转子开闭裂纹的计算机仿真与特性分析

基于所建立的开闭裂纹转子系统的非线性动力学模型，对转子裂纹在不同激励参数下的开闭状态进行计算机仿真研究，通过轨道图和频谱图对裂纹产生的机理和特征进行分析，并将仿真结果与理论计算结果进行对比。结果表明，对裂纹开闭状态的预测是正确的，同时转子出现裂纹时显示出特殊的动力学特性，其结果可用于旋转机械的故障诊断。     

含裂纹的齿轮耦合转子系统非线性动力学特性分析

在考虑滑动轴承的非线性轴承油膜力以及齿轮齿侧间隙影响的情况下,综合了转轴裂纹以及齿轮质量偏心等常见故障,建立了齿轮耦合转子系统的振动模型并推导了系统的无量纲运动方程.利用数值积分对方程进行了求解,并分析了齿侧间隙以及转轴横向裂纹对齿轮耦合转子系统非线性动力学特性的影响.     

裂纹转子的有限元模拟

运用商业通用有限元软件abaqus对裂纹转子的运动特性进行了分析和比较.通过仿真得到铰支承和油膜力支撑条件下,不同转速时,转子的运动特性,并进行了比较,为理论分析转子动力学行为提供了一条更为直观和方便的途径.     

非线性裂纹转子密封系统的耦合振动分析

随着旋转机械结构参数的提高,作用在转子上的密封中的气流激振力将显著增大。本文针对裂纹转子密封系统进行了研究。应用Muszynska非线性密封力模型,建立了在密封中的气流激振力作用下的裂纹转子系统耦合动力学方程,分析了在非线性密封力作用下的裂纹转子运动特性,并着重讨论了迷宫密封的物理和结构参数对裂纹转子运动特性的影响。研究结果表明,系统具有非常丰富的非线性动力学行为,密封中的气流激振力对裂纹转子的周期运动有明显的抑制作用,密封结构的各主要参数对系统稳定性有很大影响,故可以通过调整密封参数来改善系统的动态稳定性,这为旋转机械的理论设计和故障动态监测提供了理论依据。     

含运动副间隙的涡旋压缩机驱动轴承动力学仿真分析

以某卧式涡旋压缩机转子系统为研究对象,针对动涡盘倾覆力矩作用下运动副间隙对驱动轴承动力学特性影响问题,建立含运动副间隙的转子系统动力学模型,根据计算结果在ADAMS软件中添加气体力进行仿真分析。仿真结果表明:运动副间隙对驱动轴承的加速度和碰撞力影响较大,轴承存在固定的偏磨区域,且间隙越大影响越显著,转子系统的精度和可靠性越差。仿真结果为涡旋压缩机的优化提供了重要的理论参考。     

故障柔性转子系统的动态特性分析

针对某装甲车辆动力传动系统的主轴在行驶过程中极易出现故障的问题,以机械故障综合模拟实验台为研究对象,建立了其正常转子、裂纹转子以及弯曲转子的三维实体模型,运用ANSYS、ADAMS动力学仿真软件对转子系统进行了动力学仿真,得到了正常转子在刚体和柔性体状态下的位移响应曲线和碰撞力响应曲线,在此基础上,对裂纹转子和弯曲转子在柔性体状态下进行了仿真,得到了相应故障状态下的时频响应曲线,直观地揭示了柔性转子系统的动态特性,仿真和实验结果表明,在柔性转子系统中,转子中心振动位移变大,系统碰撞力降低;转子发生裂纹或弯曲故障时,振动强度会增大,这为后续装甲车辆传动系统主轴故障诊断提供一定的理论指导。     

含横向裂纹转子的瞬态振动

应用裂纹开闭条件由转子开裂轴段位移确定的刚度模型,借助摄动法,建立了含横向疲劳裂纹转子过临界转速瞬态振动的一阶近似微分方程。并通过数值积分,得到了这类非定常振动的近似解及其特性,进而讨论了有关因素的影响。     

裂纹角的大小对裂纹转子振动特性的影响

将离心叶轮转子系统简化为Jeffcott转子系统,在考虑非线性油膜力的基础上,综合考虑了系统的流体激振力,建立了含有裂纹故障转子的动力学模型。运用数值积分法分析了不同裂纹角下系统响应随转速变化的分岔图、相图和Poincare映射图等,结果表明,裂纹深度一定的情况下,随着裂纹角的增大,流体激振力和非线性油膜力对转子系统分岔特性的影响也逐渐增大。     

气浮轴承支撑下裂纹-碰摩转子系统动力学分析

建立了带有裂纹和碰摩耦合故障的气浮轴承支撑的弹性转子系统的动力学方程。将打靶法思想与四阶龙格库塔法结合,对转子系统由于气膜力、裂纹和局部碰摩故障导致的非线性动力学行为进行了数值模拟,借助分岔图、相图、Poincare映射和频谱图分析了转子系统的运动形态。研究结果表明,随着系统参数的变化,在特定的参数组合下系统存在周期、拟周期和混沌等复杂的非线性动力学现象。     

间隙环流对十一柱塞航空液压泵转子系统临界转速的影响分析

以十一柱塞航空轴向泵转子系统为研究对象,基于转子动力学理论,构建转子系统的离散模型;然后根据流体连续定理及动量定理建立间隙环流运动的偏微分方程组;采用线性摄动法求解得到间隙环流激振力,并以矩阵的形式施加于干转子动力学方程上,组建湿转子系统动力学方程;在MATLAB软件中编写求解程序,计算干/湿转子的临界转速;最后搭建航空泵转子系统实验平台,完成干/湿转子系统临界转速对比实验研究工作。对比分析结果表明,间隙环流产生的动态流体激振力会影响转子系统的动力学特性,一定程度上会降低系统的临界转速,且随间隙比W的增大,降低趋势更显著。     

基于轴心轨迹形态的转子裂纹故障分析与诊断

基于转子系统轴心轨迹的形态分析,提出一种对多故障中的裂纹故障进行初步诊断的简便方法。通过对转子系统1/2临界转速附近的轴心轨迹形态分析,表明在1/2临界转速附近,裂纹-碰摩双故障转子系统轴心轨迹的内环形状随着转速的变化而改变,内环的偏置方向也随转速旋转一定角度。在碰摩转子系统中,其1/2临界转速附近的轴心轨迹形态与裂纹-碰摩双故障转子有明显区别。多故障系统轴心轨迹的形态分析为对其中的裂纹故障进行初步诊断提供了新方法,使转子故障诊断效率得到提高。同时结合分岔图及频谱图对不同转子系统的动力学响应进行了分析,利用Bently转子实验台对裂纹转子系统的轴心轨迹进行了实验验证。     

Modelica-based object-orient modeling of rotor system with multi-faults

Modelica-based object-orient method is proved to be rapid, accurate and easy to modify, which is suitable for prototype modeling and simulation of rotor system, whose parameters need to be modified frequently. Classical non-object-orient method appears to be inefficient because the code is difficult to modify and reuse. An adequate library for object-orient modeling of rotor system with multi-faults is established, a comparison with non-object-orient method on Jeffcott rotor system and a case study on turbo expander with multi-faults are implemented. The relative tolerance between object-orient method and non-object-orient is less than 0.03%, which proves that these two methods are as accurate as each other. Object-orient modeling and simulation is implemented on turbo expander with crack, rub-impact, pedestal looseness and multi-faults simultaneously. It can be conclude from the case study that when acting on compress side of turbo expander separately, expand wheel is not influenced greatly by crack fault, the existence of rub-impact fault forces expand wheel into quasi-periodic motion and the orbit of expand wheel is deformed and enhanced almost 1.5 times due to pedestal looseness. When acting simultaneously, multi-faults cannot be totally decomposed but can be diagnosed from the feature of vibration. Object-orient method can enhance the efficiency of modeling and simulation of rotor system with multi-faults, which provides an efficient method on prototype modeling and simulation.     

Simulations and experimental investigation on motion stability of a flexible rotor-bearing system with a transverse crack

In the classical process for stability studies on the rotor-bearing system with crack faults, the simple discrete model is adopted for research on such problems, which neglect some needful dynamical influence factor, such as the material damping, shearing effect and gyroscopic effects, etc. Therefore, it is necessary to find a precise calculation model for simulation of the rotor-bearing system with cracks faults. In this paper, instead of the traditional simple discrete model, finite element （FE） model is adopted to investigate the motion stability of a nonlinear rotor system with crack fault. According to finite element theory, the FE model of the cracked rotor system is established firstly. It should be pointed out that the element where the crack occurs is modeled by a particular crack element and the supports at both ends are simulated by two nonlinear loads. Then, based on dimensionless and dimensionality reduction, the Newmark-[3 method and the shooting method are employed to study the effect of eccentricity and the depth of crack on instability speed and bifurcation feature. Furthermore, the simulation results are verified by some corresponding experiments. The simulation and experimental results show that instability speed does not change monotonically, but decreases firstly and then increases when the amount of eccentricity increases. Moreover, as the type of instability changes, the instability speed jumps concomitantly. Additionally, the presence of crack fault can disturb the oil whirl, as a result, instability speed tends to increase slightly, but it does not affect the type of instability and jumping phenomenon. This research presents an effective and convenient method which uses the finite element method （FEM） to research the motion stability of the nonlinear rotor-bearing system with cracked faults and other nonlinear force, and the proposed method can provide a theoretical reference for stability analysis and vibration control in more complex relevant rotor-bearing system.     

基于遗传算法的旋转机械转子裂纹识别的研究

转子裂纹是旋转机械中常见且危险的一种故障,转子裂纹的有效识别和定位也是故障诊断领域一直研究的课题。将转子裂纹的识别作为一反问题,从反问题的求解角度,提出了基于遗传算法的转子裂纹识别策略,该策略的基本思路是借助于有限元分析方法建立裂纹转子的有限元模型,并将转子裂纹识别问题形式化为一优化问题,进而利用遗传算法进行优化求解实现转子裂纹的识别。数值仿真研究表明,所提出的裂纹识别的反问题进化求解策略能以较好的精度和鲁棒性识别转子裂纹,是有效可行的,且适用于更广泛的无损检测和缺陷辨识等应用场合。     

Dynamic Characteristics of Rotor System with a Slant Crack Based on Fractional Damping

The traditional modeling method of rotor system with a slant crack considers only integer-order calculus.However,the model of rotor system based on integer-order calculus can merely describe local characteristics,not historical dependent process.The occur of fractional order calculus just makes up for the deficiency in integer-order calculus.Therefore,a new dynamic model with a slant crack based on fractional damping is proposed.Here,the stiffness of rotor system with a slant crack is solved by zero stress intensity factor method.The proposed model is simulated by Runge-Kutta method and continued fraction Euler method.The influence of the fractional order,rotating speed,and crack depth on the dynamic characteristics of rotor system is discussed.The simulation results show that the ampli-tude of torsional excitation frequency increases significantly with the increase of the fractional order.With the increase of the rotating speed,the amplitude of first harmonic component becomes gradually larger,the amplitude of the second harmonic becomes smaller,while the amplitude of the other frequency components is almost invariant.The shaft orbit changes gradually from an internal 8-type shape to an ellipse-type shape without overlapping.With the increase of the slant crack depth,the amplitude of the transverse response frequency in the rotor system with a slant crack increases,and the amplitude in the second harmonic component also increases significantly.In addition,the torsional excitation frequency and other coupling frequency components also occur.The proposed model is further verified by the experiment.The valuable conclusion can provide an important guideline for the fault diagnosis of rotor system with a slant crack.     

基于神经网络的转子系统故障诊断

提出了一种基于神经网络的转子振动故障诊断的新方法,该方法以大型机器的轴承振动裂度作为神经网络的训练样本输入,并通过神经网络的学习、聚类,产生神经网络聚类中心,根据网络聚类的特点以及聚类的中心来判断转子的振动特性和实质。实例验证表明,该方法可实现对转子系统振动故障的准确诊断。     

裂纹转子的理论分析与实验研究

对横向裂纹转子系统建立力学模型，求得刚度矩阵，建立运动微分方程。通过运动仿真对裂纹转子基本故障特征进行了分析，得到不同裂纹深度、裂纹方向下转轴的运动特性。并通过实验，得到裂纹轴运动轴心轨迹、三维频谱，证明偏心质量、裂纹深度、方向这些因素对转子振动影响特性，其理论分析和实验结果可作裂纹故障的分析和识别依据。     

变分模态分解在转子故障诊断中的应用

针对转子故障诊断问题,提出一种基于变分模态分解(variational mode decomposition,简称VMD)的信号处理方法。该方法在获取分解分量的过程中通过迭代搜寻变分模型最优解来确定每个分量的频率中心及带宽,从而能够自适应地实现信号的频域剖分及各分量的有效分离,对各单分量信号进行希尔伯特变换,即可得到瞬时的频率和幅值信息。对仿真信号和典型转子故障信号进行VMD方法和经验模态分解(empirical mode decomposition,简称EMD)方法的分析比较,以验证所提方法的有效性。仿真信号的分解结果表明,变分模态能够准确分离出信号中的固有模态分量且不存在模态混叠;转子故障实验信号的分析结果表明,所提方法能够有效提取出明显的故障特征,从而准确诊断出转子存在的故障。     

Dynamic characteristics of multi-degrees of freedom system rotor-bearing system with coupling faults of rub-impact and crack

Extensive studies on rotor systems with single or coupled multiple faults have been carried out. However these studies are limited to single-span rotor systems. A finite element model for a complex rotor-bearing system with coupled faults is presented. The dynamic responses of the rotor-bearing system are obtained by using the rotor dynamics theory and the modern nonlinear dynamics theory in connection with the continuation-shooting algorithm（commonly used for obtaining a periodic solution for a nonlinear system） for a range of rub-impact clearances and crack depths. The stability and Hopf instability of the periodic motion of the rotor-bearing system with coupled faults are analyzed by using the procedure described. The results indicate that the finite element method is an effective way for determining the dynamic responses of such complex rotor-bearing systems. Further for a rotor system with rub-impact and crack faults, the influences of the clearances are significantly different for different rub-impact stiffness. On the contrary, the influence of crack depths is rather small. The instability speeds of the rotor-bearing system increase due to the presence of the crack fault. The results obtained using the new finite element model, presented for computation and analysis of dynamic responses of the rotor-bearing systems with coupled faults, are in accordance with measurements in experiment. The formulations given can be used for diagnosis of faults, vibration control, and safe and stable operations of real rotor-bearing systems.