渐开线重载齿轮传动的弹流润滑分析

建立了重载齿轮传动的弹流润滑模型,采用多重网格法、多重网格积分法以及逐列扫描法,计算出压力、膜厚以及温度等。结果表明,固定润滑油黏度,随着润滑油黏度和齿面综合速度乘积的增大,平均膜厚单调增大,而次表面剪应力最大值单调减小。载荷越大,次表面剪应力最大值的X坐标位置越靠近出油口的位置。     

渐开线重载齿轮传动非牛顿流体热弹流润滑分析

建立渐开线重载齿轮传动的非牛顿流体热弹流润滑模型,分别采用多重网格法、多重网格积分法、逐列扫描法计算齿面压力分布、油膜厚度和齿面温度,分析润滑油黏度和齿轮转速对重载齿轮传动接触疲劳寿命的综合影响。结果表明:在润滑油黏度和齿面综合速度乘积固定不变的前提下,同时改变其中任一量对轮齿接触应力没有影响。     

齿面粗糙度对齿轮传动接触疲劳应力的影响

对齿面粗糙度呈余弦分布的渐开线圆柱齿轮进行热弹流润滑数值计算,分析齿面粗糙度对齿轮传动接触疲劳应力的影响。结果表明:粗糙度会使轮齿接触区次表面发生明显的应力集中,粗糙度波长愈小,应力集中愈明显,且愈贴近齿轮表面;随着粗糙度波幅的增大,平均油膜厚度单调增大,而接触区次表面主剪应力的最大值呈抛物线变化;随着粗糙度波长的增大,平均油膜厚度迅速减小而主剪应力的最大值急剧增大,但当波长增至一定值时,二者各自趋于光滑齿面接触时的相应值。     

齿轮传动胶合失效的解决方法

胶合是传递动力齿轮的主要失效形式,往往是最终失效形式。它属于轮齿工作面失效形式的一种,有可能引起齿轮的传动速度下降,摩擦力剧增,严重时还会冒烟,甚至在啮合处打出火花。产生胶合的原因是齿面间油膜遭到破坏。主要原因是,高速重载齿轮传动散热不好,润滑油油温急剧上升,黏度降低,齿面间的油膜难以形成;低速重载齿轮传动,则由于工作齿面间压力很大,润滑油膜被挤破,从而使啮合齿轮两齿面直接接触,破坏了油膜。     

渐开线圆柱齿轮轮齿受载变形的研究

本文从重载齿轮传动的齿廓修形和齿向修整对轮齿变形计算的实际需要出发,采用三维有限单元法对不同齿数、不同法向变位系数、不同螺旋角和不同受载位置的多个计算模型进行了计算,并对有限元计算结果进行了分析,基本摸清了几个重要影响因素对轮齿受载变形量的影响规律。     

轴承预紧力作用下的行星齿轮动态载荷研究

为分析轴承预紧量对高速重载行星齿轮传动系统接触性能影响,建立高速重载行星齿轮传动动力学模型,考虑轴承预紧量因素,分析行星销轴承预紧量对系统支撑刚度、齿面啮合性能、系统均载影响。结果表明:行星销轴承预紧量影响行星销支撑刚度、齿面啮合性能、动态均载,从负游隙到正游隙系统支撑刚度减小,齿轮副的啮合载荷最大值减小,系统的均载系数减小。研究结果可为优化高速重载行星齿轮传动的轴承预紧量提供支撑。     

考虑结构柔性的电动轮毂NW行星传动啮合特性分析

电动轮毂传动NW型行星齿轮减速器为研究对象,设计了该NW行星传动几何参数,考虑齿圈的柔性建立了电动车轮毂驱动NW轮系啮合分析模型.研究了齿圈厚度对齿圈变形和轮系传动误差的影响规律,分析了齿轮副的啮合印痕分布,并对齿轮进行了修形研究.基于行星销轴位置误差定义分析,研究了行星销轴位置误差对行星传动均载的影响.结果 表明,齿圈厚度对齿圈变形影响较大,齿圈厚度越厚,齿圈变形越小,呈现非线性变化,且轮系的传动误差减小;轮齿修形有效地改善了轮齿啮合偏载现象;行星架销轴切向位置误差对NW行星传动均载影响较大,而径向位置误差对均载影响较小.     

低速重载开式齿轮齿条传动润滑状态分析

采用三峡升船机齿条性能评定试验装置,研究低速重载、频繁换向条件下开式齿轮齿条的润滑状态。对开式齿轮齿条油膜厚度计算模型中润滑油的压黏系数进行修正以适用高黏度润滑油,利用油膜厚度准则对开式齿轮齿条的润滑状态进行分析。结果表明,采用油膜厚度准则能相对准确地判断低速重载开式齿轮齿条传动的润滑状态;转速、载荷对润滑状态有很大的影响,齿轮齿条换向时,润滑状况相对恶劣,易磨损、胶合,应尽量减小载荷和齿面粗糙度,增大润滑油黏度。     

正交面齿轮弯曲应力的分析

建立了正交面齿轮的三齿几何模型 ,形成了相应的有限元分析模型 ,研究了在不同参数下 (如模数、齿数、齿宽 )正交面齿轮三齿模型的最大弯曲应力特性。本文考虑面齿轮受载最不利的情况 ,即在面齿轮的齿顶沿齿宽方向的不同位置加集中载荷 ,通过有限元分析表明 ,面齿轮的最大弯曲应力不是在齿根而是在沿齿高方向的中部位置 ,并随力的作用点向两端移动时最大弯曲应力的位置向齿顶移动。这对于面齿轮传动设计中控制接触点的位置有重要意义     

正交面齿轮变曲应力的分析

建立了正交面齿轮的三齿几何模型，形成了相应的有限元分析模型，研究了在不同参数下（如模数，齿数，齿宽）正交面齿轮三齿模型的最大弯曲应力特性，本文考虑面齿轮受载最不利的情况，即在面齿轮的齿顶沿齿宽方向的不同位置加集中载荷，通过有限元分析表明，面齿轮的最大弯曲应力不是在齿根而是在沿齿高方向的中部位置，并随力的作用点向两端移动时最大弯曲应力的位置向齿顶移动，这对于面齿轮传动设计中控制接触点的位置有重要意义。     

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.     

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....     

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。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.