碳纤维/环氧树脂复合材料湿热老化后的力学性能

将碳纤维/环氧树脂复合材料在温度为71℃、相对湿度为85%的环境下吸湿至平衡后研究了它的吸湿行为,然后分别在室温和71,93,116,132℃下进行了弯曲性能、纵横剪切性能、动态力学性能试验,研究了该复合材料湿热老化后的力学性能。结果表明:碳纤维/环氧树脂复合材料的吸湿率较低,其饱和吸湿率仅为0.91%左右;湿热老化后,复合材料的弯曲强度保持率在50%以上,弯曲模量保持率在80%以上,纵横剪切强度保持率在55%以上,其玻璃化转变温度为195℃,极限耐热温度可达到132℃;该碳纤维/环氧树脂复合材料具有良好的耐湿热老化能力。     

T700和T300碳纤维增强环氧树脂基复合材料耐湿热老化性能的对比

在温度为70℃、相对湿度为85%的湿热环境下,分别对T700碳纤维/环氧树脂基复合材料、T300碳纤维/环氧树脂基复合材料以及两种复合材料/金属胶接结构进行了70 d的加速老化试验,并对老化前后的试样进行了力学性能试验和无损检测.结果表明:湿热环境没有改变两种复合材料的破坏模式,但使复合材料的纵、横向压缩强度和剪切强度略有降低;对复合材料/金属胶接结构,湿热老化环境不会导致胶接界面产生损伤,但会使胶接强度下降;老化前两种复合材料的力学性能基本相当,老化70 d后T700碳纤维/环氧树脂基复合材料的性能保持率略优.     

高钢级耐酸性X70MS钢螺旋埋弧焊管的生产工艺及组织性能

采用低碳、低锰、微合金化设计和洁净化冶炼等工艺生产出了高钢级耐酸性X70MS钢热轧板,通过优化焊接工艺参数,采用耐酸性焊接材料,控制焊接热输入,控制钢管成型残余应力等措施,开发出了高钢级耐酸性X70MS钢螺旋埋弧焊管,并对其力学性能、HIC性能以及SSCC性能进行研究。结果表明:耐酸管母材的屈服强度为515～525MPa,抗拉强度为615～620MPa,焊缝抗拉强度为655～685 MPa,母材和焊缝的硬度均小于250HV10,0℃下母材的冲击功大于296J,焊缝冲击功大于120J;该耐酸管具有良好的耐HIC性能和耐SSCC性能,力学性能和耐蚀性能达到和远高于API SPEC 5L(44版)标准要求。     

碳纤维环氧树脂复合材料的吸湿行为

论述由两种环氧树脂基体、两种固化条件制作的碳纤维复合材料，在两种不同条件下的湿热老化试验，取得了沸腾蒸馏水浸泡120h、湿热老化10000h的老化试验数据。揭示了复合材料力学性能和吸湿量之间以及老化时间和吸湿量之间的关系，评定了材料的耐湿热性能。     

部分扩散预合金温压铁-铜-镍-钼-碳材料的组织与性能

对部分扩散预合金Fe-2Cu-2Ni-1Mo-1C粉末的温压行为及烧结和热处理后的组织和性能进行了研究.结果表明:模壁润滑温压工艺能明显提高烧结材料的密度和性能;在130℃、400～700 MPa压力范围内材料压坯密度、烧结密度和烧结性能均随压制压力增大而提高;700 MPa下材料压坯密度7.34 g/cm3;1 150℃烧结60 min后密度为7.32 g/cm3,抗拉强度达到853 MPa,表面硬度302 HB,伸长率4.4%;热处理对烧结材料力学性能提高效果显著;880℃淬火 350℃回火60 min材料的综合性能较好,抗拉强度1 086 MPa,表面硬度295 HB,伸长率3.7%,显微组织为马氏体、回火屈氏体和残余奥氏体.     

Ti-Al/TiC+Al2O3复合材料的制备与性能

用机械合金化和热压烧结制备了Ti-Al/TiC+Al2O3复合材料.研究了不同烧结温度(1550、1650℃)和热处理温度(700、900℃)对烧结体的力学性能和显微组织的影响.结果表明烧结体具有良好的力学性能,硬度达到92 HRA,抗弯强度可大于600MPa,而断裂韧度最高可达8.021 MPa·m1/2.     

Ti-Al/TiC+Al2O3复合材料的制备与性能

用机械合金化和热压烧结制备了Ti-Al/TiC+Al2O3复合材料.研究了不同烧结温度(1550、1650℃)和热处理温度(700、900℃)对烧结体的力学性能和显微组织的影响.结果表明:烧结体具有良好的力学性能,硬度达到92 HRA,抗弯强度可大于600MPa,而断裂韧度最高可达8.021 MPa·m1/2.     

钢芯Al绞导线架空导线微动磨损行为

在自制的微动磨损试验装置上进行LGJ150/25型钢芯Al绞线(Aluminium conductor steel reinforced,ACSR)的微动磨损试验。采用扫描电镜观察分析线夹处导线的微动磨损斑形貌及导线的微动磨损行为。结果表明:内外层Al导线间及内层Al导线与钢芯线间的接触斑均为椭圆形;导线的微动磨损区域分为微动黏着区、微动滑移区和微动混合区;微动黏着区以黏着磨损为主,微动滑移区和混合区则主要呈磨粒磨损、片状剥离;磨损面上都分布着磨粒、犁沟及微裂纹,但程度不同;在内层Al股线与镀锌钢芯线的磨损面上分布着ZnO不连续的层片及磨粒,对磨损行为也会产生影响。     

架空线路碳纤维复合芯导线舞动特性实验

将风激励作用转换为导线长度的周期变化,对单档距架空线路碳纤维复合芯导线无覆冰时的舞动特性展开了实验研究。与实验研究对应,用两端简支柔索结构参数共振模型对横向风载激发的导线舞动现象进行模拟。对具有相同截面尺寸的碳纤维复合芯导线和钢芯铝绞线的舞动现象进行了对比分析,从参数共振动力不稳定区域的角度解释了实验观测到的不同激振频率下两种导线系统的舞动模态。结果表明,在相同静态张力加载下,相同截面尺寸的碳纤维复合芯导线相比于传统钢芯铝绞线更不易发生舞振现象。     

植物纤维镁合金夹层板的制备和力学性能

以稻壳粉、秸秆粉为主要原料,添加少量玻璃纤维和石膏,以工业水玻璃为粘结剂,在160℃,1.2MPa压力下热压制备了不同配比的植物纤维夹芯,并将其与镁合金板复合制得植物纤维镁合金夹层板,并对其力学性能进行了研究。结果表明:在120℃,1.2MPa条件下可成功制备出轻质、高强度的植物纤维镁合金夹层板;夹层板的压缩性能主要取决于夹芯基料和固化工艺,添加剂的影响较小;添加适量玻璃纤维和石膏可有效提高夹层板的抗弯强度,玻璃纤维和石膏的质量分数分别为8%,5%时制得的夹层板弯曲性能最优。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.