滚动轴承扩展寿命计算方法及影响因素研究

介绍了滚动轴承寿命计算方法及其特点,根据ISO281:2007详细描述了滚动轴承寿命修正系数的计算方法,并结合算例对影响轴承寿命的主要因素进行了分析.     

ISO 281:1990与ISO 281:2007滚动轴承寿命计算标准的比较

比较了标准ISO 281:1990(我国等同采用为GB/T 6391-2003)与ISO 281:2007(我国等同采用为GB/T6391-2010)关于滚动轴承寿命计算方法的差异,分析了两种标准的修正系数在含义和取值上的差异,以及修正系数对滚动轴承寿命计算结果的影响。研究结果表明,ISO 281:2007引入综合修正系数,该系数综合考虑了ISO 281:1990的材料、润滑两修正系数,此外还考虑到润滑剂中的杂质因素和轴承的疲劳载荷极限,影响因素综合程度高,计算更可靠。     

径向游隙对圆柱滚子轴承疲劳寿命的影响

应用经典的滚动轴承理论和“切片法”的基本思想,以某大兆瓦风电机组齿轮箱输出轴轴承为例,采用Romax Designer工程分析软件,计算了圆柱滚子轴承不同径向游隙时的轴承内部载荷分布、接触应力、套圈滚道当量动载荷和寿命,分析径向游隙对轴承ISO/TS 16281寿命的影响。研究结果表明：径向游隙不仅通过对轴承内部载荷分布、接触应力和套圈滚道当量动载荷的影响而对寿命产生影响,还通过对寿命修正系数等因素的影响而对寿命产生影响。研究结果可为滚子类轴承的优化设计提供参考。     

圆柱滚子轴承凸度设计及其对疲劳寿命影响

圆柱滚子轴承的凸度参数是影响其疲劳寿命的重要参数,选用对数曲线凸型由于可减轻滚子的边缘应力集中现象且应力分布较为均匀而获得了广泛应用,但轴承存在偏载时边缘应力不能得到很好的消除。基于Johns-Gohar凸度模型提出了一种新的对数曲线方程,可通过改变方程中的两个系数调整凸度设计,给出了考虑滚子凸度的拟静力学模型计算圆柱滚子轴承的应力分布,根据应力分布结果计算了滚子轴承的修正参考额定寿命。结果发现使用本文提出的滚子凸度设计方程,在偏载工况下可以显著改善应力分布,并提高滚子轴承的修正参考额定寿命。     

圆柱滚子轴承磨损的数值仿真

基于滚动轴承的动力学理论,考虑滚动轴承承受的接触压力和自转速度实时发生变化,依据零件磨损过程通用的数值仿真方法,建立了圆柱滚子轴承磨损的数值仿真模型,并对其磨损寿命进行了预测.通过算例验证,仿真结果与实际磨损相符.结果表明:通过数值仿真方法可以解决圆柱滚子轴承的磨损寿命预测问题.     

游梁式抽油机摆动轴承疲劳寿命预测

为准确预测游梁式抽油机摆动轴承在变载荷、变转速实际运行工况下的疲劳寿命,基于ISO 281:2007标准和Miner理论,提出一种基于变载荷、变转速工况的摆动轴承疲劳寿命计算方法。以CYJY12-4.8-73HB型抽油机中轴圆柱滚子轴承为研究对象,先采用ADAMS软件进行游梁式抽油机动力学分析,以确定轴承摆动载荷和摆动速度,再计算实际运行条件下的轴承疲劳寿命,并与传统摆动轴承疲劳寿命计算方法对比。结果表明,本文的疲劳寿命计算方法合理,可为该类轴承疲劳寿命预测提供参考。     

弹流润滑下航空发动机中介滚子轴承的均载修形研究

中介轴承做为双转子航空发动机的低压转子和高压转子之间连接的关键零件,其运行状态直接影响发动机的工作性能和飞机的飞行安全.中介轴承的均载修形研究对于提高航空发动机的工作寿命和可靠性具有重要意义.研究了弹性流体润滑条件下,某对转双转子发动机的中介轴承的最佳修形方式.采用切片法,计算了直线圆柱滚子轴承、修正线修形圆柱滚子轴承、全凸修形圆柱滚子轴承以及对数修形圆柱滚子轴承在受径向载荷和倾覆弯矩联合作用时轴承的受力和歪斜情况,通过对比不同修形下滚子的最大载荷数值,得出中介轴承应采取的最佳修形方式.为某型双转子发动机中介轴承设计提供了参考.     

基于多因素的风电主轴轴承疲劳寿命分析

以4.5 MW风电机组主轴固定端轴承为研究对象,基于ISO 281:2007标准和Palmgren-Miner线性损伤累积理论建立疲劳寿命理论计算模型,将其疲劳寿命计算结果与Romax仿真模型对比可知,ISO 281:2007标准修正算法及Romax仿真模型更接近实际工况。并分析了载荷、转速、润滑脂污染程度对固定端轴承疲劳寿命的影响,结果表明：轴承疲劳寿命随载荷增大快速下降,随转速增大先增大后减小,随润滑脂污染系数增大而增大。     

GB/T 4661-2002《滚动轴承圆柱滚子》标准浅析

圆柱滚子是圆柱滚子轴承的主要组件之一,其滚子质量的好坏,不仅影响轴承的旋转精度和性能,而且对轴承的寿命影响尤为突出。近几年来,电机行业和机车行业均要求供给低噪音、高精度寿命的圆柱滚子轴承。各圆柱滚子轴承制造厂都在为提高滚子轴承寿命而不断提高滚子质量。GB/T 4661—2002《滚动轴承 圆柱滚子》的发布,满足了圆柱滚子的生产和选用,并与国际标准和国外先进标准接轨。 GB/T 4661—2002代替了GB/T 4661—1989,按照GB/T 6930—2002《滚动轴承 词汇》规范术语、定义,新的标准将原来的分组批、分组批直径(长度)变动量改为规值…     

基于接触应力的圆柱滚子轴承疲劳寿命分析

首先介绍了圆柱滚子轴承疲劳寿命的经典理论计算方法.然后运用Hertz接触应力理论计算出圆柱滚子轴承的最大接触应力,结合三参数幂函数公式确立疲劳寿命曲线方程计算出轴承的疲劳寿命值.通过改变轴承滚子数目、径向力大小以及径向游隙等参数,将基于接触应力得到的疲劳寿命结果与经典理论结果进行比较,证明了该方法的合理性.并分析了在考虑离心力作用下高速圆柱滚子轴承疲劳寿命与转速之间的关系.     

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.