查询词典 maximum element

The main research tasks and results are as follows:(1) Through comparing the stress intensity factor of compact tension specimen calculated by finite element software with the theoretical value, the feasibility of calculating fracture parameters of crack tip in ABAQUS software was verified.(2) The relationship between the elastic modulus of the material and research scale was studied based on deriving the cohesive stress theory and other relevant theories. And the elastic modulus of the material on meso-scale was determined.(3) Global model and sub-model of the finite element were built in th...e macro-scale, and stress-strain field nearby the crack tip was analyzed, and the results show that the detailed stress-strain in the crack tip could be obtained by using the sub-model technique.(4) In meso-scale, the crack growth model was also established by assuming the crack propagating along the grain boundary, and the detailed stress-strain field in the crack tip was obtained.(5) The effect of crack length on Von Mises stress, and maximum principal stress and strain was analyzed in meso-scale when equivalent KI equals 30MPa.m1/2. And the results show that except for crack tip area, the stress-strain distribution in whole specimen is not affected.

主要完成研究内容和取得成果如下：(1)利用有限元软件计算出紧凑拉伸试样的裂纹尖端应力强度因子KI值，其结果与理论值一致，从而验证了利用ABAQUS计算裂纹尖端相关断裂参量的可行性；(2)在研究内聚应力等相关理论的基础上，推导出了研究尺度与材料弹性模量的近似关系，并确定了介观尺度上的弹性模量；(3)在宏观尺度上建立了全局有限元计算模型和子模型，得到了裂纹尖端应力应变场分布，结果表明利用子模型技术获得比较准确的裂纹尖端应力应变场分布是可行的；(4)在介观尺度上利用平均晶粒尺度的方式建立了裂纹沿晶扩展模型，得到了裂纹尖端断裂过程区的微观应力应变场；(5)当应力强度因子为30MPa.m1/2时，分析了介观尺度上在裂纹沿晶扩展过程中裂纹长度对Mises应力、最大主应力和应变的影响，结果表明，裂纹扩展长度对试样整体应力应变分布影响不大，而对裂纹尖端区域有较大影响；(6)介。。。

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。

Shadow effect can not be neglected for thermal analysis of spacecraft,Accroding to the angle between solar light and antenna orbit plane and its orbit location,analytical geometry method was used for accurately calculating solar radiation heat flux distribution of reflector surfaces.To analyze the temperature field under heat flux,the formulations of net radiation flux density between two gray elements and the net flux density of gray surface under external thermal flux were deduced.Based on the characteristic of space environment,the nonlinear temperature distribution in transverse direction of reflector shell self radiation were considered,the finite element formulations were given for orthogonal material layered shell by Galerkin method.A layered element including a inner heat source layer was proposed,and the finite element formulation expressed by DOF of the inner heat source layer were put forward with temperature and heat flux boundarys between adjacent layer.

单馈反射面赋形天线是未来星载天线发展的一个重要形式，分析了基于物理光学、几何光学和几何绕射理论的理想反射面辐射场；介绍了基于几何光学的反射面天线赋形方法；针对赋形过程中辐射场的快速分析要求，比较分析了基于物理光学的Fourier-Bessel和Jacobi-Bessel级数展开方法以及GB展开分析方法；利用GB展开快速分析方法在20GHz频率下对0.6m口径的天线进行赋形分析，实现中国大陆的30dB增益覆盖，通过数值计算研究了固定增益期望下的口径尺寸随频率的变化，以及频率为20GHz的不同尺寸天线赋形后的覆盖目标区域最大增益的变化情况。

In this paper we introduce a finite element program design method for solving 3 D thoracic electrical field distribution,based on Borland C++ for DOS and using isoparametric element of arbitrary hexahedron.In the process of solving final finite element equation,this paper uses the method of blocking and 'getting big number' to deal with total coefficient matrix and boundary conditions.

本文介绍了一种采用等参数8节点任意六面体单元来求解人体胸腔三维恒定电场分布的有限元程序设计方法，程序的编制基于BorlandC＋＋ForDOS的编程环境，在对最终形成的有限元代数方程的求解过程中采用了分块处理总系数矩阵及"取大数"处理边界条件的方法。

Usually, distribution networks operate in arborescence mode, so in the simulation of fault analysis the impact of faulty switch element on system reliability is apportioned to failure consequences of adjacent sections that connect to switch, and then an equivalent analytical model considering switch fault is proposed. Thus, not having to conduct the reliability analysis of switch element singly, the impact of switch element fault on system reliability can be calculated. Applying the proposed algorithm in RBTS-BDS6 system, RBTS-BUS4 system and actual medium-voltage distribution network to conduct reliability assessment, the results show that the proposed algorithm is superior in speed and possesses efficiency and engineering practicality.

配电网常具有树状运行特点，在故障解析模拟时，将开关元件故障对系统可靠性的影响分摊到连接开关的相邻分块的故障后果中，进而提出计及开关故障的可靠性等值解析模型，不需单独进行开关元件故障的可靠性分析即可计算其对系统可靠性的影响，应用该算法对RBTS-BUS6和RBTS-BUS4系统及实际中压配电网进行了可靠性评估，结果表明该算法有较明显的速度优势，具有高效性和工程实用性。

Then, taking the wave problems governed by the Helmholtz equation as an example, several conventional infinite elements such as the Bettess element, the Astley element and the Burnett element are compared and reviewed.

首先介绍无限单元的概念和无限元方法的特点；围绕求解以Helmholtz方程控制的波动问题，评述几种常规无限单元的优劣，这些单元包括Bettess元、Astley元和Burnett元。

The former, such as Bettess element and Astley element, needs geometry mapping and shape functions in terms of local coordinates, while for the latter, the shape functions are directly expressed in terms of global coordinates. This paper reviews the state-of-the-art and recent advances of the infinite element method for unbounded domains.

无限元分为映射无限元和非映射无限元：映射无限元需要引入几何映射，在局部坐标系中构造插值形状函数，如Bettess 元和Astley元；非映射无限元则直接在整体坐标系中构造插值形状函数，如Burnett元。

This paper presents the concept of structure basic element, structure variable element and the structure variable element design method.

从产品整个生命周期的产品数据模型分析入手，结合结构设计本身的特点，对结构设计的产品数据建模进行了研究。

Variable structure element design method was established, and basic structure element and variable structure element were defined.

本文以液压支架设计为背景，采用结构设计原型和基于原型的设计方法解决瓶颈问题，对结构设计、基于原型的设计方法和实现工具进行了深入的研究，主要工作如下： 1。

A comparative study of the bilinear, biquadratic quadrilateral element and quadratic triangular element for solving incompressible viscous flows was presented. These elements make use of the Galerkin/Least squares stabilized finite element formulation, in which the pressures and velocities are interpolated with the equal orders.

本文比较了用于求解不可压缩粘性流的四边形双线性、双二次单元及三角形二次单元的性能，这些单元采用GLS稳定化有限元格式，而压力和速度采用等阶数插值。

"The operators will suffer a temporary decrease in the number of consumers and short message services as people may not like having to provide their ID cards for a phone number," Xu Junqi, vice-dean with the Policy-Making Institute of the Telecommunications Research Centre under MII, said yesterday.

信息产业部下属的通信决策研究院副主任徐俊其昨天说：&实行手机实名制后，人们可能不太情愿用身份证注册手机号，所以通信运营商会暂时面临用户减少和短信用户减少的问题。&

I don't believe in make-believe!

我不相信这些虚构的故事。