高速电主轴轴系转子动力学特性分析

针对滚动轴承非线性支承的特点 ,本文应用滚动轴承的拟静力学分析方法 ,结合轴系动力学特性分析的有限元法和模态分析法 ,对以滚动轴承为支承的轴承内圆磨床高速电主轴的轴系转子动力学特性进行了理论分析和试验研究 ,编制了具有实际应用价值的计算机程序 ,实现了以滚动轴承为支承的轴承内圆磨床高速电主轴轴系转子动力学特性设计的计算机分析计算 ,提高了设计精度和可靠性。     

滑动轴承对大功率高速泵转子动力性能的影响

为解决大功率高速泵振动大、大流量工况下转子易失稳的问题,本文对高速泵轴承及转子系统建模,分析三油槽圆轴承、四瓦可倾瓦轴承对转子动力性能的影响,计算结果表明可倾瓦轴承支承下的临界转速能够与工作转速有更大的避开率且能提高系统的稳定性。试验对比了此两型轴承支承下的转子动力特性,可倾瓦轴承支承下转子的振动峰峰值显著降低,在设计极限功率对应的流量下仍能稳定工作。可倾瓦轴承的应用优化了转子的动力性能,解决了实际工程问题。     

滚动轴承的刚度理论计算研究

轴承刚度是滚动轴承的重要使用性能指标之一,具有较强的非线性,其计算方法通常建立在滚动轴承力学分析基础之上。理论和实践表明,转子-轴承系统的动力学特性在很大程度上取决于支承转子的滚动轴承的刚度特性;因此,如何准确确定滚动轴承的刚度成为转子-轴承系统理论建模的关键。通过分析研究滚动轴承的刚度理论计算,综合分析现有各种方法的优缺点,明确了下一步研究的重点,为滚动轴承刚度的理论分析及转子动力学建模的应用提供了参考。     

滚动轴承的非线性振动和损坏机理

研究了非线性滚动轴承支承转子系统的非线性振动问题以及相关的轴承损坏机理。采用滚动轴承的非线性刚度表达式，建立了滚动轴承支承刚性转子系统的力学模型和数学模型，通过时数学模型的求解，得到了系统振动的反应曲线和骨干曲线，从而揭示了滚动轴承高速运转时损坏的一种机理，并且从理论上解释了球轴承和滚子轴承的动力性能差异。     

主动电磁轴承转子系统振动模态的分析研究

概要介绍了电磁轴承支承下多质点柔性转子振动模态计算分析方法 ,对一套低温制氧高速透平膨胀机的电磁轴承转子系统的振动模态进行了分析 ,阐述了电磁轴承转子系统振动模态与传统油膜轴承转子系统振动模态的不同之处 ,指出了振动模态分析对电磁轴承系统传感器安装位置设计的重要性 ,及传感器安装位置的设计原则。     

滚动轴承-双转子系统动态性能分析

在高速圆柱滚子轴承拟动力学分析的基础上,利用整体传递矩阵法对滚动轴承-多转子系统的动态性能进行了分析,并开发了相应的分析软件,在此基础上,对高速圆柱滚子轴承径向游隙与整个系统动态特性的关系进行了研究。结果表明:圆柱滚子轴承的径向游隙直接影响着滚动轴承-双转子系统的稳定性。     

碰摩故障转子-滚动轴承耦合系统非线性动力学研究

针对滚动轴承支承下的转子碰摩故障机理分析和故障诊断问题,考虑滚动轴承非线性赫兹接触和轴承径向间隙,建立了含碰摩故障的转子-滚动轴承系统动力学模型。应用数值积分方法得到系统的非线性响应,利用时间波形图、分叉图、频谱图以及Poincaré映射图,研究了系统响应随转速、轴承间隙、碰摩刚度、偏心量以及碰摩间隙的变化规律,为有效诊断滚动轴承支承下的转子碰摩故障提供了理论依据。     

柔性转子滚动轴承系统混沌行为研究

研究了滚动轴承支承的柔性转子系统的混沌行为。考虑空间Euler-Bernoulli杆单元、刚性圆盘、圆柱滚子轴承非线性接触力、不平衡力,使用有限单元法建立了柔性转子轴承系统的非线性动力学方程组。根据FPA修正法确定求解周期,采用Runge-Kutta法、Newton-Raphson法求解非线性动力学方程组,用获得的系统最大Lyapunov指数判断系统的混沌行为。以某滚子轴承柔性转子系统为例,研究了该类转子系统在径向间隙、不平衡力、转轴刚度比对柔性转子系统混沌特性的影响规律,发现随着轴承径向间隙的增大,系统的混沌区间逐渐增大、变多。不平衡力的存在使得系统混沌的转速及范围变大。随着刚度比增大,振幅峰值及对应的转速均逐渐增大,系统混沌区间也增多,轴承非线性振动对柔性转子系统非线性行为的影响逐渐增强。     

车用增压器滚动轴承试验机的设计北大核心

针对车用增压器滚动轴承的研制需求,设计了车用增压器滚动轴承试验机。介绍了试验机的主要技术参数和功能要求。试验机由机械部分、加载系统、润滑系统和电气控制系统组成,驱动电动机采用高速电主轴,加载系统通过低压和高压2组油路实现,由温度传感器和振动传感器实现对轴承状况的实时检测。试验结果表明:该试验机性能稳定可靠,完全满足试验要求。     

车用增压器滚动轴承试验机的设计

针对车用增压器滚动轴承的研制需求,设计了车用增压器滚动轴承试验机。介绍了试验机的主要技术参数和功能要求。试验机由机械部分、加载系统、润滑系统和电气控制系统组成,驱动电动机采用高速电主轴,加载系统通过低压和高压2组油路实现,由温度传感器和振动传感器实现对轴承状况的实时检测。试验结果表明:该试验机性能稳定可靠,完全满足试验要求。     

主动电磁轴承失效后转子坠落在备用轴承过程中的非线性动力学

用有限元法建立了任意个由滚动轴承组成的固定间隙备用轴承-主动电磁轴承-多盘多质量转子系统在主动电磁轴承失效前后的动力学方程,以一个多盘转子系统为例分析了主动电磁轴承失效后转子坠落在备用轴承过程中的瞬态非线性动力学特性,讨论了柔性备用轴承的支撑刚度、支撑阻尼和间隙对转子在坠落过程中动力特性的影响。结果表明采用具有较大阻尼柔性结构的备用轴承能够显著地改善转子坠落在备用轴承上的瞬态动力特性,抑制转子在坠落过程中可能出现具有较大振动和冲击力的全间隙区的涡动运动,减小转子坠落对备用轴承寿命和可靠性的影响。柔性结构备用轴承的支撑阻尼越大,支撑刚度越小,间隙越大,转子坠落后出现全间隙区涡动运动的可能性越小。     

Dynamic responses of rotor drops onto double-decker catcher bearing

In an active magnetic bearing(AMB) system,the catcher bearings(CBs) are indispensable to protect the rotor and stator in case the magnetic bearings fail.Most of the former researches associated with CBs are mainly focused on the dynamic responses of the rotor drops onto traditional single-decker catcher bearings(SDCBs).But because of the lower limited speed of SDCB,it cannot withstand the ultra high speed rotation after rotor drop.In this paper,based on the analysis of the disadvantages of SDCBs,a new type of double-decker catcher bearings(DDCBs) is proposed to enhance the CB work performance in AMB system.In order to obtain the accurate rotor movements before AMB failure,the dynamic characteristics of AMB are theoretically derived.Detailed simulation models containing rigid rotor model,contact model between rotor and inner race,DDCB force model as well as heating model after rotor drop are established.Then,using those established models the dynamic responses of rotor drops onto DDCBs and SDCBs are respectively simulated.The rotor orbits,contact forces,spin speeds of various parts and heat energies after AMB failure are mainly analyzed.The simulation results show that DDCBs can effectively improve the CBs limit rotational speed and reduce the following vibrations,impacts and heating.Finally,rotor drop experiments choosing different types of CBs are carried out on the established AMB test bench.Rotor orbits,inner race temperatures as well as the rotating speeds of both inner race and intermediate races after rotor drop are synchronously measured.The experiment results verify the advantages of DDCB and the correctness of theoretical analysis.The studies provide certain theoretical and experimental references for the application of DDCBs in AMB system.     

滚动轴承支承的柔性转子系统的非线性动力学分析

研究滚动轴承支承的柔性转子系统的非线性动力学特性。建立柔性转子系统的有限元模型,研究不同轴承间隙系统的稳定性及分岔行为。在转子系统中考虑Hertz接触力,以及由转子质量偏心引起的不平衡力,用数值积分的方法得出系统间隙量在不同区域内的轴心轨迹、Poincaré映射图以及时域图。研究结果表明:在间隙较小时,系统表现出丰富的非线性现象,随着间隙的增大,系统的失稳区域也随之增大。     

涡轮泵流体静压轴承设计及性能特性分析

针对流体静压轴承在液体火箭发动机涡轮泵中的设计和应用,以现有的滚动轴承支承的涡轮泵转子为应用对象,提出流体静压轴承的参数设计思路,采用粒子群优化算法设计得到支承刚度最大化的轴承结构参数组合,并计算分析所设计轴承的性能以及轴承-转子系统的动力学特性。分析表明：优化设计得到流体静压轴承的承载力和支承刚度可以满足要求,但轴承总流量达泵流量的21%,这会显著降低涡轮泵的总体效率;仅将滚动轴承改为流体静压轴承,而不改变其他结构或布局,转子的稳定性不能满足要求;涡轮泵流体静压轴承转子系统设计时应尽量将轴承布置在转子位移较大的位置,以充分发挥其阻尼作用。     

Vibration response of rigid rotor in unloaded rolling element bearing

Rolling element bearings appear in nearly 90% of all rotating machinery. Their dynamic performance is often the limiting factor in the performance of the machines that use them. The specific construction of a bearing has a decisive influence on its dynamic behaviour. The paper defines a new vibration model of a rigid rotor supported by rolling element bearings. By application of the defined model, the parametric analysis of the influence of internal radial clearance value and number of rolling elements influence on rigid rotor vibrations in unloaded rolling element bearing was performed. The defined vibration model and parametric analysis were verified experimentally. The results of experimental analysis are also presented in this paper.     

Unbalance Response of a Super-Critical Rotor Supported by Foil Bearings—Comparison with Test Results©

This article compares theoretical and experimental results on the unbalance response of a super-critical rotor supported by two kinds of gas foil bearings. Analysis of the super-critical rotor is performed with viscoelastic foil bearings (VEFB) and conventional bump foil bearings and compared with early published experimental data. The vibration orbits obtained by theoretical investigation on the viscoelastic foil bearings (VEFB) and the conventional bump foil bearings are compared with the experimental vibration orbits of the super-critical rotor supported by both foil bearings. A numerical analysis program can calculate the static and dynamic characteristics of the elastically supported gas foil bearing using the measured stiffness and damping of the elastic foundation. After the stiffness and damping of both foil bearings are calculated using the perturbation method, vibration orbits of the flexible rotor modeled by the finite element method are calculated. Vibration orbits calculated by numerical analysis agree well with experimental data when the vibration amplitude is small and the rotating speed is below the bending critical speed. The numerical results also show that the enhanced structural damping of the elastic foundation reduces vibration near the bending critical speed.     

基于电磁轴承支承的转子系统动力学分析

以电磁轴承-转子系统的动力学理论研究为主要目的,在经典PID控制理论下,对转子系统进行柔性分析,得出系统的动力学方程;通过实验调试得到一组PID参数,代入上述系统进行分析运算,可求得转子的临界转速、对数衰减率以及振动模态振型等,并对理论分析结果进行实验验证和对比分析。     

Effect of rotational speed fluctuations on the dynamic behaviour of rolling element bearings with radial clearances

The behaviour of rolling element bearings is of major importance to the vast majority of rotating machines. Due to the varying assembly compliance and the internal clearance existing in the bearing in most cases, a highly non-linear behaviour of the rotor bearing system appears. Thus, a dynamic model of a horizontal rotor supported on ball bearings with radial internal clearance is considered, taking into account contact forces between the balls and the races, as well as the effect of varying compliance and of the internal radial clearance. However, since rotational speed fluctuations of various levels practically appear in all rotating equipment, their effect is now additionally considered. Their effect is examined in two characteristic rotor bearing cases. The analysis includes all the characteristic states of the dynamic behaviour of the rotor, such as periodic, unstable periodic and chaotic responses, using methods like frequency spectra, phase spaces, higher-order Poincare maps and Lyapunov exponents. All results presented show a dominant stabilization effect of the speed fluctuations with respect to the system behaviour. From the analysis performed, it is concluded that even a minimum fluctuation of the rotor speed may result in major changes of the system dynamics, indicating that speed fluctuations of the rotor are a governing parameter for the dynamic behaviour of the system.