Measurement 45 (2012) Contents lists available at SciVerse ScienceDirect. Measurement
|
|
- Charlotte Willis
- 6 years ago
- Views:
Transcription
1 Measurement 45 (22) Contents lists available at SciVerse ScienceDirect Measurement journal homepage: Faulty bearing signal recovery from large noise using a hybrid method based on spectral kurtosis and ensemble empirical mode decomposition Wei Guo, Peter W. Tse, Alexandar Djordjevich The Smart Engineering Asset Management Laboratory and the Croucher Optical Nondestructive Testing Laboratory, Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Ave., Kowloon Tong, Hong Kong article info abstract Article history: Received 8 November 2 Received in revised form 26 October 2 Accepted 5 January 22 Available online 24 January 22 Keywords: Ensemble empirical mode decomposition Spectral kurtosis Signal filtering Bearing fault diagnosis Time frequency analyses are commonly used to diagnose the health of bearings by processing vibration signals captured from the bearings. However, these analyses cannot be guaranteed to be robust if the bearing signals are overwhelmed by large noise. Ensemble empirical mode decomposition (EEMD) was developed from the popular empirical mode decomposition (EMD). However, if there is large noise, it may be difficult to recover impulses from large noise. In this paper, we develop a hybrid signal processing method that combines spectral kurtosis (SK) with EEMD. First, the raw vibration signal is filtered using an optimal band-pass filter based on SK. EEMD method is then applied to decompose the filtered signal. Various bearing signals are used to validate the efficiency of the proposed method. The results demonstrate that the hybrid signal processing method can successfully recover the impulses generated by bearing faults from the raw signal, even when overwhelmed by large noise. Ó 22 Elsevier Ltd. All rights reserved.. Introduction Rolling bearings are the most important elements in rotating machinery. Unfortunately, bearings frequently fall out of service for various reasons, such as unexpected heavy loads, inadequate or unsuitable lubrication, careless handling, and ineffective sealing. The occurrence of serious bearing faults in a machine may cause a decrease in performance. In the worst case, this results in downtime costs, significant damage to other parts of the machine, or even catastrophic failure []. Hence, the analysis of bearing vibration signals has attracted great attention in the field of condition monitoring and fault diagnosis, as these signals give rich information for the early detection of bearing failures. However, in the early stage of bearing failure, the amplitude or energy of the defects in the vibration signal is somewhat weak, and is often overwhelmed or concealed Corresponding author. Tel.: ; fax: address: meptse@cityu.edu.hk (P.W. Tse). by large noise and other structural vibrations. The recovery of the bearing vibration signal from noise while preserving its important features, including the defect features, remains a challenging problem for both signal processing and statistics [2]. Several linear filtering methods that are easy to design and implement, such as the Wiener filter and the Kalman filter, have been proposed to reduce the noise. However, in practice, machine processes often contain complex, non-stationary, noisy, and nonlinear characteristics [3], and adaptive signal processing techniques may be more suitable for vibration signal processing and analysis. The most popular signal processing methods for vibration analysis are envelope analysis [4] and wavelet transforms [5 7]. Although envelope analysis is effective in many cases, the method requires the designer to know the band filter around a resonance frequency, and it is ineffective in the presence of a high noise level [8]. One of the main problems with the wavelet transform and wavelet packet methods is the non-adaptive basis. A mother wavelet must /$ - see front matter Ó 22 Elsevier Ltd. All rights reserved. doi:.6/j.measurement.22..
2 W. Guo et al. / Measurement 45 (22) be carefully chosen so that the content of her daughter wavelets are largely similar to that of the analyzed signal to ensure good results. Although many new and complicated basic functions have been proposed to improve the effectiveness of wavelet-based methods [9 ], to date no general guideline has been proposed for the correct selection of a mother wavelet. At the same time, little attention has been paid to the inherent deficiencies of the wavelet transform, such as border distortion and energy leakage [2,3]. The ensemble empirical mode decomposition (EEMD) [4] was developed from the popular empirical mode decomposition (EMD) [5,6], which is an adaptive signal analysis method and represents a nonlinear and non-stationary signal as the sum of some signal components with amplitude and frequency modulated parameters [7], called intrinsic mode functions (IMFs) [5]. In EEMD method, white noise is introduced to help to separate disparate time scales and improve the decomposition performance of the normal EMD method. The ensemble means are chosen as the final results to minimize the effect caused by the added white noise. With the strategy of adding white noise to the analyzed signal, EEMD method can be used as a nonlinear and adaptive filter that can extract weak periodic or quasi-periodic signals from noisy signals, and especially faulty bearing signals in the presence of large noise. However, in some extreme cases, such as when the real bearing signal is completely overwhelmed by large noise, it is difficult for the EEMD to identify the impacts generated by faulty bearing elements. This is because the core algorithm of EEMD method is signal decomposition using EMD method, which is based on the existence of the extremes of a signal. When the signal is contaminated by large noise, the extremes of interest are hidden in the noise and EEMD method cannot discriminate the real bearing signal from the noise. A preprocessing method is thus needed for signal decomposition using EEMD method. Spectral kurtosis (SK) [8 2] has been proven to be efficient in detecting incipient faults buried in large noise, and offers a means of designing an optimal filter to extract faulty bearing signals. Based on the estimation of SK, filters, such as an optimal band-pass filter, are easier to implement and can recover the real bearing signal from the mask of large noise. However, there is a compromise between incipient detection ability and signal distortion, and in most cases the filtered signal still contains some noise. A signal with a higher signal-to-noise ratio can be obtained using other filters, but at the expense of further signal distortion. Applying EEMD method to the filtered signal allows the feature signal of the faulty bearing to be adaptively separated from the remaining noise without attenuating the signal amplitude or energy. In this paper, a hybrid signal processing method that combines spectral kurtosis (SK) with EEMD is proposed to recover faulty bearing signals from large noise. In this method, an optimal band-pass filter based on SK is first designed to filter the raw vibration signal to provide the necessary extremes for further signal decomposition. The filtered signal is then decomposed using EEMD method. The impulses generated by the faulty elements of the bearing are extracted from the noisy vibration signal. Noise and the other irrelevant components are thus separated from the real bearing signal. The visibility of the impulses from the faulty bearing is observably improved. The remainder of this paper is organized as follows. Section 2 briefly introduces EEMD method and compares its performance in decomposing vibration signals with EMD method. Section 3 first uses vibration signals collected from faulty bearings to analyze the individual performances of EEMD method and the filter based on SK. By considering the advantages and limitations of these methods in processing vibration signals masked by large noise, a hybrid signal processing method is proposed that combines the optimal band-pass filter based on SK and EEMD method to recover the signals of faulty bearings in large noise situations. Section 4 shows and analyzes the resultant signals by applying the proposed hybrid method to experimental and real vibration signals from faulty bearings installed in an experimental DC motor and a real traction motor. Section 5 conducts fault diagnoses on the resultant signals to validate the efficiency of the proposed hybrid method in terms of the detection of incipient bearing defects. Finally, conclusions are drawn in Section Ensemble empirical mode decomposition 2.. Brief introduction Ensemble empirical mode decomposition (EEMD) method [4] is developed from the popular empirical mode decomposition (EMD) method [5,6], which is an adaptive method to represent a nonlinear and non-stationary signal as the sum of signal components with amplitude and frequency modulated parameters and is also capable of revealing overlapping in both time and frequency components [7]. EEMD method provides the improvement over the normal EMD method and solves the problem of mode mixing when the analyzed signal contains high-frequency intermittent oscillations. It consists of sifting an ensemble of white-noise-added signals and treats the mean as the final result. Although each individual signal decomposition will generate a relatively noisy result, the added white noise is necessary to force the sifting process to visit all possible solutions in the finite neighborhood of real extreme and then generates different solutions for the final IMF [4]. Meanwhile, the zero mean of white noise is helpful for the cancellation of the added white noise in the final ensemble mean if there are sufficient trails. Hence, only the signal itself can survive in the final decomposition result. It is applicable for analyzing and identifying the vibrations in rotating machines. For more details about EEMD method, please refer to Ref. [4]. The procedure of the EEMD method is listed as follows: Step : Initialize parameters: the ensemble number, N E, and the amplitude of the added white noise, a, which is a fraction of the standard deviation of the signal to be analyzed. The index of the ensemble starts from, m =. Step 2: Perform the mth signal decomposition using the EMD method: decompose the white noise-added signal,
3 3 W. Guo et al. / Measurement 45 (22) x m = x + n m, where n m is the added white noise with the presetting amplitude, and x is the signal to be analyzed. The decomposition result is some simple signal components called intrinsic mode functions (IMFs) [5], c i,m, i =,2,..., N IMF, and a non-zero low-order residue, r m, where N IMF is the number of IMFs obtained in each decomposition. Step 3: Repeat Step 2 with m = m + until the index m reaches the presetting ensemble number, N E. Step 4: Obtain the final decomposition results by calculating the means of corresponding IMFs and the residue obtained from each signal decomposition process Parameter setting As the procedure for EEMD method indicates, two critical parameters, the amplitude of the added white noise and the ensemble number need to be prescribed. These parameters directly affect the decomposition performance of EEMD method. Wu and Huang [4] gave the relationship among the ensemble number, N E, the amplitude of the added white noise, a, and the standard deviation of error, e, by using the equation, lne +(a/2) lnn E =. The empirical setting is as follows: the amplitude of the added white noise is approximately.2 of a standard deviation of the original signal and the value of ensemble is a few hundreds. This is not always applicable for signals in various applications. Following many simulations and experiments, an empirical strategy has been devised for determining the parameter setting of EEMD method [2]. () The amplitude of the added white noise greatly influences the performance of EEMD method with regard to scale separation. The white noise with smaller amplitude added to the signal to be analyzed will result in smaller errors. However, the noise amplitude should not be too small; otherwise, it may not introduce enough changes in the extremes of the signal and will take little or no effect on separating completely different modes in the signal. (2) Once the noise amplitude is determined, when not considering the computation cost, a larger value for the ensemble number will lead to smaller errors, which are mainly caused by the added white noise, especially for the high-frequency signal component. To some degree, continuing to increase the ensemble number will result in only a minor change in errors. (3) When the signal is dominated by the high-frequency signal component, the high-frequency component is more easily separated from the low-frequency signal component and lower noise amplitude is able to separate the mixed modes. If the peak value of the high-frequency component is higher, the noise amplitude should be appropriately increased. When the signal is dominated by the low-frequency signal components, the noise amplitude should be larger Comparisons with EMD method The main improvement of EEMD method is that this method removes the problem of mode mixing in EMD method, which is defined as one or more IMFs consisting of oscillations of dramatically disparate scales and it is often caused by the intermittency of the driving mechanisms [4]. In this section, using EEMD method and the aforementioned strategy for parameter setting, two vibration signals are used to compare the decomposition performances of EMD and EEMD methods. One vibration signal, shown in Fig. a, was collected from a motor with a defect in one of the bearing elements. The decomposition results after applying EMD and EEMD methods to the vibration signals are shown in Fig. b and c, respectively. To save space, for each method only the first nine IMFs are shown in the corresponding figure. The other IMFs have very small amplitudes and are not displayed. With EEMD method, the low-frequency signal component is completely contained in the IMF8 shown in Fig. c. The impulses related to the features of the faulty bearing are mainly distributed in the first two IMFs. With EMD method, the decomposition results are shown in Fig. b. Part of the low-frequency component is mixed with oscillations in the IMF7 and the wave in the IMF8 is irregular and nonperiodic. This indicates that EMD method is very sensitive to noise or oscillations. Regardless of which method was used, the majority of the impulses generated by the faulty bearing elements reside in IMFs. A comparison of the two IMFs in the top diagrams of Fig. b and c shows that the IMF in the latter figure is clearer. It may be caused by the cancellation effect associated with the ensemble mean. The decomposition result obtained using EEMD method is thus much better than that obtained using EMD method. The other vibration signal was collected from a blower [22] and is shown in Fig. 2a. It can be seen that this vibration signal is dominated by the low-frequency signal component, whereas the vibration signal in the former example is dominated by the high-frequency signal component. EMD and EEMD methods were again used to decompose this vibration signal and the decomposition results are shown in Fig. 2b and c, respectively. With the EMD method, IMF6 includes two time scales, and the low-frequency signal component is divided into two parts that have a similar scale but are contained in different IMFs (IMF6 and IMF7). In contrast, with EEMD method the same signal component is only distributed in IMF6, as shown in Fig. 2c. This example also indicates that EEMD method has a better decomposition performance than EMD method. 3. A hybrid method based on spectral kurtosis and EEMD 3.. Problem analysis The recovery of a real signal from large noise, while preserving its important faulty features is a challenging problem for the condition monitoring and fault diagnosis of rotating machines. Although EEMD method improves the scale separation ability of EMD method, both methods are based on the existence of extremes to discriminate different signal components. When the signal of interest is completely overwhelmed by large noise, there may be a lack of necessary extremes for EEMD method to separate the real
4 W. Guo et al. / Measurement 45 (22) (a) A vibration signal collected from a faulty bearing, which is dominated by the high-frequency signal - - IMF IMF5 - IMF6 - IMF7 -.5 IMF IMF (b) The first nine IMFs obtained using EMD method, in which the mode mixing exists in IMF7 IMF IMF5 - IMF6 - IMF7 -.5 IMF IMF (c) The first nine IMFs obtained using EEMD method Fig.. A vibration signal collected from a faulty bearing and the comparison of the respective first nine IMFs obtained using EMD and EEMD methods. signal from the noise. In real cases, the faulty feature in the early stage of a bearing failure is often weak and hidden by background noise. The noise often embodies strong vibrations from several competing sources (e.g., improper installation and surfacing of the mounted sensors, random impacts from friction and contact forces, external disturbances) which span a large frequency range and strongly mask the signal of interest [9]. For a vibration signal with an extremely low signal-to-noise ratio, EEMD method may not extract the desired signal components from the noisy vibration signal. In the following, some experimental signals are used to illustrate this limitation of EEMD in recovering the faulty bearing signal masked by large noise. In the experiments, the vibration signals were collected from faulty bearings that covered four types of common faults: an outer race defect, an inner race defect, a ball defect, and a multiple defect (outer and inner race defects). Each tested bearing (SKF 26 EKTN9) was installed in a DC motor with a speed of 4 rpm, which is shown in Fig. 3a. As the figure shows, the vibration signal was measured by vertically mounting a piezo-electric accelerometer on the top of the bearing housing in each case. The sampling frequency for data acquisition was set to 8 khz. The specification of the tested bearings is given in Table. The faulty elements of the tested bearings are shown in Fig. 3c e, in which the position of the defect on each element is circled. Although the DC motor in the experiments has a relatively simple structure, it adequately serves to simulate such cases in real motors, such as a traction motor. A DC motor is the mainstay of electric traction motors, which are widely used in electrical trains. The bearings installed in a traction motor support the driving shaft of the motors. During tests, the traction motor is generally removed from the train and insulated from other elements in the train. The intention of firstly performing the experiments on the small DC motor was to ensure that the desired tests could be conducted successfully before the real test was carried out on an expensive traction motor. The vibration signals collected from the bearings in the small DC motor contained inherent background noise. To simulate large noise in a real case, a Gaussian white noise was added to
5 32 W. Guo et al. / Measurement 45 (22) Samples (a) A vibration signal collected from a garden blower [22], which is dominated by the low-frequency signal. IMF IMF IMF IMF Samples (b) The first seven IMFs obtained using EMD method, in which the mode mixing exists in IMF6. IMF IMF IMF IMF Samples (c) The first seven IMFs obtained using EEMD method Fig. 2. A vibration signal collected from a garden blower [22] and the comparison of the respective first seven IMFs obtained using EMD and EEMD methods. Accelerometer Tested bearing (a) A experimental DC motor (b) The tested bearing (SKF 26 EKTN9) (c) A defect on an outer race (d) An defect on an inner race (e) A defect in a ball Fig. 3. Experimental setup and faulty elements of the tested bearings, in which the defect on each element is circled. each vibration signal collected in the experiments. Following these experiments, a vibration signal collected from a real traction motor was analyzed, the result of which will be presented in Section 4.2.
6 W. Guo et al. / Measurement 45 (22) Table Specifications of the faulty bearings used in the experiments. Parameter Value Ball diameter, d 8mm Pitch diameter, D 47 mm No. of balls, N b 4 Contact angle, a Shaft rotation speed 4 rpm Fig. 4 shows the raw vibration signals from faulty bearings. The impulses related to the features of the faulty bearings were almost completely masked by noise. Applying EEMD method to each vibration signal resulted in its decomposition into thirteen IMFs. The correlations of the IMFs with the original signal were calculated to evaluate the significance of each signal component to the original signal. To measure the strength of the relationship between the raw vibration signal and each IMF, the index of the correlation coefficient was introduced. Table 2 lists the correlation coefficients between the bearing vibration signals and their corresponding IMFs obtained using EEMD method only. The first four IMFs for each faulty bearing have higher correlation coefficients with the raw vibration signal than the other IMFs. Thus, to save space, only the first four IMFs for each faulty bearing are displayed in Fig. 5. Fig. 5a shows the first four IMFs decomposed from the vibration signal from the bearing with an outer race defect. Part of the noise in the raw vibration signal was filtered out and resides in IMF. The periodic impulses are still masked by some noise and distributed in. A small portion of impulses and noise were distributed in. IMF,, and have larger correlation coefficients with the raw signal, which are.866,.666, and.47, respectively. This is because they are main components in the raw signal. As mentioned above, to simulate the real vibration signals, each experimental signal is composed of the vibration signal collected from the DC motor, the background noise and the additive white noise. Using EEMD method, the raw signal was decomposed to some signal components. The first three IMFs correspond to the noise and the bearing signal in the raw signal and thus have larger correlation coefficients though the raw signal is noisy. is the remainder of the raw signal, which is indicated by its lower correlation coefficient with the raw signal. The other IMFs (IMF5 ) are mainly caused by the extra sifting during the signal decomposition and their correlation coefficients are thus closer zeros. As Fig. 5a shows, in, the periodic impulses in relation to the characteristics of the outer race defect are clearer than the original signal. However, the decomposition results for the other faulty bearings are not as good as the result for the bearing with the outer race defect. Fig. 5c shows the first four IMFs for the bearing with a ball defect. Fig. 5d shows the first four IMFs for the bearing with the outer and the inner race defects. These figures show that part of the impulses was recovered from the large noise and reside in one of the IMFs, but there is still some noise in this IMF. For the signal from the bearing with an inner race defect, the first four IMFs are shown in Fig. 5b. It is difficult to observe the impulses in the first four IMFs. Although some noise was removed from the raw signal, the impulses related to the characteristics of the inner race defect are still buried in noise. This is because the impacts are caused by the inner race defect and the decomposition method lacks the necessary extremes of interest. As Fig. 3a shows, the accelerometer was mounted on the top of the bearing housing, which is a further distance from the inner race than from the outer race. Accordingly, the vibration signal collected was rather weak and easily buried in large noise. A comparison of the original signals shown in Fig. 4a and b shows that necessary extreme are lacking in the signal shown in Fig. 4b, which rendered EEMD method inefficient. For signals with a low signal-to-noise ratio, it is preferable to design a detector to find weak signals buried in large noise to facilitate signal decomposition, which is precisely what spectral kurtosis (SK) does. The SK has been proven to be a powerful statistical index for the indication of incipient bearing faults even in the presence of strong masking noise. It is large in frequency bands in which the impulsive bearing fault signal is dominant, and is effectively zero, where the spectrum is dominated by stationary components [8,9]. Hence, based on the advantages of the SK, a filter was designed to pre-process the raw signal and remove part of the noise. The following section discusses the performance of an optimal band-pass filter based on SK in recovering signals from large noise Spectral kurtosis [8 2] Since SK is a statistical tool which indicates the presence of series of transients and their locations in the frequency domain, it can be used as a defect indicator. The idea is to compute the SK and check in each frequency band for abnormally high values which may suggest the presence of an incipient fault. The maximum SK provides the references for the optimal center frequency and bandwidth of a band-pass filter, which can extract the narrowband transients buried in the broad-band background noise. The estimation for SK can be built from the short time Fourier transform (STFT) of the signal to be analyzed. For more details about the SK and the filter implementation, please refer to Refs. [8 2,23]. The filtered signals obtained by applying the optimal band-pass filter to various bearing signals are shown in Fig. 6a d. The kurtosis value of each filtered signal is marked in the caption of the figure. It can be seen that most of the impulses are separated from the noise. The kurtosis values of the filtered signals are higher than the kurtosis values of the raw signals, the latter of which are given in Fig. 4. Hence, the impacts caused by faulty elements in the bearings are recovered from large noise. However, the filtered signal for each faulty bearing still contains some noise. Using other filters, such as a matched filter, may further improve the signal-to-noise ratio of the filtered signal, but at the expense of further signal distortion. For the signal from the bearing with multiple defects, rather weak vibration signals may be attenuated, which makes fault diagnosis inaccurate. As with EEMD method, the
7 34 W. Guo et al. / Measurement 45 (22) (a) A vibration signal collected from a bearing with an outer race defect (Kurtosis = 3.69) (b) A vibration signal collected from a bearing with an inner race defect (Kurtosis = 3.7) (c) A vibration signal collected from a bearing with a ball defect (Kurtosis = 4.48) (d) A vibration signal collected from a bearing with outer and inner race defects (Kurtosis = 4.74) Fig. 4. Experimental vibration signals collected from four faulty bearings, which are overwhelmed by large noise. filtered signal provides the necessary extremes for the signal decomposition, and the method is thus suitable for further separating the feature signal of a faulty bearing from noise Hybrid signal processing method based on SK and EEMD By analyzing the individual performances of the foregoing two methods, a hybrid signal processing method that combines the two methods is proposed. The optimal band-pass filter based on SK is first employed to remove some noise from the raw signal, and the EEMD method is then used to decompose the filtered signal to separate the signal of interest (the impulses related to the bearing faults) from the noise, which allows good detection of the defects but at the same time minimizes the distortion of the impulses. Finally, a clean signal from the faulty
8 W. Guo et al. / Measurement 45 (22) Table 2 Correlation coefficients between raw bearing signals and their corresponding IMFs obtained using EEMD method only. Correlation coefficient S Outer S Inner S Ball S OI IMF IMF IMF IMF IMF IMF IMF IMF bearing is recovered from large noise and can be used for further signal analysis. The procedure for the hybrid method is briefly described as follows: Step : Filter the raw signal using an optimal band-pass filter based on SK and obtain the filtered signal. Step 2: Use EEMD method to decompose the filtered signal into IMFs. Step 3: Calculate the correlation coefficients between the IMFs and the filtered signal, and select the IMF that has the largest correlation coefficient as the resultant signal. 4. Experiments and application 4.. Experiments and results The proposed hybrid signal processing method was applied to noisy vibration signals. For each faulty bearing, the raw vibration signal was first processed using the band-pass filter based on SK. The filtered signals are shown in Fig. 6a d. The EEMD method was then used to decompose the filtered signals to further extract the impulses in relation to the bearing faults. Table 3 lists the correlation coefficients between the filtered signals and their corresponding IMFs. For each faulty bearing, the first four IMFs have much higher correlation coefficients than the others, and thus to save space, Fig. 7a d only show the first four IMFs for the faulty bearings. Using the hybrid signal processing method, the final result for the signal collected from the bearing with an outer race defect, as shown in Fig. 4a, is presented in Fig. 7a. After filtering and decomposition, the majority of the noise is distributed in, and only the periodic impulses reside in IMF. As indicated in Table 3, IMF has a larger (a) The first four IMFs for the bearing with an outer race defect 2 IMF IMF (c) The first four IMFs for the bearing with a ball defect IMF (b) The first four IMFs for the bearing with an inner race defect (d) The first four IMFs for the bearing with outer and inner race defects Fig. 5. Main decomposition results obtained by applying EEMD method to various vibration signals in the experiments. The impulses in relation to the bearing defects are still masked by noise. IMF
9 36 W. Guo et al. / Measurement 45 (22) (a) The filtered signal for the bearing with the outer race defect (Kurtosis = 8.2) (b) The filtered signal for the bearing with the inner race defect (Kurtosis = 3.97) (c) The filtered signal for the bearing with the ball defect (Kurtosis = 8.39) (d) The filtered signal for the bearing with outer and inner race defects (Kurtosis = 7.36) Fig. 6. The filtered signals obtained using an optimal band-pass filter based on spectral kurtosis. Compared with raw signals, the filtered signals have increased kurtosis values, however, they still contains some noise. correlation coefficient (.8994) than the other signal components and contains the main component in the filtered signal. Hence, IMF was taken as the final resultant signal recovered from the raw vibration signal, which can be proven by the comparison of the kurtosis values of various signals. Table 4 compares the kurtosis values of the raw signal, the filtered signal and the selected IMF for each bearing condition. For the bearing with an outer race defect, the kurtosis of the raw signal is 3.69, the kurtosis of the filtered signal is 8.2, and the kurtosis of IMF increases to.29, the last of which can clearly indicates the faulty state of the tested bearing. Similar observations can be made from the results corresponding to the bearings with an inner race defect and a ball defect, respectively. Fig. 7b shows the first four IMFs for the bearing with an inner race defect. IMF, which has the largest correlation coefficient (.8753), includes almost all of the impulses and was separated from the noise, which is mainly distributed in. The kurtosis value of the raw vibration signal collected from the bearing with an inner race defect is 3.7, whereas the kurtosis value of IMF, as shown in Fig. 7b, is By applying the proposed hybrid signal processing method, the feature signal related to the inner race defect was successfully separated from the large noise and its kurtosis value improved remarkably. The proposed hybrid signal processing method provides a relatively clean signal for further signal analysis and fault diagnosis. Fig. 7c shows the first four IMFs for the bearing with a ball defect. IMF includes the main impulses and excludes the noise. The kurtosis value of IMF also increases rapidly from 4.48 (the kurtosis of the raw signal) to 4.2. Compared with the filtered signal, IMF has clearer periodicity, and the amplitudes of the impulses are almost unaffected.
10 W. Guo et al. / Measurement 45 (22) Table 3 Correlation coefficients between the filtered signals and their corresponding IMFs obtained using the hybrid signal processing method. Correlation coefficient S F-Outer S F-Inner S F-Ball S F-OI IMF IMF IMF IMF IMF IMF IMF IMF Notes: S F-Outer, S F-Inner, S F-Ball and S F-OI are the filtered signals which were originally sampled from the bearings with an outer race defect, an inner race defect, a ball defect as well as a multiple defect (the outer and the inner race defects). The noise remaining in the filtered signal was separated and distributed in. The hybrid signal processing method thus identifies IMF as the resultant signal for this faulty bearing. For the bearing with multiple defects, i.e. the outer and the inner race defects, the first four IMFs are displayed in Fig. 7d, in which has the largest correlation value (.9344) and is finally selected as the resultant signal. Its kurtosis is 3.2, which is much larger than the kurtosis (4.74) of the raw signal. The foregoing experimental results prove that the proposed hybrid signal processing method is able to recover the feature signal related to bearing faults from large noise and provides a much cleaner signal for further analysis and fault diagnosis. The resultant signal has much a higher kurtosis value than the raw signal. The periodicity related to the bearing fault can be observed in the final resultant signal, and at the same time the amplitude or energy of the impacts has less distortion than the case when more complicated filters are used. In the following section, a vibration signal collected from a real traction motor is used to verify the performance of the proposed hybrid signal processing method Application of signal recovery from a bearing in a traction motor Another vibration signal collected from a real industrial motor (a traction motor) was used to verify the hybrid method. The traction motor is usually used in electrical trains to deliver the driving power to wheels. Generally, it is taken away from the train before the test and re-installed back IMF (Kurtosis =.29) (a) The first four IMFs for the bearing with the outer race defect IMF (Kurtosis = 4.2) (c) The first four IMFs for the bearing with the ball defect.2 IMF (Kurtosis = 8.35) (b) The first four IMFs for the bearing with the inner race defect IMF (Kurtosis = 3.2) (d) The first four IMFs for the bearing with outer and inner race defects.2 Fig. 7. Main decomposition results obtained by applying the hybrid signal processing method to vibration signals of various faulty bearings. The IMFs (bold in figures) have larger kurtosis values than that of the filtered signal.
11 38 W. Guo et al. / Measurement 45 (22) Table 4 Kurtosis values of the signals for various faulty bearings. Kurtosis Raw signal Filtered signal Selected IMF A bearing with an outer race defect A bearing with an inner race defect A bearing with a ball defect A bearing with outer and inner race defects to the train after the test. It is to ensure that the motor can be tested accurately without the influence caused by the train running on a rail. Fig. 9a shows a traction motor and its bearing, which is a single row deep groove ball bearing (SKF 625). The motor comprised a 25 kg rotor supported by two rolling element bearings, the tested of which was located on the drive end. Fig. 9b shows the schematic diagram (top view) of the traction motor. The raw vibration signal was collected using an accelerometer that was close to the bearing housing of the motor and was magnet-mounted onto the motor at the axial direction. The running speed of the motor was 498 rpm (the rotation frequency was around 25 Hz). The data collected by the accelerometer were transmitted through a signal conditioner and a data acquisition card to a PC for further analysis. The sampling frequency was 4 khz. The specification and characteristic frequency of the tested bearing in the traction motor are listed in Table 6. The raw vibration signal collected from the tested bearing is shown in Fig. a. The periodic impulses are difficult to observe from the raw signal. It is thus necessary to extract the bearing signal from the raw vibration signal. First, the raw vibration signal was filtered using the optimal band-pass filter based on SK. The filtered signal is shown in Fig. b along with the kurtosis value of the signal. After filtering, the kurtosis value increases from 2.7 to Using EEMD method, the filtered signal was then decomposed in some IMFs. The correlation coefficients of the first three IMFs with the filtered signal are.94,.59, and.4, respectively. Fig. c e shows the first three IMFs. The remaining signal components have very low correlation coefficients and are thus not displayed. As the figure shows, and mainly include the noise remaining in the filtered signal, and most of the impulsive part of the bearing signal resides in IMF, which has the highest correlation coefficient (.947) with the filtered signal and an increased kurtosis of Using the proposed hybrid method, the signal of the faulty bearing was successfully recovered from the raw signal and IMF is the resultant signal that can be used for further fault diagnosis. 5. Bearing fault diagnosis To verify whether each resultant signal recovered from the raw vibration signal maintained the defect features of the bearing, the resultant signals were analyzed using envelope spectral analysis to determine the fault types of the tested bearings. 5.. Bearing characteristic defect frequencies For a given rolling bearing, each time a rolling element in the bearing passes through the faulty surface, a series of impacts is generated. The resulting vibration repeats periodically at a rate. Hence, bearing characteristic defect frequencies have close relation with its characteristic frequencies, which are functions of its geometry and the rotation speed of the shaft in the motor. Given the geometry of a bearing, with the outer race stationary, the equations for calculating the characteristic frequencies of the bearing are given in Table 5. For the faulty bearings used in the experiments, the theoretical values of their characteristic frequencies are also shown in Table 5. For the bearing installed in the traction motor, its characteristic frequencies are shown in Table 6. Rolling bearing characteristic defect frequencies are the same as their characteristic frequencies, except for the characteristic frequency of the ball defect. The characteristic defect frequencies (CDFs) for the defects on the outer race and the inner race are BPFO and BPFO, respectively. The CDF for the ball defect is two times the BSF (2 BSF) because the defect on the ball(s) impacts both the outer and the inner races each time one revolution of the rolling element is made [24]. In fact, there may be differences between the theoretical and the real characteristic Table 5 Characteristic frequencies of the tested bearings in the DC motor. Characteristic frequency Equation Value Ball pass frequency on the F or ¼ F r N b 2 d D cos a 35 Hz outer race (BPFO) Ball pass frequency on the F ir ¼ F r N b 2 þ d D cos a 92 Hz inner race (BPFI) Ball spin frequency (BSF) F b ¼ F r D d2 cos 2 a 64.5 Hz 2d D 2 Note: F r, N b, D, d, and a represent the rotating frequency, the number of balls, the pitch diameter, the ball diameter and the contact angle, respectively. Table 6 Specifications and characteristic frequencies of the bearing (SKF 625) in the traction motor. Parameter Bearing bore diameter Bearing outside diameter Race width Shaft rotation speed Sampling frequency Ball pass frequency of an outer race (BPFO) Ball pass frequency of an inner race (BPFI) Value 75 mm 3 mm 25 mm 498 rpm 32.8 khz 4 Hz 6 Hz
12 W. Guo et al. / Measurement 45 (22) Hz BPFO Frequency (Hz) (a) Envelope spectrum of IMF for the bearing with the outer race defect Hz 2xBSF Frequency (Hz) (c) Envelope spectrum of IMF for the bearing with the ball defect Hz BPFI Hz BPFO 2Hz BPFI 2 BPFO 3 BPFO Frequency (Hz) (b) Envelope spectrum of IMF for the bearing with the inner race defect Frequency (Hz) (d) Envelope spectrum of for the bearing with outer and inner race defects Fig. 8. Envelope spectra of the selected IMFs for various faulty bearings, in which the identified CDFs and their harmonics are marked in the figures. frequencies because the above calculations are made with the assumption of pure rolling contact between the rolling balls and the races. Meanwhile, other errors, e.g. errors in accurately determining the shaft speed, may result in the difference between the theoretical and the real frequencies Bearing fault diagnosis based on the selected IMFs The envelope spectral analysis based on the Hilbert transform has been proven to be a good tool for the diagnosis of local faults in rolling bearings. It extracts the characteristic defect frequencies of faulty bearings along with the modulation so that the type of defect can be determined. In the following, bearing fault diagnosis was conducted on the selected IMFs, i.e. the resultant signals obtained using the hybrid method, to verify their features in the frequency domain. theoretical value listed in Table 5, in which the BPFO is 35 Hz. Hence, the position of the defect on the outer race of the tested bearing was successfully determined Diagnosis of the bearing with an inner race defect When the envelope spectral analysis was applied to IMF for the bearing with the inner race defect, the frequency spectrum, as shown in Fig. 8b, revealed the frequency component at the characteristic frequency of the inner race defect of 2 Hz (BPFI) and its harmonic (4 Hz). Although there is a difference of 8 Hz between Accelerometer Diagnosis of the bearing with an outer race defect According to the correlation coefficients between the IMFs and the filtered signal from the bearing with an outer race defect, which are listed in Table 3, IMF has the largest correlation coefficient of This IMF was thus selected for the fault diagnosis. The envelope spectrum of IMF is shown in Fig. 8a. To clearly display the CDFs of the tested bearings installed in the DC motor, the frequency spectra were limited to the range of Hz. As Fig. 8a shows, higher impacts can clearly be seen at the frequency of 36 Hz (BPFO) and its harmonics (around 2, 3, 4 of BPFO, etc.). The identified characteristic defect frequency of 36 Hz is only slightly different to the (a) A traction motor, the tested bearing and an accelerometer Y Horizontal Z Vertical Top View X Axial Traction Motor Ball bearing SKF 625 (b) Schematic diagram of the traction motor Fig. 9. A traction motor and its bearing (SKF 625).
13 32 W. Guo et al. / Measurement 45 (22) the theoretical value (BPFI = 92 Hz listed in Table 5) and the identified value (2 Hz), the defect on the inner race of the tested bearing was still located Diagnosis of the bearing with a ball defect Once a defect occurs in the rolling element(s) of a bearing, it will ideally strike the outer race and the inner race each time. However, the ball does not always contact both races and the corresponding impulse may be lost. Such a defect is normally difficult to detect. In the experiment, most of the impulses related to the ball defect were successfully extracted from the raw vibration signal and resided in IMF that is shown in the first diagram of Fig. 7c. The envelope spectrum of this IMF is shown in Fig. 8c, and the identified CDF for the ball defect and its harmonics are also marked in the figure. The CDF (27 Hz) identified from the IMF is very close to the theoretical value (29 Hz), indicating that at least one of the rolling balls in the tested bearing has a defect. This result matches the experimental setup, which is shown in Fig. 3e Diagnosis of the bearing with multiple defect (i.e. outer and inner race defects) A bearing with multiple defects, in this case defects on the outer and the inner races, was also considered in the experiments. Generally, as the distance between the mounted accelerometer and the defect increases, the vibration picked up by the accelerometer is attenuated. As Fig. 3a shows, the accelerometer mounted on the DC motor was closer to the outer race than the inner race. (a) 3 A raw bearing signal collected from the traction motor (Kurtosis = 2.7) (b) -3 The filtered signal (Kurtosis = 6.33) (c) -.6 IMF (Kurtosis = 7.49) (d) (e) -.2. (f) Hz BPFO The envelope spectrum of IMF.4 3x 2x Frequency (Hz) Fig.. A raw vibration signal collected from the bearing in the traction motor, the filtered signal, and main decomposition results obtained using the hybrid signal processing method, along with the envelope spectrum of IMF. The signal generated by the faulty bearing was recovered and distributed in IMF, and its CDF was accordingly identified from the envelope spectrum of this IMF.
14 W. Guo et al. / Measurement 45 (22) The impulses generated by the inner race defect were thus rather weak and easily concealed by the impulses of the outer race defect and the noise. This was also observed in the experimental results. The hybrid signal processing method successfully extracted most of the impulses and distributed to. The envelope spectrum of is shown in Fig. 8d and reveals the detected BPFO (39 Hz) and its harmonics (2 and 3 BPFO) along with the BPFI (2 Hz). Although the amplitude at BPFI is relatively small, this CDF can be clearly observed in the frequency spectrum. Therefore, the tested bearing has defects on the outer and the inner races Diagnosis of the bearing installed in the traction motor Envelope spectral analysis was also performed on the resultant signal (IMF) obtained by applying the hybrid signal processing method to the vibration signal from the traction motor. The displayed frequency range of the spectrum is 2 Hz to display the CDF clearly. The detected frequency in the envelope spectrum shown in Fig. f is Hz, which approximately matches the BPFO (4 Hz) listed in Table 6. Meanwhile, the harmonics (2,3) of the BPFO can also be observed in Fig. f. Hence, the impact is confirmed as being generated on the outer race of the tested bearing. The faulty element in the tested bearing also supports this conclusion. The fault diagnoses of the resultant signals obtained from the experiments and the application demonstrate the effectiveness of our hybrid method in recovering important faulty features hidden in raw vibration signals with strong noise. The resultant signals remove most of the noise in the raw signals. The proposed hybrid signal processing method also reveals the temporal impacts from the raw signal while preserving the important features of single or multiple defects of bearings. 6. Conclusions This paper presents a hybrid signal processing method based on spectral kurtosis (SK) and ensemble empirical mode decomposition (EEMD) that can recover faulty bearing signals from large noise. The hybrid signal processing method involves two steps. First, the raw vibration signal embedded with large noise is filtered using an optimal band-pass filter based on SK. The extracted impulsive part from the noisy signal provided the necessary extremes for the signal decomposition. The filtered signal was then decomposed using EEMD method. The transient faulty signal was then separated from the noise by distributing them into different IMFs. For each faulty bearing, the IMF with the largest correlation coefficient was selected as the resultant signal that contains the main impulses related to the bearing defect. Vibration signals collected from faulty bearings installed in an experimental motor and a real traction motor were used to prove the efficiency of the proposed hybrid signal processing method. To further validate the faulty features in the resultant signals, the envelope spectral analysis method was used. Regardless of the type of defect occurred in the tested bearings, whether a single defect (on the outer or the inner race, or in the ball) or multiple defects (on the outer and the inner races), the characteristic defect frequencies of the rolling bearings were easily identified in the respective envelope spectra of the resultant signals. As a result, the defect types of the tested bearings could be determined. In summary, the results demonstrate that the proposed hybrid signal processing method can recover faulty bearing signals from large noise and increase the kurtosis of the analyzed signal to a remarkable degree. At the same time, the resultant signals preserve the important features of faulty bearings so that the impacts caused by the faulty elements of the bearings can be easily determined. In future, the application of our method will be extended to other types of machine faults, such as gears and defective impellers in pumps that generate impacts during rotation. Acknowledgements The work that is described in this paper is fully supported by the National Natural Science Foundation of China and Research Grants Council of Hong Kong Special Administrative Region (HKSAR) Joint Research Scheme (Project No.: N_CityU6/8) and the Research Grants Council of the HKSAR (Project No.: CityU 265). References [] S. Ericsson, N. Grip, E. Johansson, L.E. Persson, R. Sjöberg, J.O. Strömberg, Towards automatic detection of local bearing defects in rotating machines, Mechanical Systems and Signal Processing 9 (25) [2] A.O. Boudraa, J.C. Cexus, EMD-Based signal filtering, IEEE Transactions on Instrumentation and Measurement 56 (27) [3] L.M. Hively, V.A. Protopopescu, Machine failure forewarning via phase-space dissimilarity measures, Chaos 4 (24) [4] Y.T. Sheen, An envelope analysis based on the resonance modes of the mechanical system for the bearing defect diagnosis, Measurement 43 (2) [5] O.C. Ugweje, Selective noise filtration of image signals using wavelet transform, Measurement 36 (24) [6] W. He, Z.N. Jiang, K. Feng, Bearing fault detection based on optimal wavelet filter and sparse code shrinkage, Measurement 42 (29) [7] D. Wang, Q. Miao, R. Kang, Robust health evaluation of gearbox subject to tooth failure with wavelet decomposition, Journal of Sound and Vibration 324 (29) [8] X. Chiementin, F. Bolaers, J.P. Dron, Early detection of fatigue damage on rolling element bearings using adapted wavelet, ASME Journal of Vibration and Acoustics 29 (27) [9] W. Han, P. Que, A modified wavelet transform domain adaptive FIR filtering algorithm for removing the SPN in the MFL data, Measurement 39 (26) [] J. Rafiee, P.W. Tse, Use of autocorrelation of wavelet coefficients for fault diagnosis, Mechanical Systems and Signal Processing 23 (29) [] K. Feng, Z. Jiang, W. He, Q. Qin, Rolling element bearing fault detection based on optimal antisymmetric real Laplace wavelet, Measurement 44 (2) [2] Z.K. Peng, M.R. Jackson, J.A. Rongong, F.L. Chu, R.M. Parkin, On the energy leakage of discrete wavelet transform, Mechanical Systems and Signal Processing 23 (29) [3] Z.K. Peng, P.W. Tse, F.L. Chu, A comparison study of improved Hilbert Huang transform and wavelet transform: application to fault diagnosis for rolling bearing, Mechanical Systems and Signal Processing 9 (25) [4] Z. Wu, N.E. Huang, Ensemble empirical mode decomposition: a noise-assisted data analysis method, Advances in Adaptive Data Analysis (29) 4.
DIAGNOSIS OF ROLLING ELEMENT BEARING FAULT IN BEARING-GEARBOX UNION SYSTEM USING WAVELET PACKET CORRELATION ANALYSIS
DIAGNOSIS OF ROLLING ELEMENT BEARING FAULT IN BEARING-GEARBOX UNION SYSTEM USING WAVELET PACKET CORRELATION ANALYSIS Jing Tian and Michael Pecht Prognostics and Health Management Group Center for Advanced
More informationBearing fault detection of wind turbine using vibration and SPM
Bearing fault detection of wind turbine using vibration and SPM Ruifeng Yang 1, Jianshe Kang 2 Mechanical Engineering College, Shijiazhuang, China 1 Corresponding author E-mail: 1 rfyangphm@163.com, 2
More informationGuan, L, Gu, F, Shao, Y, Fazenda, BM and Ball, A
Gearbox fault diagnosis under different operating conditions based on time synchronous average and ensemble empirical mode decomposition Guan, L, Gu, F, Shao, Y, Fazenda, BM and Ball, A Title Authors Type
More informationWavelet Transform for Bearing Faults Diagnosis
Wavelet Transform for Bearing Faults Diagnosis H. Bendjama and S. Bouhouche Welding and NDT research centre (CSC) Cheraga, Algeria hocine_bendjama@yahoo.fr A.k. Moussaoui Laboratory of electrical engineering
More informationUniversity of Huddersfield Repository
University of Huddersfield Repository Ball, Andrew, Wang, Tian T., Tian, X. and Gu, Fengshou A robust detector for rolling element bearing condition monitoring based on the modulation signal bispectrum,
More informationRotating Machinery Fault Diagnosis Techniques Envelope and Cepstrum Analyses
Rotating Machinery Fault Diagnosis Techniques Envelope and Cepstrum Analyses Spectra Quest, Inc. 8205 Hermitage Road, Richmond, VA 23228, USA Tel: (804) 261-3300 www.spectraquest.com October 2006 ABSTRACT
More informationSEPARATING GEAR AND BEARING SIGNALS FOR BEARING FAULT DETECTION. Wenyi Wang
ICSV14 Cairns Australia 9-12 July, 27 SEPARATING GEAR AND BEARING SIGNALS FOR BEARING FAULT DETECTION Wenyi Wang Air Vehicles Division Defence Science and Technology Organisation (DSTO) Fishermans Bend,
More informationAn Improved Method for Bearing Faults diagnosis
An Improved Method for Bearing Faults diagnosis Adel.boudiaf, S.Taleb, D.Idiou,S.Ziani,R. Boulkroune Welding and NDT Research, Centre (CSC) BP64 CHERAGA-ALGERIA Email: a.boudiaf@csc.dz A.k.Moussaoui,Z
More informationOf interest in the bearing diagnosis are the occurrence frequency and amplitude of such oscillations.
BEARING DIAGNOSIS Enveloping is one of the most utilized methods to diagnose bearings. This technique is based on the constructive characteristics of the bearings and is able to find shocks and friction
More informationAPPLICATION NOTE. Detecting Faulty Rolling Element Bearings. Faulty rolling-element bearings can be detected before breakdown.
APPLICATION NOTE Detecting Faulty Rolling Element Bearings Faulty rolling-element bearings can be detected before breakdown. The simplest way to detect such faults is to regularly measure the overall vibration
More informationCHAPTER 3 DEFECT IDENTIFICATION OF BEARINGS USING VIBRATION SIGNATURES
33 CHAPTER 3 DEFECT IDENTIFICATION OF BEARINGS USING VIBRATION SIGNATURES 3.1 TYPES OF ROLLING ELEMENT BEARING DEFECTS Bearings are normally classified into two major categories, viz., rotating inner race
More informationEnhanced Fault Detection of Rolling Element Bearing Based on Cepstrum Editing and Stochastic Resonance
Journal of Physics: Conference Series Enhanced Fault Detection of Rolling Element Bearing Based on Cepstrum Editing and Stochastic Resonance To cite this article: Xiaofei Zhang et al 2012 J. Phys.: Conf.
More informationPeakVue Analysis for Antifriction Bearing Fault Detection
Machinery Health PeakVue Analysis for Antifriction Bearing Fault Detection Peak values (PeakVue) are observed over sequential discrete time intervals, captured, and analyzed. The analyses are the (a) peak
More informationEnsemble Empirical Mode Decomposition: An adaptive method for noise reduction
IOSR Journal of Electronics and Communication Engineering (IOSR-JECE) e-issn: 2278-2834,p- ISSN: 2278-8735. Volume 5, Issue 5 (Mar. - Apr. 213), PP 6-65 Ensemble Empirical Mode Decomposition: An adaptive
More informationNovel Technology Based on the Spectral Kurtosis and Wavelet Transform for Rolling Bearing Diagnosis
Novel Technology Based on the Spectral Kurtosis and Wavelet Transform for Rolling Bearing Diagnosis Len Gelman 1, Tejas H. Patel 2., Gabrijel Persin 3, and Brian Murray 4 Allan Thomson 5 1,2,3 School of
More informationA train bearing fault detection and diagnosis using acoustic emission
Engineering Solid Mechanics 4 (2016) 63-68 Contents lists available at GrowingScience Engineering Solid Mechanics homepage: www.growingscience.com/esm A train bearing fault detection and diagnosis using
More informationFault Diagnosis of Wind Turbine Gearboxes Using Enhanced Tacholess Order Tracking
Fault Diagnosis of Wind Turbine Gearboxes Using Enhanced Tacholess Order Tracking M ohamed A. A. Ismail 1, Nader Sawalhi 2 and Andreas Bierig 1 1 German Aerospace Centre (DLR), Institute of Flight Systems,
More informationCurrent based Normalized Triple Covariance as a bearings diagnostic feature in induction motor
19 th World Conference on Non-Destructive Testing 2016 Current based Normalized Triple Covariance as a bearings diagnostic feature in induction motor Leon SWEDROWSKI 1, Tomasz CISZEWSKI 1, Len GELMAN 2
More informationINDUCTION MOTOR MULTI-FAULT ANALYSIS BASED ON INTRINSIC MODE FUNCTIONS IN HILBERT-HUANG TRANSFORM
ASME 2009 International Design Engineering Technical Conferences (IDETC) & Computers and Information in Engineering Conference (CIE) August 30 - September 2, 2009, San Diego, CA, USA INDUCTION MOTOR MULTI-FAULT
More informationPrognostic Health Monitoring for Wind Turbines
Prognostic Health Monitoring for Wind Turbines Wei Qiao, Ph.D. Director, Power and Energy Systems Laboratory Associate Professor, Department of ECE University of Nebraska Lincoln Lincoln, NE 68588-511
More informationBeating Phenomenon of Multi-Harmonics Defect Frequencies in a Rolling Element Bearing: Case Study from Water Pumping Station
Beating Phenomenon of Multi-Harmonics Defect Frequencies in a Rolling Element Bearing: Case Study from Water Pumping Station Fathi N. Mayoof Abstract Rolling element bearings are widely used in industry,
More informationVibration Monitoring for Defect Diagnosis on a Machine Tool: A Comprehensive Case Study
Vibration Monitoring for Defect Diagnosis on a Machine Tool: A Comprehensive Case Study Mouleeswaran Senthilkumar, Moorthy Vikram and Bhaskaran Pradeep Department of Production Engineering, PSG College
More informationResearch Article High Frequency Acceleration Envelope Power Spectrum for Fault Diagnosis on Journal Bearing using DEWESOFT
Research Journal of Applied Sciences, Engineering and Technology 8(10): 1225-1238, 2014 DOI:10.19026/rjaset.8.1088 ISSN: 2040-7459; e-issn: 2040-7467 2014 Maxwell Scientific Publication Corp. Submitted:
More informationVibration Signal Pre-processing For Spall Size Estimation in Rolling Element Bearings Using Autoregressive Inverse Filtration
Vibration Signal Pre-processing For Spall Size Estimation in Rolling Element Bearings Using Autoregressive Inverse Filtration Nader Sawalhi 1, Wenyi Wang 2, Andrew Becker 2 1 Prince Mahammad Bin Fahd University,
More informationTime-Frequency Enhancement Technique for Bevel Gear Fault Diagnosis
Time-Frequency Enhancement Technique for Bevel Gear Fault Diagnosis Dennis Hartono 1, Dunant Halim 1, Achmad Widodo 2 and Gethin Wyn Roberts 3 1 Department of Mechanical, Materials and Manufacturing Engineering,
More information2151. Fault identification and severity assessment of rolling element bearings based on EMD and fast kurtogram
5. Fault identification and severity assessment of rolling element bearings based on EMD and fast kurtogram Lei Cheng, Sheng Fu, Hao Zheng 3, Yiming Huang 4, Yonggang Xu 5 Beijing University of Technology,
More informationMorlet Wavelet UDWT Denoising and EMD based Bearing Fault Diagnosis
ELECTRONICS, VOL. 7, NO., JUNE 3 Morlet Wavelet UDWT Denoising and EMD based Bearing Fault Diagnosis A. Santhana Raj and N. Murali Abstract Bearing Faults in rotating machinery occur as low energy impulses
More informationA Novel Fault Diagnosis Method for Rolling Element Bearings Using Kernel Independent Component Analysis and Genetic Algorithm Optimized RBF Network
Research Journal of Applied Sciences, Engineering and Technology 6(5): 895-899, 213 ISSN: 24-7459; e-issn: 24-7467 Maxwell Scientific Organization, 213 Submitted: October 3, 212 Accepted: December 15,
More informationWavelet analysis to detect fault in Clutch release bearing
Wavelet analysis to detect fault in Clutch release bearing Gaurav Joshi 1, Akhilesh Lodwal 2 1 ME Scholar, Institute of Engineering & Technology, DAVV, Indore, M. P., India 2 Assistant Professor, Dept.
More informationFAULT DIAGNOSIS OF SINGLE STAGE SPUR GEARBOX USING NARROW BAND DEMODULATION TECHNIQUE: EFFECT OF SPALLING
IMPACT: International Journal of Research in Engineering & Technology (IMPACT: IJRET) Vol. 1, Issue 3, Aug 2013, 11-16 Impact Journals FAULT DIAGNOSIS OF SINGLE STAGE SPUR GEARBOX USING NARROW BAND DEMODULATION
More informationFAULT DETECTION IN DEEP GROOVE BALL BEARING USING FFT ANALYZER
FAULT DETECTION IN DEEP GROOVE BALL BEARING USING FFT ANALYZER Sushmita Dudhade 1, Shital Godage 2, Vikram Talekar 3 Akshay Vaidya 4, Prof. N.S. Jagtap 5 1,2,3,4, UG students SRES College of engineering,
More informationVibration Analysis of deep groove ball bearing using Finite Element Analysis
RESEARCH ARTICLE OPEN ACCESS Vibration Analysis of deep groove ball bearing using Finite Element Analysis Mr. Shaha Rohit D*, Prof. S. S. Kulkarni** *(Dept. of Mechanical Engg.SKN SCOE, Korti-Pandharpur,
More information1287. Noise and vibration assessment of permanent-magnet synchronous motors based on matching pursuit
1287. Noise and vibration assessment of permanent-magnet synchronous motors based on matching pursuit Zhong Chen 1, Xianmin Zhang 2 GuangDong Provincial Key Laboratory of Precision Equipment and Manufacturing
More informationTHEORETICAL AND EXPERIMENTAL STUDIES ON VIBRATIONS PRODUCED BY DEFECTS IN DOUBLE ROW BALL BEARING USING RESPONSE SURFACE METHOD
IJRET: International Journal of Research in Engineering and Technology eissn: 9-6 pissn: -708 THEORETICAL AND EXPERIMENTAL STUDIES ON VIBRATIONS PRODUCED BY DEFECTS IN DOUBLE ROW BALL BEARING USING RESPONSE
More informationFault Diagnosis of Gearbox Using Various Condition Monitoring Indicators for Non-Stationary Speed Conditions: A Comparative Analysis
nd International and 17 th National Conference on Machines and Mechanisms inacomm1-13 Fault Diagnosis of Gearbox Using Various Condition Monitoring Indicators for Non-Stationary Speed Conditions: A Comparative
More informationStudy Of Bearing Rolling Element Defect Using Emperical Mode Decomposition Technique
Study Of Bearing Rolling Element Defect Using Emperical Mode Decomposition Technique Purnima Trivedi, Dr. P K Bharti Mechanical Department Integral university Abstract Bearing failure is one of the major
More informationAlso, side banding at felt speed with high resolution data acquisition was verified.
PEAKVUE SUMMARY PeakVue (also known as peak value) can be used to detect short duration higher frequency waves stress waves, which are created when metal is impacted or relieved of residual stress through
More informationMechanical Systems and Signal Processing
Mechanical Systems and Signal Processing 25 (2011) 266 284 Contents lists available at ScienceDirect Mechanical Systems and Signal Processing journal homepage: www.elsevier.com/locate/jnlabr/ymssp The
More informationMechanical Systems and Signal Processing
Mechanical Systems and Signal Processing 5 () 76 99 Contents lists available at SciVerse ScienceDirect Mechanical Systems and Signal Processing journal homepage: www.elsevier.com/locate/ymssp An enhanced
More informationA simulation of vibration analysis of crankshaft
RESEARCH ARTICLE OPEN ACCESS A simulation of vibration analysis of crankshaft Abhishek Sharma 1, Vikas Sharma 2, Ram Bihari Sharma 2 1 Rustam ji Institute of technology, Gwalior 2 Indian Institute of technology,
More informationFault detection of conditioned thrust bearing groove race defect using vibration signal and wavelet transform
ISSN 2395-1621 Fault detection of conditioned thrust bearing groove race defect using vibration signal and wavelet transform #1 G.R. Chaudhary, #2 S.V.Kshirsagar 1 gauraoc@gmail.com 2 svkshirsagar@aissmscoe.com
More information1733. Rolling element bearings fault diagnosis based on correlated kurtosis kurtogram
1733. Rolling element bearings fault diagnosis based on correlated kurtosis kurtogram Xinghui Zhang 1, Jianshe Kang 2, Jinsong Zhao 3, Jianmin Zhao 4, Hongzhi Teng 5 1, 2, 4, 5 Mechanical Engineering College,
More informationAcoustic emission based double impulses characteristic extraction of hybrid ceramic ball bearing with spalling on outer race
Acoustic emission based double impulses characteristic extraction of hybrid ceramic ball bearing with spalling on outer race Yu Guo 1, Tangfeng Yang 1,2, Shoubao Sun 1, Xing Wu 1, Jing Na 1 1 Faculty of
More informationRetComm 1.0: Real Time Condition Monitoring of Rotating Machinery Failure
RetComm 1.0: Real Time Condition Monitoring of Rotating Machinery Failure Lee Chun Hong 1, Abd Kadir Mahamad 1,, *, and Sharifah Saon 1, 1 Faculty of Electrical and Electronic Engineering, Universiti Tun
More informationVibration Analysis of Rolling Element Bearings Defects
Viration Analysis of Rolling Element Bearings Defects H. Saruhan *1, S. Sardemir 2, A. Çiçek 3 and. Uygur 4 1,4 Düzce University Facult of Engineering Düzce, Turkey *hamitsaruhan@duzce.edu.tr 2,3 Düzce
More informationFrequency Response Analysis of Deep Groove Ball Bearing
Frequency Response Analysis of Deep Groove Ball Bearing K. Raghavendra 1, Karabasanagouda.B.N 2 1 Assistant Professor, Department of Mechanical Engineering, Bellary Institute of Technology & Management,
More informationFault detection of a spur gear using vibration signal with multivariable statistical parameters
Songklanakarin J. Sci. Technol. 36 (5), 563-568, Sep. - Oct. 204 http://www.sjst.psu.ac.th Original Article Fault detection of a spur gear using vibration signal with multivariable statistical parameters
More informationApplication of Wavelet Packet Transform (WPT) for Bearing Fault Diagnosis
International Conference on Automatic control, Telecommunications and Signals (ICATS5) University BADJI Mokhtar - Annaba - Algeria - November 6-8, 5 Application of Wavelet Packet Transform (WPT) for Bearing
More informationVIBROACOUSTIC MEASURMENT FOR BEARING FAULT DETECTION ON HIGH SPEED TRAINS
VIBROACOUSTIC MEASURMENT FOR BEARING FAULT DETECTION ON HIGH SPEED TRAINS S. BELLAJ (1), A.POUZET (2), C.MELLET (3), R.VIONNET (4), D.CHAVANCE (5) (1) SNCF, Test Department, 21 Avenue du Président Salvador
More informationTelemetry Vibration Signal Trend Extraction Based on Multi-scale Least Square Algorithm Feng GUO
nd International Conference on Electronics, Networ and Computer Engineering (ICENCE 6) Telemetry Vibration Signal Extraction Based on Multi-scale Square Algorithm Feng GUO PLA 955 Unit 9, Liaoning Dalian,
More informationVIBRATIONAL MEASUREMENT ANALYSIS OF FAULT LATENT ON A GEAR TOOTH
VIBRATIONAL MEASUREMENT ANALYSIS OF FAULT LATENT ON A GEAR TOOTH J.Sharmila Devi 1, Assistant Professor, Dr.P.Balasubramanian 2, Professor 1 Department of Instrumentation and Control Engineering, 2 Department
More informationNovel Spectral Kurtosis Technology for Adaptive Vibration Condition Monitoring of Multi Stage Gearboxes
Novel Spectral Kurtosis Technology for Adaptive Vibration Condition Monitoring of Multi Stage Gearboxes Len Gelman *a, N. Harish Chandra a, Rafal Kurosz a, Francesco Pellicano b, Marco Barbieri b and Antonio
More informationAutomatic Fault Classification of Rolling Element Bearing using Wavelet Packet Decomposition and Artificial Neural Network
Automatic Fault Classification of Rolling Element Bearing using Wavelet Packet Decomposition and Artificial Neural Network Manish Yadav *1, Sulochana Wadhwani *2 1, 2* Department of Electrical Engineering,
More informationROLLING BEARING FAULT DIAGNOSIS USING RECURSIVE AUTOCORRELATION AND AUTOREGRESSIVE ANALYSES
OLLING BEAING FAUL DIAGNOSIS USING ECUSIVE AUOCOELAION AND AUOEGESSIVE ANALYSES eza Golafshan OS Bearings Inc., &D Center, 06900, Ankara, urkey Email: reza.golafshan@ors.com.tr Kenan Y. Sanliturk Istanbul
More informationMachinery Fault Diagnosis
Machinery Fault Diagnosis A basic guide to understanding vibration analysis for machinery diagnosis. 1 Preface This is a basic guide to understand vibration analysis for machinery diagnosis. In practice,
More informationAppearance of wear particles. Time. Figure 1 Lead times to failure offered by various conventional CM techniques.
Vibration Monitoring: Abstract An earlier article by the same authors, published in the July 2013 issue, described the development of a condition monitoring system for the machinery in a coal workshop
More informationFrequency Demodulation Analysis of Mine Reducer Vibration Signal
International Journal of Mineral Processing and Extractive Metallurgy 2018; 3(2): 23-28 http://www.sciencepublishinggroup.com/j/ijmpem doi: 10.11648/j.ijmpem.20180302.12 ISSN: 2575-1840 (Print); ISSN:
More informationFault Diagnosis of Rolling Bearing Based on Feature Extraction and Neural Network Algorithm
Fault Diagnosis of Rolling Bearing Based on Feature Extraction and Neural Network Algorithm MUHAMMET UNAL a, MUSTAFA DEMETGUL b, MUSTAFA ONAT c, HALUK KUCUK b a) Department of Computer and Control Education,
More informationVibration analysis for fault diagnosis of rolling element bearings. Ebrahim Ebrahimi
Vibration analysis for fault diagnosis of rolling element bearings Ebrahim Ebrahimi Department of Mechanical Engineering of Agricultural Machinery, Faculty of Engineering, Islamic Azad University, Kermanshah
More information240 JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. FEB 2018, VOL. 20, ISSUE 1. ISSN
777. Rolling bearing fault diagnosis based on improved complete ensemble empirical mode of decomposition with adaptive noise combined with minimum entropy deconvolution Abdelkader Rabah, Kaddour Abdelhafid
More informationGEARBOX FAULT DETECTION BY MOTOR CURRENT SIGNATURE ANALYSIS. A. R. Mohanty
ICSV14 Cairns Australia 9-12 July, 2007 GEARBOX FAULT DETECTION BY MOTOR CURRENT SIGNATURE ANALYSIS A. R. Mohanty Department of Mechanical Engineering Indian Institute of Technology, Kharagpur Kharagpur,
More informationHow to Use the Method of Multivariate Statistical Analysis Into the Equipment State Monitoring. Chunhua Yang
4th International Conference on Mechatronics, Materials, Chemistry and Computer Engineering (ICMMCCE 205) How to Use the Method of Multivariate Statistical Analysis Into the Equipment State Monitoring
More informationCondition based monitoring: an overview
Condition based monitoring: an overview Acceleration Time Amplitude Emiliano Mucchi Universityof Ferrara Italy emiliano.mucchi@unife.it Maintenance. an efficient way to assure a satisfactory level of reliability
More informationWhat you discover today determines what you do tomorrow! Potential Use of High Frequency Demodulation to Detect Suction Roll Cracks While in Service
Potential Use of High Frequency Demodulation to Detect Suction Roll Cracks While in Service Thomas Brown P.E. Published in the February 2003 Issue of Pulp & Paper Ask paper machine maintenance departments
More informationDiagnostics of Bearing Defects Using Vibration Signal
Diagnostics of Bearing Defects Using Vibration Signal Kayode Oyeniyi Oyedoja Abstract Current trend toward industrial automation requires the replacement of supervision and monitoring roles traditionally
More informationCASE STUDY: Roller Mill Gearbox. James C. Robinson. CSI, an Emerson Process Management Co. Lal Perera Insight Engineering Services, LTD.
CASE STUDY: Roller Mill Gearbox James C. Robinson CSI, an Emerson Process Management Co. Lal Perera Insight Engineering Services, LTD. ABSTRACT Stress Wave Analysis on a roller will gearbox employing the
More informationDETECTION THE CONDITION OF A FAN TRANSMISSION IN METAL SMELTER FENI KAVADARCI USING VIBRATION SIGNATURE
DETECTION THE CONDITION OF A FAN TRANSMISSION IN METAL SMELTER FENI KAVADARCI USING VIBRATION SIGNATURE Prof. Geramitchioski T. PhD. 1, Doc.Trajcevski Lj. PhD. 1, Prof. Mitrevski V. PhD. 1, Doc.Vilos I.
More informationStudy of Improper Chamfering and Pitting Defects of Spur Gear Faults Using Frequency Domain Technique
Study of Improper Chamfering and Pitting Defects of Spur Gear Faults Using Frequency Domain Technique 1 Vijay Kumar Karma, 2 Govind Maheshwari Mechanical Engineering Department Institute of Engineering
More informationApplication Note. Monitoring strategy Diagnosing gearbox damage
Application Note Monitoring strategy Diagnosing gearbox damage Application Note Monitoring strategy Diagnosing gearbox damage ABSTRACT This application note demonstrates the importance of a systematic
More informationComparison of vibration and acoustic measurements for detection of bearing defects
Comparison of vibration and acoustic measurements for detection of bearing defects C. Freitas 1, J. Cuenca 1, P. Morais 1, A. Ompusunggu 2, M. Sarrazin 1, K. Janssens 1 1 Siemens Industry Software NV Interleuvenlaan
More informationAtmospheric Signal Processing. using Wavelets and HHT
Journal of Computations & Modelling, vol.1, no.1, 2011, 17-30 ISSN: 1792-7625 (print), 1792-8850 (online) International Scientific Press, 2011 Atmospheric Signal Processing using Wavelets and HHT N. Padmaja
More informationAcceleration Enveloping Higher Sensitivity, Earlier Detection
Acceleration Enveloping Higher Sensitivity, Earlier Detection Nathan Weller Senior Engineer GE Energy e-mail: nathan.weller@ps.ge.com Enveloping is a tool that can give more information about the life
More informationPrediction of Defects in Antifriction Bearings using Vibration Signal Analysis
Prediction of Defects in Antifriction Bearings using Vibration Signal Analysis M Amarnath, Non-member R Shrinidhi, Non-member A Ramachandra, Member S B Kandagal, Member Antifriction bearing failure is
More informationDETECTION THE CONDITION OF A FAN TRANSMISSION IN METAL SMELTER FENI KAVADARCI USING VIBRATION SIGNATURE
DETECTION THE CONDITION OF A FAN TRANSMISSION IN METAL SMELTER FENI KAVADARCI USING VIBRATION SIGNATURE Prof. Geramitchioski T. PhD. 1, Doc.Trajcevski Lj. PhD. 1, Prof. Mitrevski V. PhD. 1, Doc.Vilos I.
More informationEmphasising bearing tones for prognostics
Emphasising bearing tones for prognostics BEARING PROGNOSTICS FEATURE R Klein, E Rudyk, E Masad and M Issacharoff Submitted 280710 Accepted 200411 Bearing failure is one of the foremost causes of breakdowns
More informationDetection of gear defects by resonance demodulation detected by wavelet transform and comparison with the kurtogram
Detection of gear defects by resonance demodulation detected by wavelet transform and comparison with the kurtogram K. BELAID a, A. MILOUDI b a. Département de génie mécanique, faculté du génie de la construction,
More informationMachine Diagnostics in Observer 9 Private Rules
Application Note Machine Diagnostics in SKF @ptitude Observer 9 Private Rules Introduction When analysing a vibration frequency spectrum, it can be a difficult task to find out which machine part causes
More informationKONKANI SPEECH RECOGNITION USING HILBERT-HUANG TRANSFORM
KONKANI SPEECH RECOGNITION USING HILBERT-HUANG TRANSFORM Shruthi S Prabhu 1, Nayana C G 2, Ashwini B N 3, Dr. Parameshachari B D 4 Assistant Professor, Department of Telecommunication Engineering, GSSSIETW,
More informationBearing Fault Detection and Diagnosis with m+p SO Analyzer
www.mpihome.com Application Note Bearing Fault Detection and Diagnosis with m+p SO Analyzer Early detection and diagnosis of bearing faults FFT analysis Envelope analysis m+p SO Analyzer dynamic data acquisition,
More informationBearing Wear Example #1 Inner Race Fault Alan Friedman DLI Engineering
Bearing Wear Example #1 Inner Race Fault Alan Friedman DLI Engineering The following spectrum comes from the motor end of a horizontally oriented centrifugal pump. The data was taken in the vertical axis.
More information1190. Intelligent fault classification of rolling bearings using neural network and discrete wavelet transform
1190. Intelligent fault classification of rolling bearings using neural network and discrete wavelet transform Mehrdad Nouri Khajavi 1, Majid Norouzi Keshtan 2 1 Department of Mechanical Engineering, Shahid
More informationEmpirical Mode Decomposition: Theory & Applications
International Journal of Electronic and Electrical Engineering. ISSN 0974-2174 Volume 7, Number 8 (2014), pp. 873-878 International Research Publication House http://www.irphouse.com Empirical Mode Decomposition:
More informationAutomated Bearing Wear Detection
Mike Cannon DLI Engineering Automated Bearing Wear Detection DLI Engr Corp - 1 DLI Engr Corp - 2 Vibration: an indicator of machine condition Narrow band Vibration Analysis DLI Engr Corp - 3 Vibration
More informationDiagnostics of bearings in hoisting machine by cyclostationary analysis
Diagnostics of bearings in hoisting machine by cyclostationary analysis Piotr Kruczek 1, Mirosław Pieniążek 2, Paweł Rzeszuciński 3, Jakub Obuchowski 4, Agnieszka Wyłomańska 5, Radosław Zimroz 6, Marek
More informationVibration and Current Monitoring for Fault s Diagnosis of Induction Motors
Vibration and Current Monitoring for Fault s Diagnosis of Induction Motors Mariana IORGULESCU, Robert BELOIU University of Pitesti, Electrical Engineering Departament, Pitesti, ROMANIA iorgulescumariana@mail.com
More information1. Introduction. P Shakya, A K Darpe and M S Kulkarni VIBRATION-BASED FAULT DIAGNOSIS FEATURE. List of abbreviations
VIBRATION-BASED FAULT DIAGNOSIS FEATURE Vibration-based fault diagnosis in rolling element bearings: ranking of various time, frequency and time-frequency domain data-based damage identification parameters
More informationCurrent-Based Diagnosis for Gear Tooth Breaks in Wind Turbine Gearboxes
Current-Based Diagnosis for Gear Tooth Breaks in Wind Turbine Gearboxes Dingguo Lu Student Member, IEEE Department of Electrical Engineering University of Nebraska-Lincoln Lincoln, NE 68588-5 USA Stan86@huskers.unl.edu
More informationDIAGNOSIS OF BEARING FAULTS IN COMPLEX MACHINERY USING SPATIAL DISTRIBUTION OF SENSORS AND FOURIER TRANSFORMS
Proceedings IRF2018: 6th International Conference Integrity-Reliability-Failure Lisbon/Portugal 22-26 July 2018. Editors J.F. Silva Gomes and S.A. Meguid Publ. INEGI/FEUP (2018); ISBN: 978-989-20-8313-1
More informationEffect of parameters setting on performance of discrete component removal (DCR) methods for bearing faults detection
Effect of parameters setting on performance of discrete component removal (DCR) methods for bearing faults detection Bovic Kilundu, Agusmian Partogi Ompusunggu 2, Faris Elasha 3, and David Mba 4,2 Flanders
More informationVIBRATION SIGNATURE ANALYSIS OF THE BEARINGS FROM FAN UNIT FOR FRESH AIR IN THERMO POWER PLANT REK BITOLA
VIBRATION SIGNATURE ANALYSIS OF THE BEARINGS FROM FAN UNIT FOR FRESH AIR IN THERMO POWER PLANT REK BITOLA Prof. Geramitchioski T. PhD. 1, Doc.Trajcevski Lj. PhD. 2 Faculty of Technical Science University
More informationClustering of frequency spectrums from different bearing fault using principle component analysis
Clustering of frequency spectrums from different bearing fault using principle component analysis M.F.M Yusof 1,*, C.K.E Nizwan 1, S.A Ong 1, and M. Q. M Ridzuan 1 1 Advanced Structural Integrity and Vibration
More informationROLLING BEARING DAMAGE DETECTION AT LOW SPEED USING VIBRATION AND SHOCK PULSE MEASUREMENTS
ROLLING BEARING DAMAGE DETECTION AT LOW SPEED USING VIBRATION AND SHOCK PULSE MEASUREMENTS Abstract Zainal Abidin 1, Andi I. Mahyuddin 2, Wawan Kurniawan Mechanical Engineering Department, FTMD Institut
More informationRolling Bearing Diagnosis Based on LMD and Neural Network
www.ijcsi.org 34 Rolling Bearing Diagnosis Based on LMD and Neural Network Baoshan Huang 1,2, Wei Xu 3* and Xinfeng Zou 4 1 National Key Laboratory of Vehicular Transmission, Beijing Institute of Technology,
More informationA shock filter for bearing slipping detection and multiple damage diagnosis
A shock filter for bearing slipping detection and multiple damage diagnosis Bechir Badri ; Marc Thomas and Sadok Sassi Abstract- This paper describes a filter that is designed to track shocks in the time
More informationDevelopment of a New Signal Processing Diagnostic Tool for Vibration Signals Acquired in Transient Conditions
A publication of CHEMICAL ENGINEERING TRANSACTIONS VOL. 33, 213 Guest Editors: Enrico Zio, Piero Baraldi Copyright 213, AIDIC Servizi S.r.l., ISBN 978-88-9568-24-2; ISSN 1974-9791 The Italian Association
More informationVIBRATION MONITORING OF VERY SLOW SPEED THRUST BALL BEARINGS
VIBRATION MONITORING OF VERY SLOW SPEED THRUST BALL BEARINGS Vipul M. Patel and Naresh Tandon ITMME Centre, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India e-mail: ntandon@itmmec.iitd.ernet.in
More informationEnvelope Analysis. By Jaafar Alsalaet College of Engineering University of Basrah 2012
Envelope Analysis By Jaafar Alsalaet College of Engineering University of Basrah 2012 1. Introduction Envelope detection aims to identify the presence of repetitive pulses (short duration impacts) occurring
More informationVibration Based Blind Identification of Bearing Failures in Rotating Machinery
Vibration Based Blind Identification of Bearing Failures in Rotating Machinery Rohit Gopalkrishna Sorte 1, Pardeshi Ram 2 Department of Mechanical Engineering, Mewar University, Gangrar, Rajasthan Abstract:
More informationThe Four Stages of Bearing Failures
The Four Stages of Bearing Failures Within the vibration community, it is commonly accepted to describe a spalling process in a bearing in four stages; from the first microscopic sign to a severely damaged
More informationAnalysis Of Induction Motor With Broken Rotor Bars Using Discrete Wavelet Transform Princy P 1 and Gayathri Vijayachandran 2
Analysis Of Induction Motor With Broken Rotor Bars Using Discrete Wavelet Transform Princy P 1 and Gayathri Vijayachandran 2 1 Dept. Of Electrical and Electronics, Sree Buddha College of Engineering 2
More information