圆弧齿廓面齿轮齿面设计

针对渐开线齿轮传动存在的缺点,综合面齿轮传动的各项优点,将圆弧齿廓应用于面齿轮,提出圆弧齿廓面齿轮传动。采用理论分析、数值计算与物理实验相结合的研究方法对圆弧齿廓面齿轮齿面进行设计。基于齿轮啮合原理和微分几何理论,首先对圆弧齿条基本齿形的共轭齿形齿条齿面方程进行建模,然后利用包络成形理论推导出了加工圆弧齿廓面齿轮的刀具齿面方程,进而由刀具与圆弧齿廓面齿轮互为包络成形理论推导出面齿轮的工作齿面及过渡曲面的方程。最后应用MATLAB软件编程求解出齿面点集并导入到CATIA软件中自带宏程序的EXCEL表格中,运行宏程序并生成轮廓曲线,再利用曲面拟合的方法得到圆弧齿廓面齿轮的三维物理齿面。经与切齿包络仿真模型对比,验证了其准确性。     

基于修形蜗杆砂轮的斜齿轮参数化设计

根据蜗杆砂轮磨削加工斜齿轮的实际过程,建立了修形斜齿轮齿面及齿根过渡曲面参数化数学模型。通过对蜗杆砂轮齿廓进行修整,可得到斜齿轮齿廓修形后各截面的齿廓;通过改变蜗杆砂轮运动时径向的进给量,可得到斜齿轮齿向修形后各截面的齿廓;利用VS 2008编程计算斜齿轮齿面及齿根曲面方程以及完成软件界面的设计,并通过一个算例说明该设计方法可以实现斜齿轮的参数化建模。     

一种平行轴圆截面线齿轮齿廓的构建方法

在空间曲线啮合理论的基础上,研究平行轴线齿轮的传动机构。以螺旋线为中心线,研究截面为圆时主动线齿的曲面方程,并以此构建主动线齿轮齿面齿廓。以同轴心的圆截面为从动线齿轮的齿廓截面,并根据从动轮中心线构建从动轮齿面方程。分析线齿轮啮合传动时主动线齿上的正反转接触线,并根据空间曲线啮合方程求出从动线齿的正反转接触线。此正反转接触线应满足从动线齿轮中心线构建的圆截面从动线轮齿面方程。可通过增加齿数提高其重合度以提高传动稳定性。通过建立线齿轮副3D模型并进行运动学模拟仿真实验,结果表明,此方法构建的平行轴圆截面线齿轮装配无法向侧隙,且传动过程无干涉,能够满足设计的传动比需求。     

准双曲面齿轮数字化建模与时变啮合特性分析

针对采用刀倾半展成法(HFT)加工的准双曲面齿轮副,根据机床各部件间运动学关系,采用齐次坐标变换的方法仿真刀具运动轨迹.基于曲面成形理论及共轭啮合原理,推导大小轮齿面及齿根过渡曲面方程,建立准双曲面齿轮副啮合数学模型.采用数值算法求解齿面啮合方程并进行轮齿接触分析(TCA),获得静态传动误差及啮合印痕.采集大小轮齿面离散点云坐标并进行三维建模,基于有限元软件ABAQUS分析准双曲面齿轮副不同工况下时变啮合特性.结果 表明,载荷变化对动态啮合力、传动误差、啮合刚度等参数的影响显著.随载荷增大,传动误差及啮合刚度曲线呈明显非对称特征,相关结果为准双曲面齿轮传动特性及动力学行为分析提供了依据.     

基于包络法的正交面齿轮齿廓尖化研究

为实现正交面齿轮的加工,利用包络法对正交面齿轮齿廓进行设计,并根据齿廓仿真对正交面齿轮齿顶尖化、全齿高尖化和毛坯尖化进行研究。建立了正交面齿轮的包络坐标系,给出了产形面方程及其齿角方程,推导了面齿轮齿廓方程和过渡曲面方程,利用MATLAB和CATIA软件对面齿轮齿廓进行了仿真。根据仿真结果,分析了面齿轮尖化现象,得出尖化条件,通过最小二乘法对尖化条件的数值计算结果进行统计分析,得到面齿轮齿顶尖化、全齿高尖化和毛坯尖化的近似方程。最后通过面齿轮加工实验,验证了理论计算和近似方程的可行性。     

圆柱齿轮型端面谐波齿轮传动的研究

本文提出了一种新型的由普通圆柱直齿轮组成的端面谐波齿轮传动。给出了柔轮的原始曲面方程、柔轮和刚轮的齿廓曲面方程。讨论了该种传动的参数选择和啮合分析方法。计算结果和分析证明了这种端面谐波齿轮传动的工程实用价值,并可进一步推广使用。     

航空圆弧齿面齿轮啮合特性分析

基于啮合原理和微分几何的理论,推导出了弧齿面齿轮啮合传动的齿面方程和啮合轨迹方程,通过对啮合轨迹方程的仿真研究,得出了影响弧齿面齿轮啮合轨迹的主要参数为基本齿廓上任意点的压力角和基本齿条的法截面到端截面的垂直距离.     

内啮合曲线构型齿轮传动基本原理及接触分析

在齿轮传动共轭曲线理论研究的基础上,以内啮合曲线构型齿轮传动为对象,推导了沿给定接触角方向的空间共轭曲线副啮合方程,建立内啮合条件下空间共轭曲线副表达式,根据空间等距包络方法构建继承内啮合共轭曲线副特性的啮合齿面,通过改变成型曲面的相对运动位置及等距半径,提出凸齿廓-凸齿廓、凸齿廓-平面和凸齿廓-凹齿廓3种接触型式;以空间圆柱螺旋曲线为例,结合理论分析结果及主要设计参数,建立凸齿廓-凹齿廓内啮合曲线构型齿轮副三维实体模型;定义齿面接触点压力角,给出基于空间共轭曲线的齿面滑动率计算算法,完成内啮合齿面接触迹线计算及分析,后续将对齿面啮合性能、接触力学特性及制造方法进行研究。     

基于Matlab GUI与Creo的正交面齿轮参数化设计研究

基于正交面齿轮的齿面和过渡曲面方程,在齿根不产生根切与齿顶不变尖的前提条件下,采用Z向截面放样建模法,运用Matlab GUI编写相应程序,计算出齿面离散数据坐标点云集,将数据文件导入Creo得到高质量的三维模型,程序可视化提高了面齿轮优化和设计效率,为高质量面齿轮数字化设计提供参考。     

内啮合斜齿轮高精度三维有限元自动建模方法

为提高内啮合斜齿轮有限元接触分析的建模速度和模型精度,提出了一种齿轮高精度三维有限元模型的自动建模方法。基于齿轮插刀齿廓方程,利用齿廓法线法,得到包括齿根过渡曲线的内、外斜齿轮端面齿廓,建立了内、外齿轮参数化粗网格有限元模型。开发了表层六面体网格剖分方法,自动识别齿面接触带单元,进行分级剖分细化,保证了有限元模型的建模精度和网格密度。进行了齿面接触分析,得到了内啮合斜齿轮的弯曲应力、接触应力、接触印痕、传动误差、时变啮合刚度和载荷分配率。粗细网格有限元模型计算结果对比分析表明,该方法提高了内啮合斜齿轮有限元建模效率和计算精度,缩短了计算时间,为快速准确的齿轮接触分析奠定了基础。     

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。     

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.     

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....     

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.