有限元法

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。

In this paper, from two aspects of the total potential method and abnormal potential, three types of boundary conditions which affect calculating results in the finite element method are analyzed, and this provides a foundation for using the appropriate boundary conditions and selecting the best distance to enhance its accuracy.

本文从总电位法和异常电位法两个方面，分别就直流电法有限元中所采用的三类边界条件对计算结果的影响进行了分析，为采用合适的边界条件及选取最佳边界距离来提高正演精度提供了基础。

Using the existing conventional computing technique in general finite element method, the obtained result is incorrect.

这一方法不仅可以解决常规有限元的刚度矩阵并行组集的问题，也可实现常规有限元数据到无网格单元法的数据格式的转换与融合。

Firstly, this paper investigated roundly the basic theory of the ambient vibration method, analyzed systematically the main methods of ambient vibration identification, and discussed their advantages and disadvantages. Then we established the finite element model of structural dynamics and test model and analyzed their mutual relation, improved MUSIC method and correlation function method in the harmonic identification, and gave the subspace method and correlation function method based on continuous model, which is multi-harmonic retrieve technique. And then, this paper also puts forward least-squares method to estimate directly structural physical and modal parameters; this approach replaced the derivative operator in the continuous time model with an equivalent approximation, and estimated the physical parameters of structures by the least-squares method. And then, we discussed the approximation methods of derivative and their convergence. Finally, this paper researched the modal parameters of a frame structure by the simulation and test. The results demonstrated that subspace method, correlation function method and the least-squares method are effective and stable respectively.

全面地研究环境振动识别方法的基本理论，系统地分析环境振动识别方法的主要方法，讨论它们的优点和不足；建立结(来源：6666AB44C论文网www.abclunwen.com)构动力学的有限元模型和试验模型，分析有限元模型与试验模型之间的相互关系；改进谐波识别中的MUSIC识别方法和相关函数识别方法，给出大型结构模态识别的连续型的子空间分解识别方法和相关函数识别方法，这个方法是多元谐波识别方法；提出直接识别结构的物理参数和模态参数的最小二乘方法，这个方法利用导数的近似值代替导数值，并运用最小二乘方法识别结构的物理参数，讨论导数近似值的选择方法，分析算法的收敛性；通过仿真计算和模型实验，研究高层框架结构的模态参数识别，验证子空间分解识别方法、相关函数识别方法和最小二乘识别方法的有效性，算法的稳定性；从理论和试验两个方面分析和研究噪声对识别精度的影响，影响识别精度的因素，以及部分模态成分的模态参数不能够被识别的原因。

With the method of Stress Function,this paper analyzes the distribution of stresses of biaxial tensile and builds the finite element model of biaxial tensile test of cruciform specimens with slots on arms.

用应力函数法分析了双向拉伸的应力分布，建立了臂上开缝十字形试件双向拉伸试验的有限元模型，使用大型通用有限元软件ANSYS8.0对十字形双向拉伸试验进行模拟及分析，并对其结构尺寸进行优化设计。

Finally, by means of electrometric method, the stress of the exterior surface of the feed inlet was measured. The curvilinear figure of the stress distribution of the exterior surface was drawed and compared with the results of the finite element analysis. The rationality of theory analysis and the reliability of finite element analysis were verified.

最后，采用电测法对进料口的外表面应力进行了实验测量，绘出进料口外表面应力分布曲线并与有限元分析结果对比，验证了理论分析的合理性和有限元分析的可靠性。

Brief the; of commonly used method that narrated research to sort solid coupling problem discussed iterative method of dry mode law, across and LS-DYNA finite yuan of software analysis law, the theoretical calculation that is problem of coupling drifting solid offerred new method and train of thought, the analysis of problem of convection solid coupling has fair referenced value.

简要叙述了探究流固耦合新问题的常用方法；讨论了干模态法、交叉迭代法以及LS-DYNA有限元软件分析法，为流固耦合新问题的理论计算提供了新的方法和思路，对流固耦合新问题的分析有一定的参考价值。

On thebase of the theory, the finite element model of interaction system is constructed.

本文通过对有限元原理和子结构法的介绍，阐明了建立共同作用体系有限元模型的理论基础。

This article analyses the application conditions of freezing method, current research status and the problems in thisiold. It, points that it" s necessary to study deep freezing temperature field deeply and discusses the factors which influence the freezing wall such as soil" s nature, moisture content, geological conditions, etc. It introduces the theory, process of freezing method, the distribution of temperature field of freezing method and key thermotics parameters influencing freezing temperature field, it simplifies the deep freezing temperature field model. Through ANSYS, this article founds the deep freezing temperature field model, and simulates the field on vary heat conductivities. It analyzes the results of ANSYS simulation, gains the theoretical value of thermometric holes which is needed by back analysis. Using the simulation temperature and actual value, it gets the equivalent heat conductivity. Then it solves the deep freezing temperature field by the equivalent value, simulates the freezing wall development process and temperature change curve. Against the actual project, the results are favorable.

文中分析了冻结法施工的应用条件，目前对冻结法施工的研究现状和在此领域内存在的问题，指出了对深土冻结温度场进行深入研究分析的必要性；对影响冻结壁形成发展的因素如冻土土性、含水量、地质条件及施工方法等因素进行了论述；对冻结法施工的原理、过程，冻结法温度场的分布情况，影响冻结温度场分布的主要热学参数进行了综述；对深土冻土温度场模型进行了合理的简化，通过ANSYS大型有限元分析软件，建立了深土冻结温度场的模型，对不同导热系数情况下的深土冻结温度场进行了模拟；对ANSYS的模拟结果进行了定性的分析，通过对ANSYS结果的后处理取得了反分析时需要用到的测温孔理论温度值；经过对测温孔模拟温度值和实测温度值的分析，得到了冻结温度场的等效导热系数；使用等效导热系数对深土冻结温度场进行了求解，模拟了冻结壁发展情况和温度场中的温度变化曲线，用所得结果对比工程实际情况，取得了较好的效果。

Research results indicate that continuous Regional Identification Function is used in nodal virtual flux method, volumn integral and surface integral enhances the convergence and stabilization;using 'put a big number' to deal with the first boundary is faster than 'Remove row and column', the more the first boundary nodes are the more obvious advantage will display;PCG method is quite faster than Crout method to solve equations;it is reliable to use three-dimensional finite element simulation theories to simulate and predict deep foundation pit dewatering in such areas.

研究结果表明，在结点虚流量法及计算体积分和面积分时引入连续的区域识别函数增强了解的收敛性和稳定性；处理已知水头边界的&置大数&法在时间上要比&去行去列&法短一些，定水头边界节点越多，其优越性表现越明显；PCG法比直接解法快很多；三维有限元数值模拟理论用于模拟预测此类地区的深基坑降水具有较高的可信度。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。