专机在液压支架主肋板上的应用

针对液压支架产量大,供货周期短的特点,设计两款专机加工主肋板刀检面和销轴孔。介绍了刀检铣边专机和销轴镗孔专机的设计、制造和安装,这两款专机结构简单,操作方便,满足产品的加工要求,投入使用后大大提高生产效率和加工一致性,且保证了零件的互换性。     

A passive EMI filter with access to the ungrounded motor neutral line—Its effect on attenuating bearing current

This paper describes the effect of a passive EMI filter on preventing bearing current from flowing inside an inverter‐driven motor. Motor‐bearing damage is often caused by bearing currents resulting from the breakdown of grease films in the motor bearing. The high‐frequency common‐mode voltage generated by the PWM inverter induces a shaft voltage between the rotor and the frame. When the shaft voltage exceeds the breakdown voltage of the grease films, a destructive instantaneous discharge current with a peak value of about 1 A flows through the motor bearing. The passive EMI filter, which is unique in access to the motor neutral line, can reduce the shaft voltage as a result of eliminating the high‐frequency common‐mode voltage from the motor terminals. Hence, no breakdown occurs in the grease film, so that no bearing current flows. The viability and effectiveness of the passive EMI filter is verified by experimental results obtained from a 400‐V, 3.7‐kW laboratory system. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 78– 87, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20489     

垂直顶管计算方法的探讨

本文详细探讨了垂直顶管顶力的组成及其影响因素，并结合工程实践给出垂直顶管顸力的两种计算方法，以便更好地进行垂直顶管的设计和施工。     

Ultimate bearing capacity factor and whole process analysis for large size concrete filled steel tube columns

Based on the general theory of concrete filled steel tube (CFT), nonlinear analysis of large size CFT is performed using ANSYS, a commercially available finite element (FE) programme. A nonlinear 3-D finite element analysis (FEA) model is developed to predict the behaviour of axially loaded CFT columns. Comparisons between the predicted results and the curves of axially loaded CFT column published in the open literature show that the trend of the curves fit well. This also shows that the constitutive relation model and the basic assumptions can accurately predict the behaviour of the large size CFT. The FEA model is then used to investigate the influence of steel tube wall thickness, the width to thickness of built-in stiffener for ultimate bearing capacity of large size square CFT and so on. In addition, the whole construction process of large size rectangular CFT with holes in the middle vertical plate is analysed. The study presents the main influential factors for CFT ultimate bearing capacity and the concrete crack distribution.     

省标《先张法预应力混凝土管桩基础技术规程》DBJ13-86-2007学习札记

偏心受压时,桩身结构承载力是否“可另外再提高20%”？当地下水或土对混凝土或混凝土中钢筋有弱腐蚀时,采用PHC管桩,规定壁厚“不应小于125mm＂是否合理？本文就省地方标准《先张法预应力混凝土管桩基础技术规程》这2项规定提出疑问。     

钻井船插桩的大变形有限元数值模拟

介绍了应用一种欧拉-拉格朗日耦合的方法来模拟钻井船插桩的整个过程,得到了不同土质参数条件下的桩脚荷载-桩脚尖入泥深度的曲线,并且通过与理论公式计算结果、离心机模型试验结果的比较进一步验证了该数值模拟方法的可行性。     

玄武岩纤维加固震损混凝土框架节点承载力计算分析

对5个不同损伤程度的框架节点采用玄武岩纤维加固后进行低周反复荷载试验。考虑混凝土框架节点受损修复后初始损伤的影响,提出构件修复后混凝土承载力折减系数;基于现行设计规范,建立玄武岩纤维加固混凝土框架节点考虑构件初始损伤的承载力计算公式,为震损混凝土构件的加固设计提供参考。     

铅芯橡胶支座隔震储罐地震响应特性分析

利用双线性恢复力模型模拟铅芯橡胶支座力学特性,探讨了不同类型场地上,隔震储罐在铅芯橡胶支座(LRB)与叠层橡胶支座(RB)两种隔震方式下的地震响应特点.研究表明:铅芯屈服力、场地类型和地震强度是影响LRB减震性能的主要因素.与RB隔震方式相比,LRB具有降低基底剪力、支座位移、晃动波高等优点,但减震效果并不总是好于RB方式,与场地类型和铅芯屈服力的选取有关.特别是Ⅳ类场地上RB支座更适合储罐隔震设计.支座最优屈服力参数选取需要根据储罐自振特点、场地类型和地震强度共同确定.LRB支座更适合在高烈度地区应用,减震效率高而且稳定.     

基于缸孔珩磨表面微观特征的质量检测模式与提升监控水平的探索

分析了缸孔珩磨表面微观构造对汽车发动机性能产生极大影响的原因,指出对珩磨表面平台网纹形貌进行质量检测的重要性。强调了随着机动车节能和减排法律法规的日趋严苛,企业在质量监控方面也应持续完善提高,并对近年来在该领域的技术进展进行了介绍。     

沟槽结构对水润滑轴承润滑特性影响机制

为了研究沟槽结构对船用水润滑轴承润滑特性的影响机制，采用有限元法，通过对简化后的椭圆形沟槽的二维模型进行流体动力学CFD分析，从迹线以及涡流等方面分析沟槽结构参数对沟槽内部流体特征的影响，得到不同状态下沟槽内部的压力轮廓，并分析沟槽结构参数对水润滑轴承摩擦因数的影响和轴承的润滑机制。结果表明：沟槽的大小影响轴承间隙内流体的流通面积，沟槽的结构特征影响沟槽内的流体黏度。研究结果可为水润滑轴承优化设计提供参考。