简单链形悬挂接触网动力学性能仿真实验

为激发学生学习兴趣,培养学生的科研与创新意识,将简单链形悬挂接触网系统作为一个基准系统进行仿真试验开发。受电弓等效为3质量块-弹簧-阻尼系统,接触线及承力索采用梁单元离散,吊弦等效为非线性弹簧。通过改变弓网系统的参数,直观地展示不同参数下接触网系统的动力学响应,便于学生理解。通过仿真,提高接触网动力学理论教学效果,同时有助于培养学生运用仿真手段解决科研问题的能力。     

Concept modeling of tapered thin-walled tubes

This paper presents a method to create concept models for the tapered thin-walled tubes using beam elements and spring elements. Developed concept tapered beam models with different taper angles and cross sections are compared with those detailed models through impact analyses. Important crash results are recorded and compared, and the relatively good agreement is achieved between these analyses. Concept modeling steps are illustrated in detail, and a general concept modeling method for such thin-walled tubes is summarized and presented.     

基于Top—Down方法的自动定心钻床夹具设计

以Pro／Engineer为设计软件工具,采用其自顶向下即Top—Down的骨架法进行自动定心钻模设计,给出零组件设计和自动定位装配位置的步骤．并用约束和连接方式进行装配,便于后续的仿真与分析．本设计以一交叉正交孔零件为例,用Top—Down方法体现其具体设计过程,以夹紧杆零件的建立,说明如何在组件中将骨架零件的参照传递到一般零件中,并逐次创建特征。     

获取＂动力硬化＂的一般程式

阐述一种获取＂动力硬化＂的一般程式。基于凯恩方程导出做大范围运动任意柔体的运动方程。用几何非线性应变一位移关系和角速度的非线性表达式正确实现线性化，一般情况下可自然获取＂动力硬化＂项。休斯敦方法中偏速度和偏角速度阵列的概念和推导拓宽到柔体，并做为分析的基础。通过用于梁和板模型数值计算的结果证实了所述程式是普遍有效的。     

计算悬空管线固有频率的新方法

长输管线在石油工程中大量使用 .穿河段管线由于河水的冲刷变得悬空 ,如果管线附近的涡泻频率接近管线的固有频率 ,将引起悬空管线的共振 ,并且导致管线的破坏 .本文将悬空管线视为弹性基础上的半无限长梁 ,建立了悬空段管线和埋入土中管线的偏微分振动方程 ,提出了计算管线固有频率的迭代计算方法 ,实例计算结果同现场测试结果基本一致 .     

改进SSOR迭代法的数值保角变换计算法

针对基于模拟电荷法的数值保角变换计算法在复杂边界求解模拟电荷点电荷量时不精确及不稳定问题,提出一种基于（k,j）-Padé 迭代法改进的SSOR方法并用于求解电荷点电荷量。首先通过模拟电荷法将数值保角变换的逼近问题转换为理论上较为成熟的共轭调和函数逼近问题;然后根据边界条件、正则化条件、约束条件和柯西条件构造出约束方程组,使用改进算法计算电荷点电荷量;最后利用电荷点电荷量计算出数值保角变换函数。实验结果表明, 该方法能很好地保持映射前后角度之间的关系。与原方法相比,在橙形区域中最大精度提升率约为11.2%, 在椭圆区域中最大精度提升率为5.4%,且比原方法稳定性高。     

均布载荷作用下悬臂不可压饱和多孔梁的非线性变形

Nonlinear bending of cantilever incompressible poroelastic beams subjected to a uniform load is investigated with the constraint that fluid flow is only in the axial direction. The governing equations for large deflection of the poroelastic beam are derived from theory of incompressible saturated porous media. Then, nonlinear responses of a cantilever beam with impermeable fixed end and permeable free end are examined with the Galerkin truncation method. The deflections and bending moments of the poroelastie beam and the equivalent couples of the pore fluid pressures are shown in figures. The differences of the results between the large deflection and the small deflection theories are analyzed. It is shown that the results of the large deflection theory are smaller than those of the small deflection theory, and the time needed to approach their stationary states for the large deflection theory is shorter than that for the small deflection theory.     

基于补偿法的配电网潮流计算

主要提出对配电网中弱环网的潮流计算采用基于补偿法将弱环网转化为放射型网络后，运用前推回代法进行潮流计算，并通过算例进行验证。     

Dynamic stiffness for thin-walled structures by power series

INTRODUCTION Thin-walled structures have considerable tech-nological importance in many situations of engi-neering practice. The rotary and warping inertia terms should be considered in the analyses of thin-walled structures (Alwis and Wang, 1996), although it is difficult to obtain the analytical solutions of govern-ing differential equations, especially of thin-walled frame and spatial twisted structure. The finite element method (FEM) is widely used for vibration and sta-bility analy…     

Static analysis of a stepped main shaft in a mine hoist by means of the modified 1D higher-order theory

The analysis of a stepped main shaft by 1D refined beam theories in cylindrical coordinate system is presented. High-order displacement fields are achieved by employing the Carrera unified formulation (CUF), which takes direct implementation of any-order theory without the requirement of considering special formulations. The classical beam theories can be derived from the formulation as particular cases. The principle of minimum potential energy is used to obtain the governing differential equations and the related boundary conditions in a cylindrical coordinate system. These explicit terms of the stiffness matrices are exhibited and a global stiffness matrix is then obtained by matrix transformation. For the special working condition in a mining hoist and stepped shaft, the resulting global stiffness matrix and the loading vector are modified and applied with the boundary conditions in the static analysis of shaft parts. The accuracy of static analysis based on the refined beam theory is confirmed by comparing ANSYS solid theory and classical beam theories. An experiment for verifying the availability of the modified 1D refined beam model on the surface strain of segment 9 of the main shaft is conducted in a field experiment at Zhaojiazhai Coal Mine, China. Experimental results demonstrate the practicability of the present theory in predicting the strain field on the surface of the stepped main shaft of a mining hoist.     

轮对前2阶弯曲模态对动力学行为的影响

研究目的：扩展动力学模型的分析频域,建立能考虑轮对柔性的车辆轨道耦合动力学系统模型,为研究轮轨磨耗的形成和发展以及轮轨噪声的来源提供基础。创新要点：利用欧拉梁横向弯曲模型,建立轮轴在垂直于轨道平面和平行于轨道平面内的弯曲振动模型;建立考虑轮轴弯曲的轮对模型与轮轨接触模块之间的耦合关系,进而研究轮轨接触行为受轮轴弯曲变形的影响。研究方法：1．把轮轴模拟为欧拉梁,左右车轮模拟为固结于轮轴上的质量块;2．假设左右车轮始终垂直于轮轴,引入虚拟的两个半边刚性轮对模型,建立轮轨接触模型和柔性轮对耦合的关系;3．基于多刚体车辆．轨道耦合动力学模型,利用以上柔性轮对模型和此耦合关系,建立考虑轮轴柔性的车辆一轨道耦合动力学模型。重要结论：1．建立的刚柔耦合的车辆．轨道耦合动力学模型能够有效地描述轮轴弯曲对轮轨接触行为的影响;2．在0-150Hz的随机不平顺激励下,多刚体模型和考虑轮对柔性的模型受到的轮轨力和轮轨接触点轨迹不同;这主要是由第1阶弯曲模态被激发导致。     

二维变量化设计中的有向图理论

约束方程求解是基于约束的变量化设计方法的核心问题．本文介绍了运用图理论方法求解约束方程的过程和实现结果．     

Static and dynamic damage analysis of mass concrete in hydropower house of Three Gorges Project

This paper establishes a 3D numerical model for 15# hydropower house of the Three Gorges Project (TGP) and performs a nonlinear static and dynamic damage analysis. In this numerical model, a coupling model of finite and infinite elements for simulating infinite foundation of hydropower station is adopted. A plastic-damage model based on continuum damage mechanics, which includes the softening and damage behavior under tension is considered for the concrete material. The dynamic equilibrium equations of motion are solved by using the HilberHughes-Taylor (HHT) time integration method. Firstly, the static damage response analysis of the hydropower station is conducted due to high tensile stress resulting from large water head and diameter of an inlet pipe. Then, on the basis of static simulation, the dynamic damage analysis of hydropower house subjected to earthquake motion is simulated. Numerical results show that under large water head and diameter of an inlet pipe of the project, the damages are mainly located near the top of the spiral case from the inlet section to the 0° section; under combined loadings of static loads and earthquake, the damages of the concrete surrounding the spiral case increase insignificantly; however, some damages occur on the side walls of the main powerhouse.     

起重叉车横梁型钢(叉车立杆)的生产

文章介绍了起重叉车横梁型钢(俗称叉车立杆)从试验轧制到稳定生产的过程,分析了影响产品机械性能的因素,并提出从原料化学成分、孔型配置及生产工艺等方面采取改进措施,从而生产出断面形状良好和机械性能符合要求的产品,填补了我国的型材产品的一项空白.     

罗茨式机械增压器转子型线的改进

针对传统渐开线罗茨转子型线存在的面积利用率低的问题,提出了改变传统渐开线转子型线设计参数之间的约束关系以提高面积利用率的方法;通过分析逐步确定基本设计参数,在此基础上建立型线中渐开线段能够正确啮合的几何关系并求解渐开线坐标旋转角,对型线进行干涉分析,确定改进后型线的参数方程。     

沙溪斑岩铜矿三维建模及铜品位空间变异研究

本文针对沙溪斑岩铜矿床,首先构建了主矿体的三维实体模型,之后以此作为约束对主矿体内部的铜品位数值开展空间变异研究分析。运用地质统计学方法,分别对主矿体走向、倾斜和厚度方向上的实验变异函数进行了理论模型拟合。拟合结果显示,铜品位在矿体走向方向上具有最好的连续性,较高的块金常数则显示出铜品位在较小范围内有很大的随机性,进而建议矿山提高矿区的勘探密度,进一步对矿体及品位的分布进行控制。     

Inverse Dynamics of Delta Robot Based on the Principle of Virtual Work

While the kinematics of the parallel manipulatorhas been studied extensively during the past two dec-ades, more and more papers can be found on the dy-namics of the parallel manipulators now[1—7]. The dy-namics of robotcan be used forthe simulation, controland optimization. It plays an important role inachieving high-speed performance. There are twotypes of dynamical problems for the parallel robot: di-rect dynamics and inverse dynamics. The direct dy-namical problem is to find the response v…     

Transient Responses of Flexible Non—uniform Spinning Shaft with Nonlinear and Asymmetric Supports

In this paper ,a hybrid approach was developed to investigate the transient responses of a multi-span non-uniform flexble spinning shaft with nonlinear and asymmetric supports.The non-uniform spinning shaft with variable parmeters was modeled as a Bernoulli-Euler beam column with sectional constant cross-section properties by the finite element method.The supporting stiffness behavior of the nonlinear supports was described as a piecewise-linear and asymmetric model.The equations of motion in the matrix form of a multi-span non-uniform spinning shaft with nonlinear and asymmetric supports were formulated using Hamilton‘s principle and the assumed mode method.As an example,a spinning rocket with many variable stiffness supports was numerically simulated by the direct integration method.The transient response and dynamic behavior of this rotate-dynamic system are analyzed.     

基于T矩阵方法的弹性波散射参数计算

基于T矩阵方法,计算了位移和面力均连续的理想界面条件下单个散射体的物质参数,推导了T矩阵元素的具体表达式和散射截面公式.针对Ge-Al复合材料,用Matlab进行了编程和数值计算,并与波函数法的计算结果进行了比较,指出了T矩阵方法存在的问题,提出了改进措施.     

四边形有限元网格生成方法关键技术

本对四边形网格生成法中的边界偏移、最优分割线确定等关键技术作了改进。在该方法中，用户只需指定区域的边界以及边界上的单元尺寸，就可以生成疏密自然过渡的四边形网格。它可与二维刚塑性有限元程序集成为具有网格自动重分功能的有限元模拟系统。利用系统对火车车轮预成形过程进行了模拟，结果表明该网格生成法通用性强，自动化程度高。