Friction and cutting properties of hot-filament chemical vapor deposition micro- and fine-grained diamond coated silicon nitride inserts

The micro-crystalline diamond (MCD) and fine-grained diamond (FGD) films are deposited on commercial silicon nitride inserts by the hot-filament chemical vapor deposition (HFCVD) method. The friction and cutting properties of as-deposited MCD and FGD films coated silicon nitride (Si₃N₄) inserts are comparatively investigated in this study. The scanning electron microscopy (SEM) and Raman spectroscopy are adopted to study the characterization of the deposited diamond films. The friction tests are conducted on a ball-on-plate type reciprocating friction tester in ambient air using Co-cemented tungsten carbide (WC-Co), Si₃N₄ and ball-bearing steel (BBS) balls as the mating materials of the diamond films. For sliding against WC-Co, Si₃N₄ and BBS, the FGD film presents lower friction coefficients than the MCD film. However, after sliding against Si₃N₄, the FGD film is subject to more severe wear than the MCD film. The cutting performance of as-deposited MCD and FGD coated Si₃N₄ inserts is examined in dry turning glass fiber reinforced plastics (GFRP) composite materials, comparing with the uncoated Si₃N₄ insert. The results indicate that the lifetime of Si₃N₄ inserts can be prolonged by depositing the MCD or FGD film on them and the FGD coated insert shows longer cutting lifetime than the MCD coated one.     

Application of strut-and-tie model for design of interior anchorage zone in post-tensioned concrete structure

This paper presents an application of strut-and-tie model (STM) to design the interior anchorage zone (IAZ) in the post-tensioned concrete structure. The STM theory and range of IAZ are introduced. Then, based on the finite element analysis, a series of simplified equations to calculate internal forces in IAZ are presented. Finally, the STM model for IAZ is given. In the proposed STM model, internal forces in ties vary with the dimension ratio and the eccentricity of load. The U-turn of internal forces is suggested to allocate rebar to resist bearing flexural tensile force. Compared with the FIP (International Federation for Prestressing) model, the proposed STM model is more reasonable and applicable.     

已下挠连续梁桥加固方案研究

针对目前一些大跨径预应力混凝土连续梁桥跨中长期挠度过大的问题,以汾江大桥为工程背景,分析导致该桥主梁挠度过大的主要原因。通过实测资料进行计算分析,说明体外预应力加固未能阻止主梁进一步下挠的原因。提出一种以钢箱梁替代跨中梁段的加固方案,通过计算分析其加固效果并与体外预应力加固进行对比,简单分析其可行性并展望应用前景。     

山岭隧道震害调查及修复技术研究

“5·12”汶川地震对都汶公路多座隧道造成了较为严重的破坏。通过对都汶路、绕坝路等15座隧道震后调查、资料收集与分析,提出了隧道震后各种修复措施并分析了其使用效果。浅析了山岭隧道的抗减震原则和措施,对此进行了相应的总结。总体而言隧道震后修复措施起到了良好的效果,对救灾和灾后重建工作起到了积极的作用;同时隧道应从规划、设计阶段采取合理的抗减震措施。     

基于熵权物元模型的公交综合评价指标体系

为了综合评价快速城镇化背景下城市公共交通发展状况,通过分析城市公共交通发展特征,给出公共交通综合评价指标体系。分析利用可拓论对模糊性和不相容性进行定量评价的适用性,建立基于物元模型的可拓方法并应用于公共交通综合评价。同时,将信息熵与相离度相融合的不确定语言多属性决策方法运用于权值计算,提高了评价体系的客观性和准确性。最后通过实例证明了指标体系的合理性,以及模型方法的有效性和实用性。     

带帽刚性预应力薄壁管桩在高速公路地基处理中的应用

该文首先介绍了带帽刚性预应力薄壁管桩及其在高速公路地基处理中的应用,并分析带帽刚性预应力薄壁管桩复合地基作用机理,进而讨论了带帽刚性预应力薄壁管桩的承载力及复合地基承载力。     

郑州市积水区治理方案研究

城市积水区的形成原因比较复杂,既有气候变化、地形地势、河流水系等自然因素,也有城市建设、城市管理等人为因素。该文以郑州市陇海路京广路积水区为例,分析了郑州市积水区的成因,并提出了治理对策。     

AWP-2000纤维增强桥面防水粘结层应用与施工技术

该文通过选择新型纤维增强桥面粘结防水层来解决传统柔性防水层设置中难以解决的抗硌破问题,并对新型纤维防水层的施工技术做了较深入的介绍。     

基于ANSYS Workbench对某越重型野车转向系统的有限元分析

采用三维软件Pro/E建立转向系统的模型,导入Workbench后经修复及网格化后形成有限元计算模型并进行了计算,得到了转向系统各部件的应力分布,指出了转向系统存在的不足及影响因素。为改进设计提供了重要的理论依据。     

基于仿真分析的汽车侧翻风险研究

侧翻事故是汽车产品缺陷可能引发的一种典型风险.文中应用ADAMS软件建立仿真模型,模拟车辆侧翻事故过程以研究其发生机理,并通过正交试验分析了侧翻风险与其主要影响因素之间的关系.