Vibration analysis of rolling element bearings with various defects under the action of an unbalanced force

In this paper, a method based on the finite element vibration analysis is presented for defect detection in rolling element bearings with single or multiple defects on different components of the bearing structure using the time and frequency domain parameters. A dynamic loading model is proposed in order to create the nodal excitation functions used in the finite element vibration analysis as external loading. A computer code written in Visual Basic programming language with a graphical user interface is developed to create the nodal excitations for different cases including the outer ring, inner ring or rolling element defects. Forced vibration analysis of a bearing structure is performed using the commercial finite element package I-DEAS under the action of an unbalanced force transferred to the structure via a ball bearing. Time and frequency domain parameters such as rms, crest factor, kurtosis and band energy ratio for the frequency spectrum of the enveloped signals are used to analyse the effect of the defect location and the number of defects on the time and frequency domain parameters. The role of the receiving point for vibration measurements is also investigated. The vibration data for various defect cases including the housing structure effect can be obtained using the finite element vibration analysis in order to develop an optimum monitoring method in condition monitoring studies.     

A review of vibration and acoustic measurement methods for the detection of defects in rolling element bearings

A review of vibration and acoustic measurement methods for the detection of defects in rolling element bearings is presented in this paper. Detection of both localized and distributed categories of defect has been considered. An explanation for the vibration and noise generation in bearings is given. Vibration measurement in both time and frequency domains along with signal processing techniques such as the high-frequency resonance technique have been covered. Other acoustic measurement techniques such as sound pressure, sound intensity and acoustic emission have been reviewed. Recent trends in research on the detection of defects in bearings, such as the wavelet transform method and automated data processing, have also been included.     

Application of acoustic emission technique for the detection of defects in rolling element bearings

The usefulness of acoustic emission (AE) measurements for the detection of defects in roller bearings has been investigated in the present study. Defects were simulated in the roller and inner race of the bearings by the spark erosion method. AE of bearings without defect and with defects of different sizes has been measured. For small defect sizes, ringdown counts of AE signal has been found to be a very good parameter for the detection of defects both in the inner race and roller of the bearings tested. However, the counts stopped increasing after a certain defect size. Distributions of events by ringdown counts and peak amplitudes are also found to be good indicators of bearing defect detection. With a defect on a bearing element, the distributions of events tend to be over a wider range of peak amplitudes and counts.     

Fault diagnosis of rolling element bearing using a new optimal scale morphology analysis method

Periodic transient impulses are key indicators of rolling element bearing defects. Efficient acquisition of impact impulses concerned with the defects is of much concern to the precise detection of bearing defects. However, transient features of rolling element bearing are generally immersed in stochastic noise and harmonic interference. Therefore, in this paper, a new optimal scale morphology analysis method, named adaptive multiscale combination morphological filter-hat transform (AMCMFH), is proposed for rolling element bearing fault diagnosis, which can both reduce stochastic noise and reserve signal details. In this method, firstly, an adaptive selection strategy based on the feature energy factor (FEF) is introduced to determine the optimal structuring element (SE) scale of multiscale combination morphological filter-hat transform (MCMFH). Subsequently, MCMFH containing the optimal SE scale is applied to obtain the impulse components from the bearing vibration signal. Finally, fault types of bearing are confirmed by extracting the defective frequency from envelope spectrum of the impulse components. The validity of the proposed method is verified through the simulated analysis and bearing vibration data derived from the laboratory bench. Results indicate that the proposed method has a good capability to recognize localized faults appeared on rolling element bearing from vibration signal. The study supplies a novel technique for the detection of faulty bearing.     

轧钢机主传动系统扭振故障分析

在测量和计算了产生轧钢机主传动系统扭振故障的轧制力矩基础上,分析了引起轧钢机主传动系统扭振的原因;设计了扭振监测、诊断和控制系统,这个系统在钢铁企业的应用取得了令人满意的效果。     

基于小波原理的滚动轴承振动信号包络提取法

小波分析是获得广泛应用的信号处理新技术。这里根据小波能对信号包络提取的原理对滚动轴承的振动信号进行了研究，应用基于小波原理的自信息包络提取法，同时把该方法应用于分析滚动轴承故障，证明该方法能更有效地提取滚动轴承的信号包络，适用于分析滚动轴承故障。     

滚动轴承动力学仿真与分析

为研究滚动轴承的动态特性和振动特性,在ANSYS/LS-DYNA中建立了滚动轴承有限元模型,对外圈固定,内圈施加压力和转速,实现了滚动轴承的显式动力学仿真,得到了滚动轴承的应力分布和动态响应。仿真结果表明,滚动轴承最大应力出现在滚动体与内圈和外圈接触处,滚动体的最大线速度和最小线速度分别出现在滚动体与内圈和外圈接触点上,滚动体受到的应力最大,保持架的应力变化最为剧烈。     

起重机用滚动轴承有限元分析及故障检测

针对起重机用滚动轴承故障率高且难以检测的问题,首先采用Ansys软件对起重机用滚动轴承进行基于实际接触状态的有限元分析,然后采用基于小波包能量法和Hilbert变换方法对滚动轴承进行信号处理、分析以及故障检测。结果表明:滚动轴承的滚动体与内外圈接触部位存在较大应力集中,最易在此处首先发生破坏;根据轴承故障特征频率与内圈、外圈、滚动体三种故障类型所对应的频谱特征和能量谱相比较,可有效判断轴承故障类型。研究所采用的检测方法可为起重机用滚动轴承的故障预防和检测提供一定理论依据和指导作用。     

A weighted multi-scale morphological gradient filter for rolling element bearing fault detection

This paper presents a novel signal processing scheme, named the weighted multi-scale morphological gradient filter (WMMG), for rolling element bearing fault detection. The WMMG can depress the noise at large scale and preserve the impulsive shape details at small scale. Both a simulated signal and vibration signals from a bearing test rig are employed to evaluate the performance of the proposed technique. The traditional envelope analysis and a multi-scale enveloping spectrogram algorithm combining continuous wavelet transform and envelope analysis (WT-EA) are also studied and compared with the presented WMMG. Experimental results have demonstrated the effectiveness of the WMMG to extract the impulsive components from the raw vibration signal with strong background noise. We also investigated the classification performance on identifying bearing faults based on the WMMG and statistical parameters with varied noise levels. Application results reveal that the WMMG achieves the same or better performance as EA and WT-EA. Meanwhile, the WMMG requires low computation cost and is very suitable for on-line condition monitoring of bearing operating states.     

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.     

A 3-D finite element method analysis of cold rolling of thin strip with friction variation

In this paper, a three-dimensional rigid-plastic finite element method (FEM) model to simulate the cold rolling of thin strip with different friction models is described. The effects of rolling parameters, such as work roll diameters and reductions, are analysed in this study. The simulation and experimental values of rolling pressure and spread (the difference of strip width before and after rolling) show a good agreement when friction variation in the roll bite is considered. The roll separating force, spread and forward slip for constant friction and friction variation models are also compared. The friction variation in the roll bite has a significant effect on the simulation results.     

滚动轴承噪声与振动测试环境系统的改进

针对常规轴承噪声与振动测试环境系统的不足,提出一种更加完善的轴承噪声与振动测试系统。该系统采用房中房结构,内房和外房采用浮动连接,轴承驱动装置设计为穿墙驱动与无级调速等;测量载荷设计为无级可调,自动加载,测试装置所处环境的周边安装吸声尖劈,减少了外界环境的干扰。该测试环境系统用于测试和分析中小型家电轴承、电机轴承、汽车轴承、医疗器械等用各类轴承的噪声和振动,也可以测试轴承声压级噪声和声功率级噪声等。     

轴承辗扩锻件常见缺陷的形成和预防

针对轴承碾扩锻件常见缺陷,分析了产生的原因,提出了避免的具体措施,对提高成品锻件质量有一定帮助     

基于神经网络的滚动轴承振动预测

以神经网络与MATLAB实现理论为依据,提出了一种新的滚动轴承振动预测方法。这种方法根据轴承的加工质量试验数据,建立轴承振动预测的BP网络试验模型,在MATLAB开发环境下输入训练样本数据矩阵和目标矩阵。经过训练后,网络误差达到要求,预报结果的最大相对误差小于10％。     

Bi-spectrum based-EMD applied to the non-stationary vibration signals for bearing faults diagnosis

Empirical mode decomposition (EMD) has been widely applied to analyze vibration signals behavior for bearing failures detection. Vibration signals are almost always non-stationary since bearings are inherently dynamic (e.g., speed and load condition change over time). By using EMD, the complicated non-stationary vibration signal is decomposed into a number of stationary intrinsic mode functions (IMFs) based on the local characteristic time scale of the signal. Bi-spectrum, a third-order statistic, helps to identify phase coupling effects, the bi-spectrum is theoretically zero for Gaussian noise and it is flat for non-Gaussian white noise, consequently the bi-spectrum analysis is insensitive to random noise, which are useful for detecting faults in induction machines. Utilizing the advantages of EMD and bi-spectrum, this article proposes a joint method for detecting such faults, called bi-spectrum based EMD (BSEMD). First, original vibration signals collected from accelerometers are decomposed by EMD and a set of IMFs is produced. Then, the IMF signals are analyzed via bi-spectrum to detect outer race bearing defects. The procedure is illustrated with the experimental bearing vibration data. The experimental results show that BSEMD techniques can effectively diagnosis bearing failures.     

Faults diagnosis of rolling element bearings based on modified morphological method

In order to effectively smooth noise and extract the impulse components in the vibration signals of defective rolling element bearings, a new modified morphology analytical method has been proposed. In this method, average of the closing and opening operator has been used as the morphology operator. Being the flat and zero adopted as the shape and the height of structure element (SE), respectively, the optimized length of SE is defined by a new proposed criterion (called SNR criterion). The effect of the new method is validated by both simulated impulsive signal and vibration signal of three defective rolling bearings with an outer, an inner and a rolling element faults and compared with Nikolaou’s method. The result shows that the proposed method has the superior performance in extracting impulsive characteristics of vibration signals, especially for the high level noise signals, and can implement better in diagnosis of defective rolling element bearing.     

Simulating gear and bearing interactions in the presence of faults: Part II: Simulation of the vibrations produced by extended bearing faults

This paper presents a combined dynamic model for gears and bearings, in which an extended fault in the inner/outer race of rolling element bearings can be studied in the presence of gear interaction. A combined gear/bearing model has been made to obtain a better understanding of the interaction of the two components. The essentials of the gear/bearing model and the results of simulating the vibration of localized faults in rolling element bearings in a gearbox environment have been discussed and illustrated in the first part of this paper (part I). The simulation model has now been modified to model extended faults of the type that do not necessarily produce high frequency impact responses, but do modulate the gearmesh signals. The paper compares the simulated and actual signals from the gear/bearing test rig for inner and outer race extended faults, and in particular demonstrates that they react similarly to existing diagnostic techniques.     

Diagnosis of faults in rolling element bearings by using directional spectra of vibration signals

Backward and forward defect frequencies of rolling element bearings are experimentally investigated utilizing the two-sided directional spectra of the complex-valued vibration signals measured from the outer ring of defective bearings. The experimental results show that the directional zoom spectrum is superior to the conventional spectrum in identification of bearing defect frequencies, in particular the inner race defect frequencies.     

滚动轴承振动的模拟和实验分析

模拟任何振动系统的振动,都必须要先解决两个基本问题:首先就是振动激励,即引起振动的作用力问题,其次是振动系统的动态性能问题。现研究一下,球轴承在传动装置中按轴承工业常规方法进行实验时,其外圈的振动[1]。文献[2]已解决的是,球和套圈沟道具有波纹度之类工艺误差的球轴承在轴向载荷下的振动激励问题,从而可以确定套圈及钢球的谐波与轴向、径向和角向振动激励的频谱之间的关系。径向振动激励的相应关系式(初次近似的频谱)列于表1中。根据资料得知,只有钢球和套圈沟道波纹度谐波为偶数时,才会引起径向振动激励,其谐波号与钢球数ｎ的倍数…     

基于有限元的摩托车振动分析与控制

振动是影响汽车、摩托车等车辆乘坐舒适性和可靠性的重要因素,运用有限元分析和实验模态分析方法对车辆的 振动进行分析,可以将振动问题在设计阶段解决,以缩短产品开发周期,节约开发成本。以摩托车为对象,建立了摩托车 的有限元模型,对模型进行理论模态分析和谐响应分析,并用实验分析对比验证理论模型,通过分析找到摩托车振动的 原因和控制振动的有效方法。