计入曲轴受载变形的粗糙表面曲轴轴承弹性流体动力润滑分析

对一四缸内燃机曲轴轴承进行了计入曲轴受载变形和表面形貌的弹性流体动力润滑分析.计算中采用动力学法进行曲轴轴承的润滑分析,采用变形矩阵法计算油膜压力作用下轴瓦表面的变形.结果表明,表面形貌对曲轴轴承轴心轨迹影响较大,表面弹性变形对曲轴轴承轴心轨迹影响很小;计入表面形貌,曲轴轴承最大油膜压力增大显著,最小油膜厚度明显减小,端泄流量在大部分时间几乎没有变化;计入表面弹性变形,轴承最大油膜压力基本都有不同程度的减小;表面弹性变形对端泄流量、轴颈摩擦因数以及最小油膜厚度的影响甚小.     

Laboratory investigation of boundary effect on pressure-settlement behavior of foundation soil with limited thickness involving geosynthetics

Plate loading tests were conducted to investigate the effect of a bottom boundary condition on the pressure-settlement behavior of a footing on sand with a limited thickness involving geosynthetics. Seven boundary materials including geosynthetics were used to create different boundary conditions at the bottom of the sand. Interface direct shear tests were conducted first to determine the interface friction angles between these boundary materials and sand, followed by plate loading tests to determine their pressure-settlement curves. Test results show that the sand with a limited thickness by a rigid bottom boundary had a higher bearing capacity than that with a larger thickness. The ultimate bearing capacity of the footing on the sand with a limited thickness generally increased with the increase of the interface friction angle. Geosynthetics provided better lateral restraint than other materials. An equation was developed to describe the relationship of the bearing capacity ratio of the sand with a limited thickness to that with a large thickness versus the soil thickness and the interface interaction coefficient. The effect of the boundary material on the back-calculated modulus of the sand was also evaluated.     

局部加载下中空夹层钢管混凝土的试验研究

对局部受压下的中空夹层钢管混凝土进行试验研究。分别对含内外两层钢管的14个圆形构件和15个方形试件进行试验,试验参数包含:空心率、顶端板厚度、局压面积比。结果表明:局部受压下中空夹层钢管混凝土呈现延性。各试验参数对局部受压中空夹层钢管混凝土短柱的性能和破坏模型有很大影响。最后,提出分析局部受压下中空夹层钢管混凝土承载力的简化计算模型。     

立式钢制储罐基础设计

以某罐区立式钢制储罐基础设计为例,探讨预制桩、灌注桩和浅基础应用于储罐基础的设计方法。储罐基础设计可比拟为“板-柱结构”体系,借助pkpm结构软件分析两种桩型承载力、浅基础设计、场地条件影响及桩-土共同作用。储罐桩基设计应对水平承载力、竖向承载力和配筋量三控制设计,对于端承型桩基,一般情况下单桩水平承载力起控制作用。相同桩数时,采用方形布桩的边桩配筋比环形布桩的更易产生突变。应用于软土场地的砼预制桩不仅应进行桩基承载力计算,还应加强桩基配筋验算。     

The possibility of evaluating turbo-set bearing misalignment defects on the basis of bearing trajectory features

This paper presents the results of computer simulation of bearing misalignment defects in a power turbogenerator. This malfunction is typical for great multi-rotor and multi-bearing rotating machines and very common in power turbo-sets. Necessary calculations were carried out by the computer code system MESWIR, developed and used at the IFFM in Gdansk for calculating dynamics of rotors supported on oil bearings. The results are presented in the form of a set of journal and bush trajectories of all turbo-set bearings. Our analysis focuses on the vibrational effects of displacing the two most vulnerable machine bearings in horizontal and vertical directions by the maximum acceptable range calculated with regard to bearing vibration criterion. This assumption required preliminary assessment of the maximum values for the permissible bearing dislocations. We show the relations between the attributes of the particular bearing trajectories and the bearing displacements in relation to their base design position. The shape and dimensions of bearing trajectories are interpreted based on the theory of hydrodynamic lubrication of oil bearings. It was shown that the relative journal trajectories and absolute bush trajectories carry much important information about the dynamic state of the machine, indicating also the way in which bearings are loaded. Therefore, trajectories can be a source of information about the position and direction of bearing misalignments. This article indicates the potential of using trajectory patterns for diagnosing misalignment defects in rotating machines and suggests including sets of trajectory patterns to the knowledge base of a machine diagnostic system.     

LMD及马氏距离敏感阈值的滚动轴承故障诊断

针对滚动轴承非平稳性的振动信号,提出了基于局部均值分解(Local Mean Decomposition,LMD)及马氏距离敏感阈值的滚动轴承故障诊断方法。首先,对振动信号进行LMD分解,获得一系列乘积函数(Production Function,PF),有的PF分量包含的故障信息多,有的包含的少,为此采用K-L散度法提取出主要PF分量;计算主要PF分量的时域参数指标,将其组合成特征向量,根据马氏距离提出马氏距离敏感阈值来表征不同的故障状态,取多组正常信号的特征向量均值作为标准特征向量,计算未知特征向量与标准特征向量的马氏距离敏感阈值,从而对其故障状态进行识别。试验结果表明,在不同转速下,该方法能够有效的对滚动轴承故障进行识别,且效果较EMD方法好。     

轴向混合磁悬浮轴承磁场与控制研究

采用有限元法对轴向混合磁悬浮轴承的磁场进行分析,应用三角剖分单元建立了磁悬浮轴承模型,在泛函分析基础上归纳出了磁位势的计算方程。根据所建模型,分析了永磁偏置磁场的磁通与磁感应强度分布特点、研究了电流控制磁场独自存在时的磁通分布和磁感应强度分布规律,描述了磁场力与控制电流的关系曲线。进而深入解析了永磁偏置磁场和电流控制磁场叠加条件下的磁通与磁感应强度分布特点,并得出磁场力与控制电流的关系。     

深度残差网络在滚动轴承故障诊断中的研究

近年来,由于传统人工提取特征的方法不足以准确表征滚动轴承的健康状态,深度学习算法被逐渐应用于滚动轴承的故障诊断中,它能够自适应的从输入数据中学习出所需要的特征.其中,相较于普通的深度学习算法,深度残差网络通过恒等映射的方式可以大幅度降低模型的训练难度.因此,采用了一种用于滚动轴承故障诊断的深度残差网络(ResNet),...     

西北某电厂工业厂房强夯加固地基处理技术研究

火力发电厂工业厂房结构对地基的变形要求较高,在天然地基承载力或变形不能满足上部结构要求时,一般要采用人工方法对地基进行强化处理。本文通过工程实际,介绍了在火力发电厂工业厂房结构地基处理工程中强夯技术的设计、施工、检测及效果。表明了强夯在工业厂房结构地基工程中技术上是可行的,在施工质量和处理效果上可以满足要求,地基承载力和稳定性都得到了较大的提高。     

青铜峡电厂七号机组推力轴承受力调整

水轮发电机组的正常运转要求各推力轴承轴瓦应均匀地承受推力负荷。青铜峡电厂是黄河上建成较早的一座水电厂，机组老化程度严重，其刚性支柱式的推力轴承受力调整的好坏直接影响着机组的安全与稳定运行。本文论述了青铜峡水电厂七号水轮发电机组推力轴承的受力调整过程，对类似机组的推力轴承受力调整具有一定指导意义。