材料塑性应变对某钢制车轮残余应力测试的影响

针对车轮轮辋与轮辐组合焊缝附近结构的残余应力测试通常采用盲孔法,孔边由于应力集中易产生塑性变形的问题,采用有限元仿真与测试相结合的方法分析在钢制车轮加工的不同阶段,轮辋焊缝区残余应力测试时材料塑性变形对应变释放因数和残余应力测试结果的影响,并分析由Kirsch解析解确定的应变释放因数A和B计算车轮焊缝区残余应力测试所带来的误差.发现当孔边塑性变形较大时,用Kirsch解析解确定的应变释放因数计算残余应力会产生很大误差.     

轮轴压装过程的有限元分析

由于轮轴压装质量直接影响轨道列车的安全运行,针对轮轴压装不当产生轮轴内表面严重机械损伤的问题,应用有限元法对其进行研究.用Abaqus建立过盈配合下轮轴的有限元模型,仿真分析压装过程中压装力和等效应力的变化及分布规律,发现应力集中位置位于车轴轮座与轮毂孔的结合处及注油孔的外沿,因此应对应力集中位置做重点探伤;压装过程中压装力和最大等效接触应力都不断变化,其中压装力随着压装位移的增大而逐渐增大,而最大等效接触应力随着压装位移的增大呈先增大后减小的趋势;通过对比不同压入位移时轮轴的等效应力发现,压入位移超过190 mm时,车轴左端卸荷槽处开始发生形变,出现应力集中现象,因此压入位移应控制在190 mm以内.     

改进的蚁群算法求解连续函数约束优化问题

对基本蚁群算法框架进行了改进,采用轮盘赌选择代替了基本框架中通过启发式函数和信息素选择路径,同时对信息素的更新方式也做出调整,提出了一种新的蚁群算法,使得其更适合解决连续函数问题.将这种改进的蚁群算法应用于带有约束条件的连续函数问题中,在典型实例中进行仿真测试,实验结果表明,提出的改进蚁群算法可以很好地解决带有约束条件的连续函数问题,并能迅速找到最优解.     

Interaction Mechanics Model for Rigid Driving Wheels of Planetary Rovers Moving on Sandy Terrain with Consideration of Multiple Physical Effects

Predicting wheel‐terrain interaction with semiempirical models is of substantial importance for developing planetary wheeled mobile robots (rovers). Primarily geared toward the design of manned terrestrial vehicles, conventional terramechanics models do not provide the sufficient fidelity required for application on autonomous planetary rovers. To develop a high‐fidelity interaction mechanics model, in this study the physical effects of wheel lug, slip sinkage, wheel dimension, and load are analyzed based on experimental results, including wheel sinkage, drawbar pull, normal force, and moment, which are measured on a single‐wheel test bed. The mechanism of lug‐terrain interaction is investigated systematically to clarify the principle of increasing shear stress, conditions of forming successive shearing among adjacent lugs, and the influence on shear displacement of soil. A mathematical model for predicting the concentrated forces and torque of rigid wheels with lugs for planetary rovers moving on sandy terrain is derived by integrating the improved models of normal and shearing stress distributions. In addition to the wheel parameters, terrain parameters, and motion state variables, wheel‐terrain interaction parameters, such as the linear varying sinkage exponent, the soil displacement radius, and load effect parameters, were proposed and explicitly included in the model. In the single‐wheel experiments, the slip ratio was increased approximately from 0.05 to 0.6, and the relative errors of the predicted results using the proposed model are less than 10% for all the wheels when compared with the experimental data. The proposed model has been used in the simulation of a four‐wheeled rover, and its effectiveness is evaluated by comparing the simulation results with experimental results.     

火车轮踏面在役自动检测技术研究

较全面地分析了国内外在火车轮检测方面的研究现状。在此基础上 ,提出了火车轮踏面的在役自动检测技术 ,并研制出相应的原型系统 ,同时给出了实验结果 ,为火车轮踏面的在役自动检测提供了一条崭新思路。     

RV 减速器针齿受力分析及设计改进

RV(Rotor Vector)减速器是一种工业机器人关节高精密减速传动装置,通常由第一级渐开线行星传动机构和第二级摆线针轮传动机构组成。该研究工作基于针齿理论受力模型,参照针齿的实际磨损情况,对传统针齿受力分析方法进行了改进。通过改进方法分析发现针齿上存在明显的剪切力和弯曲应力分布,为了消除相关应力影响,该文采用短针齿取代传统长针齿。实验结果显示,新的设计方案不仅能够有效减少剪切力和消除弯曲应力,而且能够显著减少啮合时打滑现象的发生,具有更高的安全系数。     

浅析3DX-50前面板控制技术

目前越来越多的中波发射站使用了技术上较为新颖的3DX系列数字发射机产品,相比以前的DX系列,3DX的操作更为数字化。与传统DX系列的LED灯表示运行状态相比,3DX简化到只有一块14VGA显示面板,但数字化的前面板有着更多的操作功能,可通过旋转指轮和面板上的按钮直接切换激励器等完成复杂操作。以实际使用中的3DX-50数字中波发射机为例,分析了新一代数字发射机的前面板控制技术。     

基于Abaqus的浆液搅拌车驱动轮轮缘的结构应力分析

本文对液下搅拌机器人在水煤浆储罐中工作时驱动轮的动态性能与结构进行了研究,使用有限元分析软件Abaqus对车轮进行了有限元应力分析,其中包括驱动轮选择不同轮齿时冲击应力值的对比。根据对冲击应力仿真结果的分析并结合驱动轮工作环境来选择驱动轮轮缘的轮齿数量。对行走机器人轮系设计有一定的指导意义。     

长玻纤增强热塑性复合材料车轮径向载荷下的强度仿真

为提高复合材料车轮仿真的准确性,采用高性能长玻纤增强热塑性复合材料作为车轮材料,探索在考虑材料各向异性的情况下联合使用Moldflow,Digimat和Abaqus对车轮强度进行仿真的方法,并针对具体车轮采用该方法按照国家标准进行径向载荷下的强度仿真与分析.研究结果表明：复合材料各向异性特性对车轮应力、应变的分布及最大值均有较大影响;在同一位置是否考虑材料各向异性影响得到的应力值最大相差达314%.该方法可提高长玻纤增强复合材料车轮强度仿真计算结果准确性,可为车轮的进一步轻量化提供参考.     

车轮与高速道岔翼轨的接触分析

为合理设计道岔,更好地匹配轮对和道岔型面,用有限元法求解车轮与高速道岔翼轨的接触问题.建立4种不同型面车轮与高速道岔翼轨接触的有限元模型,分析车轮通过高速道岔翼轨的轮岔接触斑和等效应力的变化规律,计算结果表明:机车车轮与翼轨的接触斑位于翼轨轨顸外侧,动车车轮与翼轨接触的接触斑位置在翼轨轨顶中部;磨耗后JM3型面车轮与翼轨接触时,容易出现应力集中,尤其是在距离心轨尖端50 cm位置处;磨耗后JM3型面车轮与翼轨接触产生的等效应力最大.     

聚氨酯橡胶摩擦轮有限元及疲劳寿命分析

针对汽车滑板输送机聚氨酯橡胶摩擦轮的开裂问题,对摩擦轮与滑板之间的相互作用进行预压紧力和接触摩擦驱动有限元分析,获得摩擦轮的应力和变形分布等结果.在获得摩擦轮周向应力分布的基础上,根据疲劳裂纹扩展公式对聚氨酯橡胶部分进行疲劳寿命分析,验证是否满足设计要求.分析过程和结果能为聚氨酯橡胶摩擦轮的详细设计提供参考.     

不同地铁车轮结构几何参数下踏面制动热负荷分析

针对频繁踏面制动产生的热负荷易导致地铁车轮损伤失效的问题,从制动热负荷分析的角度研究车轮设计.采用有限元法建立地铁车轮的踏面制动热负荷分析的数值模型,分析闸瓦宽度、轮辋厚度和辐板形式等结构参数对车轮的三维瞬态温度场及热应力场的影响,提出基于较小制动热负荷的车轮结构几何参数设计建议.     

聚氨酯橡胶摩擦轮有限元及疲劳寿命分析

针对汽车滑板输送机聚氨酯橡胶摩擦轮的开裂问题,对摩擦轮与滑板之间的相互作用进行预压紧力和接触摩擦驱动有限元分析,获得摩擦轮的应力和变形分布等结果. 在获得摩擦轮周向应力分布的基础上,根据疲劳裂纹扩展公式对聚氨酯橡胶部分进行疲劳寿命分析,验证是否满足设计要求. 分析过程和结果能为聚氨酯橡胶摩擦轮的详细设计提供参考.     

滚动接触疲劳载荷对铁轨表面接触疲劳裂纹应力强度系数的影响

为研究轮轨滚动接触疲劳(Rolling Contact Fatigue,RCF)载荷对铁轨表面裂纹应力强度系数的影响,以UIC60铁轨轮廓尺寸为依据建立轮轨接触的三维有限元模型,通过改变RCF载荷大小、轮轨表面摩擦因数和接触中心位置等轮轨接触的输入参数,计算铁轨表面接触裂纹尖端的应力强度系数,分析RCF载荷对铁轨表面接触疲劳裂纹的影响.结果表明RCF载荷作为控制铁轨表面接触裂纹的重要因素,其变化直接导致裂纹尖端应力强度系数的变化,从而改变裂纹的扩展状况.为减缓铁轨表面裂纹的扩展,可以针对载荷采取均匀分布载重量、使用润滑剂降低轮轨摩擦因数等相应措施.     

A study on wear evaluation of railway wheels based on multibody dynamics and wear computation

The wear evolution of railway wheels is a very important issue in railway engineering. In the past, the reprofiling intervals of railway vehicle steel wheels have been scheduled according to designers’ experience. Today, more reliable and accurate tools in predicting wheel wear evolution and wheelset lifetime can be used in order to achieve economical and safety benefits. In this work, a computational tool that is able to predict the evolution of the wheel profiles for a given railway system, as a function of the distance run, is presented. The strategy adopted consists of using a commercial multibody software to study the railway dynamic problem and a purpose-built code for managing its pre- and post-processing data in order to compute the wear. The tool is applied here to realistic operation scenarios in order to assess the effect of some service conditions on the wheel wear progression.     

改进的车载全息透明影像方法

汽车本身的结构, 决定了汽车周围存在大量视野盲区, 驾驶员无法对行车周围环境做出准确判断, 不利于安全驾驶. 全息透明影像能够为驾驶员提供行车周围以及车底全部盲区信息辅助安全驾驶. 为解决图像拼接处有明显拼接缝的问题, 提出了基于距离的Alpha图像拼接算法, 并为拼接算法重新设计了三维模型. 对透明底盘功能做了如下3方面优化. 改进自行车模型算法, 在不影像效果的前提下, 减小了计算复杂度. 利用查表法提高方向盘角度转换为轮转角的精度, 解决了透明底盘与周围拼接错位问题. 采用分层渲染的方法, 优化透明底盘功能拼接缝问题. 实验表明该技术能够有效地提升渲染效果.     

Digital redesign of uncertain interval systems based on extremal gain/phase margins via a hybrid particle swarm optimizer

In this paper, a hybrid optimizer incorporating particle swarm optimization (PSO) and an enhanced NM simplex search method is proposed to derive an optimal digital controller for uncertain interval systems based on resemblance of extremal gain/phase margins (GM/PM). By combining the uncertain plant and controller, extremal GM/PM of the redesigned digital system and its continuous counterpart can be obtained as the basis for comparison. The design problem is then formulated as an optimization problem of an aggregated error function in terms of deviation on extremal GM/PM between the redesigned digital system having an interval plant and its continuous counterpart, and subsequently optimized by the proposed optimizer to obtain an optimal set of parameters for the digital controller. Thanks to the performance of the proposed hybrid optimizer, frequency-response performances of the redesigned digital system using the digital controller evolutionarily derived by the proposed approach bare a far better resemblance to its continuous-time counter part in comparison to those obtained using existing open-loop discretization methods.     

轮辋与轮辐间焊缝参数对钢制车轮弯曲应力影响的仿真分析

为考察轮辋与轮辐间焊缝对钢制车轮强度的影响,建立包括该焊缝在内的钢制车轮的有限元模型,分析在弯曲载荷作用下,钢制车轮轮辋与轮辐间的焊脚高度、焊缝截面形状以及焊缝布置位置对车轮应力的影响．仿真结果表明：对于该钢制车轮,轮辋与轮辐间焊脚高度可以由目前的3.5mm减至2.5mm,这为焊接工艺参数的调整提供一定参考;焊缝截面边界为直边时焊缝处应力较小;当每段焊缝的一半对着通风孔时焊接区域应力较小．该仿真分析可用于钢制车轮轮辋与轮辐间焊缝结构的优化,并为钢制车轮在弯曲载荷作用下的疲劳寿命估算提供更准确的应力计算结果．     

An energy-aware heuristic framework for virtual machine consolidation in Cloud computing

Virtual machine (VM) consolidation in Cloud computing provides a great opportunity for energy saving. However, the obligation of providing suitable quality of service to end users leads to the necessity in dealing with energy-performance tradeoff. In this paper, we propose a redesigned energy-aware heuristic framework for VM consolidation to achieve a better energy-performance tradeoff. There are two main contributions in the framework: (1) establish a service level agreement (SLA) violation decision algorithm to decide whether a host is overload with SLA violation; (2) minimum power and maximum utilization policy is then proposed to improve the Minimum Power policy in previous work. Finally, we have evaluated our framework through simulation on large-scale experiments driven by workload traces from more than a thousand VMs, and the results show that our framework outperforms previous work. Specifically, it guarantees 21–34 % decrease in energy consumption, 84–92 % decrease in SLA violation, 87–94 % decrease in energy-performance metric, and 63 % decrease in execution time. And we further discuss why the redesigned framework outperforms the previous design.     

钢圈强度有限元分析

应用有限元分析理论,对钢圈的结构进行强度分析,得到钢圈的应力分布图. 通过分析,能对钢圈的结构优化提供基础,进而提高钢圈的性能.