接触问题

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 the course of numerical calculation, the influence among asperities, the coupling problems of the variation of temperature and pressure on contact surfaces, the variation problems of the maximum temperature, maximum contact pressure, maximum stress were taken account into.

在数值计算过程中，着重考虑了微凸体之间的相互影响，温度变化与接触区域压力变化的耦合问题，最高温度、最大接触压力以及最大等效应力的变化问题。

In order to solve the theoretical backlash problem of the teeth, which is crucial to the number of actual contact pairs of teeth in the research on multi teeth contact of crown gear coupling , the theoretical backlash of teeth flank with the concept of backlash angle is first time defined and described in the paper, and the minimization model of its variables is set up.

为解决鼓形齿联轴器多齿接触研究课题中的实际接触齿对数的关键技术轮齿理论间隙的问题，首次用间隙角的概念对轮齿理论间隙作了定义和描述；建立了该变量的极小化模型；对一鼓形齿联轴器作了实际优化计算，得出了鼓形齿联轴器多齿接触研究中计算实际接触齿对数所需的不同啮合状态下的最小间隙角

For the first time, the notion of translational accessibility and detachability during fixture loading and a sufficient and necessary condition for judging its existence are presented.

解决了对给定的测量力／力矩的集合，以及假设的可能接触状态和不确定性建模，对接触物体间接触状态进行识别这一基本问题。

Based on the equations, the contact spots on the face gear are simulated and analyses are conducted on the rule of the principal curvature of the contact points on the pinion and the face gear as well as the rule of the maximum press stress of the contact areas on the face gear.

根据布希涅斯克问题的求解方法，给出了传动中面齿轮上接触区域的椭圆长、短半径、中心最大变形量、最大压应力以及载荷分布的方程，分析了接触中心最大压应力的变化规律，实现了接触斑点的可视化仿真。

Yield rule, intensify rule, fluxion rule, types of contact and diathermanous model of metal cutting were also analyzed detailedly.

本文在直角自由切削过程分析的基础上，讨论了金属切削过程中的弹塑性变形理论和温度场理论，详细分析了屈服准则、强化准则、流动准则、金属切削传热模型、接触类型等问题，并利用有限元的基本思想，建立了直角自由切削应力场和温度场的有限元模型，进行了状态非线性、材料非线性和几何非线性的热力耦合分析，重点研究了切屑分离标准的确定、表面接触类型的处理等问题。

Based on the analysis of the process of free orthogonal metal cutting, the theory of elastic-plastic distortion and temperature field was discussed. Yield rule, intensify rule, fluxion rule, types of contact and diathermanous model of metal cutting were also analyzed detailedly. The FEA model of stress field and temperature field of free orthogonal metal cutting were established by the fundamental idea of FEA. State nonlinear, material nonlinear and geometry nonlinear thermal-stress coupling were analyzed by FEA technology. The separate criterion of chip and dispose of contact types were research emphatically.

本文在直角自由切削过程分析的基础上，讨论了金属切削过程中的弹塑性变形理论和温度场理论，详细分析了屈服准则、强化准则、流动准则、金属切削传热模型、接触类型等问题，并利用有限元的基本思想，建立了直角自由切削应力场和温度场的有限元模型，进行了状态非线性、材料非线性和几何非线性的热力耦合分析，重点研究了切屑分离标准的确定、表面接触类型的处理等问题。

In this dissertation, first, based on theory of cutting tooth about the gleason spiral bevel gear, the equation of meshing in the process of cutting tooth, the surface equation of generating gear as well as the general tooth surface equation of the double circular arc spiral bevel gear, using GB12759-1991 type of double circular arc gear as a basic gear profile, a three-dimension solid model of double circular arc spiral bevel gear which has the good adaptability was carried out by used of Unigraphics software;Second, by researching of the algorithm about contact and collision as well as various contact types based upon Contacting Finite Element Method, a foundation was laid for selecting the contact type in analyzing contact stress of double circular arc spiral bevel gearing;Finally, through the connection port of PARASOLID between UG software and ANSYS/LS-DYNA software, the three-dimension solid model of double circular arc spiral bevel gearing obtained above in UG was imported into ANSYS/LS-DYNA, a finite element analyzing about contact stress of double circular arc spiral bevel gearing was carried out by applying new loading method.

本文首先基于格利森弧齿锥齿轮加工原理及切齿啮合过程中的啮合方程、产形轮齿面方程以及双圆弧弧齿锥齿轮的齿面方程，选用GB12759-1991型双圆弧齿轮基本齿廓为基准齿形，利用Unigraphics软件的建模功能，绘制了有较好适应性的双圆弧弧齿锥齿轮传动三维实体模型。其次，描述了应用有限单元法进行实体接触与碰撞问题算法的公式，研究了有限元分析中的各种接触类型以及双圆弧弧齿锥齿轮接触应力分析中所选择接触类型的依据。最后，通过UG软件和ANSYS/LS-DYNA之间的PARASOLID接口工具包，将UG软件中得到的啮合齿轮模型导入ANSYS/LS-DYNA有限元分析软件，给出一种新的加载方法，进行了双圆弧弧齿锥齿轮传动的接触应力的有限元分析。

The paper describes how the local force of the main web is considered as the force caused by the Contact pressure among the trolley wheel, rail and top flange, and how the contact analysis model for the local force is built by means of both Hertz theory and finite element software ANSYS combined. Also, it analyzes the variation of the local stress under the different conditions and comes to a conclusion, and compares the results derived from the experimental formula with the result from ANSYS.

本论文的主要内容：将Hertz接触理论和有限元软件ANSYS结合起来，把主腹板的局部受力问题视为小车轮与轨道及轨道与上翼缘板之间发生接触行为作用下的受力问题，建立了小车轮压作用处偏轨箱形梁主腹板局部受力的接触分析模型，研究不同情况（小车轮压、箱形梁几何参数和轨道截面惯性矩）下局部应力的变化规律，得出相关结论；最后将经验公式解与ANSYS数值解进行对比分析论证。

Initially, assuming that the contact between cam and tappet is"dry contart", a dynamics model of Hertzin contact stiffness and impact damping is established. Next, with dynamic load on cam—tappet pair from the model, an analysis is made both to unsteady EHD oil film in cam—tappet pair under condition of full and partial lubrtication and to wear characteristics of cam profile. then, according to the fact that the lubrication in cam—tappet contact surface is EHD lubrication, taking the interaction between stiffness and damping of unsteady EHD oil film and rigidity of solid object contact into account, a dynamics equation of valve train relating to the dynamic effect of EHD oil film is built up and solved. Consequently, a further study is made on the dynamic characteristics of valve train under interaction of EHD oil film dynamic behavior and the problem of EHD lubrication in cam—tappet pair. Finally, the dynamic effect of full and partial EHD oil film is studied accordingly.

首先，通过对凸轮—挺杆接触为&干接触&的假设，建立了考虑赫兹&接触刚度&和冲击&阻尼&的配气机构动力学模型，用由此求得的凸轮—挺杆表面动载荷对凸轮—挺杆进行了全膜状态和部分膜状态非稳态弹流润滑分析，并研究了凸轮轮廓的磨损规律；然后，是在凸轮挺杆表面存在弹流动压油膜这一事实的基础上，相当于在动力学方程中考虑非稳态弹流油膜的&刚度&、&阻尼&和固体接触&刚度&的耦合作用，建立并求解了考虑弹流润滑行为动力学效应的配气机构的动力学方程，从而深入地研究了弹流润滑行为与动力学行为耦合作用下的配气机构动力学特征以及凸轮挺杆弹流润滑问题；作为前面工作的对应部分，考虑弹流油膜动力学效应的研究工作也同样分为全膜状态和部分膜状态进行。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷