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具有裂纹-碰摩耦合故障转子-轴承系统的动力学研究 总被引:9,自引:0,他引:9
以非线性动力学和转子动力学理论为基础,分析了带有碰摩和裂纹耦合故障的弹性转子系统的复杂运动,在考虑轴承油膜力的同时构造了含有裂纹和碰摩故障转子系统的动力学模型。针对短轴承油膜力和碰摩-裂纹转子系统的强非线性特点,采用Runge-Kutta法对该系统由碰摩和裂纹耦合故障导致的非线性动力学行为进行了数值仿真研究,发现该类碰摩转子系统在运行过程中存在周期运动、拟周期运动和混沌运动等丰富的非线性现象,该研究结果为转子-轴承系统故障诊断、动态设计和安全运行提供理论参考。 相似文献
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研究了转子-机匣系统发生碰摩时的分叉与混沌行为,分析了转子机匣频率比与刚度比、偏心质量等参数对系统分叉与混沌特性的影响.当转子机匣系统发生碰摩时除了通过倍周期、阵发性和拟周期分叉进入混沌外,还发现了孪生叉形分叉现象,呈现出非常丰富的动力学行为. 相似文献
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研究叶片与转子-轴承系统的耦合非线性振动,建立了一个带叶片的双盘转子-轴承系统的非线性动力学模型,其中包含一个弹性转轴、两个滑动轴承、两个刚性圆盘和两组弹性叶片.为了分析叶片的惯性影响,将其简化为单摆模型.采用4阶Runge-Kutta法进行了数值模拟,并利用分岔图、三维谱图、轴心轨迹和Poincaré映射图等方法分析了系统的非线性动力学特性.研究发现,随着转速的变化,系统响应演化出了倍周期运动、概周期运动、混沌运动和倍周期分岔等典型的非线性动力学行为.在与忽略了叶片振动的转子系统对比后发现,叶片振动使转子发生混沌运动的转速区域增大.在某些参数条件下,采用不同的叶片刚度,叶片振动可能引起转子系统产生混沌运动. 相似文献
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非线性转子-轴承系统的周期解及近似解析表达式 总被引:2,自引:0,他引:2
通过对普通打靶方法进行改造提出一种确定非线性系统周期轨道及周期的新型打靶算法。首先通过改变系统的时间尺度,将非线性系统周期轨道的周期显式地出现在非线性系统的系统方程中,然后对传统打靶法进行改造,将周期也作为一个参数一起参与打靶法的迭代过程,迭代过程包含对周期轨道和周期的求解,迭代过程中的增量通过优化方法选择,从而能迅速确定出系统的周期轨道及其周期。应用所求的结果结合谐波平衡方法求得了非线性系统的周期轨道的近似解析表达式,理论上通过增加谐波的阶数任何精度的周期解都可以得到。最后将该方法应用于非线性转子轴承系统,求出了在某些参数下转子的周期解及其近似解析表达式,通过与四阶Runge-Kutta数值积分结果比较,验证了方法的有效性,计算结果对于转子系统运动的定量控制有重要理论指导意义。 相似文献
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研究了受横向不平衡电磁激励的转子.轴承系统的非线性振动响应。首先将转子.轴承系统简化为带有质量不平衡并受横向激励的连续梁,由于短轴承的油膜力和电磁力的共同激励,系统振动具有强非线性特性。用Galerkin方法把偏微分控制方程离散为常微分方程组,采用四阶Runge—Kutta法对该系统进行数值仿真研究。其次比较了转轴分别在电磁力、油膜力单独作用和两种力共同作用下的振动特性,研究表明电磁力和油膜力对转子系统的非线性振动和分岔有着不同的贡献:油膜力的存在抑制了拟周期运动的发生,延长了稳定运行区域;电磁力拉长了拟周期发生的区域,降低了转子系统发生突发性破坏的风险。最后给出了系统响应随转速、电磁参数、油膜粘度等控制参数变化的分岔图,表明:系统在两个方向的运动随控制参数的变化趋势基本相同,经历了周期、倍周期、拟周期等非线性运动交替出现的过程;且油膜粘度的增大有利于转子系统的安全运行。 相似文献
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磁浮轴承-转子系统非线性动态特性分析 总被引:3,自引:0,他引:3
考虑非线性电磁力对刚性Jeffcott转子系统的影响,采用Hopf分岔理论及CPNF法对系统平衡点解和周期解进行研究,数值仿真得到系统Jacobi矩阵特征值、轴心轨迹图和Poincare映射图。转子运动呈现Hopf分岔、倍周期分岔及拟周期运动等复杂的非线性动力学特征,其结果可为磁浮轴承-转子系统设计和运行状态控制提供理论依据。 相似文献
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以双盘悬臂立式转子-轴承系统为研究对象,建立了系统运动微分方程,并用数值方法分析了在非线性密封力和非线性油膜力作用下的裂纹转子的动力学特性。分析表明,在一定深度裂纹下,转子系统响应随不同角频率比表现出复杂的非线性现象,出现了周期k运动、拟周期运动和混沌运动等多种运动形式。在一定角速度时,工作在远离临界角速度区的转子系统对裂纹非常敏感,而工作在近临界角速度区的转子系统对裂纹不是特别敏感,但是裂纹对它的运动状态影响较大。该研究结果为该类转子-轴承系统的安全运行与故障诊断提供了一定的理论参考。 相似文献
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Yujie We 《Acta Mechanica Sinica》2014,(6):846-848
The construction and operation of high-speed rail(HSR)grid within the past two decades in China,in terms of the scale,may be possibly comparable to any national-wide construction in the history of China,even the Great Wall.By counting railways with commercial train service at the speed of200 km/h,China has the world’s longest HSR network with over 19 369.8 km of track in service today and this number 相似文献
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Cécile Lemaitre Md. Mahmud Alam Pascal Hémon Emmanuel de Langre Yu Zhou 《Comptes Rendus Mecanique》2006,334(3):158-163
Rainwater rivulets appear on inclined cables of cable-stayed bridges when wind and rain occur simultaneously. In a restricted range of parameters this is known to cause vibrations of high amplitudes on the cable. The mechanism underlying this effect is still under debate but the role of rainwater rivulets is certain. We use a standard lubrication model to analyse the dynamics of a water film on a cylinder under the effect of gravity and wind load. A simple criterion is then proposed for the appearance and position of rivulets, where the Froude number is the control parameter. Experiments with several geometries of cylinder covered with water in a wind tunnel show the evolution of the rivulets with the Froude number. Comparison of the prediction by the model with these experimental data shows that the main mechanism of rivulet formation and positioning is captured. To cite this article: C. Lemaitre et al., C. R. Mecanique 334 (2006). 相似文献
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R. J. Sobey 《国际流体数值方法杂志》1982,2(3):277-297
Space-time finite element solutions of the convection–dispersion equation using higher-order nodal continuity and Hermitian polynomial shape functions are described. Five separate elements ranging from a complete linear element with C0,0 nodal continuity to a complete first-order Hermitian element with C1,1 nodal continuity are subjected to detailed analysis. Wave deformation analyses identify the source of leading or trailing edge oscillations, trailing edge oscillations being the major source of difficulty. These observations are confirmed by numerical experiments which further demonstrate the potential of higher-order nodal continuity. The performance of the complete first-order Hermitian element is quite satisfactory and measurably superior to the linear element. 相似文献
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We establish a theoretical model to explain the nucleation of a crystal of helium by an acoustic over-pressure. We explain the interfacial laws for this ultra-fast cristallization, close to the sound speed. Assuming spherical symmetry and taking into account the experimental data, we recover the dynamics of the growth and melting during an over-pressure impulse. To cite this article: M. Ben Amar et al., C. R. Mecanique 331 (2003). 相似文献
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Based on the use of two different preparation procedures for reconstituting triaxial samples of sand, i.e. wet tamping and dry pluviation, significant differences in associated mechanical behaviour are observed on a reference sand with respect to the phenomenon of ‘static’ liquefaction. Wet tamping favours the initiation of liquefaction instability, whereas dry pluviation favours a more stable behaviour, less susceptible to liquefaction. Microscopic observation of corresponding sand specimens allows us to identify two well differentiated structures, i.e., for wet tamping, an irregular structure with predominance of aggregates (aggregated grains) and macropores, very contractant and unstable and, for dry pluviation, a more regular structure, without macropores, more dilatant and more stable. These observations show the importance of further characterization, based on the introduction of appropriate parameters, of the initial structure of sandy materials, strongly dependant upon their mode of formation (natural or artificial). To cite this article: N. Benahmed et al., C. R. Mecanique 332 (2004). 相似文献
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Sources of Complexity in Human Systems 总被引:3,自引:0,他引:3
Complex is a special attribute we can give to many kinds of systems. Although it is used often as a synonym of difficult, it has a specific epistemological meaning, which is going to be shared by the incoming science of complexity. Difficult is an object which, by means of an adequate computational power, can be deterministically or stochastically predictable. On the contrary complex is an object which can not be predictable because of logical impossibility or because its predictability would require a computational power far beyond any physical feasibility, now and forever. For complexity refers to some observing system, it is always subjective, and thus it is defined as observed irreducible complexity. Human systems are affected by several sources of complexity, belonging to three classes, in order of descending restrictivity. Systems belonging to the first class are not predictable at all, those belonging to the second class are predictable only through an infinite computational capacity, and those belonging to the third class are predictable only through a trans-computational capacity. The first class has two sources of complexity: logical complexity, directly deriving from self-reference and Gödel's incompleteness theorems, and relational complexity, resulting in a sort of indeterminacy principle occurring in social systems. The second class has three sources of complexity: gnosiological complexity, which consists of the variety of possible perceptions; semiotic complexity, which represents the infinite possible interpretations of signs and facts; and chaotic complexity, which characterizes phenomena of nonlinear dynamic systems. The third class coincides with computational complexity, which basically coincides with the mathematical concept of intractability. Artificial, natural, biological and human systems are characterized by the influence of different sources of complexity, and the latter appear to be the most complex. 相似文献