循环自相关函数在轮边减速器故障诊断中的应用

在故障诊断领域,循环平稳信号处理方法正逐渐成为一种重要的信号处理工具。模拟内齿圈局部故障振动信号,利用循环自相关函数很好地提取了矿用自卸车轮边减速器中局部故障频率,有效地抑制噪声的效果,为矿用自卸车轮边减速器故障诊断提供了较好的处理方法,具有较广的应用前景。     

基于活齿传动的电动轮自卸车轮边减速器设计

针对重型矿用电动轮自卸车轮边减速器工作条件恶劣且需承受较大负载和冲击载荷,故障率高的问题,根据GE788型电动轮自卸车轮边减速器设计满足该型号自卸车使用要求的活齿传动轮边减速器,确定了活齿传动轮边减速器的结构和基本尺寸,分析了活齿传动啮合件的受力情况并进行了强度估算.研究结果表明,该活齿传动轮边减速器满足设计要求,为基...     

浮动式齿圈行星齿轮箱齿轮故障振动频谱模型

齿轮箱振动信号频谱结构的深入研究,对齿轮箱的故障诊断有很大帮助。但是到目前为止,还没有对齿圈浮动的行星齿轮箱频谱结构的相关研究。针对浮动式齿圈行星齿轮箱传动结构的特点,研究了振动信号传递路径对频谱结构的影响,得到了浮动式齿圈行星齿轮箱齿轮故障振动信号的频谱模型。利用包络谱对故障信号的幅值调制进行分析,简化了故障诊断工作。最后,运用所提频谱模型进行了故障诊断试验,准确发现了变速箱中的故障。     

矿用重型减速器行星机构功率谱分析

分析了矿用重型减速器行星机构结构特点和频谱分析难点。介绍了随机振动信号功率谱分析方法。以某重型减速器行星机构为研究对象,对其进行了加载试验和振动测试。采集了测点振动加速度信号,应用小波阈值去噪方法,进行了振动信号预处理,滤除了信号噪声。计算了测点振动信号自相关函数,对自相关函数做傅里叶变换获得测点振动信号功率谱。提出了行星机构振动信号故障特征频率计算方法。分析了该重型矿用减速器行星机构功率谱,获得了行星机构振动谱峰,提出了减速器设计优化建议。为矿用减速器可靠性提升奠定了基础。     

矿用自卸车轮边减速系统可靠性建模分析

矿用自卸车轮边减速系统具有较大的传动比,受制于空间限制,而减小行星齿轮太阳轮齿数,因此会降低齿轮的可靠性。针对于此以某矿用自卸车轮边三级行星减速器为研究对象,根据系统结构和工作原理,基于Romax搭建轮边三级行星减速器虚拟样机有限元模型,对不同工况下各级齿轮的强度和疲劳寿命进行校核,解决传统计算对减速器所受径向载荷、自重及变形等因素考虑不足的问题,分析结果更加精确。结果表明轮边减速系统的齿轮接触疲劳强度、弯曲疲劳安全系数高,使用寿命达到设计标准要求,为同类矿用自卸车轮边减速系统设计研究提供理论依据和分析参考。     

新书介绍

1．《齿轮及齿轮箱故障诊断实用技术》一书系统论述了齿轮箱中的三大零部件——齿轮、滚动轴承和轴的常见失效形式，振动噪声产生的机理和故障的主要形式，调制现象和边频带分布特点，齿轮及齿轮箱振动信号的时域、频域和现代解调分析的各种处理方法，提取了十种典型故障振动信号特征。从现场诊断技术需要的角度出发介绍了齿轮箱故障诊断常用的振动噪声故障诊断方法、     

基于局部特征尺度分解和数学形态滤波的齿轮故障诊断方法研究

为了实现齿轮故障的精确诊断,针对齿轮早期故障振动信号非线性、非平稳且信噪比低的特点,提出了一种基于局部特征尺度分解(LCD)和数学形态滤波的齿轮故障诊断方法。首先,对齿轮振动信号进行局部特征尺度分解,得到若干内禀尺度分量(ISC);然后,依据峭度准则,选取峭度最大的ISC作为故障特征分量,再运用形态差值滤波器对其进行滤波;最后,对滤波结果求取频谱并进行故障诊断。通过对仿真结果和实验数据的分析,说明了该方法的可行性和有效性。结果表明,该方法具有抑制噪声和提取故障冲击特征的能力,能够有效地实现齿轮故障的精确诊断。     

优化设计汽车轮边减速器内齿圈基体硬度及齿壁厚度

本文详细介绍汽车轮边减速器内齿圈的材料选择、内齿加工工艺、基体硬度的选择,提出齿壁厚度的优化设计步骤.     

基于噪声测试的轴承滚动体划伤故障特征识别

围绕航空发动机轴承典型故障不易诊断的问题，提出了基于噪声信号的非接触式测量方法。在实验室条件下设计并搭建具有复杂传递路径的轴承故障模拟转子试验台，用线切割的方法加工了轴承滚动体划伤故障，开展了该种故障下不同转速工况的试验测试，获取了故障轴承噪声信号及振动信号。对采集到的噪声信号进行频谱分析和小波阈值变换分析，振动信号进行包络谱分析。分析结果表明：基于噪声信号的诊断方法避免了复杂传递路径对信号的衰减作用，可以有效提取轴承滚动体划伤故障信号特征，识别效果明显优于振动信号。这里提出的基于噪声信号诊断的方法为航空发动机轴承故障诊断提供了新手段。     

基于ATF与ASAD的变转速齿轮故障诊断

针对变工况、强噪声状态下齿轮的故障特征难以提取的问题,提出了一种基于自适应时变滤波(Adaptive time-varying filtering,ATF)与角域同步平均降噪(Angle domain synchronous average denoising,ASAD)的齿轮故障诊断方法.将ASAD与ATF相结合,对降噪后的信号进行阶次谱分析,并通过阶次谱中的调制边频带即可诊断齿轮局部故障.通过分析模拟数据及变转速齿轮箱试验台的数据表明,该方法对变转速状态下的齿轮振动信号有很好的信号分析自适应性,不仅能很好地滤除噪声干扰,提升通带内的噪声抑制效果,且能有效凸显变转速下的齿轮故障特征.     

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.