高速履带车辆扭杆弹簧疲劳寿命的数值计算

由于在分析高速履带车辆扭杆弹簧疲劳寿命的过程中传统方法采用静态最大载荷计算不能考虑动态载荷的影响,以多柔体动力学和有限元模态应力分析法为分析手段,通过数值仿真计算得到不同载荷作用下履带车辆扭杆弹簧的应力时间历程曲线．依据Miner线性损伤累积理论,结合车辆行驶环境和行驶工况的分配比例和扭杆弹簧材料特性曲线,采用Goodman法和Gerber法2种等效应力修正方法,对扭杆弹簧的疲劳寿命进行分析和预测,其计算结果表明Goodman法比Gerber法保守,两者之间的预测结果相差约7倍．该研究为设计阶段履带车辆关键零部件疲劳寿命预测提供可行的分析方法．     

基于主S-N曲线的带止裂槽焊接接头疲劳寿命预测及改进

以带止裂槽焊接接头为研究对象,提取可能发生疲劳失效的焊趾截面、焊喉截面和止裂槽截面的节点力,基于主S N曲线法求解截面的等效结构应力,评估焊缝的疲劳寿命,并提出改进接头的建议。分析发现：止裂槽的存在会显著增加局部位置的应力,导致疲劳寿命明显降低。填充止裂槽并适当增大水平方向焊脚尺寸,可以提高该位置疲劳寿命10倍左右。     

某型圆柱螺旋弹簧设计与疲劳寿命分析

圆柱螺旋弹簧是某型机械传动系统的关键部件,其设计的可靠性直接影响该结构的稳定和安全.首先对某型圆柱螺旋弹簧进行工况分析,进而基于机械设计原则对其刚度、强度进行理论校核,最后基于有限元应力仿真,在MSC Fatigue中计算出该弹簧最危险节点的寿命.所得结论表明设计弹簧的疲劳寿命满足疲劳可靠性的要求.     

基于ALGOR的汽车钢板弹簧疲劳仿真分析

针对汽车平衡悬架钢板弹簧设计过程中,对力学特性和疲劳寿命仿真计算效率、精度等要求很高的问题,利用Auotodesk Inventor建立某汽车多片钢板弹簧的CAD模型并进行合理的模型简化;应用ALGOR的非线性MES模块求解接触应力及总成预应力;通过ALGOR Fatigue Wizard进行疲劳寿命预测,提出S-N曲线的获取方法并对比修正结果.结果表明：在交变载荷作用下,最小疲劳寿命处于最大主应力位置;Goodman的结果修正更可靠.另外,ALGOR中的自动六面体网格技术、S-N曲线自动生成等前后处理技术可大大降低仿真技术应用的难度.     

基于等效结构应力的铝合金地铁车体疲劳寿命预测

为评估某铝合金地铁车辆的疲劳寿命,采用美国ASME标准中的网格不敏感的主S-N曲线法对该车焊缝进行疲劳寿命预测.用HyperMesh对车体进行有限元建模,并对焊缝处网格细化;用ANSYS计算焊缝处应力;运用自主开发的FE-Weld软件对其进行等效结构应力的计算和疲劳寿命的预测;对疲劳寿命不符合设计要求的结构进行改进和优化,改进后结构的疲劳寿命符合设计要求.网格不敏感的主S-N曲线法具有重要工程应用推广价值.     

摩擦因数对钢丝绳应力和疲劳寿命的影响分析

以6×36+WS结构钢丝绳为研究对象,在SolidWorks中建立了其三维模型,并导入ABAQUS中,通过定义接触对、设置边界条件,建立了钢丝绳有限元模型。在相同的轴向载荷下,仿真分析了不同摩擦因数对钢丝绳应力分布和疲劳寿命的影响。结果表明,钢丝绳在拉伸状态下,绳股外侧钢丝应力较大,且绳股与绳股接触处钢丝应力最大;随着摩擦因数的增大,钢丝绳应力逐渐增大,疲劳寿命逐渐减小,钢丝绳在应力最大处疲劳寿命最小。     

基于主S-N曲线法的T形接头疲劳评估和试验验证

以T形焊接接头为研究对象,将可能发生疲劳破坏的焊趾截面和焊喉截面的节点力转换为相对于中面焊线的等效节点力和弯矩,并利用平衡等效原理转化为线力和线弯矩,基于材料力学公式求出截面的结构应力,解决应力对网格尺寸敏感的难题。从焊缝疲劳破坏的机理出发,基于Paris断裂力学公式推导以等效结构应力为变量的一条主S-N曲线,评估焊缝的疲劳寿命。分析结果发现：采用主S-N曲线法评估的寿命与试验值最接近且破坏位置准确,该主S N曲线法准确性较高。     

基于名义应力法的弹性链型接触网疲劳寿命预测

针对高速铁路弹性链型接触网进行接触线疲劳寿命预测分析.利用ANSYS,采用直接积分法对弓网耦合系统进行动态仿真,得到接触线的应力时程;运用雨流计数法得到离散的应力循环,采用应力修正算法得到平均应力为零的疲劳应力谱;通过简化方法估算获得材料S-N曲线,从而计算得到疲劳破坏次数;最终运用线性累积损伤理论预测接触线的疲劳寿命.对比分析接触线不同位置的疲劳寿命值,结果表明:接触线每跨疲劳寿命趋势一致;每跨在吊弦处和定位点处疲劳寿命较低,其中寿命最低值出现在左侧第一根吊弦处,疲劳寿命最低值为20 a左右.结果可为高速铁路弹性链型接触网接触线的实际施工维护和更换周期的确定提供参考.     

基于主S-N曲线法的地铁制动箱焊接疲劳分析

为研究地铁车辆制动箱焊接接头的疲劳寿命,根据实际结构建立4节点壳单元有限元模型,给出搭接焊和T型焊的焊缝建模方法.在3种振动工况下,运用主S N曲线法计算焊缝的等效结构应力和对应损伤比.结果表明：该地铁车辆制动箱焊接结构设计合理可靠;通过与实体单元模型计算结果进行对比证明壳单元模拟焊缝的合理性;在不同尺寸单元下对比2种疲劳评估方法,结果表明名义应力法预测疲劳寿命的准确性较低.     

自行火炮履带板多载荷疲劳寿命仿真

履带板的疲劳寿命是自行火炮维修保障体系中急缺的指标,但因测试动载荷和确定受力部位困难,至今无人尝试分析其疲劳寿命.测试动载荷是通过前人所建自行火炮行走系虚拟样机在虚拟路面上行驶实现的.通过重现仿真过程,观察履带板位置和载荷分量的幅值的对应情况,推断载荷分量的产生机理与履带板的受力部位.分析了履带板有限元多工况静应力分布.利用静应力结果和动载荷进行多载荷疲劳寿命仿真,找出了疲劳寿命薄弱位置,给出了疲劳寿命值.说明计算机仿真手段分析履带板的疲劳寿命,可以得到物理实验难以测试到的动载荷,避开繁琐的传统疲劳物理实验方法.最后提出了需进一步讨论的问题.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。