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The basic approach of protecting people from being hurt or killed in an accident is to improve crashworthiness of vehicles. This paper starts with discussing theories and methods for vehicle passive safety design, which included experiential methods, analytic methods, multi-body dynamics methods, crash test methods and the finite element method. Emphasis will be paid to the basic FEM theories and algorithms of impact problems. Topics discussed include the governing equation, element discretization, hourglass control, time integration, material model, shell element algorithms and contact-impact algorithms. For more reliable simulation results, this paper then conducts study on how to accurately get material model parameters by combining the FEM method with experimental method, and develops relevant material test machine and parameter calculating software. Based on that, basic typical impact simulation and test validation study are conducted. On the basis of the above work, the paper studies the thin-shell structures'crashworthiness, which was affected by the following factors: spot-weld features, shell thickness, cross-section and pre-deformation. As to vehicle parts'crashworthiness, the paper conducts simulation study of designing energy-absorbing steering system and adaptive airbag system. A practical energy-absorbing steering wheel is designed as an example. In further depth research, the paper suggests several inverse quantificational methods for vehicle crashworthiness design based on the ideal crash characteristics. The above theories and methods are applied with good results through several practical vehicles' crashworthiness design and improvement.

文中对汽车碰撞安全性的设计理论和方法进行了归类和总结，其中包括经验法、解析法、多刚体动力学法、试验法以及有限元方法等；重点介绍了碰撞有限元法的基本理论和有关算法，涉及到有限元求解控制方程、单元离散、沙漏模态控制、时间积分、材料模型和应力修正、薄壳单元算法以及接触碰撞界面算法等，探讨了有限元计算中的材料模型参数获取技术，开发了相应的材料试验装置及材料模型参数反求软件，在此基础上进行了基本的碰撞仿真算例和试验对比研究；文中通过应用有限元方法研究了薄壁构件的碰撞吸能特性，指出了设计薄壁吸能构件时需要考虑的几个主要影响因素，即焊点、壁厚、横截面和预变形等；在关于车辆部件的碰撞安全性能设计中进行了吸能转向机构和自适应安全气囊的仿真研究，提出了吸能转向机构和自适应安全气囊的仿真研究方法；文中最后探讨了整车碰撞性能的设计与改进方法，提出了以理想碰撞特性为目标，采用分段加速度或者根据碰撞时间进行设计的反推设计法、部件吸能仿真优化设计法等量化设计方法，并通过综合应用文中所讨论的相关技术进行了整车碰撞性能的设计与改进实例研究，所选定的车型是大众化的普通轿车和碰撞安全性基础较差的微型面包车，研究结果表明，本文所提出的设计与改进方法是适用而有效的，具有重要的工程实用意义和价值。

Tool paths, and working procedure effecting machining residual stress as well as the law of its releasing were analyzed systemically by using three-dimensional Elasto-plastic FEM, which can optimize the tool paths and make the working procedure more rational.In the course of FEM simulation, the birth-death element arithmetic was introduced into simulating material remove, and the kinetic Load-step was used to simulated tools work.

第四，在上述研究的基础上，利用三维弹塑性有限元技术系统地分析了铣削力要素下铣削加工中走刀路径对已加工表面残余应力分布状态的影响规律以及铣削加工工序间残余应力的相互影响规律，为优选出较为合理的走刀路径和加工过程中安排去应力工序提供指导。

The comparison based on FEM, SEA and the closed form solution reveals th e effectiveness of SEA in the prediction of high-frequency response. Next, the energy transmission between two coupled beams is obtained through FEM, and then the CLF used by SEA is built.

然后以耦合梁为例，通过有限元法得到两个梁之间的能量传递，并进而得到SEA所需的耦合损耗因子；将有限元计算结果和SEA结果对比验证了该方法的有效性，以期建立一种用有限元法获得SEA参数的新途径。

In this paper, the 3D FEM models of cone-tread and worn-tread locomotive and vehicle wheels are firstly established, which come into contact with the rail of standard size. There hasn't been any more refined 3D FEM computation model of wheel/rail up till now. The elastic effect of crosstie and roadbed is also considered.

本文建立了锥形踏面、磨耗形踏面的机车和车辆车轮分别与标准轨道相接触的三维有限元计算模型，模型还考虑了轨枕和部分道床的弹性作用。

In this paper, the 3D FEM models of cone-tread and worn-tread locomotive and vehicle wheels are firstly established, which come into contact with the rail of standard size. There hasnt been any more refined 3D FEM computation model of wheel/rail up till now. The elastic effect of crosstie and roadbed is also considered.

本文建立了锥形踏面、磨耗形踏面的机车和车辆车轮分别与标准轨道相接触的三维有限元计算模型，模型还考虑了轨枕和部分道床的弹性作用。

The shape-form analysis and load analysis were done by nonlinear FEM. On the basis of surface FEM grid nodes, geometry property research of structure curved surface was progressed, including normal vector, GAUSS curvature, mean curvature and principal direction vector. In this process, the approximate expression of surface didn't need to he known.

采用非线性有限元法进行了膜结构的形态分析和荷载分析，得到了曲面有限元网格；通过离散微分几何方法，研究了薄膜结构曲面的几何性质，包括曲面的法线向量、高斯曲率、平均曲率和主方向矢量，避免了复杂的曲面拟合过程。

At present, although finite element methods is a kind of effective measures in analyzing metal plastically forming problems with friction, dynamic friction in the process of metal forming is substituted with static friction and constant frictional force as one of independent constraint conditions is transposed to equivalent node-load or FEM unit is divided into contact unit and inner unit in numerous studys and applications, so that it result in relative bad accuracy and awkward operation. These defects mostly attribute to the fact that FEM bases on the variational equality principles, however frictional constraint will actually result in variational inequality energy functional.

目前，应用于分析金属塑性成形的有限元法是一种有效的处理摩擦效应的定量计算方法，但是许多应用和研究是用常摩擦来代替金属塑性成形过程中的动态摩擦；把常摩擦力作为单独的约束条件移置到等效结点载荷上或把有限元单元划分成接触单元和内单元，这些将导致解的精度相对不高及实际操作不方便等一系列问题，产生这些不足的重要原因之一在于它的理论基础是变分等式原理。

At last ,taking Kash as an example ,it evaluates this areas Groundwater Resources ,and give out three predicting projects by making use of visual FEM mesh generation software and the numerical solution of Galerkin FEM equations for multiaquifers .

最后以喀什噶尔地下水资源评价工作为例，利用可视化有限元自动剖分软件，以及伽辽金有限元数值解法进行了该地区的地下水资源评价，进行了多种开采方案的预测和对比工作。

Special FEM analysis considerations of pantadome system are taken into account in the mechanical theoretical analysis. The problem of initial deformation and initial stress of pantadome, serialization treatment of the FEM results are discussed, the treatment methods of calculate results are deduced, membrane stress and flexural stress of gyrate shell are deduced in this paper.

在攀达穹顶的力学理论分析中，针对攀达穹顶体系的特殊性进行了有限元分析，研究了攀达穹顶体系分析中的初始变形与初始应力问题，对攀达穹项体系有限元计算结果进行了连续化处理，提出了计算结果的连续化处理方法，推导了连续化处理时各个力的求解方法并求解了旋转壳的膜应力和弯曲应力。

According to the studied results at present, the studied objects are mainly thin plate and beam about sound radiation mode, a method computed sound radiation mode of complex structure is presented in this dissertation, according to the results of the previous two chapter, a theoretical method to solve acoustical radiation mode and acoustical radiation efficiency of complex structure by boundary element method and acoustical radiation theory is posed, the acoustical radiation power is expressed as a Hermitian quadratic form, while the radiation modes is determined by general eigenvalue decomposing, and then the radiation efficiency is computed via the orthodoxy of radiation modes with regard to impedance matrix and average velocity matrix; lastly, the validity of the method is proved by pulsating sphere and radiating cube with analytical results. According to results of the form three chapter, the structure sound radiation sensitivity is studied in detail, the sound radiation power of structure can be expressed as positive Hermitian quadratic form, the sound radiation sensitivity can be expressed as two parts by partial differential with respect to design variable, which are sensitivity of boundary velocity and impedance matrix, combined with the theory of FEM and BEM, the structure sound radiation can be translated to the analysis of structure dynamic sensitivity and impedance matrix sensitivity. The theory posted in this dissertation is tested by the FEM software ANSYS and the software AAS programmed by author.

在前几章的基础上，通过结构声辐射的模态理论对结构的声辐射的机理进行了深入地探讨，针对目前声辐射模态的研究对象主要是简单的板和梁类结构，提出了一种计算复杂结构声辐射模态的方法，利用前两章研究所得的结论，将边界元方法与广义特征值的理论结合起来研究了复杂结构的声辐射模态与声辐射效率，先将结构的声辐射功率表示为一个正定的厄米特二(来源：ABb7C论文0909网www.abclunwen.com)次型，运用广义特征值分解求解了复杂结构的声辐射模态，然后利用声辐射模态关于阻抗矩阵与均方速度耦合矩阵的正交性，求解了复杂结构的声辐射效率，最后用具有解析解的脉动球与辐射立方体验证了该方法的有效性。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。