Modeling Measured 3D Tire Contact Stresses in a Viscoelastic FE Pavement Model

Three‐dimensional (3D) contact stresses occurring between the road surface and the tire that were measured with the South African Vehicle Road Surface Pressure Transducer Array (VRSPTA) device under a moving wheel are transformed to a corresponding force/stress pattern representing the actual contact stress state under the tire by means of a software program. In combination with a dynamic load function such force patterns derived from these Stress‐in‐Motion (SIM) measurements with the VRSPTA device are used to introduce a more advanced load representation of the tire‐pavement interface into a three‐dimensional (3D) finite element (FE) model. Further, a method is presented to derive viscoelastic material properties of asphalt concrete (AC) mixes from dynamic frequency sweep shear (FS‐S) tests of lab specimens or field cores that can be used to define material behavior of the AC layers in the 3D FE pavement model. Linear elastic layered theory is utilized to validate the results of the FE computations in order to demonstrate that the FE method can successfully be used to include SIM measurements for more advanced analysis and design of pavements. First results of the 3D FE simulation of a load circle of the Heavy Vehicle Simulator (HVS) during accelerated pavement testing of a pavement test section are presented. These results encourage employment of the FE pavement model for further simulation work to assess the rutting potential of AC mixes in combination with different tire types and loading situations.     

一种板式过滤机滤箱试压装置的设计研究

文章设计了一种板式过滤机滤箱试压装置,该装置是一种对中间滤箱进行渗漏检验的试验平台,结构简单,易于操作;另外还介绍了对该装置试压工况下进行设计计算的方法。     

四辊CVC冷轧机辊间压力影响因素分析

CVC轧机辊间接触压力分布不均,辊间压力峰值易引起严重的支撑辊不均匀磨损,甚至造成轧辊的剥落。采用影响函数法,分析了轧件宽度、工作辊横移位置、弯辊力以及支撑辊凸度对辊间压力分布的影响;研究了在应力集中最严重的横移位置时,支撑辊端部采用圆弧形倒角和抛物线形倒角时,倒角参数变化对辊间压力分布的影响规律。结果表明:CVC轧机辊间压力成S形分布,在轧辊右端存在较大的应力集中;轧件越宽,应力集中越严重;横移位置为负向最大时,辊间应力集中最严重;增加支撑辊凸度能减小辊间接触压力的峰值,但是对辊间压力分布的改善不明显;弯辊力对辊间压力有较大的影响;使用合适的抛物线形倒角和圆弧形倒角均能很好的减小辊间接触压力的峰值,并使辊间压力分布更均匀。研究结果可为CVC轧机支撑辊辊形设计提供理论依据。     

双压力角非对称齿廓齿轮接触应力的计算研究

文章提出了工作齿面采用大压力角的双压力角非对称齿廓渐开线圆柱齿轮齿面接触应力的解析计算方法,推导出了双压力角非对称齿廓渐开线圆柱齿轮工作齿面在任意啮合点上接触应力的计算公式,特别就工作齿侧齿面在节点和小齿轮单对齿啮合区下界点处的齿面接触应力进行了研究。通过与常规的对称渐开线圆柱齿轮和工作齿面采用小压力角的双压力角非对称齿廓渐开线圆柱齿轮齿面接触应力对比,论证了这种双压力角非对称齿廓渐开线圆柱齿轮能够有效地提高齿面接触强度。     

压力对碳纤维—铜—石墨复合材料接触电压降的影响

在电磨损条件下,研究了压力变化（7．5－30N/cm^2)对碳纤维－铜－石墨复合材料接触电压降的影响,结果表明,电磨损初期,接触电压降随磨损时间的延长而增加;随着压力的增加,复合材料接触电压降下降,但压力超过一定值后,接触电压降变化不大。分析了接触电压降的变化机理。     

钢轨的抗接触疲劳伤损性能研究

研究了一种与常规的金属材料接触疲劳性能试验不同的,更接近线路钢轨轮轨接触状态的钢轨接触疲劳试验方法,对不同钢轨在车速160 km/h、半径800 m、轴重25 t条件的抗接触疲劳伤损性能进行模拟试验研究.结果表明,在一定的试验(工况)条件下,裂纹萌生和扩展速率较低、磨损量大的钢轨接触疲劳伤损相对较轻.在试验的几种钢轨中1 000 MPa级的U75V热轧钢轨接触疲劳伤损最重.根据各钢轨的接触疲劳伤损特点,1 300 MPa级热处理钢轨适宜在小半径的重载线路上使用,强度和裂纹扩展速率低的钢轨适宜在高、快速线路上使用.     

连铸坯中心偏析对LX72A钢帘线合股断丝的影响

70 t BOF-LF-Φ380 mm CC-开坯成150 mm×150 mm方坯-CR和200 t BOF-LF-200 mm×200mm CC-CR两种工艺路线所生产的Φ5.5 mm盘条经拉拔成Φ0.22 mm钢帘线合股过程的断丝率为Φ380mm圆铸坯工艺-2.86次/t,200 mm×200 mm方坯工艺-<1次/t。检验结果表明,圆坯工艺生产的盘条严重的中心偏析是大量断丝的主要因素,150mm×150 mm轧坯的宏观碳偏析高达1.11。采用断面尺寸200 mm×200 mm以上的方坯连铸工艺流程,中间包钢水过热度15～25℃,拉速恒定,采用结晶器和末端电磁搅拌,可有效地减轻中心偏析。     

铍铜电极在接触类焊机上的应用研究

接触焊用电极材料是接触类焊机的核心部件，要求具有优良的导电率，强度和高的耐高温性能（软化温度）等综合性能，本项目采用含铍多元铜合金，利用含铍铜合金具有较高的硬度，耐高温性能，强度和导电率的综合性能，研制出一种达到进口电极性能要求的长寿命新型电极材料，通过在进口及国产设备使用完全满足要求，解决了国产焊接电极长期存在的焊接质量差，寿命短的问题。     

Effects of Administrator-Witness Contact on Eyewitness Identification Accuracy.

Concern that lineup administrators can influence eyewitness identifications has led researchers to suggest implementing double-blind testing, an idea that police resist. Using a typical eyewitness paradigm (video event followed by photographic identification test), the present study demonstrated that an alternative technique, minimizing the level of contact between lineup administrators and witnesses, could reduce false identifications without reducing hits. Specifically, witnesses were more likely to make decisions consistent with lineup administrator expectations when the level of contact between the administrator and the witness was high than when it was low. These results are explained within the experimenter expectancy framework. Implications for applied settings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of Contact Pressure on Bond Strength of Fiber-Reinforced Polymer to Concrete

In this technical note, the importance of contact pressure (0.03 N/mm2) during curing of adhesive between fiber reinforced polymer (FRP) and concrete is addressed. The shortcoming of fast-curing epoxy resin is pointed out. Different pressures and an ordinary epoxy resin were chosen to assess the effectiveness of contact pressure on FRP-to-concrete bond strength. The test results showed that the bond quality could be significantly improved by exerting a contact pressure ≥ 0.01 N/mm2. A simple and easy site-operation method for exerting contact pressure is also introduced.     

新型铜基电接触材料的高温氧化性能研究

研究了铸态和热处理态新型铜基电接触材料的高温氧化行为,并用SEM观察了表面氧化膜的微观形貌。结果表明,与铸态材料相比,热处理态铜基电接触材料表面氧化膜的致密性和连续性较高,氧化增重较低,表现出更好的高温氧化性能。     

TRT故障时对高炉顶压的影响及对策

介绍了TRT的工艺过程及控制方式,叙述了在发生静叶突然全关、UPS电源停电、入口压力测量信号等几起故障时对高炉顶压的影响以及解决问题的办法     

一种新型Ag-SnO2触头材料的制备及对性能的影响

采用化学共沉淀法和粉末热锻相结合的工艺，研制出新型的Ag—SnO2触头材料，并对其组织结构进行了观察分析，同时还测试了材料的密度、硬度、电阻率等物理性能。     

高铁闪锌矿低温低压浸出新工艺研究

在硫熔点温度以下对铁闪锌矿进行加压浸出试验研究,重点考察浸出温度、时间、矿物粒度、氧分压、初始酸度等因素对锌、铁浸出率的影响。结果表明,在115℃、氧分压500kPa下浸出3h,锌浸出率可以达到97%以上,溶液铁含量低于2g/L。     

微量铈和铬对Cu-0.1Ag合金接触线的性能影响

采用显微硬度计、电子拉伸试验机、光学显微镜和TEM等，通过与Cu-0．1％Ag合金对比，分析了Cu-0．1％Ag-0．06％Ce合金和Cu-0．1-kAg0．1％Cr合金的抗软化性能、合金元素的作用及组织形貌特征。结果表明：Cu-0．1％Ag合金中分别加入铬和稀土铈后，综合性能明显提高。软化温度分别提高了110和35℃，稀土化合物以小球状分布在晶体内，细化晶粒，提高硬度（强度）和抗软化性能。     

两种加压浸出工艺处理锌浸出渣试验

开展了两种加压浸出工艺处理锌浸出渣的试验研究。“加压还原浸出+氧压浸出”取代原针铁矿工艺的“三段逆流热酸浸出+还原”,锌焙烧矿到铅渣的渣率为15.74%,锌、铁、铜、铟、镁的浸出率分别为99.32%、93.50%、95.02%、91.03%、99.97%,各项指标均优于原工艺,锌、铟的浸出率分别提高了1.82、11.03个百分点,反应时间由14 h缩短为4 h,液固分离次数由4次减少为2次。“两段逆流加压浸出”取代原黄钾铁矾工艺的“硅浸+预中和+黄钾铁矾沉铁”,锌焙烧矿到二段渣的渣率为35.88%,锌、铁、铜、铟、镁的浸出率分别为98.50%、4.94%、90.48%、2.69%、93.77%,各项指标均优于原工艺,浸出后液（相当于水解除铁后液）可以直接返回中性浸出工序,反应时间由16 h缩短为4 h,液固分离次数由3次减少为2次。加压浸出采用密闭的加压釜,更容易实现整个炼锌系统蒸汽平衡,无需额外增加蒸汽锅炉。     

一种尾矿物料的压滤脱水试验研究

针对堆积型铝土矿开发应用过程中洗矿尾矿固液分离难题,在应用压滤脱水技术处理铝土矿微细尾矿的试验研究基础上,开展铝土矿尾矿泥的压滤脱水半工业―工业试验研究,探讨压滤机滤室腔型、滤布、入料浓度和助滤介质等因素对矿泥压滤效率的影响。研究发现压滤机滤腔结构、滤室厚度等制造参数对尾矿泥压滤脱水效率有显著影响,滤布的透气、滤水性能对压滤生产影响较大,入料浓度与压滤效率呈显著的正相关关系,添加改性助滤剂有利于提高压滤效率和降低滤饼含水率。该研究可为完善压滤生产技术,寻求经济合理的配套生产工艺、设备,实施大规模工业化的压滤生产提供科学依据。这种提升压滤效率和降低处理成本的方法途径探索,对矿山尾矿及其他难处理物料的固液分离具有较好的借鉴价值。     

元江红土镍矿加压浸出试验研究

对元江铁质和镁质红土镍矿进行加压浸出试验,详细考察了浸出温度、反应时间和初始酸度对镍浸出率及酸耗的影响。结果表明,铁质矿的镍浸出率可达90%以上,吨镍酸耗可降低至45t以下;镁质矿的镍浸出率可达80%,吨镍酸耗70t左右。采用两段加压浸出工艺处理该红土矿,镍浸出率可达88%以上,吨镍酸耗50t左右。     

铜转炉白烟尘加压浸出工艺研究

针对铜冶炼转炉白烟尘中有价金属的综合利用,开展了加压浸出工艺研究。在液固比6∶1(mL/g)、初始硫酸浓度0.6mol/L、浸出温度120℃、氧分压0.6 MPa、浸出时间3h、搅拌速度500r/min的条件下,Cu、Zn浸出率均高于95%,Cd浸出率大于90%,As、Fe浸出率可以控制在10%以下。同步实现Cu、Zn、Cd高效浸出与As、Fe的抑制,有利于后续加压浸出液中的有价金属的分离。     

On the Effects of Subgrade Erosion on the Contact Pressure Distribution under Rigid Surface Structures

The performance of rigid surface structures such as concrete pavements and slabs-on-grade supported by a deteriorated subgrade and experiencing local contact loss is investigated experimentally and numerically in this study. A laboratory setup has been designed to facilitate the simulation of subsurface erosion and measure the changes in contact pressure at selected locations under a slab-on-grade supported on granular material. The presence of erosion voids under a slab-on-grade can lead to rapid increase in the contact pressure in the immediate vicinity of the void in addition to an increase in tensile stresses at the outermost fibers of the slab. This preliminary study suggests that efforts to detect and arrest the growth of erosion voids under slabs-on-grade should be made before the voids reach the size where significant loss of support develops and the tensile strength of the slab material is exceeded.