An NMR Imaging Study of the Interface of Epoxy Resin-Glass Fiber Reinforced Composites

NMR imaging was used to analyze E-glass fiber/epoxy composites. The NMR images revealed specific interactions between the glass fiber and epoxy, as indicated by the different degree of curing in the proximity of the fiber. When as-received glass fibers were used, an accelerated degree of curing in the proximity of the fibers as compared with the bulk was observed, whereas when heat-treated glass fibers were used the above trend was substantially inhibited. Finally, when E-glass fibers treated with an aminosilane coupling agent (γ-APS) were used, no variation in the degree of curing in the proximity of the glass fiber was observed. The above results suggest that physisorbed or chemisorbed molecular water present in the surface of the glass fiber assists in the opening of the epoxy ring by hydrogen bonding effects.     

Influence of the Film Former on Fibre-Matrix Adhesion and Mechanical Properties of Glass-Fibre Reinforced Thermoplastics

The film former is in mass percentage the main component in most glass fibre sizes. Its influence on the fibre-matrix adhesion and the compound properties is studied in two thermoplastic matrices, i.e. polypropylene (PP) and rubber-modified styrene-co-maleic anhydride. The composition of the size is varied by changing the chemical nature and molecular mass of the film former and by leaving out the silane. The size's morphology on the glass fibres is studied with scanning electron microscopy and X-ray photoelectron spectroscopy. The effect on fibre-matrix adhesion is inferred from 0° bending and interlaminar shear strength measurements of unidirectional, continuous fibre reinforced composites. The possible effect of the film former on matrix crystallinity in PP is studied with differential scanning calorimetry and polarized-light microscopy. The same sizes are also tested in injection moulded, short fibre reinforced compounds by measuring their mechanical properties. In addition, the diffusion of the size into the matrix is studied by confocal scanning laser microscopy. The main conclusion of this study is that the film former plays a crucial role in the level of fibre-matrix adhesion because it does not diffuse away from the fibre-matrix interface into the matrix. Its effect may be larger than that of the silane. In addition, most mechanical properties of short fibre reinforced compounds improve with increasing fibre-matrix adhesion.     

Methane oxidative coupling on the Au/La2O3/CaO catalyst in the presence of hydrogen peroxide

Methane oxidative coupling in the presence of the catalyst 1% Au/5% La₂O₃/CaO and gas-phase initiator hydrogen peroxide at the temperature 700–800°C under normal pressure has been studied. It has been shown that hydrogen peroxide remarkably increases the yield of C₂₊ products without the loss of selectivity. The maximal yield of C₂₊ products under the conditions studied was 27% with the formation of a noticeable quantity of benzene. It has been proposed, that the observed effect is due to hydroxyl radical formation from hydrogen peroxide, which could be essential under definite conditions also in a conventional catalytic methane oxidative coupling.     

漏磁检测旋转探头供电及信号的无线传输研究

在探头旋转的漏磁检测中，检测元件随探头高速运动，如采用滑环传输电源及信号时，最高转速受到限制。提出采用无线方式，根据电磁耦合原理设计供电系统，并采取多种措施提高能量传送效率，以满足检测元器件长时间稳定供电的需要。信号传输系统采用红外无线传输方式，通过压频和频压转换器将模拟信号转换为数字信号，大大加强了信号传输的可靠性和稳定性。     

数据融合在电梯群控系统中的应用

将数据融合技术引入电梯群控系统中,建立了基于数据融合技术的模糊联结聚合神经网络模型,对影响电梯调度的各因素进行充分有效的数据处理后,得到的电梯控制参数作为电梯调度单元的输入.应用实例表明了该方法是方便且有效的.     

基于子模型技术的滑块式万向联轴器叉头强度分析

在对滑块式万向联轴器主要部件叉头进行有限元整体分析的基础上,采用子模型法对其应力集中区域进行了细化分析,得到了其应力分布,确定了其能长期承受的扭矩和短时能承受的最大扭矩.对该叉头强度的分析表明,采用子模型技术可以减少计算时间,得到精度较高的计算结果.     

金属材料表面激光藕合系数的反演

为了能通过背光面温度测量获得材料激光耦合系数,从傅里叶热传导方程出发,在一定的近似条件下推导出了不透明金属材料的表面激光耦合系数与背光面温升的关系表达式,给出了工程反演算法.采用两种不同的方法对反演算法进行了验证:一是用反演算法计算30CrMnSiA材料的1.3μm激光耦合系数,与文献报道的实验测量值进行比较;另外是实...     

金属表面KH-560硅烷膜的粘结性能研究

利用KH-560在不同溶剂中水解的硅烷溶液,在金属基体上加热固化形成硅烷膜。研究了水解溶剂、水解时间、溶液浓度和固化温度对硅烷膜与基体粘结强度的影响,揭示了结合机理。结果表明：采用混合溶剂水解48h,硅烷质量分数在10％左右,在100～200℃固化时硅烷膜与基体具有良好的粘结性能。     

发动机活塞的热结构耦合分析

用ANSYS计算了该发动机活塞二维轴对称简化模型单独在燃气压力和燃气温度作用下以及在燃气压力和温度共同作用下的温度分布、应力和位移,并且计算了活塞三维1/4模型的温度场;最后对计算结果进行了全面的综合比较分析.     

侧压过程板坯温度变化的研究与分析

利用热力耦合有限元的理论,建立了板坯侧压过程的三维热力耦合有限元仿真模型.得到了板坯在稳态变形区内节点温度和轧制力随时间的变化规律,通过轧制力的模拟结果和试验数据比较可知,两者吻合良好.分析结果为板坯侧压规程的制定和轧制力的在线预报提供了理论依据.