气浮轴承在航天器质量特性综合测试设备中的应用

文章首先介绍了气浮轴承在航天器质量特性综合测试设备中的应用情况及测量原理,之后对一种球面气浮轴承进行了计算流体动力学（CFD）软件仿真计算,得出了承载力与不同参数的关系及提高承载力的方法;最后总结了航天器质量特性综合测试设备发展趋势。     

Nonlinear vibration response characteristics of a dual-rotor-bearing system with squeeze film damper

Rolling bearing and Squeeze Film Damper (SFD) are used in rotor support structures, and most researches on the nonlinear rotor-bearing system are focused on the simple rotor-bearing systems. This work emphasizes the comparative analysis of the influence of SFD on the nonlinear dynamic behavior of the dual-rotor system supported by rolling bearings. Firstly, a reduced dynamic model is established by combining the Finite Element (FE) method and the free-interface method of component mode synthesis. The proposed model is verified by comparing the natural characteristics obtained from an FE model with those from the experiment. Then, the steady-state vibration responses of the system with or without SFD are solved by the numerical integration method. The influences of the ball bearing clearance, unbalance, centralizing spring stiffness and oil film clearance of SFD on the nonlinear steady-state vibration responses of the dual-rotor system are analyzed. Results show that SFD can effectively suppress the amplitude jump of the dual rotor system sustaining two rotors unbalance excitations. As the ball bearing clearance or unbalance increases, the amplitude jump phenomenon becomes more obvious, the resonance hysteresis phenomenon strengthens or weakens, the resonant peaks shift to the left or the right, respectively. SFD with unreasonable parameters will aggravate the system vibration, the smaller the oil film clearance, the better the damping performance of the SFD, the larger the centralizing spring stiffness is, the larger resonance amplitudes are.     

一种全复合材料卫星天线承力筒的研制

针对卫星天线承力筒轻质、高轴向模量、低轴向热膨胀的需求,文章开展了承力筒总体成型方案设计、材料基础热力学性能测试及产品试制等工作,并通过了实验考核。结果表明:对于材料的热力学性能,按经纬向比例1︰2编织的M40J炭布层压板在常温下纬向拉伸模量为118GPa,纬向拉伸强度为771MPa;在(?190~150)℃范围内,纬向热膨胀系数为(0.3~1.4)×10?6℃?1,经向热膨胀系数为(0.3~5.3)×10?6℃?1。该复合材料承力筒比铝质承力筒质量减少40%以上。复合材料承力筒经过(?170~120)℃/24h、6.5个循环的高低温循环实验考核,产品无残余变形,内部未出现开裂、分层等现象。     

Nonlinear resonance characteristics of a dual-rotor system with a local defect on the inner ring of the inter-shaft bearing

In this paper, the nonlinear resonance characteristics of a dual-rotor system are investigated with the consideration of a local defect on the inter-shaft bearing of the system. A simplified model of the dual-rotor system is proposed by considering that there is a local defect on the inner ring of inter-shaft bearing. The local defect is modelled as an inverted isosceles trapezoidal groove, which can make great influence on the inter-shaft bearing force due to the change of radial clearance of the inter-shaft bearing. The motion equations of the dual-rotor system are formulated by using the Lagrange equation. The Runge-Kutta method is employed to solve the motion equation. The amplitude-frequency response curve of the dual-rotor system is obtained, the abnormal resonance characteristics are analyzed. In addition, the influence of defect parameters, rotors and support parameters and inter-shaft bearing parameters on the amplitude-frequency characteristics of the system are discussed. The results show that there are two main resonance peaks and four abnormal resonance peaks on the amplitude-frequency response curve of the dual-rotor with a local defect on the inner ring of the inter-shaft bearing. Through analyzing the vibration response of the abnormal resonance peaks, it is found that the first two abnormal resonances are caused by the combined resonance, which are related to the inner ring fault and the rotational speed of high or low pressure rotors, and the last two resonances are caused by the induced resonance of the inner ring fault. At the same time, when the parameters of defect, rotors and support and inter-shaft bearing change, the resonance of the system also shows the corresponding change law.     

某磁悬浮飞轮控制模型及其转子质心轴向偏移仿真分析

基于某磁悬浮飞轮转子动力学模型,根据现代控制理论构建了该飞轮系统的状态控制模型。由极点配置法设计了全状态反馈控制器,用Matlab/Simulink软件仿真分析了转子系统质心的轴向偏移对控制器设计和整个系统性能的影响。结果表明:设计的飞轮转子系统满足要求。分析对磁悬浮飞轮系统的优化设计有一定的参考意义。     

航空发动机转子-滚动轴承-支承-机匣耦合系统的碰摩故障分析与验证

针对实际的航空发动机转子系统,建立了含碰摩故障的转子-滚动轴承-支承-机匣耦合动力学模型.在模型中,考虑了机匣运动,弹性支承、挤压油膜阻尼,充分考虑了轴承间隙、滚珠与滚道的非线性赫兹接触力以及由滚动轴承支撑刚度变化而产生的变柔性(VaryingcomplianceVC)振动.运用数值积分方法获取了系统响应,并建立带机匣的航空发动机转子实验器进行碰摩故障实验,仿真结果与实验结果比较分析表明了模型的有效性.      

基于支持向量机的滚动轴承状态寿命模型

使用状态寿命(即状态良好、初始损伤、故障发展和即将失效4个寿命阶段)描述滚动轴承的使用寿命,并建立了滚动轴承的状态寿命评估模型.状态寿命评估模型建模的关键是振动信号的特征提取和状态的识别算法.针对滚动轴承振动的特点,提取小波包重构信号的频带能量构造特征向量,利用支持向量机作为辨识算法建立滚动轴承状态寿命评估模型,并讨论了模型参数确定等关键问题.滚动轴承全寿命试验验证了模型的有效性和可信性.      

一种民航发动机滚动轴承故障预警方法

为了提前感知滚动轴承故障,避免民用航空发动机非计划维护带来的损失,提出了一种故障预警方法.对轴承振动信号进行特征工程,提取其时域和频域特征,引入梯度提升决策树(Gradient boosting decision tree,GBDT)算法,量化了特征重要度;在特征相关性分析的基础上,利用核主成分分析(Kernel pr...     

高速滚动轴承-转子系统的摩擦阻尼减振

为了抑制高速滚动轴承-转子系统在通过临界转速时的过大振动,本文采用了摩擦阻尼弹性支承结构.分析了该支承的减振机理和支承特性,设计了摩擦阻尼器,研究了其对转子系统不平衡响应的影响.结果表明,采用适当的机械结构,阻尼器的刚度因子和摩阻因子只与内环的锥角和接触面摩擦因数有关.通过改变这两个参数和外壳轴向刚度,可改变其刚度和阻尼特性.在转子系统支承中引入摩擦阻尼器能够降低支承刚度,从而降低系统的临界转速,避开工作转速.此外,还可增大支承阻尼,抑制临界振幅,减小系统的振动外传力.