Effect of a large asymmetrical wheel burden on flexural response and failure of railway concrete sleepers in track systems

In many railway networks, the dynamic loads on the track can be detected and they are highly diverse. In most cases, the dynamic wheel load could be treated as a quasi-static load whereas it is later employed in flexural response and failure analysis of railway structures, according to the current design standard: AS1085. This paper presents the effect of a large asymmetrical wheel load on the flexural response and failure criteria of the concrete sleepers in railway track systems. The finite element model updating of the concrete sleeper was earlier established and verified against experimental dynamic characteristics by the authors. Using a finite element package STRAND7, the nonlinear finite element model is capable of simulating the tensionless ballast support whereas the supporting boundary condition provides resistance to only compression. The numerical investigations are carried out to provide guiding criteria to railway track engineers for crack and failure analysis of the railway concrete sleeper subjected to a large quasi-static asymmetrical wheel burden. The normalized quasi-static responses are demonstrated in order to illustrate the critical effect of the large wheel unbalance on the flexural responses of the concrete sleeper in railway track system.     

贵德盆地地热井井内热交换工艺应用

地热作为一种绿色能源,具有分布广、无污染、易开发利用等优点,在供暖、旅游、温泉洗浴、医疗保健、种植养殖等领域具有不可替代的作用。贵德地区地处"三江源"地区,地热资源开发利用将对"三江源"地区生态环境保护起到一定作用,通过对贵德盆地DR1地热井深井内热交换工艺,使该井出水温度由41℃提高到46℃,实现了利用井底高温岩石自行热交换方式提高地热井出口温度的目的。同时,为类似地层地热增温提供了示范。     

Y06108 ZQ铁型覆砂曲轴产生灰化的原因及解决办法

对YC6108ZQ曲轴灰化原因进行了分析,通过采用铁型覆砂铸造工艺和工艺过程的控制等几方面的结合,明显提高曲轴整体质量水平,按此工艺生产,基本解决了灰化问题。     

3D graphical evaluation of micron-scale protrusion topography of diamond grinding wheel

A new graphical evaluation of micron-scale wheel protrusion topography is proposed by using 3D coordinate data derived from contact measuring of 180 diamond grinding wheel. The objective is to quantify 3D distribution of grain protrusion height, gain rake angle and grain relief angle on wheel working surface in dressing. First adaptive measuring was conducted on the base of topographical curvature to identify grain cutting edge in 3D space, second grain protrusion mode was established by polar coordinate transfer so as to ascertain datum plane of grain protrusion, then linear approximation graphics was conducted to display wheel protrusion topography, finally distributions of gain rake angle and grain relief angle were investigated with reference to grain protrusion height. Analytical results show that higher outer grains have more and shaper cutting edges, but lower layer grains retain approximately original crystal forms. In wheel protrusion topography, grain protrusion heights, grain rake angles and grain relief angles are dispersedly distributed in the range 0–28 μm, −45.0° to −89.1° and 1.2–73.1°, respectively, which can be increased by dressing. It is concluded that 3D grain protrusion attitudes distributed on wheel working surface can be quantified by 3D graphical evaluation method.     

车轮钢AG400CL的研制与开发

采用低碳低硅的成分体系,在1780mm热连轧生产线上开发出了车轮钢AG400CL.并进行了卷取温度对车轮钢性能影响的试验,结果表明:卷取温度从600℃降到560℃,对车轮钢的强度和韧性影响较小.     

基于adams／vibration的内燃机机体振动特性研究

本文以一台多缸柴油机为例,采用结合有限元法（FEM）的多体系统仿真（MSS）方法,建立了内燃机机体振动特性分析模型。通过仿真分析,得出了机体主要激励对应的机体表面振动传递函数。     

火车车轮轮辋超声相控阵检测

采用某超声相控阵检测设备对火车车轮轮辋做检测,检测结果表明相控阵设备具有灵敏度高、覆盖范围广、能多角度检测、曲线显示直观等优点。对超声相控阵检测同仁有一定借鉴意义。     

基于分割导向滤波的亚像素精度立体匹配视差优化算法*

针对局部立体匹配中存在的弱纹理区域匹配精度较低、斜面等区域容易产生视差阶梯效应等问题,文中提出基于分割导向滤波的视差优化算法,以获得亚像素级高精度匹配视差.首先依据左右一致性准则对立体匹配的初始视差进行误匹配检验及均值滤波修正.然后在修正视差图上确定区域分割导向图,对修正视差进行区域导向滤波优化,获得亚像素级高精度的视差结果.实验表明,文中算法能有效改善斜面等区域的视差不平滑现象,降低初始视差的误匹配率,获得较高精度的稠密视差结果.     

微量Sc对2A14铝合金轮毂组织与性能的影响

采用铸锭冶金及等温复合锻造方法,制备了含Sc的2A14铝合金轮毂锻坯,研究了Sc对锻坯组织与性能的影响。结果表明,Sc含量提高至0.3%时,2A14铝合金的晶粒得到明显的细化,大部分晶粒呈等轴晶状态。添加Sc提高了2A14铝合金的伸长率,但其抗拉强度明显降低,使其低于400MPa,原因在于添加Sc后,大量消耗2A14铝合金中的Cu元素,导致强化相θ′-Al2Cu体积分数减少。但Sc能有效抑制合金中的再结晶,减小轮毂锻坯各部位的性能差异,并提高合金的耐热性能。     

格里桥水电站2号机组下导轴承摆度值偏大的原因分析及处理

格里桥水电站2号机组检修过后,开机运行出现了下导轴承摆度偏大的情况。当振动超过规定的允许值时,便会影响机组的供电质量、安全运行和机组的寿命,需及时找出原因并采取措施减小或消除。针对格里桥水电站2号机组的具体情况,探讨了影响水轮发电机组的振动的因素,并通过变转速试验、变励磁试验、动平衡试验对可能引起格里桥电站机组振动的因素进行了逐一分析和排除,最终解决了下导轴承摆度值偏大的问题,并在处理过程中发现油盆的结构不足也会导致下导摆度持续变化并偏大的问题。此次原因分析及处理过程,通过动平衡和机械部件结构的排查,为其他类似电站机组处理摆度值偏大的问题提供了参考处理意见。