低速重载轴承的故障诊断

分析了低速重载轴承的故障特点及其诊断方法,分别就内圈故障、外圈故障、滚动体故障、保持架故障的诊断方法以及故障的严重程度的判断进行了讨论,并用此方法对两例轴承故障实例进行了分析。     

汽轮发电机振动故障专家系统诊断方法研究

通过对汽轮发电机振动故障机理、故障特征和故障原因的分析,建立了汽轮发电机振动故障特征表,根据振动故障特征表的知识以决策树的形式构建了汽轮发电机振动故障专家系统知识库,并建立了汽轮发电机振动故障专家系统决策树诊断模型。最后通过发电机振动故障实际案例对汽轮发电机振动故障专家系统诊断方法进行了验证,证明了其准确性和可行性。     

棒线裙板中继故障的解决方法

裙板中继故障是棒材生产线的一种主要故障,发生频繁、故障较难预测,同时处理时间较长,对生产影响较大。文章介绍了描述了八钢2#棒材裙板中继故障的解决办法,较好解决了此故障。     

GK1F型机车柴油机机油压力低故障的分析与处理

分析了GK1F型机车柴油机机油压力低故障的危害,介绍了机油压力低故障产生的原因,针对故障原因提出了运用系统性方法判断处理机油压力低故障。     

液压缸的故障判断

文章介绍了液压缸的故障现象，深入分析了产生故障的原因以及排除液压缸故障的种种措施。     

板带轧机HAGC系统基于小波变换的传感器故障诊断

 提出了一种基于小波分析的HAGC系统传感器故障诊断方法。通过建立系统的MA模型，建立残差信号，利用离散小波变换对残差信号进行多分辨率分析。通过残差信号的故障高低频特性，提取故障敏感特征，实现了传感器故障时间、故障原因、故障程度的诊断。仿真研究表明，该方法凸现故障特征，时域定位准确，不但适用于突变故障，对渐变故障同样有效。     

逆变器故障处理实践

介绍了石钢小型棒材连轧生产线西门子传动柜3次过流报警故障经过,故障均为F011报警信号,记录波形和现场状况有很大差异。按照事故处理原则,通过分析和试验找出了原因,分别为:触发板故障、控制电源板连线故障和负荷故障。为今后快速查找故障,积累了实践经验。     

一起220kV输电线路故障及保护动作分析

通过对现场设备和线路的检查、故障动作报告、故障录波,分析了一起线路接地故障的类型、过程和产生原因,对故障存在的疑点进行了分析和排查,并对故障中继电保护的动作行为进行了分析,得出了结论及工作改进的方向。     

Boomer系列台车断钎原因及对策

针对Boomer系列台车发生断钎的故障现象，分析故障原因，探讨了故障的处理程序和方法，提出了处理故障的对策。并介绍了Boomer系列台车不同凿岩机配置的推进压力设置标准。     

6kV同步电动机定子绕组故障修复

分析同步电机定子绕组匝间短路故障,采用甩掉故障线圈的局部修理方法对6kV同步电机定子绕组匝间故障进行修复,减少了故障停机时间,取得了良好效果。     

Failure Model for Rate-Dependent Polymer Matrix Composite Laminates under High-Velocity Impact

A modified Hashin failure model is developed to characterize different failure modes related to high-velocity impact of composite laminates. Hashin’s compressive fiber failure mode has been extended to consider the shear stress effect. Several micromechanics-based degradation rules are developed and applied to the stress and material property calculations according to different failure modes after the corresponding failure criterion is satisfied. This model has been implemented into a recently developed micromechanics model. Computational results show that this model is able to address shear failure, delamination, and tearing failure observed in the high-velocity impact of composite laminates.     

Analytical Approach to Calculate Rate of Bank Erosion

Bank erosion consists of two processes: basal erosion due to fluvial hydraulic force and bank failure under the influence of gravity. Because bank resistance force varies with the degree of saturation of bank material, the probability of bank failure is the probability of the driving force of bank failure being greater than the bank resistance force. The degree of saturation of bank material increases with river stage; therefore, the frequency of bank failure is correlated to the frequency of flooding. Consequently, the rate of bank erosion is due to both basal erosion and bank failure, and bank failure is a probabilistic phenomenon. In this paper, for cohesive bank material experiencing planar bank failure, a deterministic approach was adopted for basal erosion analysis, whereas the probability of bank failure was included in the analysis of bank failure. A method for calculating the rate of bank erosion was derived that integrates both basal erosion and bank failure processes, and accounts for the effects of hydraulic force, bank geometry, bank material properties, and probability of bank failure.     

Two antipeptide monoclonal antibodies that recognize adhesive sequences in fibrinogen: identification of antigenic determinants and unrelated sequences using synthetic combinatorial libraries

Fulminant hepatic failure is infrequently seen as a consequence of acute congestive heart failure. Recognition of this entity is important as treatment directed towards heart failure should help resolve the liver failure. A case of fulminant hepatic failure due to previously unrecognized cardiomyopathy is presented. A liver transplantation was being considered for fulminant hepatic failure until hemodynamic monitoring studies demonstrated that, in fact, the patient had severe cardiomyopathy. Treatment directed at his cardiomyopathy resolved the liver failure. Therefore, prompt recognition of such a phenomenon would enable early institution of appropriate therapeutic measures with the hope of clinical benefit to the patient.     

Model Tests and Analyses of Bearing Capacity of Strip Footing on Stiff Ground with Voids

A series of 1G loading tests under the plane-strain condition were conducted on stiff ground with continuous square voids with the view of shallow foundation on calcareous sediment rocks, which contain voids because of their susceptibility to water dissolution. Detailed experimental observation revealed three types of failure modes for a single void: bearing failure without void failure, bearing failure with void failure, and void failure without bearing failure, depending on the location of the void as well as the size of the void. Upper-bound calculations were presented to interpret the changes of bearing capacity observed because of the existence of a void.     

Failure of resistance spot welds: tensile shear versus coach peel loading conditions

Abstract

This paper aims at investigating the failure behaviour of resistance spot welds under tensile shear (TS) and coach peel (CP) loading conditions. A failure mechanism was proposed to describe both interfacial and pullout failure modes in each loading condition. The mechanisms were confirmed by SEM investigations, examining the cross-sections of the fractured welds to detail the fracture path. The experimental results showed that in the pullout failure mode during TS testing, necking is initiated at the nugget circumference in the base metal, and then failure propagates along the nugget circumference in the sheet, leading to the final fracture, while pullout failure during the CP test occurred by crack initiation and propagation near the weld nugget/heat affected zone boundary. The interfacial failure to pullout failure mode transition in the TS and CP tests was also studied. The critical weld nugget size required to ensure the pullout failure mode was obtained for each loading condition. The critical fusion zone size to ensure pullout failure mode during the TS test was larger than that of the CP test. It was found that the load bearing capacity of the spot welds under CP is significantly lower than that of the TS test.     

宝钢RH真空系统稳定运行的研究与实践

在炼钢厂生产高附加值的品种钢必须通过RH精炼工序,而RH装置中的真空系统是否稳定是决定钢水质量的关键因素。介绍RH真空系统故障的分类,包括能源介质的故障、漏气故障及真空元件的故障。对每类故障的原因进行分析,并结合现场实际案例,快速确认故障原因。从真空度维护方面介绍了几种有助于真空系统稳定运行的措施,经实践证明非常有效,对同类真空系统的运行有一定借鉴意义。     

Creep of udimet 500 during thermal cycling: II. The time to failure

The effect of rapid temperature cycling on the time to failure of Udimet 500 superalloy was investigated. It was found that the time to failure is determined only by the minimum creep rate and not by the thermal history. For this reason the time to failure under thermal cycling conditions is longer than the time to failure calculated from isothermal data.     

Creep of udimet 500 during thermal cycling: II. The time to failure

The effect of rapid temperature cycling on the time to failure of Udimet 500 superalloy was investigated. It was found that the time to failure is determined only by the minimum creep rate and not by the thermal history. For this reason the time to failure under thermal cycling conditions is longer than the time to failure calculated from isothermal data.