A modified single edge V-notched beam method for evaluating surface fracture toughness of thermal barrier coatings

The surface fracture toughness is an important mechanical parameter for studying the failure behavior of air plasma sprayed(APS)thermal barrier coatings(TBCs).As APS TBCs are typical multilayer porous ceramic materials,the direct applications of the traditional single edge notched beam(SENB)method that ignores those typical structural characters may cause errors.To measure the surface fracture toughness more accurately,the effects of multilayer and porous characters on the fracture toughness of APS TBCs should be considered.In this paper,a modified single edge V-notched beam(MSEVNB)method with typical structural characters is developed.According to the finite element analysis(FEA),the geometry factor of the multilayer structure is recalculated.Owing to the narrower V-notches,a more accurate critical fracture stress is obtained.Based on the Griffith energy balance,the reduction of the crack surface caused by micro-defects is corrected.The MSEVNB method can measure the surface fracture toughness more accurately than the SENB method.

Temporal-Spatial Variation of Surface Suspended Matter and Controlling Factors in the Inner Shelf of the East China Sea in Winter

Based on the observed surface suspended matter in the East China Sea in February 2007 and June 2015, an empirical model was established using L1 b's band 4 data to retrieve surface suspended matter from the Moderate Resolution Imagine Spectroradiometer Terra imagery. The squared correlation coefficient is 0.8358, and the root mean square error is 0.4285 mg L-1. The model reflects the distribution characteristics of surface suspended matter in the inner shelf of the East China Sea. In this paper, the satellite images of the study area were retrieved in January from 2001 to 2015, and the monthly distribution of surface suspended matter were obtained. The inter-annual distribution of the study area is similar, and the concentration of surface suspended matter is higher near the shore than offshore. A large amount of surface suspended matter is transported southeast under the influence of Zhejiang and Fujian coastal current and Taiwan warm current. Only a small amount of surface suspension can reach the Kuroshio area. The surface suspended matter concentration changes obviously near the estuary because of the effect of differences in the flux of the Yangtze River. Meanwhile, winter monsoon, temperature front, El Ni?o events, and other factors affect the distribution of surface suspended matter in 100 m isobath to coastal water but minimally influence the distribution in 100 m isobath to deep sea.

Deposition of Diamond-Like Carbon on Inner Surface by Hollow Cathode Discharge

A cylindrical hollow cathode discharge （HCD） in CH4/Ar gas mixture at pressure of 20-30 Pa was used to deposit diamond-like carbon （DLC） films on the inner surface of a stainless steel tube. The characteristics of the HCD including the voltage-current curves, the plasma im- ages and the optical emission spectrum （OES） were measured in Ar and CHn/Ar mixtures. The properties of DLC films prepared under different conditions were analyzed by means of Raman spectroscopy and scanning electron microscopy （SEM）. The results show that the electron exci- tation temperature of HCD plasma is about 2400 K. DLC films can be deposited on the inner surface of tubes. The ratio of sp3/sp2 bonds decreases with the applied voltage and the deposition time. The optimizing CH4 content was found to be around CH4/Ar =1/5 for good quality of DLC films in the present system.

Measurement of inner surface roughness of capillary by an x-ray reflectivity method

The inner surface roughness of a capillary is investigated by the reflectivity of x-rays penetrating through the capillary. The results are consistent with the data from atomic force microscope （AFM）. The roughness measured by this new method can reach the order of angstroms with high quality capillaries.

Experimental Investigation on the Bush Inner Surface Temperature of a High Speed Spiral Oil Wedge Sleeve Bearing

The temperature of bush inner surface temperature is measured by using infrared thermometer and transparent bearing,and temperature rise is measured by using thermocouple. The influence of rotating speed and axial location on the bush inner surface temperature is studied,and the influence of supply pressure and rotating speed on the temperature rise is analyzed. The results show the bush inner surface temperature and temperature rise of spiral oil wedge hydrodynamic bearing increase with the increase of rotation speed. In axial direction,the temperature is higher around the oil return hole. The temperature rise decreases with the increase of supply pressure. The highest temperature of bush inner surface and temperature rise are higher at higher speed,so the temperature rise is the fundamental reason which restricts the increase of rotation speed for high speed sleeve bearing.

Improvement of plasma uniformity and mechanical properties of Cr films deposited on the inner surface of a tube by an auxiliary anode near the tube tail

In order to improve the length of plasma in a whole tube and mechanical properties of Cr films deposited on the inner surface of the tube, a high-power impulse magnetron sputtering coating method with a planar cathode target and auxiliary anode was proposed. The auxiliary anode was placed near the tube tail to attract plasma into the inner part of the tube. Cr films were deposited on the inner wall of a 20# carbon steel tube with a diameter of 40 mm and length of 120 mm. The influence of auxiliary anode voltage on the discharge characteristics of the Cr target, and the structure and mechanical properties of Cr films deposited on the inner surface of the tube were explored. With higher auxiliary anode voltage, an increase in substrate current was observed, especially in the tube tail. The thickness uniformity, compactness, hardness and H/E ratios of the Cr films deposited on the inner surface of the tube increased with the increase in auxiliary anode voltage. The Cr films deposited with auxiliary anode voltage of 60 V exhibited the highest hardness of 9.6 GPa and the lowest friction coefficient of 0.68.

Double Temperature and Density Phenomenon in Grid Enhanced Plasma Source Ion Implantation for Inner Surface Modification of Tubes

Inner surface coating for tubular samples was realized by the grid enhanced plasma source ion implantation （GEPSII） method. In the GEPSII system, two electrodes, a central rod electrode and a coaxial grid electrode were coaxially assembled inside the tube. Plasma was generated between the electrodes by a radio-frequency （RF） oscillating power source. Plasma then diffused through the grid and realized inner surface ion implantation by a negative high voltage applied to the tube. The plasma was then divided, by the grid, into two regions, namely the source plasma region and the diffused plasma region. The plasma＇s self-bias between two RF power source electrodes was measured. At the same time, the electron temperature and plasma density in the GEPSII system were measured by a scattering spectrometer. Results showed that the plasma properties of the two regions were entirely different; the plasma self-bias, which might greatly affect the sputtering rate of the central titanium electrode, depended on the electrode structure, gas pressure and RF power.

Modeling of Inner Surface Modification of a Cylindrical Tube by Plasma-Based Low-Energy Ion Implantation

The inner surface modification process by plasma-based low-energy ion implantation（PBLEII）with an electron cyclotron resonance（ECR）microwave plasma source located at the central axis of a cylindrical tube is modeled to optimize the low-energy ion implantation parameters for industrial applications.In this paper,a magnetized plasma diffusion fluid model has been established to describe the plasma nonuniformity caused by plasma diffusion under an axial magnetic field during the pulse-off time of low pulsed negative bias.Using this plasma density distribution as the initial condition,a sheath collisional fluid model is built up to describe the sheath evolution and ion implantation during the pulse-on time.The plasma nonuniformity at the end of the pulse-off time is more apparent along the radial direction compared with that in the axial direction due to the geometry of the linear plasma source in the center and the difference between perpendicular and parallel plasma diffusion coefficients with respect to the magnetic field.The normalized nitrogen plasma densities on the inner and outer surfaces of the tube are observed to be about 0.39 and 0.24,respectively,of which the value is 1 at the central plasma source.After a 5μs pulse-on time,in the area less than 2 cm from the end of the tube,the nitrogen ion implantation energy decreases from 1.5 keV to 1.3 keV and the ion implantation angle increases from several degrees to more than 40°;both variations reduce the nitrogen ion implantation depth.However,the nitrogen ion implantation dose peaks of about 2×10^（10）-7×10^（10）ions/cm^2 in this area are 2-4 times higher than that of 1.18×10^（10）ions/cm^2 and 1.63×10^（10）ions/cm^2 on the inner and outer surfaces of the tube.The sufficient ion implantation dose ensures an acceptable modification effect near the end of the tube under the low energy and large angle conditions for nitrogen ion implantation,because the modification effect is mainly determined by the ion implantation dose,just as the mass transfer process in PBLEII is dominated by low-energy ion implantation and thermal diffusion.Therefore,a comparatively uniform surface modification by the low-energy nitrogen ion implantation is achieved along the cylindrical tube on both the inner and outer surfaces.

Effect of inner-surface roughness of conical target on laser absorption and fast electron generation

The effect of inner-surface roughness of conical targets on the generation of fast electrons in the laser-cone interaction is investigated using particle-in-cell simulation. It is found that the surface roughness can reduce the fast-electron number （in the energy range E 〉 1 MeV） and energy, as compared to that from a cone with smooth inner wall. A scaling law for the laser reflectivity based on the vacuum-heating model is derived. Both theory and simulation indicate that laser reflection increases with the height-to-width ratio of the periodic inner surface structure and approaches that of a smooth cone as this ratio becomes zero.

光致变色纱线在多层织物设计中的应用

为了丰富织物的多样性,利用光致变色纱线,结合表里换层双层组织,设计与开发了“P”字图案表里换层光致变色面料;并进一步设计与开发了上、中层表里换层结构的“E”字图案三层组织光致变色面料,实现了织物在光线照射下单面变色,而反面不显变色的特殊效果。将光致变色纱线与表里换层结构的双层或多层织物相结合,可以形成新型光致变色功能面料,为此类产品的开发与设计提供了一种新思路。

轴承内圆轴向超声高速磨削理论建模与试验研究

目的以GCr15材料的6309型轴承内圆为研究对象,探究高转速超声磨削过程中超声辅助振动对磨粒运动轨迹、磨削后表面粗糙度、圆度以及微观形貌的影响规律。方法基于超声内圆磨削磨粒切削轨迹及超声振幅与砂轮转速对轨迹影响的理论仿真,构建磨削去除量与磨削表面粗糙度的理论模型,通过对轴承内圆进行超声磨削试验,研究高转速(16000~22000 r/min)下各工艺参数对内圆表面质量的影响并验证理论粗糙度评价模型。结果超声振幅的增大使磨粒与内圆接触轨迹变长,但随砂轮转速的提高,磨粒切削轨迹的密集程度也有所下降。振幅和砂轮转速的增大可使切削去除量增大、粗糙度降低,铬刚玉粒度100#陶瓷结合剂砂轮磨削GCr15轴承内圆后,其表面质量更有优势,单因素下表面质量变化趋势与理论分析结果相一致。结论在相同磨削参数下,1.5μm振幅超声磨削可使内圆圆度降至0.92μm,粗糙度降至130.5 nm,与传统磨削相比,粗糙度最高减小了41.5%,圆度最高减小了52.6%。在高转速下,各因素按砂轮对磨削后表面质量的影响由大到小的顺序依次为砂轮转速、超声振幅、进给速度,当磨粒线速度超过41.8 m/s、进给速度超过600 mm/min、振幅超过1.5μm时,表面质量呈下降趋势。

小孔内表面磁力研磨加工技术研究进展

磁力研磨加工是提高小孔内表面质量的一种重要光整技术,利用该技术能高效提升小孔类零部件在极端环境下的使役性能。针对小孔内表面的磁力研磨光整加工,按其发展历程对磁力研磨加工技术进行总结,归纳了磁性磨粒研磨、磁针磁力研磨、液体磁性磨具研磨、超声辅助磁力研磨和电解磁力复合研磨等加工方法的技术特点,并分析评述了其局限性。对磁力研磨加工过程中材料去除机理进行了研究,材料主要以微量切削与挤压、塑性变形磨损、腐蚀磨损、电化学磨损等方式去除,材料种类不同,去除机理也不同。其中,硬脆性材料主要以脆性断裂、塑性变形和粉末化的形式去除;塑性材料在经历滑擦阶段、耕犁阶段和材料去除阶段后主要以切屑的形式去除。此外,还对磁力研磨加工过程中的材料去除模型进行了研究,对单颗磁性磨粒材料去除模型和“磁力刷”材料去除模型进行了分析讨论。最后,对磁力研磨加工技术今后的研究发展给出了建议并进行了展望。

基于内外侧联动式抽芯的多分型面镂空式收纳桶模具设计

根据产品的使用性能和工艺特点,对镂空式收纳桶的产品结构和工艺进行了分析。基于产品镂空和桶槽分布位置的不同,设计了3层分型面的模具结构,以实现对各个成型部分的运动控制;镂空形状分布面积比较大,为提高成型质量、节省模具空间,巧妙设计了定模侧爆炸式滑块抽芯机构;由于产品底部的侧凹形状位于定模底部,空间狭窄且缺乏动力源,因此在定模底部设计了型腔侧浮动式斜顶机构,完成了底部侧凹的抽芯动作;针对产品边缘具有内外圆角的大尺寸桶槽,在动模内部设计了内外侧联动式抽芯机构。模具投产后,各个抽芯机构动作顺畅,产品脱模顺利,达到了预期目的。

基于低相干干涉的孔类零件内表面测量系统研究

对孔类零件的内表面进行测量是判断其加工质量和使用寿命的重要手段。针对精密孔类零件内表面测量的需求,提出一种基于低相干干涉的内表面测量及信号处理方法,并搭建了完整的检测系统。对低相干干涉的测量原理进行了分析;搭建了以迈克尔逊干涉仪为主体,主要包含光源、探测器、数据采集仪、参考臂、样品臂等部分的检测系统;研究了干涉信号滤波以及包络峰值提取算法;最后,通过实验验证了此系统可以表征孔类零件的内部特征,并且其测量精度可达10μm以内。

2022年7月内蒙古干旱半干旱区涝—旱转折事件的成因分析

2022年7月内蒙古中西部地区降水明显偏少,且呈前期偏多、后期偏少的涝—旱转折性分布特征,分析不同阶段环流分布差异和影响系统间的配置对进一步做好内蒙古汛期降水预测具有重要作用。利用内蒙古116站逐日降水量、国家气候中心130项气候指数、美国国家环境预报中心/国家大气科学研究中心(National Center for Enviromental Prediction/National Center for Atmospheric Research,NCEP/NCAR)逐日再分析资料和美国国家海洋和大气管理局(National Oceanic and Atmospheric Admin⁃istration,NOAA)逐月海表温度资料,分析2022年7月内蒙古中西部地区涝-旱转折事件的成因。结果表明:(1)2022年7月内蒙古中西部地区降水量严重偏少,为该地区1991年以来同期降水最少、气象干旱最为严重。(2)7月1—11日降水相对偏多,冷空气路径偏北且强度较弱,西太平洋副热带高压强度偏弱,位置偏北、偏西,冷暖空气在内蒙古中西部地区交绥,加之这一时段高空西风急流位置偏北,内蒙古中西部位于急流轴以南,有利于高层辐散和上升运动发展。7月12—31日降水明显偏少,环流经向度加大,冷空气活动路径偏南且强度增强,西太平洋副热带高压强度偏强且位置明显偏南,不利于水汽输送,加之高空西风急流位置偏南,内蒙古中西部位于急流轴以北,不利于高层辐散和上升运动发展;7月中旬后期至下旬高空西风急流南北向扰动偏强有利于激发东亚—西北太平洋经向遥相关波列,使得西太平洋副热带高压位置偏南从而导致降水偏少。(3)日本海至北太平洋西北部地区的海温异常是影响内蒙古中西部地区降水多寡的重要外强迫信号之一。2022年7月该海区海温异常偏高,其上空激发的气旋式环流减弱了南方暖湿水汽的经向输送,是导致内蒙古中西部降水由涝转旱的原因之一。

半干旱草原露天矿区生态累积效应:评估模型与应用

为揭示半干旱草原露天矿区生态环境质量状况,分离矿区人类活动生态累积效应并识别其演变态势,在厘清矿区生态累积效应概念的基础上,构建适用于半干旱草原的露天矿区生态环境质量评估指数(Surface Mining Areas Eco-environmental Evaluation Index,SMAEEI)以及矿区生态累积效应定量评估模型。选取内蒙古胜利矿区为研究区,量化分析1986—2020年区域生态环境质量和生态累积效应的时空分布规律,以及主要人类活动的生态累积效应差异。结果表明:①SMAEEI适用于半干旱草原露天矿区,能客观呈现各地类生态环境质量高低顺序。35 a间研究区生态环境质量呈极显著下降趋势,且其空间差异显著减弱。露天矿场、城镇扩张区、锡林河湿地及北侧草地生态环境质量出现极显著、显著的退化趋势。②半干旱草原露天矿区生态累积效应定量评估模型能剔除气候因素对生态系统的耦合影响,分离并量化人类活动对矿区生态系统的累积效应,揭示累积的方向、程度和空间范围。35 a间研究区生态服务价值累积量(Change of Ecosystem Service Value Cumulant,COESVC)共减少1186157.03万元,出现负向生态累积效应,生态系统服务功能下降。高度、中度负向累积区集中在湿地和草地退化区、城镇区、露天矿场。③露天开采、城镇建设造成的单位面积负向生态累积效应最明显,前者在单位时间内带来的负向累积变化最剧烈,后者负向累积效应的局部影响程度和偏离度最大;放牧活动引起的负向生态累积效应影响范围最广、总量最大,但局部影响程度最小,生态系统服务功能较其余人类活动更稳定。研究成果可将矿区人类活动引起的生态环境实物量变动转化为价值量描述,为采用货币形式测算矿区生产生活行为的环境损害成本提供可行方法。

盖挖法基坑开挖对临近桥梁桩基的影响研究

城市交通建设往往临近既有建筑结构,为了掌握盖挖法深基坑开挖对临近桥梁桩基的影响,依托之江路输水管廊及道路提升工程,建立数值模型并对工程现场展开监测,分析对比了基坑开挖导致的围护结构变形及桥桩变形规律。结果表明:围护结构最大位移出现在基坑北侧坑中坑开挖后,为6.14mm,最大位移深度随基坑开挖而下移,且坑中坑开挖完成后,其对侧围护结构变形反而减小,坑中坑开挖布置在敏感结构对侧时对临近结构具有一定控制效果;桥梁桩基最大沉降出现在首道混凝土支撑安装后,但随基坑开挖而逐渐减小,盖挖造成的沉降主要水平影响范围距围护结构约为12.71m,对邻近桥桩的影响主要发生在基坑开挖的早期阶段,各项变形均在安全范围内,且不均匀沉降控制效果明显。

复杂山区地表温度模拟及影响——以内蒙古大青山为例

地表温度(LST)是影响植物分布和生态系统过程的重要因素。本研究利用天气研究与预测模式(WRF)模拟大青山保护区的高时空分辨率LST,通过气象站点观测值和MODIS LST值对比验证模拟结果的准确性,并通过综合影响因素和单一影响因素分析LST与环境因子之间的关系。综合影响因素分析是基于区域模拟LST和区域环境因子进行的分析;单一影响因素分析是首先固定其他环境因子,然后分析LST和单一环境因子的关系。结果表明:模拟值与3个站点观测值相关系数均超过0.97(P<0.001),与MODIS LST空间相关性为0.73(P<0.05),表明WRF在山区有很好的实用性。经综合影响因素分析,年均LST与高程的相关性最大(R>0.97),与2 m气温和2 m水汽混合比次之(R>0.8),与植被覆盖度和坡度较小(R>0.3),其他因素影响微弱。经单一影响因素分析,在春夏秋冬4个季节,随高程升高LST下降速率分别为0.83 K·(100m)^(-1)、0.79 K·(100m)^(-1)、0.80 K·(100m)^(-1)、0.32 K·(100m)^(-1);坡度每增加10°,LST在春夏秋冬分别升高-0.05 K、0.17 K、-0.14 K、0.02 K;植被覆盖度每增加10%,LST在夏冬两季分别升高0.31 K、1.41 K,其他季节则没影响;坡向对4个季节平均LST的影响均为南>西南>东南>西>东>西北>东北>北;年均LST与2 m水汽混合比呈对数关系,与2 m气温呈指数关系。研究结果可为大青山自然保护区管理提供基础数据,也为山地研究提供可借鉴的方法。

一种优化的钢卷内曲面贴标自动化系统设计与实现

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