SHAPE DESIGN SENSITIVITY ANALYSIS AND OPTIMIZATION FOR STRUCTURAL DURABILITY

In this paper, a design sensitivity analysis (DSA) method for fatigue life of 3-D solid structural components of mechanical systems with respect to shape design parameters is presented. The DSA method uses dynamic stress DSA obtained using an analytical approach to predict dynamic stress increment due to design changes; computes fatigue life of the component, including crack initiation and crack propagation, using the predicted dynamic stress; and uses the difference of the new life and the original life at the same critical point to approximate the sensitivity of fatigue life. A tracked vehicle roadarm is presented in this paper to demonstrate accuracy and efficiency of the DSA method. Also, this method is applied to support design optimization of the tracked vehicle roadarm considering crack initiation lives as design constraints. © 1997 by John Wiley & Sons, Ltd.     

基于虚拟高冲击样机的装备寿命预测研究

讨论了虚拟样机(virtual prototyping)的意义和必要性，简要介绍了ADAMS仿真系统。以承受高冲击激励的火炮为研究对象，分析了影响火炮工作性能的主要因素，总结了火炮正常工作的三个基本准则。运用Fortran语言编制了火炮故障仿真模块，在ADAMS环境下建立了火炮高冲击虚拟样机。结合层次分析法(AHP)确定了性能的影响权重，制定了基于虚拟高冲击样机的火炮工作性能评估方案，进而对火炮剩余寿命进行预测，仿真结果证明了评估和预测研究的有效性。最后，展望了虚拟样机的应用前景和下一步的研究重点。     

Structural integrity in electronics

With continuing miniaturisation, increased performance demands and the requirement to remove lead from solder alloys, the challenges to structural integrity and reliability of electronic equipment are substantial and increasing. This paper outlines typical features in electronic equipment of which the structural integrity community may be generally unaware. Potential failure modes in service are described, and the problems of scale and material characteristics are considered. Progress in the application of fracture mechanics to the life prediction of interconnections is reviewed. The limited evidence available suggests that the crack growth resistance of silver‐containing lead‐free solders is superior to that of the traditional Sn‐37Pb under cycle‐controlled conditions but there is no difference when time‐dependent conditions prevail. In several respects, it is contended that the electronics sector is faced with challenges at least equivalent to those encountered in gas turbines and nuclear power generation.     

锻锤基础的冲击疲劳损伤分析

用损伤力学的概念提出了一种研究由锻锤锻打引起锻锤基础系统的疲劳损伤增长和疲劳寿命估计的方法。该方法通过定义,引入锻锤基础系统中减振垫与基础块的损伤状态寿命因子,能够估计出锻锤基础系统的减振垫和基础块的损伤疲劳寿命上、下限。通过分析发现,长期的重复冲击载荷会引起锻锤基础系统发生疲劳微损伤积累,疲劳损伤积累的宏观损伤又引起锻锤基础的动力响应随宏观损伤发展而增大,动力响应的增大又加剧基础系统的损伤发展。因此,为减少周围环境的振动以及保护周围环境免受锻锤冲击损伤,在锻锤基础系统设计中需考虑吸振和损伤控制。     

脉冲电磁处理参数对YT15硬质合金服役寿命的影响

采用COMSOL Multiphysics有限元分析软件对脉冲电磁处理设备进行仿真建模,利用正交试验的方法研究了磁通密度、磁脉冲个数、脉冲电压、电脉冲组数对YT15硬质合金刀具服役寿命的影响规律。通过极差分析得到了各因素的影响主次关系以及最佳脉冲电磁处理参数,并分析了切削过程的主切削力及磨损量变化,结果表明:脉冲电磁处理可使YT15硬质合金刀具服役寿命增长57.2%;最佳的处理参数组合为磁通密度2T,磁脉冲个数10,脉冲电压0.8V,电脉冲组数20;磁通密度和磁脉冲个数对其寿命影响较大,脉冲电压和电脉冲组数影响较弱;脉冲电磁处理后的刀具切削力较未处理有所降低,后刀面磨损速度明显减缓。     

一种新型大跨空间结构--张拉整体索穹顶

介绍了一种新型大跨空间结构———张拉整体索穹顶结构的发展和应用 ,并对其建筑特点作了分析。     

面对突发疫情的城市防控空间单元体系构建 ——突发公共卫生事件下对健康城市的思考

从传染性疾病发生依赖的传染源、传播途径、易感人群三个环节来看,早期的城市公共卫生运动致力于通过改 善城市物理环境来消除传染源,近年的健康城市运动侧重于通过促进居民体力活动来提高易感人群的体质,而对于传 染病发生的中间环节——传播途径的切断,城市的应对却缺乏有效的训练。梳理了中国此次战“疫”的过程,总结城 市防疫管控中“隔离- 治疗- 恢复”的应对措施,以及“市- 区- 社区”各级行政和空间单元发挥的作用,从中探 讨其对丰富健康城市建设实践的启示,认为完善健康城市建设需要树立三个思维：一是针对突发疫情采取快速隔离与 治疗的有效性思维;二是在疫情影响长期化背景下关注生命支持与生活质量的人本性思维;三是加强健康城市指标体 系的空间属性思维。在此基础上,提出构建健康城市防疫空间单元体系的设想：在城市层面,建立“市- 区- 社区” 多级联动的防疫体系,以加强面对应急隔离的防疫制动能力,建立资源的联动分配和共享机制;在社区层面,在满足 基本隔离防疫管理的空间尺度上,从人本性出发建立一套能满足人基本生命需求的支持系统,以保障人在防疫期间依 然能够获得身心的健康。     

高应变法在大直径长桩桩身完整性检测中的应用

分析低应变法、声波透射法和钻芯法在大直径长桩完整性检测中的局限性,结合实际工程中大直径长桩的检测实践,通过高应变法、低应变法、声波透射法、钻芯法等方法的对比,论述了高应变法在大直径长桩完整性检测上的独特优势.     

Environmental Open Data in Urban Platforms: An Approach to the Big Data Life Cycle

ABSTRACT

Through a literature review, this paper proposes an assessment framework to evaluate environmental open data in urban platforms under the data life cycle approach. For this purpose, a set of quantitative and qualitative indicators has been defined for each of the stages of the data life cycle: acquisition, access, analysis, and application. As confirmation of the capabilities of this approach, we illustrate the results of its application in six data portals along with analyses, comparisons, and conclusions regarding the results. The cases reveal that an interest exists in providing environmental information, but the capability to transform the data information into knowledge relevant for cities is rather low.     

钢轨磨削机械臂结构设计与优化

钢轨倒棱常用便携式倒棱机具进行现场倒棱,存在作业精度不高,人工操作随意,安全隐患大等风险。设计专用钢轨倒棱机械臂,对钢轨轨头横断面进行自定位倒棱磨削加工,实现精确定量和微量控制的高精度磨削。钢轨倒棱作业对钢轨接头的全寿命养护具有重要意义。