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Effects of axial preload of ball bearing on the nonlinear dynamic characteristics of a rotor-bearing system 总被引:2,自引:0,他引:2
This research studies the effects of axial preload on nonlinear dynamic characteristics of a flexible rotor supported by angular
contact ball bearings. A dynamic model of ball bearings is improved for modeling a five-degree-of-freedom rotor bearing system.
The predicted results are in good agreement with prior experimental data, thus validating the proposed model. With or without
considering unbalanced forces, the Floquet theory is employed to investigate the bifurcation and stability of system periodic
solution. With the aid of Poincarè maps and frequency response, the unstable motion of system is analyzed in detail. Results
show that the effects of axial preload applied to ball bearings on system dynamic characteristics are significant. The unstable
periodic solution of a balanced rotor bearing system can be avoided when the applied axial preload is sufficient. The bifurcation
margins of an unbalanced rotor bearing system enhance markedly as the axial preload increases and relates to system resonance
speed. 相似文献
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根据Floquet理论关于线性周期系数系统解的性质及稳定性条件 ,定义了衡量非线性非自治系统周期解受扰后的衰减速率指标—稳定度。从动力系统流的概念出发 ,给出了利用非线性非自治系统稳态周期解受扰后的瞬态响应信息计算周期解稳定度的方法。以不平衡滑动轴承 弹性转子系统为例 ,说明了该方法的有效性。将稳定度等于零作为临界判据 ,该方法不仅解决了工频周期解失稳边界的确定问题 ,而且解决了渐进稳定域的估计和抗冲击扰动裕度的计算问题 相似文献
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Jean-Jacques Sinou 《International Journal of Non》2007,42(7):959-972
The stability of a rotor system presenting a transverse breathing crack is studied by considering the effects of crack depth, crack location and the shaft's rotational speed. The harmonic balance method, in combination with a path-following continuation procedure, is used to calculate the periodic response of a non-linear model of a cracked rotor system. The stability of the rotor's periodic movements is studied in the frequency domain by introducing the effects of a perturbation on the periodic solution for the cracked rotor system.It is shown that the areas of instability increase considerably when the crack deepens, and that the crack's position and depth are the main factors affecting not only the non-linear behaviour of the rotor system but also the different zones of dynamic instability in the periodic solution for the cracked rotor. The effects of some other system parameters (including the disk position and the stiffness of the supports) on the dynamic stability of the non-linear periodic response of the cracked rotor system are also investigated. 相似文献
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The influence of labyrinth seal on the stability of unbalanced rotor system was presented . Under the periodic excitation of rotor unbalance , the whirling vibration of rotor is synchronous if the rotation speed is below stability threshold, whereas the vibration becomes severe and asynchronous which is defined as unstable if the rotation speed exceeds threshold . The. Muszynska model of seal force and shooting method were used to investigate synchronous solution of the dynamic equation of rotor system. Then , based on Floquet theory the stability of synchronous solution and unstable dynamic characteristic of system were analyzed. 相似文献
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针对由一个线性子系统和一个非线性子系统构成的两自由度非自治分段光滑非线性平面运动系统的响应特性开展了研究. 该分段光滑非线性模型可用来确定对称转子/定子系统的主要碰摩响应, 且在反映非光滑系统典型特性上具有明显的特征:(1) 切换分界面是由两自由度坐标共同决定的一个幅值曲面;(2) 子系统周期解与分界面的擦碰, 不是发生在一个点上, 而是同时发生在解的所有点上;(3) 完整系统未发现由两子系统共同作用而产生的周期解. 因此, 对于该非光滑系统响应特性的研究, 很难直接利用目前有关非光滑系统平衡点和周期解分岔分析的方法. 为此, 尝试了根据子系统的响应特性, 划分出完整系统响应对分界面处切换的敏感区和非敏感区, 并针对非敏感区可由子系统解的特性求得完整系统的响应, 而针对敏感区通过子系统动力学特征的分析有助于解释完整系统响应的生成机制. 相似文献
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Nonlinear dynamic analysis of a rotor system with fixed-tilting-pad self-acting gas-lubricated bearings support 总被引:1,自引:0,他引:1
Based on the nonlinear theory, the unbalanced responses of a fixed-tilting-pad gas-lubricated journal bearing-rigid rotor system are investigated. A?time-dependent mathematical model is established to describe the pressure distribution of gas-lubricated journal bearing with nonlinearity. The rigid rotor supported by a fixed-tilting-pad self-acting gas-lubricated journal bearing is modeled. The differential transformation method has been employed to solve the time-dependent gas-lubricated Reynolds equation, and the dynamic motion equation has been solved by the direct integral method. The unbalanced responses of the rotor system supported by fixed-tilting-pad gas-lubricated journal bearings are analyzed by the orbit diagram, Poincaré map, time series, and spectrum diagram. The numerical results reveal periodic, period-3, and quasiperiodic motions of nonlinear behaviors of the system. Finally, the effects of pivot ratio and preload coefficient on the nonlinear dynamic characteristics of the fixed-tilting-pad self-acting gas-lubricated journal bearing-rotor system are investigated. 相似文献
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Nonlinear dynamic behaviors of a rotor-labyrinth seal system 总被引:2,自引:0,他引:2
The nonlinear model of rotor-labyrinth seal system is established using Muszynska’s nonlinear seal forces. We deal with dynamic
behaviors of the unbalanced rotor-seal system with sliding bearing based on the adopted model and Newmark integration method.
The influence of the labyrinth seal one the nonlinear characteristics of the rotor system is analyzed by the bifurcation diagrams
and Poincare’ maps. Various phenomena in the rotor-seal system, such as periodic motion, double-periodic motion, quasi-periodic
motion and Hopf bifurcation are investigated and the stability is judged by Floquet theory and bifurcation theorem. The influence
of parameters on the critical instability speed of the rotor-seal system is also included. 相似文献
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Concerning the polluted environment in inshore areas and the effects of unbalanced impulsive diffusion between inshore and
offshore areas on the size of fish population, based on optimal harvesting policy, a logistic offshore fishery system with
impulsive pollutant input in inshore areas and impulsive diffusion at different fixed time is formulated, and we investigate
the dynamics of such system. The sufficient conditions are obtained for the existence of the positive periodic solution and
the global asymptotic stability of both the trivial periodic solution and the positive periodic solution. Moreover, the maximum
sustainable yield and the corresponding harvesting effort are obtained. 相似文献
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弹性转子-滑动轴承系统稳定性分析 总被引:7,自引:0,他引:7
对一人考虑不平衡力和非线性油膜力的弹性转子 -轴承系统 ,用数值方法研究其稳定性和油膜失稳运动 (自激振动 )特性 ;推导出转子受冲击的运动模型 ,并分析了冲击对系统稳定性的影响规律。 相似文献
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Interaction of forced and self-sustained vibrations of one disk rotor is described by nonlinear finite-degree-of-freedom dynamical system. The shaft of the rotor is supported by two journal bearings. The combination of the shooting technique and the continuation algorithm is used to study the rotor periodic vibrations. The Floquet multipliers are calculated to analyze periodic vibrations stability. The results of periodic motions analysis are shown on the frequency response. The quasi-periodic motions are investigated. These nonlinear vibrations coexist with the periodic forced vibrations. 相似文献
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We present an analysis of a two-plane automatic balancing device for rotating machinery. The mechanism consists of a pair of races that contain balancing balls which move to eliminate imbalance due to rotor eccentricity or principal axis misalignment. A model is developed that includes the effect of support anisotropy and rotor acceleration. The symmetry of the imbalance is considered, and techniques from equivariant bifurcation theory are used to derive a necessary condition for the stability of balanced operation. The unfolding of the solution structure is explored and we investigate mechanical systems in which either the supports or the automatic ball balancer is asymmetric. Here it is shown that, provided the imbalance is small, the balanced state is robust to the considered asymmetries. 相似文献
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The effects of unbalance on oil whirl 总被引:2,自引:0,他引:2
The nonlinear behavior of an unbalanced rotor supported in a fluid film bearing is analyzed. A simplified two dimensional model is adopted which uses the long-bearing approximation with a -film to account for cavitation. This model has been thoroughly studied by Myers [1] in the balanced case, where it is shown that the whirl instability is the result of a Hopf bifurcation. The implications of imbalance are studied in this paper. This leads to the study of a periodically perturbed Hopf bifurcation. It is shown that the dynamics in this situation can, especially under certain nonlinear resonance conditions, have an extremely complicated dependence on the system parameters and the rotor speed. Complete bifurcation diagrams are presented for a particular rotor model which demonstrate this dependence. 相似文献
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Leike Zhang Zhenyue Ma Bingwei Song 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(6):817-830
Electromagnetic and mechanical forces are main reasons resulting in vibrations in hydraulic generating set. The non-symmetric air-gap between the rotor and stator creates an attraction force called unbalanced magnetic pull (UMP). The UMP can produce large oscillations which will be dangerous to the machines. In this paper, the nonlinear dynamic characteristics of a rotor-bearing system with rub-impact for hydraulic generating set under the UMP are studied. The rubbing model is established based on the classic impact theory. Through the numerical calculation, the excitation current, mass eccentricity, stiffness of shaft and radial stiffness of stator are used as control parameters to investigate their effect on the system, by means of bifurcation diagrams, Poincaré maps, trajectories and frequency spectrums. Various nonlinear phenomena including periodic, quasi-periodic and chaotic motions are observed. The results reveal that the UMP has significant influence in the response of the rotor system that the continuous increase in the excitation current induces the alternation of quasi-periodic and chaotic motions, the co-occurrence of oil whip and rub in a wide excitation range aggravates the vibration and leads to the instability of the system. In addition, the large eccentricity and radial stiffness of stator, as well as the small stiffness of shaft may lead to the occurrence of full annular rubbing while increasing the stiffness of the shaft can play an important role of suppressing the chaotic motion, reducing the vibration and improving stability of the system. 相似文献
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NONLINEAR STABILITY OF BALANCED ROTOR DUE TO EFFECT OF BALL BEARING INTERNAL CLEARANCE 总被引:2,自引:0,他引:2
Stability and dynamic characteristics of a ball bearing-rotor system are investigated under the effect of the clearance in the ball bearing. Different clearance values are assumed to calculate the nonlinear stability of periodic solution with the aid of the Floquet theory. Bifurcation and chaos behavior are analyzed with variation of the clearance and rotational speed. It is found that there are three routes to unstable periodic solution. The period-doubling bifurcation and the secondary Hopf bifurcation are two usual routes to instability. The third route is the boundary crisis, a chaotic attractor occurs suddenly as the speed passes through its critical value. At last, the instable ranges for different internal clearance values are described. It is useful to investigate the stability property of ball bearing rotor system. 相似文献
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The order-1 periodic solution of the system with impulsive state feedback control is investigated. We get the sufficient condition for the existence of the order-1 periodic solution by differential equation geometry theory and successor function. Further, we obtain a new judgement method for the stability of the order-1 periodic solution of the semi-continuous systems by referencing the stability analysis for limit cycles of continuous systems, which is different from the previous method of analog of Poincarè criterion. Finally, we analyze numerically the theoretical results obtained. 相似文献