考虑误差、轴变形和轴承刚度的弧齿锥齿轮LTCA

加工误差、安装误差、轴变形及轴承刚度会对弧齿锥齿轮的接触轨迹及传递误差曲线产生影响,基于加载接触有限元分析原理,给出考虑加工误差、安装误差、轴变形及轴承刚度的弧齿锥齿轮有限元加载接触分析方法,以一对准双曲面齿轮为对象,研究在考虑上述条件下接触轨迹的变化及传递误差曲线的变化情况,为高质量弧齿锥齿轮传动提供了一种有效设计与分析方法。     

弹性支承条件下中央弧齿锥齿轮传动的接触稳定性研究

为了提高弹性支承条件下中央弧齿锥齿轮的工作可靠性，首先应保证其接触的稳定性。本文针对某航空发动机转子，计算了在转子不平衡量和齿轮啮合力同时作用下，弧齿锥齿轮支承处的变形大小；依据支承变形对齿轮接触特性的影响机理，将变形转化为齿轮安装调整值ΔＨ、ΔＪ和ΔＶ；利用空间啮合理论，建立了弧齿锥齿轮传动的接触稳定性条件以及接触特性分析方法。分析计算了不同转速和不同功率下弧齿锥齿轮的齿面接触印痕和传动曲线，研究了转子共振时齿轮接触的失稳现象，获得了提高弹性支承条件下中央弧齿锥齿轧传动的接触稳定性的措施。     

具有最佳加载接触性能的弧齿锥齿轮主动设计研究

基于局部综合理论的弧齿锥齿轮齿面接触分析(TCA )和接触性能预控技术可保证弧齿锥齿轮在无载时具有较理想的接触区域和传动误差 ,但无法保证其加载接触性能。本文在柔性多体运动学基础上 ,建立了两弹性共轭齿面运动基本方程。将啮合点弹性变形分解为支承变形、轮体变形和接触变形 ,获得了变形前后齿面几何量的变化规律以及两弹性点共轭齿面间的接触条件。提出了一种在初始设计阶段就可保证弧齿锥齿轮具有预期加载接触性能的主动设计方法 ,并将其用于某航空发动机中央传动弧齿锥齿轮的齿面综合     

加载螺旋锥齿轮接触轨迹变化规律的研究

螺旋锥齿轮的接触轨迹直接反映传动质量,基于加载接触有限元分析原理,给出螺旋锥齿轮有限元加载接触分析模型的构建方法,取一对三齿螺旋锥齿轮模型,研究在轻载和重载情况下轮齿的接触力变化情况,得到载荷对接触轨迹及传动误差的影响规律,为高质量弧齿锥齿轮传动提供了一种设计方法与手段。     

一种弧齿锥齿轮时变啮合刚度和传动误差半解析计算方法

弧齿锥齿轮时变啮合刚度传统计算方法大多采用有限元静态分析方法,但需计算多次,且采用节点弹性变形平均值计算的单齿啮合刚度存在较大误差。为此,改进了弧齿锥齿轮时变啮合刚度计算方法,在传统计算方法上引入单个节点啮合刚度,将工作齿面各个节点啮合刚度叠加,得到单齿啮合刚度,计算精度更高;基于有限元显式动态分析计算弧齿锥齿轮时变啮合刚度和传动误差,计算1次而不需要进行多次有限元分析,减少了整个计算时间周期。研究了不同负载转矩下时变啮合刚度和传动误差变化规律,分析了接触椭圆长轴长度、接触轨迹方向两个接触参数对时变啮合刚度和传动误差的影响。研究结果表明,时变啮合刚度和传动误差随负载转矩增大而增大,但时变啮合刚度峰-峰值和传动误差峰-峰值(PPTE)随负载转矩增大而变小;随着接触椭圆长轴长度增大,时变啮合刚度和传动误差呈增大趋势;随着接触轨迹方向增大,时变啮合刚度存在突增现象,而传动误差变化很小。     

基于有限元法的双圆弧弧齿锥齿轮章动传动接触特性分析

接触特性是表征齿轮传动性能的重要指标。为明晰双圆弧弧齿锥齿轮章动传动的接触特性,利用有限元法对其进行加载接触分析。首先,基于啮合原理推导双圆弧弧齿锥齿轮齿面方程并生成齿轮副的三维模型;其次,利用Ansys Workbench建立齿轮副有限元模型,分析了双圆弧锥齿轮副的齿面啮合状态;最后,分析负载与安装误差对齿轮副传动性能的影响规律。结果表明：双圆弧弧齿锥齿轮存在分别位于凹、凸齿面上的双点接触状态,且锥齿轮靠近小端部位为应力危险点;增大负载有利于提高齿轮啮合的重合度,降低齿间载荷分配系数,一定程度上可提高齿轮传动的平稳性;安装误差对齿轮副齿面接触状态有较大影响,负向偏置误差与正向章动角误差不利于齿轮承载与传动稳定,在实际应用中应合理调控。     

双圆弧弧齿锥齿轮齿面接触分析

齿面接触分析是双圆弧弧齿锥齿轮啮合分析的有效工具,是进行加载齿面接触分析、有限元分析的基础.文中利用齿面接触分析(Tooth Contact Analysis,TCA)原理,结合双圆弧弧齿锥齿轮的齿形特点,对其TCA程序的关键内容及实现方法进行了介绍,实现了对双圆弧弧齿锥齿轮传动啮合质量的数值仿真分析.最后通过实例对该TCA程序进行了验证,为双圆弧孤齿锥齿轮的设计提供了有效的手段和方法.     

基于齿面通用模型的不同齿廓内啮合章动锥齿轮建模与接触分析

内啮合章动弧齿锥齿轮齿面数学模型推导过程较为复杂。为了建立不同齿廓章动锥齿轮模型并进行加载接触分析,利用通用法向基本齿廓建立了假想媒介冕齿轮齿面通用数学模型。根据冕齿轮与章动内啮合弧齿锥齿轮的啮合关系,推导得到适于不同齿廓的章动弧齿锥齿轮齿面通用数学模型。再以渐开线与双圆弧为法向基本齿廓,分别建立了渐开线和双圆弧两种齿廓的章动弧齿锥齿轮齿面模型及其三维模型。利用有限元软件分别对高低功率、不同齿廓的章动内啮合弧齿锥齿轮进行了加载接触分析。结果表明,负载大小对渐开线弧齿锥齿轮的加载接触特性影响较大;双圆弧弧齿锥齿轮相对于渐开线弧齿锥齿轮具有承载能力更大、传动更平稳的优点。     

双圆弧弧齿锥齿轮重合度研究

重合度是影响弧齿锥齿轮传动啮合性能的主要因素。双圆弧弧齿锥齿轮的端面重合度为零,其连续传动由纵向重合度保证。根据弧齿锥齿轮重合度的定义,提出了双圆弧齿廓弧齿锥齿轮重合度的定义,并采用线图法对其啮合过程进行了分析;建立了双圆弧齿廓弧齿锥齿轮重合度、多点啮合系数和多齿对接触系数等计算方法,给出了双圆弧弧齿锥齿轮连续传动的条件。应用提出的方法对试验齿轮的重合度进行了理论计算,计算结果与TCA分析结果相同,验证了所提出方法的正确性。     

弧齿锥齿轮传动的多目标优化设计

本文通过对影响弧齿锥齿轮传动设计的最小体积原则、接触强度计算的许用传递功率最大原则、弯曲强度计算的许用 传递功率最大原则等因素的分析,提出弧齿锥齿轮传动优化设计的数学模型及其求解方法。     

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.