预紧高速角接触球轴承动力学特性分析

以弹性力学理论、滚动轴承动力学分析理论和沟道控制理论为基础,建立了预紧高速角接触球轴承的动力学方程,采用Newton-Raphson迭代法进行求解,对预紧高速角接触球轴承的动力特性进行分析。实例表明:随着预紧力的增加,内接触角减小而外接触角增大,球的离心力、陀螺力矩和旋滚比减小,球与内、外圈的接触变形、接触应力、接触载荷及轴承刚度增大;定压预紧轴承动力特性参数受预紧力变化的影响较大,而定位预紧轴承的接触变形、接触应力、接触载荷及刚度等动力特性参数值较大。     

一种考虑润滑效应的角接触球轴承接触刚度计算方法

建立了润滑工况下的高速角接触球轴承动力学模型,在滚珠与内/外圈的接触变形和接触刚度计算中,考虑高速转动中润滑油卷吸作用和挤压效应的影响,通过接触角和接触刚度的耦合迭代,得到考虑润滑效应的高速角接触球轴承轴向及径向刚度计算方法.结果表明,考虑润滑效应后,滚珠与内/外圈的接触角减小,轴承轴向/径向刚度增大;轴向载荷增加使轴向/径向刚度增大,且轴向载荷愈低,滑油作用愈明显;径向载荷增加使轴向刚度增大,径向刚度减小;滚珠数增加使轴向/径向刚度增大,且滑油作用更明显;相较4019型,4106型润滑油使轴承轴向/径向刚度增大;陶瓷滚珠轴承轴向/径向刚度比钢滚珠轴承大,且与转速呈近似线性关系.     

向心关节轴承承载能力分析

利用ANSYS软件APDL编写了某型号向心关节轴承静载荷下的应力场分析程序,在有限元模型中用刚性面来替代芯轴和轴承座。通过分析、对比关节轴承在不同载荷下轴承内、外圈的应力场分布,得到了关节轴承能承受的极限静载荷;在进一步的分析中,通过采用线性最小二乘法,得到了向心关节轴承径向载荷与轴承内、外圈最大接触应力间的关系公式,为关节轴承的结构强度设计提供了理论依据与参考。     

基于ANSYS的平地机用向心关节轴承的改进

针对某国产160马力平地机上的GE60ES向心关节轴承使用中经常出现外圈碎裂的现象,对该轴承的工作特点及承载特性进行了分析;利用软件,建立关节轴承有限元计算模型,计算出了径向载荷和轴向载荷下轴承的应力分布云图。可知外圈油槽处有明显的应力集中,通过取消外圈上的油槽使轴承外圈应力分布均匀,解决了轴承外圈碎裂问题。     

圆柱滚子轴承径向跳动的仿真分析

根据拟静力学条件下轴承零件的几何协调关系和受力平衡方程,建立了圆柱滚子轴承径向跳动的数学仿真模型,并采用Nowton-Raphson法进行求解,分析了外圈滚道圆度误差幅值、谐波阶次及径向载荷、转速等工况条件对轴承径向跳动的影响规律。结果表明:随轴承外圈滚道圆度误差幅值和外圈转速的增大,圆柱滚子轴承径向跳动值增大;随外圈滚道谐波阶次增大,径向跳动值呈周期性变化;随径向载荷增大,径向跳动值减小。     

高速滚动轴承的负荷分布研究

高速滚动轴承的负荷分布特性对转子系统的动态特性有着非常重要的影响,为尽可能得到真实的轴承载荷分布情况,采用拟动力学分析方法,并通过考虑轴向负荷、径向负荷、离心力以及陀螺力矩对其的影响,建立了滚动轴承的动力学分析模型。采用Matlab编程求解非线性方程组,研究了不同径向负荷、轴向负荷及转速条件下滚动轴承的负荷分布特性,得到了滚动轴承接触角和变形的变化规律。     

基于有限元的关节轴承研究

关节轴承的接触特性对其运行性能具有重要影响,为了研究关节轴承的接触特性,利用有限元软件ANSYS建立了关节轴承有限元模型.分析了轴向载荷、径向载荷和轴径复合载荷下关节轴承的应力分布,并研究了导油槽对接触应力的影响.结果表明:轴向载荷、径向载荷和轴径复合载荷下的应力分布和应力集中部位不同,但各种载荷下关节轴承外圈球面边缘处都产生应力集中;轴承外圈的最大应力比轴承内圈最大应力大;合理的导油槽能够起到减小应力集中的作用.     

风力发电机偏航轴承载荷分布及接触角数值解法研究

基于赫兹弹性接触理论,推导了滚子与轴承内外圈接触变形时的接触刚度,建立了偏航轴承受复杂载荷时受力平衡的非线性方程组,井运用带有松弛因子的牛顿-拉夫逊法求解非线性方程组,得到了承载时偏航轴承各滚子的接触应力和接触角.最后,用经典理论公式和有限元方法对此方法计算结果进行了验证,证明了文中计算方法的正确性,为兆瓦级风力发电机轴承的设计计算提供了参考依据,具有一定的工程应用价值.     

径向载荷作用下高速交叉滚子轴承的载荷分布

对径向载荷作用下的高速交叉滚子轴承进行了受力分析,建立了考虑离心力的滚子载荷方程,用Matlab分析了转速、径向外载荷、游隙对交叉滚子轴承载荷分布的影响,为高速交叉滚子轴承的结构优化设计中参数的确定提供了依据。     

基于神经网络与遗传算法的关节轴承挤压模具优化

针对实际生产中关节轴承内外圈间隙分布不均问题,以GEW12关节轴承为例,应用ABAQUS软件对关节轴承挤压装配过程进行了数值模拟。采用BP神经网络建立了挤压模具形状与内外圈最大间隙与最小间隙之差的映射关系。以关节轴承内外圈间隙均匀分布为目标,结合遗传算法,提出了一种集数值仿真、人工神经网络和遗传算法为一体的关节轴承挤压模具型腔优化设计方法。实验结果表明,模具型腔经过优化后,轴承内外圈间隙均匀性得到了很大的改善,轴承金属流动速度更加均匀。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.