【作者】 徐刚；

【导师】 姜德生；

【作者基本信息】 武汉理工大学 ， 机械制造及其自动化， 2013， 博士

【摘要】 大型机械装备日益向着大型化、复杂化、高速化、高效化和自动化的方向发展,这些发展取得了巨大的社会效益和经济效益,但同时也带来了一些新的问题,特别是机械装备状态物理量的变化呈现出随机性、多维性、时变性、耦合性和非线性等特点,使其事故更具突发性、灾难性和社会性。因此,针对这些大型装备系统的运行状态深度感知、智能监测与故障诊断技术一直是机械装备状态监测领域极为关注的热点和迫切需要的技术。目前机械设备的状态监测主要采用传统的电磁类传感器,但该类传感器具有测点参数单一、抗电磁干扰能力弱、以及信号远距离传输能力较差等局限性,从而使得其在机械设备多参数分布式动态监测中的应用受到限制。采用光纤传感技术对机械设备进行实时监测,具有防爆、抗电磁干扰、耐高温高压等电磁类传感器所无法比拟的优势,而更易于多路复用组网,适于远距离监测。利用光纤传感技术对机械设备进行状态监测已有学者进行研究,但多处于理论阶段或侧重于静态测量,且研究内容单一、不够系统。鉴于此,本文研究适于机械设备长期、动态、多参量监测的检测方法与诊断系统以及研制相应的光纤传感器,无疑具有十分重要的意义。论文根据机械设备典型部件(轴承、转轴、叶片等)的主要特点,在分析各自工况下动态特性的基础上,系统研究并提出了基于光纤传感技术的动态监测理论与检测方法；研制了多种光纤光栅振动传感器,并将这些传感器应用到机械设备的状态检测中。本文的主要研究内容及结论如下：1.系统研究了机械设备动态监测理论,重点对轴承、转子和叶片等机械设备中典型部件的动力学特性及相关的耦合系统动力学进行了分析；结合机械设备动态在线检测特点以及光纤传感技术的独有特性,提出了基于光纤传感器的动态信号数据测量与后处理方法。2.针对机械设备动态监测的不同需求,研制了两种不同类型的光纤光栅加速度传感器。第一种为“L”型悬臂梁结构,属于波长解调型的高灵敏度传感器,频率检测范围为0-60Hz,灵敏度达到60pm/m/s2,加速度测量范围大于25m/s2,适用于低速重载装备的检测；第二种属于强度解调型高频加速度传感器,采用双FBG光栅匹配解调和光强比值算法,解决了检测频率不高和光强不稳对信号干扰等问题,传感器频率检测范围大于500Hz,并在此原理基础上设计了三维一体化光纤光栅加速度传感器,可用于高转速机械设备的振动测量。3.讨论了采用双光纤光栅对转轴扭矩和温度进行同时测量的可行性,理论表明转轴的扭矩大小对光栅的差模波长变化产生影响,而温度变化只改变共模波长的数值,因此允许对温度和扭矩进行同时测量。由此,搭建实验系统对转轴的扭矩和温度测量分别进行了静态和动态实验,在该系统中,由扭矩引起的差模波长变化率为12.88pm/Nm,对应的温度灵敏度为-1.28pm/℃；与扭矩测量相反的是,共模波长的温度灵敏度为18.5pm/℃,扭矩引起的差模波长的交叉变化率为-1.25pm/Nm。在动态在线实验中,对不同工况下的转轴扭矩进行了测试,结果表明：采用光纤传感技术可以较好的反应转轴的实时负载状态,并且对其信号进行深层次分析,甚至可分析系统不平衡、不对中等设备故障。4.研究了旋转部件运行状态中裂纹扩展的在线检测方法,以旋转叶片为例进行了验证。采用飞秒激光微加工技术在叶片上制作了微裂纹,以期达到在叶片状态检测中模拟故障叶片的目的,并通过有限元分析和实验对模拟的真实性进行了验证。对叶片进行在线状态检测采用光纤光栅和光纤旋转连接器相结合的方法,将光纤光栅粘贴于叶片的敏感部位检测在运转过程中的应变和频率变化,光纤旋转连接器负责将旋转过程中光栅信号传输到解调系统,通过对叶片应变和频率的变化判断叶片的实时状态；最后利用已有叶片研究了裂纹对叶片疲劳断裂的影响和破坏速率。5.以一种石化设备的状态监测实例,讨论了动态监测关键技术在工程中的应用。在石化行业中,机械设备安全运行的重要性显得尤为突出。本文将所研制的光纤光栅振动传感器和状态监测系统应用到了石化机械装备的故障检测中,以往复式氢气压缩机为监测对象,对设备的曲轴箱、十字头和缸盖的振动情况以及气阀位置的温度变化进行了长期在线测量,并取得了良好的效果。实测结果证实了光纤传感技术在大型机械设备安全运行监测中具有广阔的应用前景。更多还原

【Abstract】 The large mechanical equipment is stepping into large-scale, complication, high speed, high efficiency and automatization, which has made great social and economic benefits, but also brings some new issues, especially the change of mechanical equipment state physical quantity showing randomness, multi-dimensional, time-varying, coupling and nonlinear features, then making accidents more abrupt, catastrophic, and social. Therefore, it has been the hot topic and urgent technology to depth perception, intelligent monitoring and fault diagnosis for machinery equipment condition monitoring.Currently mechanical equipment condition monitoring mainly use conventional electromagnetic-type sensors, but such sensors have some limitations such as measuring parameters single, anti-electromagnetic interference capability weak, as well as long-distance signal transmission capacity poor, making application limited in the multi-parameters distributed dynamic monitoring of machinery equipment. Using optical fiber sensing technology for real-time monitoring of the mechanical equipment, there is increasing incomparable advantages than conventional sensors in explosion-proof, anti-electromagnetic interference, heat resistance and high pressure resistance, easier to multiplex network, and suitable for remote monitoring. The mechanical equipment condition monitoring has been studied by optical fiber sensing technology, but mostly in the stage of theory or focus on the static measurement, single content and not systematic. In view of this, this paper undoubtedly has a very important significance to study detection methods and diagnosis system and develop fiber optic sensor for mechanical equipment long-term, dynamic, multi-parameters monitoring.According to the main features of typical parts (bearings, shaft, blades, etc.) in mechanical equipment, on the basis of the analysis of the dynamic characteristics of the respective conditions, this paper systematically researched and proposed dynamic monitoring theory and detection methods based on optical fiber sensing technology; developed a variety of fiber Bragg grating vibration sensors, and then these sensors are applied to the state detection of the machinery.The main contents and conclusions of this paper are as follows:1. Systematically studied the dynamic monitoring theory of mechanical equipment, the dynamics characteristics of the typical components (bearings, rotor and blades) of the mechanical equipment and associated coupling system dynamics are analyzed; combined with the characteristics of dynamic online detection of mechanical equipment and the unique properties of optical fiber sensing technology, proposed a dynamic signal data measuring and processing method based on optical fiber sensor.2. According to the different needs of dynamic monitoring of machinical equipment, two different types fiber accelerometer were developed. The first one is "L" shaped cantilever beam, which belong to wavelength demodulation type high-sensitivity sensor, the frequency detection range of0-60Hz, sensitivity to60pm/m/s2, and acceleration measurement range greater than25m/s2, suitable for low speed heavy equipment; The second is intensity-demodulation high frequency acceleration sensor, which adopts double FBGs matching demodulation and light intensity ratio algorithm to solve problems about the detection frequency not high and the signal intensity instability. The frequency detection range of this sensor was greater than500Hz, so based on this principle, the three-dimensional integrated optical fiber accelerometer was designed, which can be used for vibration measurement of high speed equipment.3. Discusses the feasibility of simultaneous measurement of temperature and torque in a rorating shaft using a dual fiber grating sensor. It shows theoretically that torsion affects the differential-mode wavelength of the gratings in the proposed configuration, whereas temperature changes only the common-mode wavelength, allowing measurement of both torsion and temperature. Thus, the experimental system was set up to carry out static and dynamic experiments of shaft torque and temperature. For the particular system investigated experimentally, the differential wavelength change due to torque was12.88pm/Nm, and the corresponding temperature sensitivity was-1.28pm/℃. In contrast to these values, the temperature sensitivity of the common-mode wavelength change was18.5pm/℃, and its torque cross-sensitivity was-1.25pm/Nm. In the dynamic experiment, shaft torque was tested in different conditions, the results showed that:optical fiber sensing technology can reflect real-time shaft load state, and in-depth analysis of its signal, even analysis some equipment failure such as system imbalance and misalignment fault.4. Studied on-line detection method of crack propagation in the rotating components—a case study of rotating blades. The micro-cracks were processed on the blades using femtosecond laser micromachining technology in order to purpose of fault simulation of blade in the blade state detection, and validated by the finite element analysis and experiment on the authenticity of simulation. The blade-line state detection was taken by combining FBG sensor and fiber optic rorating joint (FORJ), FBG sensors pasted on sensitive parts of the blades detect strain and frequency variations, FORJ is responsible for transferring FBG signal to the demodulation system. The blade strain and frequency variations were used to judge the real time status of blades. Finally the blade crack was studied effects on fatigue fracture and failure rate.5. Discussed the key technologies of dynamic monitoring in engineering applications—taken petrochemical equipment condition monitoring as an example. In the petrochemical industry, the importance of the safe operation of mechanical equipment is particularly prominent. In this paper, the fiber Bragg grating vibration sensor and the condition monitoring system is applied to fault detection of petrochemical machinery equipment. Reciprocating hydrogen compressor as the monitoring object was taken for a long time online measurement and achieved good results on the equipment vibration of crankcase, cross head and cylinder head and temperature variation of valve position. Experimental results confirmed that the fiber optic sensing technology had broad application prospects in monitoring the safe operation of large machinical equipment.更多还原