【作者】 史丽晨；

【导师】 段志善；

【作者基本信息】 西安建筑科技大学 ， 机械设计与理论， 2009， 博士

【摘要】 随着工业生产与科学技术日新月异的发展,现代机械设备的复杂化、高效化、智能化程度越来越高,与此同时,设备的状态运行的可靠性、安全性得到越来越多的重视,复杂现代机械设备的运行状态及其状态监测就成为众多学者研究的热点问题。本文以现代新兴大型设备——往复式活塞隔膜泵为载体,进行了基于故障机理研究的往复式机械设备状态监测与故障诊断技术的研究。本文探讨了往复式活塞隔膜泵的振动机理及故障类型,并从磨损故障入手进行其故障机理研究。文中将磨损故障视为运动副之间的间隙,借助于接触-分离二状态建模方法建立了不同连接处产生磨损的动力学模型。模型建立过程中充分考虑了往复式活塞隔膜泵的实际工况,各零部件之间的连接关系以及液体脉动现象,并考虑了不同运动副处磨损的耦合现象。通过数值求解,详细分析了不同故障的动力学响应与隔膜泵工况(转速、负荷、磨损间隙)的关系,为充分认识隔膜泵的故障机理提供了理论依据。同时为了验证理论分析的结论,在实验室中用模拟替代设备进行实验,对以上各种故障状态采集信号进行分析,验证了理论结论的可行性。在往复式活塞隔膜泵磨损故障机理理论研究的基础上,结合实验,将小波技术、分形理论和混沌理论引入到其运行状态和故障诊断的分析中。本文利用小波技术所具有的良好时频显微特点和扑捉微弱信号的能力,根据小波函数选择及分解层次确定原则,采用db4小波对往复式活塞隔膜泵的振动信号进行多分辨分析,选取相对能量和峰值因素作为诊断指标,成功地将小波多分辨分析技术运用于往复式活塞隔膜泵的状态监测中。非线性系统的一个标志是自相似性和标度不变性的分形,以关联维数作为主要特性参数。本文分别计算了相同磨损处不同工况,以及相同工况不同磨损处磨损的关联维数。发现相同工况时,不同磨损处磨损故障的关联维数区别明显,因此可以用关联维数作为特征进行故障识别。当磨损发生在同一处时,在吸液口压力或者曲轴转速发生变化时关联维数也发生一定变化,因此可以通过关联维数进行这两种工况的状态监测。但是磨损量大小发生变化时,相同磨损处的关联维数的变化很细微,因此文中采用小波分析技术进行进一步的研究,通过不同小波包重构信号的关联维数的计算,发现可以进行较为明显的区分。文中采用庞加莱截面和最大李雅普诺夫指数法验证了在考虑流体脉动工况下,往复式活塞隔膜泵各种工况下不同磨损处磨损的故障状态均为混沌状态,而在无磨损情况下为准周期态。各种磨损故障状态的庞加莱截面图为成片密集的点集,且结构形式有所变化,说明了隔膜泵的不同磨损处的故障状态所具有的吸引子的结构不尽相同。为了对各种故障状态进行正确的判断,文中采用了最大利亚普诺夫指数作为诊断参数。同时将小波包分析和混沌理论相结合,定义了最大利亚普诺夫指数相对增长率作为特征参数。通过最大李雅普诺夫指数的计算说明了不同磨损处的最大李雅普诺夫指数处于不同的数量级,且指数的变化反映了故障程度的发展趋势。通过小波包的重构,运用最大利亚普诺夫指数相对增长率,有效地区分了磨损量的变化和吸液口压力变化两种故障类型。本文以往复式活塞隔膜泵的故障机理为基础,进行状态监测与故障诊断的方法探索,从理论上有可靠的依据,对往复式机械设备的故障诊断技术的研究起到了一定的借鉴作用。更多还原

【Abstract】 With the development of industry and science, the modern machine is more and more complex, higher and higer efficient. So the reliability and the safty of the machinery have been more and more important. Now the research on failure machinery and diagnosis technology of the modern complex equipment have become the hot spots of modern diagnosis technology. The article studies the fault technique to the reciprocating membrane pump based on the analysis of fault mechanism.After the discussion of the vibration mechanism and the types of the faults, the article focuses the wear fault. The wear fault can be looked as the clearance between the pairs. Different kinds of dynamatic models are set up according to the separation-contact state contact force model. In the models, many working situations are considered,such as the impluse of the fluid, the linkage of different compents, the intercoupling of different faults. Based on the simulation numerical solutions, the relations between the dynamatic response and different kinds of the pump’s working situtations are researched. All these are beneficial to the realization of the pump’s falut mechanism.Modern nonlinear theories such as wavelet, fractal and chaos theories are used in the status analysis of the reciprocating membrane pump.According to the excellent characteristics of wavelet transformation to micro signal in time domain and frequency domain and the ability to catch faint signals, based on the factors of relative energy and peak value, wavelet multi-resolution analysis through db4 wavelet is useful to the diagnosis of the membrane pump.Considering the fuild’s impulse, the status of the reciprocating membrane pump’ wear fault are all in chaos, which is proved by Poincare sections and the largest Lyapunov exponent. But without the wearing clearance, the status of the pump is quasiperiod. Because the Poincare sections are different concentrated point set, the attractors’ structures are diffent with different status. The Lyapunov exponents of different working status and different faults are calculated. It is found that the Lyapunov exponent of different fault varies in the same order of magnitude with different working status. This is showed that the Lyapunove exponent can be used to express different fault of the pump.The chaos of nolinear system has another characteristic, which is the fractal with self-similarity and graduation invariability. The fractal’s main parameter is correlation dimensions. The correlation dimensions of different faults and different working status are also calculated. According to the research, the correlation dimensions of the same working status are different, so they can also be used to discribe different fault of the pump. The correlation dimensons are also vary in some degree with different pressure, different rotate speed, different clearance, thus they can be used to monitor the working status. With further study, the article used wavelet fractal technology to study the signals of different clearance. According to the correlation dimensions of different frequency segments which are achieved by wavelet packet decomposition and reconstruction technique, the messages of different situation vibration can be caught.In the study, it is also found that the value of the chaos characteristic parameters can reflect some messages of the system, such as the degree of nonlinear states, the complexion of the states, and the energy dissipation of the system.The article explores the method of status monitoring and fault diagnosis of reciprocating membrane pump based on the anlysis of fault mechanism and its dynamtic response. As an attemption, it pioneers a useful directon for further studies on diagnosis of modern complex or reciprocating machines.更多还原