剪应变与体应变耦合特性、细观结构和宏观剪切异向性以及土颗粒破碎等物态变化特性的土与结构接触面弹塑性损伤本构数学模型，并采用多种法向边界条件复杂加载路径的试验成果验证了新模型的合理性和有效性；(5)提出了新模型的二、三维有限元格式并结合实际边值问题进行了应用计算分析，比较了不同接触面本构模型对计算结果的影响，证实了新模型及其有限元格式不仅能够合理地描述土与结构接触面的主要力学特性，还能够较好地反映土体与结构物在接触面处的滑移、脱开等不连续现象。

Furthermore,3-D FEM algorithm based on the division of tetrahedral grids is deduced by the equations of point electrical source field.

同时，从点电源场满足的方程出发，本文推导了三维复杂地形条件下有限元数值模拟算法，并编制了计算程序。

Compared with traditional numerical methods such as the FEM, FDM, etc, the LB method has several important features, including: simplicity in algorithm, easily programming, direct calculation of pressure from a state equation and amenability to simulate all kinds of flow field with complex boundaries, it also has much advantage in the respect of parallel computation because of its regional evolution.

与传统的计算方法如FEM、FDM等相比，LB方法具有算法简单、编程容易、压力可以通过状态方程直接求解、能够模拟各种复杂边界的流场等优点，并且计算的局域性使其在并行计算方面也具有很大的优势。

A reciprocal FEM analogue method is brought forward, by means of taking into account the interaction of tunneling, the peripheral soil and underground utilities. And the calculating program, DLFEA-TPR, is developed to calculate the tunneling-induced deformation and stress of adjacent utilities.

考虑隧道开挖与周围土体以及地下管线的相互作用，提出了相应有限元模拟方法，开发了隧道施工引起邻近地下管线变形及应力的计算程序DLFEA—TPR。

Evolvement of plate wave in level was studied by using both analytic geometry and FEM .

用几何分析和数值模拟相结合的方法，研究了具有横向浪形的中厚板在矫直过程中的演化。

Evolvement of plate in fifteen-roller combination leveler are studied in this paper using both analytic geometry and FEM.

用几何分析和数值模拟相结合的方法，研究了中板采用十五辊组合矫直机矫直过程中的变形演化状况。

The work of this paper is as follows: 1. Looking back the progressing history of the linear motor, introducing the features of the elevator driven by linear induction motor, radicating the topic of this paper "the digital frequency variable control of the elevator bi-side direct driven by linear induction motor". The research of this paper covers the conventional VVVF control, space vector based VVVF control, vector control and DTC.

本文主要开展了以下几个方面的工作： 1 回顾了直线电机发展历史，电机的驱动技术演变，特别是针对直线电机的驱动，简要介绍了直线感应电机驱动电梯的优点和不同结构类型，对传统的v／f控制，基于空间矢量法的v／f控制，矢量控制，和基于电压空间矢量的直接转矩控制进行了比较，确立了本课题的研究主题：直线感应电机双边直推式驱动电梯的全数字变频控制。

The article combines with the treatment of a superficial civil air defense work to introduce how the grouting method to improve the performance of the backfill soil.

文章从治理漂浮人防工事的角度提出了注浆技术在改善回填土性质方面的应用，并详细阐述了注浆技术的施工流程。