端墙升降加载装置的设计与改进

本文设计了一种可满足BS EN12663-1:2010+A1:2014标准6. 2. 3条款要求的车体端墙加载试验的端墙升降加载装置,可以实现3种不同高度的载荷试验需求,并进行了静强度分析。对试验中发现的问题进行了改进,增加了加载装置的安全裕量,提高了端墙升降加载装置的安全系数。     

基于AMESim仿真的电液比例加载系统性能分析

为了研究电液比例模拟加载系统的加载的性能,分析电液比例溢流阀加载与电液比例节流阀加载特点以及适用场合。首先分析两种阀的加载原理,然后在AMESim中建立两种加载系统的仿真模型,最后在实验台上进行实验验证。结合仿真结果与实验数据对比两种加载系统的性能特点可得:受到最小稳定流量的影响溢流阀加载适用于马达输出扭矩比较大的场合,而节流阀进出口压差较大时节流损失较大,节流加载适用于马达输出扭矩比较小的场合。在建立模拟加载系统时,同时建立溢流加载与节流加载系统,这样充分利用两种加载的优势,使得加载系统应用范围更广。     

钢结构两种载荷施加方式的仿真方法对比分析

对仿真模拟加载时两种不同的加载方式进行了分析,并将得到的结果与试验值进行对比,提供了一种较为简单且与试验值基本符合的仿真加载方法。     

轴承试验径向加载结构设计与优化

以轴承试验中径向加载结构为研究对象,通过对不同径向加载轴承结构特点分析,设计了几种不同的径向加载结构,并对径向加载结构设计思路及使用过程中的注意事项进行了介绍。根据以往使用经验,对两种径向加载结构进行优化设计,为航空发动机轴承试验中径向加载结构选取提供参考依据。     

大型钛合金构件等温局部加载过程晶粒尺寸演变规律

为研究大型钛合金构件等温局部加载过程中的微观组织演变规律,基于TA15钛合金内变量法微观组织模型,模拟分析了大型钛合金筋板构件等温局部加载过程的初生α相晶粒尺寸变化规律,并与变换局部加载顺序及整体加载两种方式进行了对比.结果表明:过渡区因受到加载区材料跨区转移的影响,两个加载步后的初生α相晶粒尺寸均有所减小,使得该区域...     

专用传感器加载定度装置和方法的研究

研究设计了法码式和顶杆式两种用于专用（六维力／力矩）传感器的加载定度装置，介绍了它们的加载原理和加载布置方式，并对加载力／力矩的方法进行了分析。这两种装置的加载力分别为１００－３００Ｎ、３００－１０００Ｎ，最大加载力矩分别为１５Ｎｍ、５０Ｎｍ，加载精度分别是０．０５％．０．５％。     

风机叶片静力加载电液控制系统研究

设计了可实现风机叶片静力加载的电液控制系统,对两种控制方案——比例调压方案和变频调速方案——进行了数学建模和理论分析,指出叶片等效刚度对系统的动态性能有直接的影响。在此基础上采用了PID控制器对两种控制方案进行了理论研究和试验对比,证明了比例溢流阀调压方案的动态性能不能满足加载的控制要求,而变频调速方案能较好地实现叶片加载控制,保证了特定阶段的加载精度。     

大型钛合金构件等温局部加载过程晶粒尺寸演变规律#br#

为研究大型钛合金构件等温局部加载过程中的微观组织演变规律,基于TA15钛合金内变量法微观组织模型,模拟分析了大型钛合金筋板构件等温局部加载过程的初生α相晶粒尺寸变化规律,并与变换局部加载顺序及整体加载两种方式进行了对比。结果表明：过渡区因受到加载区材料跨区转移的影响,两个加载步后的初生α相晶粒尺寸均有所减小,使得该区域的初生α相晶粒尺寸小于远离过渡区区域的晶粒尺寸;先后加载顺序的转变会改变材料的跨区转移量,以致模具分区两侧的晶粒尺寸产生差异;与整体加载方式相比,局部加载过渡区的晶粒尺寸较小;在三种加载方式下,远离过渡区晶粒尺寸的差异不大。     

泵控马达电液比例加载系统的研究

针对泵控马达系统,提出两种加载方法,即电液比例溢流阀加载与电液比例节流阀加载。针对电液比例溢流阀加载系统,运用建模的方法,分别对电液比例溢流阀、DS1二次元件等子系统进行建模。在此基础上,得出了电液比例溢流阀加载系统整体数学模型。通过仿真分析,验证了加载系统的良好的动态性能。     

TBM滚刀在不同加载方式下的破岩机理研究

针对全断面岩石隧道掘进机(TBM)工作中刀具选型和刀盘中滚刀布局的问题,采用光滑粒子流(SPH)方法和有限元方法复合建模,对TBM常用的V型和常截面(CCS)盘形滚刀分别在同时加载和顺次加载两种情况下的破岩机理进行数值试验研究,得到了两种不同截面滚刀在不同加载顺序下破岩的动态过程和滚刀侵入过程中岩石裂纹的产生和扩展过程.研究结果表明:V型滚刀顺次加载下的破岩效果好于同时加载,CCS滚刀顺次加载时有利于大块岩屑的形成.     

Comparative Investigation on Tribological Properties of Ion-Sulfuration Layers Under Dry Friction

Four kinds of steel, including high-speed steel (M2), die steel (L6), stainless steel (420) and plain carbon steel (1045), were treated by low-temperature ion sulfuration. Sulfide layers, dominated by the FeS phase, were produced on the surfaces of the four steels. The tribological properties of sulfide layers were investigated on a block-on-ring test rig under dry friction conditions. The results showed that the tribological properties of all sulfurized steels were remarkably improved. The tribological properties decreased in the order of high-speed steel—die steel—1045 steel—stainless steel. The hardness, microstructure and corrosion resistance of the substrate determined the differences in the tribological properties of different steels.     

2014上海法兰克福汽配展又创新高

<正>2014年12月9日,Automechanika品牌展会上海国际汽车零配件、维修检测诊断设备及服务用品展览会(以下简称2014上海法兰克福汽配展)在上海新国际展览中心开幕。同期,上海法兰克福汽配展举办了新闻发布会。中国汽车工业国际合作有限公司董事长张福生、总经理纪学成出席并作发言。新闻发布会重点就2014上海汽配展的展会亮点、各项数据、创新纪录和未来规划进行发布,并从行业高度分析了未来发展趋势。     

Effect of baffles on orbital accelerations - Induced bubble oscillations in microgravity

The behavior of sloshing dynamics modulated fluid systems driven by the orbital accelerations including gravity gradient and jitter accelerations with partially-filled rotating fluids has been studied. Present study is applicable to a full-scale Gravity Probe-B Spacecraft dewar tank with and without baffle. Results of slosh wave excitation along the liquid—vapor interface induced by jitter acceleration-dominated orbital accelerations provide a torsional moment with an up-and-down movement of bubble oscillations in the rotating dewar. The results show rightward and leftward movement of bubble oscillations transverse to the rotating axis, and up-and-down movement of bubble oscillations longitudinal to the rotating axis of dewar container. The orbital accelerations also induce an eccentric contour of bubble oscillations in a horizontal r—θ plane. As viscous force between liquid—solid interface, and surface tension force between liquid—vapor—solid interface can greatly contribute to the damping effect of slosh wave excitation, the rotating dewar with baffle provides more areas of liquid—solid and liquid—vapor—solid interfaces than that of a rotating dewar without baffle. Results show that the damping effect provide by a baffle reduce the amplitude of slosh wave excitation and reduce the degree of asymmetry in liquid—vapor distribution. Computation of bubble (helium vapor) mass center fluctuations also verifies that a rotating dewar with baffle produces less fluctuations than that of a rotating dewar without baffle.     

Prediction of wear-resistant thin diffusive coatings

Friction and wear process are investigated using experimental data and mathematical modeling of the specimen contact interaction. To study the wear in the system, ‘a rigid punch—thin coating—elastic base’, a mathematic statement of the problem was formulated. The integral equations were obtained and the solutions to the problems for punches, containing parabolic and wedge-shaped profiles, and also with a flattened basis were constructed. New regularities of deformation and wear of thin coatings on solids were obtained. The methods for crack growth resistance calculations in the coatings allow us to predict by the physicochemical, tribotechnical and geometrical characteristics the coatings life-time, which is proved experimentally on chromium-based coatings applied on carbon steels.     

NSFC机械工程学科2014年度管理工作综述

介绍了2014年度国家自然科学基金委员会(NSFC)机械工程学科科学基金项目的申请、评审及资助情况;以机构学与机器人和微/纳机械系统两个领域的申报项目为例,对申请、评审和资助情况进行了分析。概述了2013年度科学基金项目的结题/进展情况,总结了项目执行过程中存在的问题。回顾了学科在“十三五”战略规划制定、重大项目立项、学术交流与合作、人才培养与团队建设和鼓励创新等方面的管理举措。综述了2014年度我国机械工程领域的国际学术影响和取得的最新进展;对2015年度学科工作进行了展望。     

Wear and micropitting of steel ball sliding against TiN coated steel plate in dry and lubricated conditions

Wear of the steel part sliding against titanium nitride both in lubricated and unlubricated conditions have been investigated. An unexpected micropitting like wear on the steel surface was found in lubricated conditions, after very short run time. Possible wear mechanisms—fatigue, chemical reaction or electrical discharge—are discussed. A special attention is given to electrical discharge mechanism. A remarkable result was obtained when the lubricant, white oil—a good insulator fluid—was replaced with glycerin, an electrical conductive fluid. With glycerin as lubricant no micropitting was observed on the steel surface even after long run time.In unlubricated condition intense, predominant oxidative wear of steel part was found.     

Numerical modelling of sub-surface stress in magnetic data tape heads due to the dynamic contact with a tape

The stress field at the subsurface of the ceramic used as a tape-bearing surface (TBS) in magnetic head construction is calculated by means of numerical methods taking into account roughness and friction forces at the head to tape interface (HTI). A two-dimensional model confirms the purely elastic character of the contact. However, only a three-dimensional model allows a quantitative interpretation, and thus to estimate the real area to apparent area of contact ratio—in agreement with a previous formal calculation—as well as the depth of the maximum von Mises stress—i.e. the depth at which a crack is more likely to form and extend—near 30 nm, comparable to the pullout depth observed at the surface of the ceramic used in actual heads.     

Prerotation flow measurement

Different measuring methods relating to the prerotation flow in the entrance pipe of radial pumps are analyzed. The appearance of the prerotation flow is a result of the complicated fluid flow model, which appears as a consequence of the pump operating out of design limits and reduces pump efficiency. The goal of this contribution is in estimating the best measuring method, taking into account the inconvenience of conventional hot-wire and laser-Doppler anemometry. Therefore, two measuring systems—multiblade (ASB) and single blade (ASSB) anemometer—are introduced, analyzed and compared. The advantages of the introduced measuring system—ASB—are in its simple construction and simple use and its low price. The direction and swirl flow intensity in the entrance pipe of radial pumps and fans could be measured using this method.     

An optimum surface of revolution for pressurised shells

This paper determines the surface of revolution which forms the shallowest pressurised shell—or the shallowest end closure to a pressurised cylinder—consistent with the avoidance of compressive membrane stresses.     

Applying the Adiabatic Demagnetization Technique to Detect Explosive Substances by the Nuclear Quadrupole Resonance Method

An experiment in applying the adiabatic demagnetization technique to considerably increase the sensitivity of the nuclear quadrupole resonance (NQR) method for the multipulse detection of one of the most widely used explosives—pentaerythritol tetranitrate (PETN)—is described. The results were obtained using a highly inhomogeneous magnetic field produced by permanent magnets. The dependences of the NQR signal enhancement on the carrier frequency offset and the time during which the sample was kept in the magnetic field were studied while using the adiabatic demagnetisation technique.__________Translated from Pribory i Tekhnika Eksperimenta, No. 3, 2005, pp. 132–135.Original Russian Text Copyright © 2005 by Mikhaltsevich, Belyakov.