疏浚刀齿表面的介质拉伸实验

疏浚机具在土壤切削过程中,由于处土部分与土壤之间的粘附,会使得切削阻力增大,疏浚效率降低。相互接触的两个刀齿界面上存在不同的粘性物质如水、空气、黄油时,会使得界面的粘附力不同,从而导致拉伸所需的拉力大小不同。通过试验,分别对光滑表面刀齿和凹坑形表面结构刀齿,以及两刀齿界面间采用不同的粘性物质,来研究两相互接触的刀齿界面间粘附力大小的影响因素。试验表明：对于相同的刀齿表面,当界面采用空气、水、黄油时,其界面的粘附力依次增大;对于界面间采用相同的粘性物质时,凹坑表面结构刀齿的界面间的粘附力较光滑表面刀齿较小。     

凹坑形仿生刀齿土壤切削力分析

土壤对疏浚机具的粘附会增加切削阻力、降低切削效率。土壤动物的非光滑表面为疏浚机具的仿生设计提供了参考。非光滑表面切削土壤具有减阻的作用,针对凹坑形非光滑表面的刀齿切削土壤的的受力情况进行理论分析,建立了其土壤切削模型。利用软件Fluent进行了凹坑形光滑表面刀齿在土壤切削过程中的力学分析,结果表明:在一定的土壤条件下,与光滑表面刀齿相比,非光滑凹坑形刀齿粘附对土壤粘附力较小,受到的切削阻力也较小。理论分析和与数值模拟均验证了非光滑凹坑形仿生刀齿能够起到预期的减粘减阻的效果。     

硅微机械动平板表面粘附阻力

以MEMS动平板模型为研究对象,建立了微间隙动平板表面粘附阻力的理论模型,利用界面化学中表面能和粘附功的概念,推导出了光滑平板和开孔平板的表面粘附阻力公式,并探讨了影响表面粘附阻力的诸多因素。在此基础上还设计了拉簧-平板-弯簧器件以进行相应的表面粘附阻力实验研究。理论分析和实验验证均表明,表面粘附阻力随单位面积的液气界面表面能以及平板宽度的增大而增大,随着接触角的减小而增大,且平板工艺开孔的总宽度增大以及平板移动方向的孔数的增多将显著增大表面粘附阻力。     

仿生刀齿表面结构优化设计

土壤粘附是影响疏浚刀齿切削效率的重要因素之一.降低粘性土壤对刀齿表面接触面积可以减小土壤对刀齿的粘附和降低刀齿切削土壤的阻力.针对两种典型非光滑刀齿结构用遗传算法进行了优化设计,得到了在一定压力条件下非光滑表面仿生刀齿结构的最优参数,为疏浚刀齿表面结构仿生减粘降阻设计提供了参考.     

波纹形仿生疏浚绞刀刀齿的减粘减阻研究

土壤对水下作业的疏浚绞刀的粘附是影响其工作效率的主要原因,而土壤动物的非光滑表面为疏浚绞刀的减粘减阻仿生设计提供了参考。针对河蚌表面进行研究,应用相似原理设计出4种波纹形仿生疏浚绞刀刀齿,并进行离散元仿真。仿真结果表明,在波纹参数设计合理的条件下,河蚌非光滑波纹表面具有减粘减阻效果,为波纹形仿生疏浚绞刀刀齿参数优化设计奠定了基础。     

沟槽织构化表面影响摩擦振动噪声机理

在列车制动盘蠕墨铸铁材料表面上制备出平行间隔分布的沟槽表面织构,将其和光滑表面进行摩擦噪声对比试验,并利用有限元软件ABAQUS/Explicit(显式动态求解器)对试验进行数值模拟分析,研究沟槽织构化表面影响摩擦振动噪声的机理。结果表明,本试验条件下的光滑表面会产生较高强度的噪声而沟槽表面几乎不产生噪声,利用有限元软件ABAQUS/Explicit可以很好地模拟试验现象并揭示沟槽表面织构影响界面摩擦振动噪声的机理,即沟槽织构表面在对磨球滑过并碰击沟槽时引起的摩擦力波动能有效的打断摩擦界面的连续接触,作为不连续激励扰乱系统的自激振动,抑制界面摩擦力和振动加速度高频成分的形成并最终降低摩擦噪声。     

激光微造型表面固体润滑性能研究

采用声光调Q二极管泵浦固体光源(DPSS)Nd:YAG激光器,在45#钢试样表面进行表面微造型加工。以聚酰亚胺(PI)和二硫化钼(MoS2)复合固体润滑材料作为固体润滑剂,通过两步加温固化黏结工艺成功制备微造型固体润滑试样。在MMW-1A型摩擦磨损试验机上进行光滑无润滑试样、光滑表面固体润滑试样和微造型固体润滑试样的摩擦性能对比试验,以及微造型固体润滑试样在不同转速和压力下的摩擦性能试验。结果表明,在经过激光加工的微凹坑中填充复合固体润滑材料的试样,在摩擦过程中微凹坑中填充的固体润滑材料能有效转移到在摩擦表面,补充消耗掉的润滑材料,因而表现出更好的摩擦学性能。     

表面微凹坑和纹理方向对界面摩擦的耦合影响

选取三种不同纹理的铝合金试样,并在试样上加工不同面积占有率的规则圆形微凹坑,利用自制的摩擦试验装置,在油润滑条件下以不同接触压力进行摩擦试验,试验过程中滑动方向与表面纹理方向的夹角分别为0°、45°、90°。利用非接触式三维轮廓仪测量试验前后试样的三维表面形貌,并选取Sa、Str、Vvv、Vvc等表面表征参数来分析滑动接触界面表面形貌的变化。结果表明：表面纹理方向的差异导致铝合金表面在滑动接触摩擦过程中表现出各向异性,而在其表面加工不同面积占有率的微凹坑,减弱了铝合金表面纹理方向性对界面摩擦的影响,反映出表面微凹坑和纹理对界面摩擦的耦合作用。同时界面摩擦对试件的表面形貌也有明显的影响,Str、Vvv、Vvc在试验后发生了规律性的变化。     

粘度对超疏水固体表面减阻影响的实验研究

为了研究流体粘度对微细结构固体表面减阻特性的影响,用飞秒激光加工技术在光滑K9玻璃表面加工出光栅微细结构,并对光滑K9玻璃和光栅结构K9玻璃表面进行硅烷化处理,用AR-G2流变仪测量了不同粘度甘油溶液在两表面的扭矩与剪切速率,根据推导出的减阻率计算公式,计算出它们各自的减阻率。结果表明:超疏水光栅微结构表面与疏水光滑表面相比具有明显的减阻特性;微细结构固体表面的减阻效果随着流体粘度的增加而显著提高。     

模型铲刀表面法向压力测量方法的试验研究

针对推土铲刀表面受力特点,本文设计了模型铲刀和小型压力传感器,测量了模型铲刀表面的法向压力,观察并探讨了土壤沿模型铲刀表面流动和粘附情况,拟合出模型铲刀表面法向压力的回归方程.     

多功能冻土三轴试验机的研制与应用

冻土三轴试验机是研究冻土力学性质的基本试验设备。根据冻土试验规程以及目前煤矿建设的特点，研制出高性能多功能的冻土三轴试验机。它可以用于冻土静三轴剪切试验、冻土动三轴试验、冻土三轴蠕变试验、三轴应力路径试验、三轴比例协调加载试验、三轴循环加载试验和分级加载试验及三轴固结试验等，并实现高围压。可以根据要求设定试验参数，全部试验实现微机控制，自动记录试验数据，是目前功能较全的一种新型的三轴试验设备。     

面向快速成型制造的CAD平台内嵌式通用接口

面向快速成型设备的CAD平台中的内嵌式通用接口，可直接在CAD建模环境下零件模型实施自适应直接切片操作，同时生成以片层结构数据为单位的快速成型接口文件，该接口使用NURBS曲线对各截面的片层结构轮廓进行精确地解析重构；依据重构后的NURBS截面轮廓，自动填充功能可精确地生成快速成型设备的X，Y向栅线扫描路径。实验数据表明，与利用STL模型切片获得的得的多义线轮廓对比，经NURBS解析重构后的自适应直接切片轮廓与原始轮廓间的拟合误差降低98％以上，所需的NURBS线段数目减少77％以上。     

新型多功能膜/基结合力测定仪的研制

采用改进划痕法原理及切向力检测临界载荷方法，研制了一种新型多功能膜／基结合力测定仪。该仪器结构新颖，实用简便，不仅能测定金属膜层与基体的结合强度，还能对金属膜层进行模拟单颗粒磨损试验。试验表明，该仪器具有较高的可靠性。     

Drainage of a Wetting Liquid: Effective Slippage or Polymer Depletion?

A surface force apparatus has been used to investigate the drainage of a viscosity improver lubricant. The characterization of the VI confined interface has been performed. Surprisingly, dynamical measurements enlighten a significant negative value of the immobile layer thickness. This result is discussed in terms of occurrence of slip at the wall, liquid–solid interface wettability, surface roughness and cleanliness, and friction experiments. Consequently, an interface molecular organization modelling is proposed based on polymer depletion near the solid–liquid interface.     

亚微米铜薄膜界面结合强度的测定

基于薄膜／基体界面结合强度对膜基体系的使用效果有直接影响，采用压痕法测定了1Cr18Ni9Ti钢基材表面物理气相沉积铜薄膜的界面结合强度，并通过分析界面处的受力情况，建立相应的数学模型计算出界面结合力。     

大气压力二等标准装置不确定度测试和评定

本文根据国军标GJB/J2749《建立测量标准技术报告的编写要求》和总装电子信息基础部《测量标准技术报告》编写要求的补充说明,结合气象计量的实际情况,给出了大气压力二等标准装置不确定的测试与评定方法。     

Interferometry Measurement of Lubricating Films in Slider-On-Disc Contacts

Interferometry proves to be an efficient way to measure thin lubricant film thickness. However, there are very few reports on the film thickness measurement of conformal lubricated contacts using optical interferometry due to experimental difficulties. In this article, a custom-built test apparatus is introduced, in which a lubricated conformal contact is made between a stationary fixed-incline slider and a moving transparent disc. With a flexible holder, the slider can be positioned in such a way that a specified inclination with respect to the flat disc plane can be obtained. When the disc rotates and the slider is loaded against it, lubricating films are generated. The minimum film thickness h _m at the exit can be determined by interference intensity changes. Measurement error correction in the film thickness was discussed. Case experiments were carried out using the new test apparatus. The credibility of the measurement system is validated by good correlation between the experiments and the theoretical results. The applicability is demonstrated by the film thickness measurement under different inclinations, loads, velocities, lubricants and slider materials. Amongst those case experiments, it is highlighted that the influences of solid/liquid interface properties on the lubrication behaviours can be clearly identified in terms of film thickness.     

Experimental study on pullout performance of sensing optical fibers in compacted sand

The distributed optical fiber sensing systems have played an increasingly important role in monitoring civil infrastructures over the past few years. One of the main challenges of their applications to geotechnical monitoring is to increase the reliability of strain sensing optical fibers in measuring the deformation of surrounding soil masses. In this paper, a pullout test method is proposed to characterize the deformation compatibility between an optical fiber and soil. A series of pullout tests on three types of sand-embedded optical fibers are conducted to investigate the performance of the fiber–sand interface. Based on the test results, an explicit tri-linear pullout force–displacement relationship is proposed to describe the mechanical behavior of the fiber–sand interface. The performance of the three fibers regarding fiber–sand interaction mechanism is evaluated in terms of ratio of effective pullout displacement to diameter, ratio of residual pullout displacement to diameter, peak shear strength and residual shear strength. All four parameters of the three fibers are found to have approximately linear relationships with the applied confining pressure, which reveals that the deformation compatibility of the fiber–sand interface is utterly dependent on the confining pressure. For all the three fibers, the first shear stiffness coefficient is about 8 N/mm and the ratio of residual to peak shear strength is about 0.5. Furthermore, the Mohr–Coulomb failure criterion is used to get the cohesions and friction angles of the three fiber–sand interfaces. Through a comparison of the pullout performance, one out of three types of fibers tested is found to be more preferable for soil deformation measurement in laboratory-scale tests. The conclusions can provide valuable references for predicting the fiber–soil interface behavior and evaluating the reliability of strain monitoring data.     

High temperature tribological behaviour of tool steels during sliding against aluminium

Soldering and abrasive wear of die-casting tools are some of the biggest problems facing the aluminium die-casting industry. The understanding of the tribological behaviour is crucial to design new tool steels and tool steel-coating systems. The present study aims at investigating aluminium adhesion of aluminium/tool steel pair, performing sliding tests at high temperature with ball-on-disc configuration to reproduce solid/solid interaction. Different test conditions have been conducted in order to select the optimal test parameters to obtain aluminium adhesion on disc surface. Once the lab test has been designed, the high temperature tribological performance of different hot work tool steels (uncoated and coated by PVD) sliding against aluminium has been studied to allow proper die material design and selection.     

Hopkinson杆三点弯曲试验中试样与支座接触状态分析

分析Hopkinson杆动态断裂试验中试样与支座的接触状态.研究表明,试样与支座的接触状态取决于试样几何和材料性能参数.在按现行三点弯曲试验方法进行的试验中,确实存在试样与支座脱离接触的现象,并且试样在支座开始受力前起裂.因此,所谓Hopkinson杆三点弯曲试验实际上是单点弯曲试验.并给出标准Charpy试样在Hopkinson杆动态断裂试验中试样与支座之间保持接触的条件.