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  本文選題：非線性動力學(xué)　切入點：轉(zhuǎn)子—軸承系統(tǒng)　出處：《西安科技大學(xué)》2012年碩士論文

【摘要】：在不對中故障轉(zhuǎn)子—軸承系統(tǒng)的動力學(xué)分析中，往往忽略了轉(zhuǎn)子間存在的運動約束或耦合關(guān)系，而這些約束在某些情況下有可能極大地改變系統(tǒng)的動力學(xué)特性。因此深入研究具有不對中約束的復(fù)雜轉(zhuǎn)子—軸承耦合系統(tǒng)的非線性動力學(xué)行為對系統(tǒng)的動力學(xué)設(shè)計和故障診斷具有重要的理論及工程意義。 本文以轉(zhuǎn)子間具有廣義位移約束關(guān)系的不對中轉(zhuǎn)子系統(tǒng)為研究對象，基于轉(zhuǎn)子動力學(xué)、非線性動力學(xué)和流體動壓潤滑理論，建立了具有完整約束的多轉(zhuǎn)子耦合系統(tǒng)的動力學(xué)模型。采用數(shù)值分析以及試驗方法，重點研究了在非線性軸承力作用下轉(zhuǎn)子間具有定常和非定常完整約束的不對中轉(zhuǎn)子—軸承耦合系統(tǒng)的非線性動力學(xué)行為。探討了具有平行不對中及交角不對中約束的轉(zhuǎn)子系統(tǒng)非線性故障振動機理和特征。主要研究內(nèi)容和成果如下： 1.以國產(chǎn)某發(fā)電機轉(zhuǎn)子為研究對象，建立了具有平行不對中和質(zhì)量不平衡故障的非對稱柔性轉(zhuǎn)子系統(tǒng)力學(xué)模型，利用多種分析方法研究了系統(tǒng)的非線性動力學(xué)行為，并討論了轉(zhuǎn)子參數(shù)對系統(tǒng)動力學(xué)特性的影響。結(jié)果顯示：在較低轉(zhuǎn)速和微小不對中量時，系統(tǒng)的穩(wěn)態(tài)響應(yīng)主要呈現(xiàn)出與轉(zhuǎn)速同步的周期運動特性，隨著轉(zhuǎn)速的提高，頻域內(nèi)諧波分量增多，振幅也隨之增大。另外，轉(zhuǎn)子間不對中量、轉(zhuǎn)軸剛度不對稱度以及質(zhì)量偏心等參數(shù)的改變使得系統(tǒng)的運動更加復(fù)雜，出現(xiàn)分叉、跳躍以及混沌等非線性動力學(xué)現(xiàn)象。 2.研究了一個具有交角不對中約束的轉(zhuǎn)子—軸承系統(tǒng)動力學(xué)行為。建立了具有非定常完整約束的柔性多轉(zhuǎn)子系統(tǒng)動力學(xué)模型，分析了系統(tǒng)的非線性振動特征和參數(shù)變化對系統(tǒng)動力學(xué)行為的影響。數(shù)值結(jié)果表明：在較低轉(zhuǎn)速時，交角不對中量對系統(tǒng)的運動影響較小。隨著轉(zhuǎn)速的增加，其軸心軌跡出現(xiàn)明顯的“8”字形，特征頻率為工頻的兩倍。在較高轉(zhuǎn)速時，出現(xiàn)倍周期分叉、混沌運動等復(fù)雜動力學(xué)現(xiàn)象。另外，轉(zhuǎn)子間的交角不對中量，轉(zhuǎn)軸剛度、質(zhì)量偏心等參數(shù)對系統(tǒng)的非線性動力學(xué)行為也具有重要影響。 3.建立了在油膜軸承支承下多轉(zhuǎn)子—軸承系統(tǒng)試驗平臺，，對不對中轉(zhuǎn)子的動力學(xué)特性進行了試驗研究。重點探討了平行不對中和交角不對中轉(zhuǎn)子—軸承系統(tǒng)的動態(tài)響應(yīng)，例如，頻域特征、軸心軌跡等。試驗結(jié)果顯示：具有不對中故障的轉(zhuǎn)子系統(tǒng)穩(wěn)態(tài)響應(yīng)中除了存在工頻和倍頻分量之外，還存在一些組合頻率成分，其中工頻和2倍頻成分占優(yōu)，這些非線性動力學(xué)現(xiàn)象證明了理論模型的合理性。
[Abstract]:In the dynamic analysis of rotor-bearing systems with misalignment faults, the kinematic constraints or coupling relationships between rotors are often ignored, and these constraints may greatly change the dynamic characteristics of the system in some cases.Therefore, it is of great theoretical and engineering significance to study the nonlinear dynamic behavior of a complex rotor-bearing coupling system with misalignment constraints for the dynamic design and fault diagnosis of the system.Based on rotor dynamics, nonlinear dynamics and hydrodynamic lubrication theory, this paper focuses on the misalignment subsystem with generalized displacement-constrained relationship between the rotors, which is based on the rotor dynamics, nonlinear dynamics and hydrodynamic lubrication theory.The dynamic model of multi-rotor coupling system with complete constraints is established.In this paper, numerical analysis and experimental method are used to study the nonlinear dynamic behavior of an unsteady and unsteady rotor-bearing coupling system with steady and unsteady holonomic constraints under the action of nonlinear bearing forces.The mechanism and characteristics of nonlinear fault vibration of rotor system with parallel misalignment and angular misalignment constraints are discussed.The main contents and results of the study are as follows:1.A mechanical model of an asymmetric flexible rotor system with parallel misalignment and mass imbalance is established. The nonlinear dynamic behavior of the system is studied by using a variety of analytical methods.The influence of rotor parameters on the dynamic characteristics of the system is also discussed.The results show that the steady-state response of the system mainly presents periodic motion characteristics synchronizing with the rotational speed when the speed is low or small misalignment. With the increase of the rotational speed, the harmonic component in the frequency domain increases and the amplitude increases with the increase of the rotational speed.In addition, the system motion is more complicated by the change of rotor misalignment, rotation axis stiffness asymmetry, mass eccentricity and other nonlinear dynamic phenomena such as bifurcation, jump and chaos.2.The dynamic behavior of a rotor-bearing system with angular misalignment constraint is studied.A dynamic model of flexible multi-rotor system with unsteady holonomic constraints is established, and the influence of nonlinear vibration characteristics and parameter changes on the dynamic behavior of the system is analyzed.The numerical results show that the angular misalignment has little effect on the motion of the system at lower rotational speed.With the increase of rotational speed, the axis center locus appears obviously "8" zigzag, and the characteristic frequency is twice as high as the power frequency.At higher rotational speed, complex dynamic phenomena such as period doubling bifurcation, chaotic motion and so on appear.In addition, the misalignment of the rotor angle, the stiffness of the shaft and the mass eccentricity also have an important effect on the nonlinear dynamic behavior of the system.3.A multi-rotor-bearing system test platform supported by oil film bearing is established and the dynamic characteristics of the mismatched rotor are experimentally studied.The dynamic response of the rotor-bearing system with parallel misalignment and angular misalignment is discussed, such as the frequency domain characteristics, the axis trajectory, and so on.The experimental results show that there are some combined frequency components in the steady state response of rotor system with misalignment fault, in addition to the power frequency and frequency doubling components, the power frequency and 2 times frequency are dominant.These nonlinear dynamics phenomena prove the rationality of the theoretical model.
【學(xué)位授予單位】：西安科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH113

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