涡流探伤技术诊断与监测齿轮裂纹

振动诊断与监测技术是检测齿轮裂纹的方法之一,近年来受到越来越普遍的重视。国内外学者已经找到了许多用来诊断齿轮裂纹的方法,如频谱分析法、倒频谱分析法、时间平均法、幅值和相位解调法等,这些方法都获得了一定的成功,但对微小的裂纹都很难给出准确可靠的诊断。与此相比,用于静态检验的     

齿轮早期疲劳裂纹诊断的研究

在分析齿轮振动信号的幅值调制和相位调制信息的基础上 ,通过实验研究提出一种诊断齿轮早期疲劳裂纹的方法     

旋转机械振动诊断的AE信号处理技术

声发射(AE)技术,是采用声学的方法处理材料中微裂纹发生时所产生的弹性波信息.它可以获得用其它方法难以检测的微裂纹发生,发展的信号大小、频度及位置等信息.AE技术在工程监视、质量管理、设备诊断中,取得越来越广泛的应用.近年对旋转机械的振动故障诊断倍受重视.本文应用WFT频率分析技术,实现快速、可靠地处理AE信号.     

单级齿轮箱的振动监测

从裂纹齿局部刚度变弱的情况出发，研究裂纺故障对齿轮合振动的影响。分析了裂纹故障引起的相位调制信息的分布规律及传递特性，并分别研究了单齿裂故障的相位诊断。通过在单级齿轮箱上进行的裂纹齿轮故障诊断实验研究行知，裂纹齿局部刚度变弱，反映出相位周期性跃方向和测点与故障在传动系统中的相对位置有关，以识别局部故障所在位置。     

齿轮故障识别

通过对振动信号进行解调,提取相位调制信号,得到了故障信息。根据齿轮啮合振动频谱,对齿轮的裂纹进行诊断。     

用振动相位信息提取齿轮疲劳裂纹特征

本文根据齿轮局部啮合刚度变化引起振动信号时间的延迟,指出振动信号的时域相位跳变信息反映齿轮疲劳裂纹特征,并且利用希尔伯特变换原理由解析信号提取相位,通过对齿轮疲劳裂纹实测,这个特征在诊断齿轮故障中得到证实。     

基于共振区幅值-相位解调技术的早期齿轮齿根裂纹故障检测

常用齿轮故障诊断方法中窄带解调分析存在低频干扰的问题,共振解调分析不涉及相位调制信息。针对传统方法的不足,提出了一种以共振频率作为载波的共振区幅值-相位解调技术。方法首先通过快速谱峭度算法寻找齿轮振动信号的共振区,然后在共振区中通过幅值最大搜索法获得共振频率,并以该共振频率为载频进行解调分别得到幅值和相位调制信号。该方法结合共振区对弱信号的放大以及对低频干扰的隔离作用,可有效提取齿轮的故障信息。仿真及试验研究表明,所提出的共振区幅值-相位解调技术可以有效检测早期齿轮齿根裂纹故障信息,是对传统方法的有效补充。     

相位在风机振动监测中的应用

针对当前风机振动监测与诊断存在的误区,提出了振动相位的概念和测量方法,介绍了振动相位所包含的故障信息,指出了振动相位对于振动分析的重要性.     

转轴横向裂纹诊断的扭振监测法

对调相信号进行解调,提取相位调制信号,可得到扭振信息。用最大熵谱检测扭转转频的二次分量大小和变化,对转轴组件的裂纹进行诊断。     

旋转机械振动诊断的AE信号处理技术

声发射(AE)技术，是采用声学的方法处理材料中微裂纹发生时所产生的弹性波信息。它可以获得用其它方法难以检测的微裂纹发生，发展的信号大小、频度及位置等信息。AE技术在工程监视、质量管理、设备诊断中，取得越来越广泛的应用。近年对旋转机械的振动故障诊断倍受重视。本文应用WFT频率分析技术，实现快速、可靠地处理AE信号。     

机车关键部位焊缝随车检测的开发

目前机车的关键部位焊缝裂纹没有准确的预测方法,本文采用涡流检测技术,应用DDS芯片,开发出一套机车焊缝随车检测装置。该装置能够产生频率和相位可控的信号激励涡流传感器,同时能够对涡流传感器二次绕组的反馈信息进行幅值和相位分析,并能将反映焊缝状态的信息传送到机车的故障诊断系统中完成故障诊断。     

基于全矢谱的旋转机械回转相位及应用研究

研究了旋转机械故障诊断中转子截面相互垂直两个同频信号的相位差信息,揭示了相互垂直两个信号的不同相位差对应不同的合成运动轨迹图形,推导出全矢谱分析理论中初相位的角度大小,并由初相位绘制出双截面、多截面转子的空间振形,最后通过实例将全矢谱理论结合转子空间振形和初始相位差信息应用到旋转机械不平衡故障分类中。结果表明:由初相位绘制的空间振形图可以有效地区分旋转机械不平衡故障中发生的具体形式,提高了故障诊断的准确性。     

GEARBOX FAULTDIAGNOSIS BASED ON EMPIRICAL MODE DECOMPOSITION

Time synchronous averaging of vibration data is a fundament technique for gearbox diagnosis. Currently, this technique relies on hardware tachometer to give phase synchronous information. Empirical mode decomposition (HMD) is introduced to replace time synchronous averaging of gearbox vibration signal. With it, any complicated dataset can be decomposed into a finite and often small number of intrinsic mode functions (IMF). The key problem is how to assure that vibration signals deduced by gear defects could be sifted out by HMD. The characteristic vibration signals of gear defects are proved IMFs, which makes it possible to utilize EMD for the diagnosis of gearbox faults. The method is validated by data from recordings of the vibration of a single-stage spiral bevel gearbox with fatigue pitting. The results show EMD is powerful to extract characteristic information from noisy vibration signals.     

On the Application of Six-Port Technology (SPT) in Ultrasonic Imaging for Medical Diagnosis

In this paper, an introduction of six-port technology to ultrasonic imaging for medical diagnosis is presented for the first time. Calculations are made to explore the possibilities and advantages of this application. Analysis shows that the introduction of six-port technology for medical ultrasonic imaging to detect the phase information of the reflected signal will improve the measurement accuracy and simplify the instrumentation of imaging technologies used in medical diagnosis.     

一种转速信号测量和相位信息获取的方法

为了得到在旋转机械的振动监测与故障诊断中起着至关重要作用的转速和相位信息,介绍了一种利用鉴相脉冲触发各振动信号并行采集及获取转子转速和各振动信号相位的方法,这种软硬件触发采集的方式不仅可以实现整周期采样,而且可大大减小相位误差。实例验证了鉴相信号在相位信息的获取中起着决定性的作用。     

基于1 1／2维谱的滚动轴承故障诊断

提出了基于１１／２维谱的滚动轴承故障诊断新方法。１１／２维谱保留了信号的相位信息且能够有效抑制噪声。用１１／２维谱分析滚动轴承振动信号,可以提取由于二次相位耦合产生的非线性特征,识别故障模式。试验结果表明,这种方法能有效地诊断滚动轴承故障,且对初期故障很敏感。     

An improved data fusion technique for faults diagnosis in rotating machines

The composite spectrum (CS) data fusion technique has been shown to simplify rotating machines faults diagnosis by earlier studies. Faults diagnosis with the earlier CS relied solely on the amplitudes of several harmonics of the machine speed, owing to the loss of phase information leading to its computation. The proposed improved CS applies the concept of cross power spectrum density for computing a poly-Coherent Composite Spectrum (pCCS) of a machine, which retains amplitude and phase information at all measurement locations. The present study compares the proposed pCCS method with the earlier CS method for faults diagnosis in rotating machines, using experimental data from a rotating rig. Results and observations show that the proposed pCCS offered a much better representation of the machines dynamics when compared to the earlier CS method and hence better fault diagnosis.     

故障诊断综合信息Petri网的研究

为了解决故障诊断中的冲突消解问题,将故障概率信息和管理信息引入模糊Ｐｅｔｒｉ网,故障诊断综合信息网模型。研究了基于综合信息网的故障诊断问题,对故障进行分类、分析了不同类型的故障诊断所需管理信息的内容,确立了概率与管理信息的关系,通过机械手掉刀故障的诊断,验证了该模型和方法的正确性与可行性。     

双相干谱和RBF网络在旋转机械故障诊断中的应用

双相干谱保留了信号的相位信息，可以用来描述非线性相位的耦合，径向基函数网络具有良好的推广能力和分类能力。文中将双相干谱和径向基函数网络结合，提出一种基于双相干谱与径向基函数网络相结合的旋转机械故障诊断方法，即以双相干谱为故障特征向量，以径向基函数网络作为分类器，对旋转机械的故障进行分类，并以转子不平衡、转轴碰摩、油膜涡动为例进行实验研究。实验结果表明，结合双相干谱和径向基函数网络的旋转机械故障诊断方法是有效的。     

Hilbert versus Concordia transform for three-phase machine stator current time-frequency monitoring

This paper deals with mechanical fault diagnosis in three-phase induction machines from stator current measurements. According to machine models, mechanical faults lead to amplitude and/or phase modulations of the measured stator current with possibly time varying carrier frequency. The modulation diagnosis requires a univocal definition of the instantaneous phase and amplitude. This is performed by associating a complex signal to the real measured one. For a convenient separate modulation diagnosis, the complex signal instantaneous phase and amplitude are expected to carry, respectively, information about the phase and amplitude modulations. The complex signal is classically obtained through the Hilbert transform. Under Bedrosian conditions, the so-called analytic signal allows a separate modulation diagnosis. However, mechanical faults may also produce fast modulations violating the Bedrosian conditions. This study proposes an alternative complex signal representation which takes advantage of the three stator current measurements available in a three-phase machine. From two stator current measurements, the Concordia transform builds a complex vector, the so-called space vector, which unconditionally allows separate modulation diagnosis. This paper applies and compares the Hilbert and Concordia transforms, theoretically and in case of simulated and experimental signals with various modulation frequency ranges.