环形动力吸振器进行转子振动控制的实验

对环形动力吸振器在转子振动控制中的应用进行了实验研究,基于单圆盘转子模型和振动特征,设计了一种安置于轴承上的对分式环形动力吸振器.吸振器可以安装在两轴承间任意位置,不改变原有支撑结构,不影响转子动力特性.建立了转子吸振器减振实验台,对转子经过临界转速时的振动进行了实验,结果表明吸振器能有效降低转子经过临界转速时70%以上的振动.增加吸振器质量,可以精确调节吸振器固有频率,并拓宽减振频带.实验研究了吸振器安装位置与减振效果的关系,结果表明在转子振幅较大区域,减振效果较好.对比了不同数量吸振器在转子不平衡振动下的减振效果,结果表明安装2个吸振器的减振效果要好于单独1个作用时.      

一种转子动力吸振器的参数优化方法

对用于抑制转子系统启机过临界转速时过大振动的动力吸振器进行参数优化设计,以达到最优抑振目的。利用有限元方法建立动力吸振器-转子耦合系统的动力学方程,求得耦合系统的半数值半解析的响应表达式。设计优化策略利用响应解与限边界的坐标轮换法相结合,寻找动力吸振器的最佳设计变量;将所得最优参数的动力吸振器与常规优化设计方法设计的动力吸振器的抑振性能进行对比,并分析动力吸振器对参数最优偏离的敏感性。结果表明:该参数优化方法优化的动力吸振器能降低1阶共振幅值达45.4%,说明了该方法的有效性;该方法比两种有效的常规优化方法优化的动力吸振器的抑振效果分别高11.2%、9%,可见其优化效果的优异性;与阻尼最优偏离相比,该参数优化方法优化的动力吸振器的抑振性能对刚度最优偏离具有更高的敏感性。      

复合材料整流罩减振降噪的动力吸振器设计

运载火箭整流罩的隔声性能设计对内部设备的选型、试验和安全运行至关重要。为改善整流罩内低频声振环境,提高整流罩低频段隔声性能,首先,针对复合材料整流罩结构开展力学等效建模;其次,提出一种基于基变换模态空间内降维理论,解决了考虑多模态耦合的动力吸振器(DVA)设计问题;最后,基于整流罩等效力学模型开展了动力吸振器位置及材料参数的优化设计。针对某型复合材料整流罩开展仿真研究,验证新方法的有效性。结果表明：针对某型质量为1 177.3 kg的整流罩模型,添加总质量为14.6 kg的动力吸振器之后,0～100 Hz频段内声功率级均方根(RMS)值从254.8 dB降至238.8 dB,设计频段内声振响应被有效控制,声振环境得到改善。     

关于S76D型直升机双线摆吸振器的维护技术研究

双线摆吸振器是一种被动式动力吸振器,安装在直升机桨毂上,通过阻断旋翼平面内激振力的传递从而降低机身振动。本文从运行维护角度出发,以桨毂安装4个相同的双线摆构成的双线摆吸振器为研究对象,重点介绍双线摆吸振器工作原理,并指出了日常维护注意事项。     

基于结构奇异值理论的压电柔性结构振动鲁棒控制

基于结构奇异值μ理论,针对含压电作动器和传感器的柔性结构,提出了不确定性振动控制系统的一般分析框架和鲁棒控制器设计方法.考虑了结构的模态参数不确定性和高阶未建模动态,通过引入适当的虚拟输入、输出和相应的加权函数分离出系统的不确定部分,建立适合于鲁棒μ控制器设计的增广系统,用D_K迭代算法求解控制器,以使闭环系统同时满足鲁棒稳定性和鲁棒性能要求.以含一个压电作动器和传感器的悬臂梁为例设计了鲁棒控制器,仿真结果表明对结构振动具有很好的抑制效果.     

动力吸振器用于飞机壁板减振降噪的研究

在对飞机壁板附加动力吸振器前后的振动分析基础上,设计了适合于飞机壁板安装的动力吸振器,在~块飞机壁板上进行了实验,结果与理论计算~致。研究表明,动力吸振器用于飞机壁板减振降噪具有良好的前景。     

直升机旋翼双线摆式吸振器的关键技术

导读:对直升机的振动水平控制方法进行了综述,着重讨论了旋翼双线摆式动力吸振器的应用情况.对双线摆式吸振器的基本原理进行了介绍,并对设计中的几个关键问题进行了分析.阐述了该类吸振器在直升机型号设计中的应用潜力和待解决的关键问题.     

直升机桨毂动力吸振器的研究

提出了分析与设计桨毂动力吸振器的力学模型;探讨两种分析方法（频域法和时域法）及其适用性;并对吸振器的特性进行了分析;给出了经试验验证的旋转旋翼动柔度表达式。算例证实本文提出的力学模型、分析方法以及这类吸振器的有效性。     

多维动力吸振器对复杂悬臂结构减震之应用

一个复杂悬臂结构在20赫芝附近有两个密接的共振峰,导致结构根部破坏。本文提出了用多维动力吸振器对它进行减震,为了克服通常的调谐吸振器对结构频率十分敏感的缺点,在结构的某一截面上悬挂了六个吸振器,吸振器随着结构沿任意方向振动,而且六个吸振器的刚度与阻尼参数可以互不相同,以展宽其吸振频带,为了寻找最优参数和研究这些参数变化时对结构响应之影响,计算了大量的响应曲线,因为结构阻尼很小,吸振器阻尼较大,所以这是一个非比例阻尼的动力分析问题。本文用复特征解法和模态综合法处理了这个问题。     

转子吸振器挤压油膜系统的研究

本文发展了传统的动力吸振器,提出了用于旋转机械减振的转子吸振器。研究了刚性转子、柔性Je-ffcott转子在挤压油膜阻尼器、转子吸振器减振作用下的动力特性,并进行了初步试验研究。研究表明转子吸振器能有效地改善转子系统的动力特性,为旋转机械的减振提供了一种新方法。      

An active vibration control method based on energy-fuzzy for cantilever structures excited by aerodynamic loads

In wind tunnel tests for the full-model fixed with sting, the low structural damping of the long cantilever sting results in destructive low-frequency and large-amplitude vibration. In order to obtain high-quality wind tunnel test data and ensure the safety of wind tunnel tests, an energy-fuzzy adaptive PD (Proportion Differentiation) control method is proposed. This method is used for active vibration control of a cantilever structure under variable aerodynamic load excitation, and real-time adjustment of parameters is achieved according to the system characteristics of vibration energy. Meanwhile, a real-time method is proposed to estimate the real-time vibration energy through the vibration acceleration signal, and the average exciting power of aerodynamic load is obtained by deducting the part of the power contributed by the vibration suppressor from the total power. Furthermore, an energy-fuzzy adaptive PD controller is proposed to achieve adaptive control to the changes of the aerodynamic load. Besides, the subsonic and transonic experiments were carried out in wind tunnel, the results revealed that comparing to fixed gain PD controllers, the energy-fuzzy adaptive PD controller maintains higher performance.     

基于导航姿态解算的光纤陀螺平台低频角振动测试方法研究CSCD

为准确评价光纤陀螺平台的低频角振动特性,提出了一种基于导航姿态解算的光纤陀螺平台低频角振动测试方法。首先,通过角振动台精确模拟载体的低频角振动状态,并通过光纤陀螺平台飞行导航过程中的断调平差分信号,实现平台框架角度信号与角振动台激励角度信号的数据同步;然后,利用平台式惯导系统的导航姿态解算方法,实时解算低频角振动过程中光纤陀螺平台的台体姿态,并通过坐标系转换得到平台基座系相对于地理系的实时姿态;最后,通过对光纤陀螺平台稳定回路的幅相特性分析,得到低频角振动激励下稳定回路的幅值和相位特性,实现对光纤陀螺平台角动态特性的准确评估。     

An active damping vibration control system for wind tunnel models

In wind tunnels, long cantilever sting support systems with low structural damping encounter flow separation and turbulence during wind tunnel tests, which results in destructive low-frequency and big-amplitude resonance, leading to data quality degradation and test envelope limitation. To ensure planed test envelope and obtain high-quality data, an active damping vibration control system independent of balance signal based on stackable piezoelectric actuators and velocity feedback using accelerometer, is proposed to improve the support stability and wind tunnel testing safety in transonic wind tunnel. Meanwhile, a design of powerful sting-root embedded active damping device is given and an active vibration control method is presented based on the mechanism analysis of aircraft model vibration. Furthermore, a self-adaptive fuzzy Proportion Differentiation(PD) control model is proposed to realize control parameters adjustment automatically for various testing conditions. Besides, verification tests are performed in laboratory and a continuous transonic wind tunnel. Experimental results indicate that the aircraft model does not vibrate obviously from -4° to 11° at Ma = 0.6, the number of useable angle-of-attack has increased by 7° at Ma = 0.6 and 5° at Ma = 0.7 respectively, satisfying the requirements of practical wind tunnel tests.     

基于扩张状态观测器的DGMSCMG框架伺服系统振动抑制方法

针对带有谐波减速器的双框架磁悬浮控制力矩陀螺(DGMSCMG)框架系统存在较低频率谐振点的问题,提出了一种基于扩张状态观测器(ESO)振动抑制的控制方法。在谐波减速器的输入端和输出端分别设计三阶扩张状态观测器,通过电机及负载端的角位置信号不但能够估计电机和负载的角速率,而且可以比较准确地估计到扭转刚度的非线性变化及外部扰动力矩引起的综合扰动,通过反馈及前馈补偿对综合扰动进行抑制。设计的基于扩张状态观测器的控制器抑制了框架伺服系统的振动、提高了框架的速率输出精度。仿真及实验结果表明了该控制算法是有效的并具有较强的鲁棒性。     

用于直升机振动控制的主动调谐式吸振器研究

振动问题是直升机设计中的难题,会导致机体结构疲劳、舒适性降低和高噪声等问题。通常的单桨叶控制方案由于受压电驱动器机电性能的限制而难以实现。智能弹簧是一种采用单桨叶控制原理的主动调谐式吸振器,它通过压电驱动器自适应控制桨叶根部的结构阻抗,达到振动控制目的。建立了智能弹簧的简化模型,对其谐波响应控制特性进行研究;采用频率分析和数字信号合成技术产生参考信号,在DSP平台上设计自适应陷波算法对智能弹簧驱动器组件进行控制;模拟和风洞实验结果均表明智能弹簧能够在较宽频率范围内对桨叶的谐波响应进行有效控制,验证了通过主动阻抗控制实现直升机桨叶振动控制的可行性。     

Synchronous chirp mode extraction: A promising tool for fault diagnosis of rolling element bearings under varying speed conditions

As critical components in modern aerospace productions, rolling element bearings(REBs) generally work under varying speed conditions, which brings great challenges to their operating health monitoring. Some novel time–frequency decomposition(TFD) algorithms are established recently to extract nonlinear features from the non-stationary signals effectively, which are promising for realizing fault diagnosis of REBs under varying speed conditions. However, numerous personal experiences must be incor...     

失谐叶栅的受迫振动响应特性分析

采用基于计算流体力学(CFD)方法的降阶气动力模型并耦合结构运动方程,实现了存在外激励载荷时失谐叶栅受迫振动响应的快速分析。针对典型的跨声速叶栅,通过求解其位移响应幅值较系统地研究了失谐方式、失谐强度和叶片质量比对失谐叶栅受迫振动响应幅值的影响。研究表明文中刚度失谐形式可以改善叶栅振动的稳定性,同时导致系统受迫振动响应局部化程度的增加,并且受迫响应的最大振幅放大因子随失谐强度增加或者质量比降低存在先增大后减小的一个峰值,不同失谐形式则对这个峰值的大小有着明显的影响。由于该方法可高效地分析失谐叶栅受迫振动各参数对模态局部化的影响,在工程上有一定的应用价值。     

Vibration signal-based chatter identification for milling of thin-walled structure

In high speed milling aeronautical part, tool condition monitoring(TCM) is very important, because it is prone to get a chatter owing to the low stiffness of thin-walled structures. And the TCM is key technology for automated machining. In this paper, aiming to chatter monitoring in thin-walled structure milling, a variational mode decomposition – energy distribution(VMD-ED)method is proposed to improve the identification accuracy. And a moving average root mean square – mean value(MARMS-MV) ide...     

In-process adaptive milling for large-scale assembly interfaces of a vertical tail driven by real-time vibration data

Assembly interfaces, the joint surfaces between the vertical tail and rear fuselage of a large aircraft, are thin-wall components. Their machining quality are seriously restricted by the machining vibration. To address this problem, an in-process adaptive milling method is proposed for the large-scale assembly interface driven by real-time machining vibration data. Within this context, the milling operation is first divided into several process steps, and the machining vibration data in each pro...     

Experimental and modeling study of surface topography generation considering tool-workpiece vibration in high-precision turning

High-precision turning(HPT) is a main processing method for manufacturing rotary high-precision components, especially for metallic parts. However, the generated vibration between tool tip and workpiece during turning may seriously deteriorate the surface integrity. Therefore,exploring the effect of vibration on turning surface morphology and quality of copper parts using3D surface topography regeneration model is crucial for predicting HPT performance. This developed model can update the machin...