六排滚子转盘轴承的有限元分析北大核心

针对转盘轴承套圈断裂和滚道剥落2种失效形式,提出了一种通过有限元分析对六排滚子转盘轴承进行强度校核的方法。该方法在建立转盘轴承有限元模型时将滚子滚道的非线性接触等效为非线性弹簧单元,并计算轴承套圈的内部应力分布,根据最大内部结构应力校核轴承的结构强度;采用滚子与滚道之间的接触模型计算滚子与滚道之间的最大接触应力来校核轴承的接触强度。该模型考虑了轴承套圈的结构变形,比传统轴承理论刚性套圈假设的计算结果更能反映实际情况。有限元计算结果与工程实际中该类型转盘轴承的失效情况相符。     

六排滚子转盘轴承的有限元分析

针对转盘轴承套圈断裂和滚道剥落2种失效形式,提出了一种通过有限元分析对六排滚子转盘轴承进行强度校核的方法。该方法在建立转盘轴承有限元模型时将滚子滚道的非线性接触等效为非线性弹簧单元,并计算轴承套圈的内部应力分布,根据最大内部结构应力校核轴承的结构强度;采用滚子与滚道之间的接触模型计算滚子与滚道之间的最大接触应力来校核轴承的接触强度。该模型考虑了轴承套圈的结构变形,比传统轴承理论刚性套圈假设的计算结果更能反映实际情况。有限元计算结果与工程实际中该类型转盘轴承的失效情况相符。     

高速空心滚子轴承的性能研究

根据接触力学理论,利用有限元软件ABAQUS,合理建立了空心圆柱滚子轴承的分析模型,研究了某高速空心滚子轴承的应力分布情况,并对滚子的空心度进行了优化设计.结果表明:在一定工况条件下,只要空心度合适,空心圆柱滚子轴承的应力分布情况要远好于实心滚子轴承.研究结果为高速空心圆柱滚子轴承的设计提供了指导.     

弹性复合圆柱滚子轴承接触特性分析

为探讨弹性复合圆柱滚子轴承滚动体与滚道的接触问题,首先采用有限元方法和经典赫兹接触理论计算方法对实心圆柱滚子轴承的接触应力与变形进行计算,并将两种方法得到的计算结果进行比较,比较结果表明:两种计算方法结果误差在10%以内,由此可知,有限元方法对计算轴承接触问题具有准确性。鉴于实心圆柱滚子轴承与弹性复合圆柱滚子轴承的内外圈接触副相似,可采用有限元方法对弹性复合圆柱滚子轴承接触应力分析。通过有限元方法对不同载荷下的弹性复合圆柱滚子轴承的接触应力、接触半宽、接触位移以及接触应力沿轴向分布进行计算与分析,得到的结果表明:一定载荷下,弹性复合圆柱滚动体的接触位移及接触半宽随着填充度的增大而增大;不同载荷下,弹性复合圆柱滚动体接触应力及等效应力随填充度的增大均存在极小值,且随着载荷的增大,极小值呈一定规律变化。弹性复合圆柱滚子轴承较实心圆柱滚子轴承在接触应力方面具有明显优势,设计合理的填充度能降低弹性复合圆柱滚子轴承的接触应力和改善"边缘效应"。     

考虑滚子位置变化的圆柱滚子轴承非线性刚度特性分析

以圆柱滚子轴承为研究对象,考虑轴承运转过程中滚子周向位置分布的周期性变化,对经典圆柱滚子轴承载荷分布理论进行改进,并对由此引起的轴承刚度时变特性进行分析,同时研究圆柱滚子轴承平均刚度及平均接触滚子数随径向力的非线性变化规律。为了对改进理论算法进行验证,采用有限元接触分析方法对圆柱滚子轴承刚度及滚子接触状态进行分析。研究结果表明,改进理论算法和有限元接触法均能准确预测轴承瞬时刚度的时变特性及平均刚度随径向力的非线性变化特性,同时证明轴承平均接触滚子数的改变是轴承刚度变化的根源。基于改进理论算法进而分析轴承初始径向游隙、径向力、滚子设计数量等关键参数对圆柱滚子轴承性能的定量影响规律。     

交叉滚子转盘轴承的有限元分析

通过分析交叉滚子转盘轴承两组滚子的载荷分布情况,确定受载最大滚子,计算接触表面及次表面应力值,利用Pro/E和ANSYS Workbench之间的无缝连接,将在Pro/E中建立的三维几何模型导入ANSYS Work-bench中进行有限元分析,并与传统的理论分析计算结果进行比较,证明有限元分析的正确性,为转盘轴承的设计优化和疲劳寿命分析提供了科学依据。     

圆柱滚子轴承次表面裂纹区域应力分布规律研究

圆柱滚子轴承套圈滚道次表面裂纹将改变滚子表面与滚道之间的接触特性，从而影响轴承的工作特性。针对这一问题，研究了次表面裂纹的长度、宽度和倾斜度对裂纹区域应力分布的影响规律。首先，采用有限元方法，建立了轴承滚子与滚道等效接触的计算模型，并将有限元模型与赫兹接触理论的算例计算结果进行了对比，对有限元模型的正确性进行了验证；然后，基于圆柱滚子轴承次表面裂纹的形态特征，提出了含次表面裂纹的滚子与滚道接触有限元计算模型；最后，基于有限元模型，分析讨论了次表面裂纹的深度、宽度和倾斜角度对滚道次表面应力区分布范围的影响规律。研究结果表明：当次表面裂纹的宽度增大时，应力区的深度和宽度都迅速增大；当次表面裂纹的深度增大时，应力区的深度和宽度都迅速降低；当次表面裂纹的高度与宽度一定时，次表面裂纹的倾斜角越大，次表面应力区越小，次表面裂纹对轴承接触特性的影响也越小。     

轴向游隙对圆锥滚子轴承应力分布的影响

针对轴向游隙对圆锥滚子轴承接触应力及其应力区域的变化情况的影响,基于ABAQUS建立了圆锥滚子轴承的有限元模型,计算了圆锥滚子轴承在径向载荷作用下最大受力滚子滚道母线上的应力分布值,并与基于Hertz理论的切片法做出对比,两者的计算结果具有较好的一致性.在整体分析的基础之上,调整圆锥滚子轴承的正负轴向游隙,分析了在轴向游隙变化的情况下圆锥滚子轴承最大应力和接触区域的变化,结果显示圆锥滚子轴承的最大接触应力会在较小的负游隙的情况下出现最小值,从而为下一步研究圆锥滚子轴承的疲劳寿命和结构优化提供依据.     

球磨机滚动轴承模型分析

以鲁南矿业有限公司MQG210/300球磨机改造用的大型双列向心球面滚子轴承为分析对象,基于有限元分析软件ANSYS,建立了滚动轴承接触分析的三维有限元模型,对轴承的接触问题进行了数值模拟,得到了轴承承载过程中的应力和变形分布。通过与hertz理论计算结果对比分析,两者结果比较接近,承载能力足够。     

空心圆柱滚子与滚道接触应力及位移分析

根据接触力学理论，用有限元方法对空心滚子轴承受载后的应力、位移和接触等情况进行了全面分析，结果表明，设计合理的空心滚子可以降低轴承的等效应力，然而，降低应力的效果与轴承所受载荷的大小有关；空心滚子轴承与实心滚子轴承同样不可避免地存在等效应力的“边缘效应”，因而，有必要通过其他设计方法来避免或降低这种等效应力的“边缘效应”，进一步提高轴承的承载能力和疲劳寿命。     

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...     

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.     

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.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

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....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.