网架螺栓球节点锥头和封板的承载力

螺栓球节点网架的杆件与螺栓球通过锥头或封板连接。采用轴对称有限元方法，对静载作用下的锥头连接和封板连接进行了弹塑性分析，探讨了这两种连接的应力分布、位移、塑性区发展过程和破坏模式，研究了锥头和封板的构造尺寸对其连接承载能力的影响，绘制了承载力－构造尺寸的关系曲线，在此基础上提出了这两种连接的计算公式及设计建议。     

铁封元件非匹配封接原理和结构设计

本文探讨了铁封元件的非匹配封接原理及其结构设计。试验表明,对带芯材的环状铁封元件应用非匹配压缩封接技术进行封接,元件的应力性能最佳。     

HM1500无机水性水泥密封防水剂的性能和应用

HM1500无机水性水泥密封防水剂能堵塞水泥构筑物内部空隙,封闭毛细管通道,明显提高混凝土、砂浆等材料的抗渗性、密封防水性和抗风蚀碳化等性能,是一种适用于水泥构筑物密封、防水、防护的新颖材料。     

Development and Electrochemical Testing of Novel Bipolar Nickel Metal Hydride Batteries

With the enhancement of consciousness of envi-ronmental protection and the increasing exhaustion ofoil resources,study on electric vehicles(EV)or hy-brid electric vehicles(HEV)are being actively con-ductedin the countries worldwide[1-3].Ni/MHbat-tery is p…     

多孔质机械密封耦合润滑模型与密封性能分析

考虑多孔质材料内密封介质渗流与密封端面润滑液膜间的传质耦合关系,建立了一种多孔质机械密封的流体润滑模型,采用有限单元法求解液膜润滑方程和多孔质内部渗流控制方程,研究了膜厚、渗透率、多孔质环几何参数对密封性能的影响规律,揭示了多孔质机械密封的工作机理。结果表明：多孔质机械密封依靠流体静压效应在密封端面成膜,相较于普通平行端面密封,其液膜承载力和轴向刚度更大;随多孔质渗透率的增大,多孔质机械密封泄漏率和开启力逐渐增大,而液膜刚度逐渐减小;液膜厚度的增大会导致泄漏率的增大和开启力的减小,而液膜刚度先增大后减小,且不同渗透率下的最大刚度分别对应不同的膜厚值。研究结果可为多孔质机械密封的工程设计提供新的思路和理论指导。     

乘用车尾门密封条的压缩仿真分析

先对乘用车尾门密封条三元乙丙橡胶密实胶和海绵胶进行力学性能试验,确定2种材料的本构模型,然后采用Abaqus有限元分析软件对尾门密封条的压缩过程进行仿真分析。结果表明:尾门密封条的海绵胶泡管应力、应变和应变能均较大,海绵胶与密实胶接触部位有较大的应变和应变能;尾门密封条的仿真与试验压缩力-压缩量曲线拟合良好,试验压缩力平均误差不超过10%,仿真与试验结果一致性好。     

镁合金表面锌系磷化膜及硅酸盐封闭工艺与性能

为提高镁合金的耐蚀性能,在镁合金表面制备锌系磷化膜,并对磷化膜进行封闭。比较了未封闭磷化膜、浸油封闭磷化膜、铬酸盐封闭磷化膜和硅酸盐封闭磷化膜的表面形貌、元素组成、厚度和耐蚀性能,结果表明:浸油封闭、铬酸盐封闭和硅酸盐封闭对镁合金表面磷化膜的厚度基本没有影响,但封闭前后磷化膜的表面形貌和元素组成有所不同。Cr、Na和Si元素分别通过形成化学转化膜、胶体状膜或物理填充孔隙被引入封闭后磷化膜中。硅酸盐封闭磷化膜的致密性相对较好,使镁合金的耐蚀性能得到有效提高。在铬酸盐封闭逐渐被弃用的趋势下,效果较好并且低污染环保的硅酸盐封闭在磷化膜封闭中具有应用潜力。     

WO3对零膨胀锂铝硅封接玻璃流动性的影响与作用机理

密封连接石英玻璃被广泛应用于航空航天、半导体加工以及微机电系统真空连接等领域。改进的低膨胀Li₂O-Al₂O₃-SiO₂(LAS)系微晶玻璃可以用于封接石英玻璃,但存在流动性不佳的难题。本文通过掺入WO₃对LAS系微晶玻璃进行改性,利用线膨胀系数分析仪、差示扫描量热仪、X射线衍射仪、高温烧结影像仪、扫描电镜,研究了掺入WO₃后LAS玻璃封接石英玻璃的机理。结果表明:WO₃对LAS玻璃的析晶产生先增强后削弱的影响; WO₃掺量越大,热膨胀系数越大,当掺量达到5.0%(质量分数)时,热膨胀系数提升至5.69×10^-7 ℃^-1;流动性与润湿性随着掺量增加而提升,铺展面积随掺量增加而增大,润湿角随掺量增加而减小,有效改善了LAS玻璃本身流动性不足的问题;LAS玻璃与石英玻璃之间主要是通过化学元素迁移实现封接。     

Kinetics of crack healing and self-repair behaviors in a sealant glass for SOFC applications

A sealant is required for the solid oxide fuel cell (SOFC) to maintain hermeticity at high operating temperatures, keep fuel and oxidant from mixing, and avoid shorting of the cell stack. Glass and glass–ceramic materials are widely used as a sealant because their properties can be tailored to meet the stringent requirements of SOFC stack, but they are susceptible to cracking. In contrast, a promising concept of self-repairable glass for seals is pursued for making reliable seals that can self-repair cracks at the SOFC operating temperatures. This concept is studied through measuring crack-healing kinetics and independent measurement of glass viscosity for relating to the observed self-repair. The cracks on the glass surface are created using a Vickers indenter to achieve a well-defined crack geometry, and then the glass is exposed to elevated temperatures for different length of times to study the crack-healing kinetics. The crack-healing kinetics is compared with the predictions of our theoretical model and found to be in good agreement. In addition, glass viscosity is extracted from the healing kinetics and compared with the independent measurement of viscosity measured from the dilatometry and sintering data to further validate the crack-healing theoretical model. These results are presented and discussed.     

浅析沥青路面裂缝填封机理

从裂缝填封的最终目的出发,通过对裂缝填封材料的受力分析,提出了裂缝填封的要求,从而得出了裂缝填封的机理,并对裂缝填封机理进行了研究,以期对裂缝填封材料和填封工艺的研究具有指导意义。