复合材料水润滑艉轴承结构设计研究

基于ANSYS CFX流固耦合数值计算方法,对水润滑复合材料艉轴承的润滑性能及结构设计开展研究,阐述了不同水槽结构、间隙比、长径比、直径等对轴承承载力以及水膜压力、轴承变形量、最小水膜厚度、轴承摩擦因数的影响规律。并利用水润滑轴承试验台研究了不同水槽结构对轴承启动摩擦转矩、转变速度以及摩擦因数的影响。研究表明,轴承摩擦因数、水膜最大压强、轴承最大变形随水槽数增多而增大;轴承承载力、最小水膜厚度随间隙比增大而减小,随长径比增大而增大。总结了直径为100~500 mm、长径比为2~3、间隙比为0.1%~0.2%的水润滑艉轴承承载力的变化规律,为水润滑艉轴承设计提供一定的理论依据。     

任意偏斜下水润滑橡胶艉轴承混合润滑性能*

为探究大偏心率(ε≥1)下水润滑橡胶艉轴承沿端面偏斜的混合润滑性能,综合考虑表面粗糙度、弹性变形、接触压力、偏斜角对水润滑橡胶轴承混合润滑特性的影响,提出大偏心率(ε≥1)下滑动轴承沿端面任意偏斜的膜厚计算方法,并应用于艉轴承缩比模型混合润滑分析。通过数值模拟研究重载条件下水润滑橡胶艉轴承水膜压力、接触压力随偏斜角的变化规律,分析偏斜角、偏斜方向角等对水润滑橡胶轴承混合润滑性能参数的影响。研究表明：在混合润滑条件下,轴颈沿端面偏斜对流体载荷影响相对较小,但会显著增强润滑界面的接触效应从而恶化其润滑性能;横向偏斜一定程度上会提高直槽式水润滑橡胶轴承的承载能力,偏斜角增加到一定程度时会引起最大水膜压力沿偏斜端反向移动;偏斜角对水润滑轴承润滑特性的影响在混合润滑阶段内较为显著,在弹流润滑阶段其影响将会削弱。     

内衬厚度对水润滑橡胶艉轴承摩擦性能的影响

基于流固耦合的基本理论,考虑橡胶衬层弹性变形因素,构建出水润滑艉轴承橡胶内衬有限元模型,利用MATLAB软件数值分析橡胶内衬厚度对水膜厚度和水膜压力的分布状况及摩擦性能的影响规律,并在SSB-100型艉轴承试验机上进行试验验证。研究结果表明:在相同的工况下,随着内衬厚度的增加,橡胶衬层弹性变形增大,水膜厚度增大,水膜压力减小;相应地,流体润滑效果越好,摩擦因数越小;在相同厚度下,随着转速的增大,摩擦因数先减小后趋于平稳。试验结果验证了仿真分析的正确性。     

水润滑橡胶轴承特性仿真与试验研究

为研究水润滑橡胶轴承特性,采用软件仿真与试验相结合的方法对轴承偏心率、摩擦因数、橡胶变形量、最小水膜厚度、长径比和水膜压力等参数及其与轴转速和载荷之间的关系进行深入探讨。应用Pro/E软件分别建立了轴承及其间隙的3D模型,并采用流固耦合方法及气穴模型在ANSYS和Fluent软件中对轴承动态特性进行模拟。为获得实际工况下的橡胶轴承径向截面全周连续水膜压力分布,研究轴承润滑状态,采用特殊的转轴设计,将压力传感器安装在轴端,并应用无线测试技术对水膜压力信号进行采集与传输。给出水润滑轴承试验台、转轴设计与传感器布置方案,最后应用无线测试系统对八纵向沟槽水润滑凹面橡胶轴承的水膜压力进行测试,并与仿真结果比较分析。研究结果表明,多沟槽凹面橡胶轴承不存在全周完全连续水膜,处于混合润滑状态;沟槽对水膜压力分布的影响较大;轴承某些板条上会出现水囊,形成明显的压力双峰;降低转速或者增加载荷都会增大橡胶变形量与轴承摩擦因数,引起轴与轴承接触。长径比越大,轴承越不容易与轴发生接触。     

ANCO水润滑高分子轴承摩擦性能的研究

采用MPV-50试验台架对ANCO水润滑轴承系统地研究了载荷、线速度、水温、润滑介质等因素,对ANCO水润滑轴承的摩擦磨损性能的影响。研究结果表明,ANCO水润滑轴承具有较低的水润滑摩擦因数和较高的耐磨性能,完全适合作为船舶艉/舵轴承使用。     

基于BP神经网络的水润滑艉轴承故障诊断研究

水润滑艉轴承是一种广泛应用于船舶等水中航行器推进系统的特种轴承,由于其工作的环境具有很大的不确定性,产品很容易出现各种故障,一旦故障产生将直接影响舰艇的安全航行和经济效益。本文利用Matlab软件的相关工具箱,基于神经网络的相关理论和方法,构建了BP神经网络模型来研究水润艉轴承工作时的摩擦因数、温度、噪声、振动等特征参数与轴承状态的关系,从而实现了对水润滑艉轴承工作状态的故障诊断。从Matlab仿真结果与实际情况的比对看,建立的BP神经网络可以很好的判断水润滑艉轴承的故障状态,能够在轴承早期故障时发出预警信号,提前对将要发生故障的轴承进行维修或更换,利用该方法可以有效提高水润滑艉轴承的使用性和安全性。     

无轴轮缘推进器水润滑轴承的结构设计与仿真分析

目前,水下无轴轮缘推进器的水润滑轴承是直接对船舶艉轴承进行缩短然后应用的。船舶艉轴承的长径比远大于无轴轮缘推进器,加之水润滑轴承沟槽结构复杂,会造成润滑性能降低。针对这一问题,设计了一种适用于无轴轮缘推进器的水润滑轴承,在结构上采用半开槽结合承载区开设小沟槽,形成混合沟槽。基于润滑理论,使用ANSYS Fluent软件仿真,分析开槽结构和小沟槽的不同组合方式对水膜压力与承载力的影响,进而得出润滑性能最佳的水润滑轴承结构。结果表明,半开槽结构结合承载区开设矩形小沟槽能够有效提升水润滑轴承的润滑性能,改善使用传统船舶艉轴承结构的无轴轮缘推进器润滑性能降低问题。     

弹性模量对水润滑轴承的性能影响

从材料的角度,研究弹性模量对水润滑塑料合金轴承的性能影响,包括轴承承载能力、水膜形状曲线、压力曲线和最小水膜厚度等。研究表明:在选择水润滑轴承材料时应根据其承载能力来确定轴承材料的弹性模量范围;在承载能力范围内,从弹性模量这个角度来说,应当尽可能选择弹性模量低并具有良好摩擦磨损性能的材料,因为选择较小弹性模量的材料有利于提高最小水膜厚度,从而改善水润滑轴承摩擦副的摩擦磨损性能。     

改性尼龙水润滑轴承摩擦学性能试验研究

针对舰艇推进系统用水润滑轴承低噪声设计需求,研制改性尼龙（PA）的轴承材料及轴承样机,利用多功能摩擦磨损试验机对改性PA材料样品进行摩擦学性能试验,并与丁腈橡胶和赛龙SXL材料的摩擦学性能进行对比;在水润滑轴承试验台上开展PA轴承样机转速特性试验和载荷特性试验,获取不同比压和转速下摩擦因数和振动特性数据。研究结果表明：与丁腈橡胶和赛龙SXL材料相比,改性PA材料具有摩擦因数小、磨损率低的优点;低转速下,水润滑轴承摩擦因数随转速增大而减小,随比压增大而增大,转速增加至100 r/min后,摩擦因数变化趋势逐渐减缓;在工作转速范围内改性PA材料水润滑轴承无异常摩擦振动和噪声。研究结果为舰艇低噪声水润滑艉轴承设计提供参考。     

屏蔽泵水润滑石墨推力轴承摩擦学性能的研究

本文分析了影响水润滑石墨推力轴承摩擦学性能的主要因素,如润滑水膜厚度、温升、载荷及转速、轴承材料的性能等,提出了提高水润滑轴承摩擦学性能的主要方法,如创建容易获得稳定润滑水膜的工况条件,缩短轴承的启动时间,减小轴承负载,选用合适的摩擦副材料等。     

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.