【作者】 马辉；

【导师】 闻邦椿；

【作者基本信息】 东北大学 ， 机械设计及理论， 2007， 博士

【摘要】 随着科学技术的进步和现代工业的发展,旋转机械在电力、能源、交通、国防和化工等领域中得到了广泛应用并发挥着越来越重要的作用,对旋转机械动力学特性的研究也逐渐得到了人们的重视。复杂旋转机械,时常由于各种线性或非线性因素激发起各种故障,进而会使机器发生严重事故,甚至是机毁人亡的重大事故。因此,研究转子系统故障机理和诊断技术有着十分重要的意义,目前国内外科技工作者在这些方面进行了大量的研究,并取得了丰硕成果。本课题以沈阳鼓风机集团有限公司与东北大学联合进行的“大型压缩机转子振动实验系统”项目为背景,以试验台轴系为研究对象。首先利用闻邦椿教授提出的面向产品广义质量的1+3综合设计法对轴系进行了设计和校核,确定了系统的一些动力参数；然后利用非线性有限元方法研究了考虑碰摩故障、裂纹故障以及裂纹—碰摩耦合故障的多盘悬臂转子—轴承系统的动力学特性,并利用小型转子试验台对转子—轴承系统的若干故障进行了模拟实验,对实验所测的带有各种故障的振动信号进行了详细的时频故障特征提取；最后对碰摩转子响应时间序列的混沌特性进行了研究。本文具体研究内容如下：(1)利用闻邦椿教授提出的面向产品广义质量的1+3综合设计法对试验台轴系进行了设计,首先把试验台轴系作为一个产品,进行产品功能优化设计,形成初步的轴系设计图纸,接着对设计的轴系进行了动态优化设计并对碰摩系统进行了智能优化设计,最后,对轴系进行了可视优化设计。(2)介绍了求解非线性问题的非线性有限元方法,利用非线性有限元方法研究了单点碰摩、局部弧形碰摩和整周碰摩情况下转子的动力学特性,并考察了碰摩间隙、碰摩刚度、碰摩位置和偏心量等参数对系统动力学特性的影响。研究发现单点碰摩主要是冲击碰撞,频率成分以高倍频成分为主,局部弧形碰摩则碰撞和摩擦都很严重,频率成分低频和高频并存,随着碰摩的弧形区域的加大,出现了更低的频率成分,整周碰摩则以摩擦为主,幅值谱图出现连续谱。(3)利用非线性有限元方法对转轴出现的裂纹故障进行了研究,并考察了裂纹深度和裂纹位置对系统动力学特性的影响。研究发现浅裂纹对系统动力学影响不大,当裂纹扩展到半径深度以后,对系统的动力学特性有很大影响,裂纹位置在远离叶轮时,主要以2X为主,裂纹位置逐渐靠近叶轮时,主要以5X为主；但裂纹激起的主要是规则的高倍频成分。(4)利用非线性有限元方法对裂纹—碰摩耦合故障进行了研究,研究表明当裂纹加深时,引发的碰摩更加严重,从轴心轨迹可以清楚看到碰摩引起的反进动。对于弧形碰摩和整周碰摩,幅值谱图上均有连续谱出现,其中5X比较明显。(5)利用小型转子试验台,对转子系统经常发生的转定子碰摩、转轴裂纹、裂纹—碰摩和油膜失稳—轴承碰摩耦合故障进行了实验研究,对测得的振动信号,利用三维谱振图、重排小波尺度图、幅值谱图、轴心轨迹进行了故障特征提取。对单点碰摩研究表明,频率成分主要以高倍频成分为主,出现的频率成分越高,表明碰摩越严重；局部弧形碰摩研究表明,在临界转速前发生的碰摩主要以低频成分为主,产生的频率系列越低,表明碰摩越严重,在临界转速附近发生的碰摩低频和高频成分并存,且当碰摩较轻时以高倍频为主,严重时出现不可公约的低频成分和有色噪声成分。(6)对裂纹—碰摩耦合故障的研究表明,碰摩较轻时以规则的X/2谐波系列为主,当碰摩加重时产生X/4谐波系列,再加重时幅值谱图产生连续谱。通过小波分解后,再利用重排小波尺度进行故障特征提取,可以有效的提取碰摩引起的冲击成分,研究结果表明发生轻微碰摩时,一周碰一次且碰摩程度一次轻一次重交替出现。(7)对发生油膜失稳—轴承碰摩故障进行了研究,结果表明油膜失稳前引发的碰摩主要以高倍频成分为主；油膜失稳后引发的轻微碰摩出现组合频率成分,但成分较少；油膜失稳后引发的严重碰摩时出现较多的组合频率；其中出现较低的组合频率时,暗示系统发生油膜振荡,此时的碰摩也是最严重的。(8)对碰摩转子响应时间序列的混沌特性进行了研究。首先利用代替数据法对实验和仿真数据进行非线性识别,接着计算其最大Lyapunov指数、关联维数、复杂度、近似熵和混沌度等非线性参数。结果表明,对碰摩仿真数据而言,碰摩严重时系统所具有的非线性参数,均较轻微碰摩时大。利用关联维数、复杂度和近似熵对碰摩实验数据进行分析,结果表明关联维数对碰摩程度敏感度最高,近似熵次之,复杂度再次之,最大Lyapunov指数最差。(9)通过对裂纹—碰摩实验数据在3个不同碰摩阶段的实验数据利用混沌指数进行分析表明,在14s～15s和17s～18s的碰摩具有相近的混沌指数,同属于轻微碰摩阶段；而在18s～19s的碰摩混沌指数最大,表明系统碰摩最严重。更多还原

【Abstract】 With the development of science & technology and modern industry, rotating machinery is taking more and more important part in many fields such as power system, transportation, national defense and chemical industry, etc., consequently, the study of the dynamics of rotating machinery receives more and more recognition. A complicated machine system may vibrate violently due to nonlinearity that inherently exists in the system and multi-kind of faults, catastrophic disasters may occur if the vibration is violent enough, which can cause the machine to destroy and the operators to death. So it signifies much to study the nonlinear dynamics of rotor systems with faults or malfunctions and the technology to diagnosis the faults. Researchers all over the world made much study in these fields and made great progress.The dissertation takes the project, Vibrating Test System of Large Scale Air-compressor Rotor, conducted by the Shenyang Blower (Group) Ltd. Corp and Northeastern University, as the background and Test Rotor-Bearing System is regard as the research subject. Firstly, "1+3 Synthesis Design Method for Product-Oriented generalized mass" presented by professor Bangchun Wen is used to design and check the test rotor-bearing system and some dynamic parameters are determined. Subsequently, the dynamic characteristics of multi-disk over-hung rotor-bearing system with rub-impact fault, crack fault and the coupling fault with crack and rub-impact are studied by nonlinear finite element method and some faults of rotor-bearing system are simulated by small-size rotor test rig. The time-frequency features of the various fault vibration signals collected by experiment are extracted in detail. Finally, the chaotic characteristics of response time series of rub-impact rotor system are researched. The main research contents are as follows:(1) "1+3 Synthesis Design Method for Product-Oriented generalized mass" presented by professor Bangchun Wen is used to design the test rotor-bearing system. Firstly, the function optimization design of the test rotor-bearing system is performed, subsequently, the dynamic optimization design of the test rotor-bearing is performed and the rub-impact system of the test rotor-bearing system is designed by intelligent optimization method. Lastly, the visual optimization of the test rotor-bearing system is carried out.(2) Introduce the principal theory of modern contact mechanics and the nonlinear finite element method for solving the contact problems, the dynamic characteristics of rotor system are studied by nonlinear finite element method under three kinds of rub-impact conditions, namely the single rub-impact, local arc-shaped rub-impact and the annular rub-impact. And the effects of the clearance between rotor and stator, stiffness of stator, the position of rub-impact and the eccentricity are investigated. The results show that the single rub-impact mainly arouses impact and the frequency components are mainly high-level double frequency; local arc-shaped rub-impact mainly arouses impact and rubbing, the frequency components include low frequency components and high frequency components and the lower frequency components appear with the broadening of rub-impact arc-shaped region; the annular rub-impact mainly arouses rubbing and continuous spectrum appears in the amplitude spectrum.(3) The rotor crack fault is studied by nonlinear finite element method and the effects of crack depth and position are investigated. The results show that shallow crack has little effect on dynamic characteristics of rotor system. When the crack propagates radius depth, the system dynamic characteristics will greatly change. When the crack position keeps away from impeller, the amplitude of 2X is secondary to that of 1X(X denotes rotating frequency). When the crack position is close to impeller, the amplitude of 5X is secondary to that of 1X. The frequency components caused by crack are mainly regular high frequency components.(4) Finally, the coupling fault with crack and rub-impact is studied by nonlinear finite element method. The research results show that the rub-impact aggravates and backward whirl can be clearly seen from the trajectory. For arc-shaped rub-impact and annular rub-impact, the continuous spectra all appear and the 5X frequency component is comparatively obvious.(5) The dynamic characteristics of rotor-system with rotor-stator rub-impact, rotor crack, coupling fault with crack and rub-impact and coupling fault with oil-film instability and bearing rub-impact are studied by experiments. The fault features of the collected vibration signals are extracted by spectrum cascade, reassigned wavelet scalogram, amplitude spectrum and trajectory.The results show that frequency components are mainly high-level double frequency for the single rub-impact. The arisen frequency component is higher, the rub-impact degree is more serious. The local arc-shaped rub-impact research shows that the frequency components are mainly low frequency components and the frequency is lower the rub-impact is more serious when rub-impact occurs before the critical speed. Low frequency and high frequency components all exist, high frequency components are main in slight rub-impact stage and irreducible low frequency and color noise components appear in serious rub-impact stage.(6) The research result for coupling fault with crack and rub-impact shows that the frequency components are mainly X/2 harmonic series in slight rub-impact stage, X/4 harmonic series appear when rub-impact aggravates and continuous spectra appear in amplitude spectra plot when rub-impact becomes serious. The wavelet-decomposed signals are analyzed by reassigned wavelet scalogram, which can effectively extract the impact components caused by rub-impact. The analyzed results show that rub-impact appear once in a rotation period and one times slight rub-impact and next times serious rub-impact appear alternately.(7) The coupling fault with oil-film instability and bearing rub-impact is studied. The results show that the frequency components are mainly high-level doubling frequency components when rub-impact appears before oil-film instability; the slight bearing rub-impact caused by oil-film instability will arouse the combination frequency components of rotating frequency and oil whirl frequency and the combination frequency components are few; the serious bearing rub-impact will caused many combination frequency components; the appearance of the lower combination frequency component suggests that oil whip appears and at this time rub-impact is also most serious.(8) Chaotic characteristics of rub-impact rotor system response time series are studied. Firstly, Surrogate data method is used to carry out nonlinear identification of experimental and simulation data of rub-impact rotor system, subsequently, the nonlinear parameters, such as maximal Lyapunov exponent, correlation dimension, complexity, approximate entropy and chaotic degree, are computed. The results show that the nonlinear parameters of serious rub-impact are greater than these of slight rub-impact; correlation dimension is most sensitive for rub-impact degree, approximate entropy is secondary to complexity is tertiary and maximal Lyapunov exponent is most insensitive.(9) The experiment data of coupling fault with crack and rub-impact in three different rub-impact stages are analyzed by chaotic exponent. The results show that the chaotic exponents are approximate in 14s-15s and 17s～18s and they are all in slight rub-impact stage; the chaotic exponent is maximum in 18s～19s,which shows that rub-impact is most serious.更多还原