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关键词： 作战舰艇   柴油机   属性约简   磨损故障   粗糙集   极限学习机  

摘要： 为了提高作战舰艇柴油机的可靠性和安全性,在油液检测数据基础上,提出了一种基于粗糙集(RS)与核极限学习机(KELM)的作战舰艇柴油机磨损故障诊断方法。利用一种启发式的RS属性约简算法,对作战舰艇柴油机油液光谱和直读铁谱特征进行降维;由约简后的特征集数据构建KELM诊断模型,对作战舰艇柴油机磨损故障模式进行检测识别。仿真结果表明,通过RS属性约简,简化KELM模型结构,改善模型性能,预测结果也优于BP神经网络和ELM模型。从而验证了该方法用作战舰艇柴油机磨损故障诊断的可行性和有效性。

关键词： 受电弓滑板   接触网   载流摩擦   磨损  

摘要： 高速列车与由很多系统组成的,其中弓网系统主要是为电力机车供电,受电弓滑板是电力机车与牵引网之间重要的连接元件,滑板位于受电弓的最上部,可以与接触网的导线直接接触。接触网与受电弓滑板直接接触可以获得电能,通过受电弓为电力机车供电。受电弓滑板与接触网接触时因为摩擦而导致磨损的出现。通过对不同材质的受电弓滑板和不同型号的接触线相组合,进行摩擦磨损的实验探究找出改良方法,以便于提高弓网的使用寿命。

关键词： 等离子增强磁控溅射   TiN   TiAlN   E690钢   摩擦磨损  

摘要： 采用等离子增强磁控溅射(PEMS)技术在海工用钢E690表面沉积Ti N与Ti Al N涂层。采用划痕仪测量膜基结合力、X射线衍射仪(XRD)分析薄膜物相、摩擦磨损试验机测量摩擦系数、SEM观察磨痕形貌。结果表明:涂层Ti N具有强烈(111)择优取向,Ti Al N择优取向为(200)。Ti N、Ti Al N涂层的平均结合力为35.3、32.9 N;Ti N、Ti Al N涂层后E690钢的摩擦系数分别为0.19、0.11,与E690钢基体相比分别降低了29.6%、59.3%。E690钢试样的磨损机制主要为黏着磨损,涂层后以疲劳磨损为主。涂层后的E690钢具有更好的减摩性、耐磨性,其中沉积Ti Al N涂层的抗磨减摩效果更好。

关键词： 球盘摩擦   激光选区融化(SLM)   18Ni300马氏体时效钢   热处理   磨损机制  

摘要： 采用SLM成形技术制备18Ni300马氏体时效钢,并对其进行时效热处理,采用球-盘摩擦磨损试验模拟局部高应力摩擦磨损工况。研究热处理前后试样微观组织及力学性能变化对摩擦磨损性能的影响。对热处理前后的试样进行微观组织观察,并测量其密度、硬度、抗拉强度和伸长率变化,利用3D轮廓仪和扫描电镜观察磨损区域。热处理后试样的密度变化不大,硬度由37.7 HRC提高至54.5 HRC,抗拉强度由1108 MPa提高至2028 MPa,伸长率由14.5%下降至4.6%。热处理前,试样的摩擦因数为0.40,体积磨损率为1.87×10^(-4)mm^(3)·(N·m)^(-1),热处理后试样的摩擦因数为0.41,体积磨损率为1.41×10^(-4)mm^(3)·(N·m)^(-1)。磨损机制以磨粒磨损和粘着磨损为主,伴有轻微氧化磨损。

关键词： 白层   硬切削   摩擦系数   磨损  

摘要： 为了研究硬切削白层对试件表面摩擦磨损性能的影响,采用聚晶立方氮化硼刀具对GCr15轴承钢进行硬切削,测试了白层硬度,使用销盘式摩擦磨损机对已切削试样和未切削试样进行摩擦磨损试验,采用扫描电镜观察了磨损表面。结果表明:与未切削试样表面相比,已切削试样表面会产生厚度为6μm的白层;马氏体的产生和晶粒的细化导致硬切削试件表面的硬度高于未切削试样表面;与未切削试样表面相比,含白层的已切削试样表面的摩擦系数更低,磨损量更小,硬切削试样表面的白层可改善其表面的摩擦磨损性能.

摘要： Structural health monitoring has been the focus of recent developments in vibration-based assessment and, more recently, in the scope of the internet of things as measurement and computation become distributed. Data has become abundant even though the transmission is not always feasible, especially in remote applications. It is thus essential to devise data-driven model workflows that ensure the best compromise between model accuracy for condition assessment and the computational resources needed for embedded solutions. This topic has not been widely used in the context of vibration-based measurements. In this context, the present research proposes two approaches for two applications, a static and a rotating one. In case one, a modeling workflow capable of reducing the dimension of autoregressive model features using principal component analysis and classifying this data using some of the main machine learning techniques such as logistic regression, support vector machines, decision tree classifier, k-nearest neighborhood and random forest classifier was proposed. The three-story building example was used to demonstrate the method s effectiveness, together with ways to assess the best compromise between accuracy and model size. In case two, a test rig composed of rotating inertias and slender connecting rods is used, and the monitoring solution was tested in an embedded GPU-based platform. The models implemented to effectively distinguish between different friction states were principal component analysis, deep autoencoder and artificial neural networks. Shallow models perform better concerning running time and accuracy in detecting faulty conditions.

关键词： 机械零件制造   材料选择   遵循原则  

摘要： 现阶段,在机械零件生产加工行业中有各式各样的新材料可供选择.若无法提高原材料的性能,生产过程就会产生产品质量的问题.所以机械制造业必须合理选用原材料,坚持合理选用原则,以适应当前的实际发展需要.基于此,文章先是概述了在机械设计中注重材料选择以及应用的意义,论述了金属材料的力学性能及基本特性,最后分析了机械零件制造的材料选择原则,供相关学者借鉴.

摘要： To verify that components last for an expected lifetime an Accelerated Life Testing (ALT) can be used. One of the main aspects that can ruin an ALT of plastic components is if the contact temperature rises above the glass transition temperature, since this changes the material properties of the tested component. To prevent this from occurring in a ALT, a test rig was built with temperature sensors to monitor this contact temperature. If the contact point is modified with a temperature sensor, this will change the surface and make the test invalid. The method is instead to couple surface temperature measurements with a Finite Element Model (FEM) to estimate the contact *** thesis compares the two techniques Thin Film RTD and Thin Thermocouple Wire Type T in conjunction with the building of a heat transfer Finite Element Method (FEM)-model. It also investigates which technology of Non Contact IR Single Point sensor or Thin Film RTD have the highest performance in use with the test rig with regard to four quality *** conclusions are that RTD and the Thermocouple Type T sensors both provide equal precision in measurement to build a useful FEM model. In application on the test rig, the Thin Film RTD is better than the Infrared (IR)-sensor in three out of four areas when compared in the four defined quality parameters. Thin Film RTD is the recommended technology in this application.