The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Failures on a rolling bearing in the gearbox drive system can be detected via vibration sensors or accelerometers. Measured signals include rotating harmonics, noises, signals associated with a bearing fault. Characteristic frequencies of a faulty bearing are very close to the higher harmonics of rotor frequency. This causes a big challenge to know if a bearing is in a faulty or healthy condition...
As one of the important equipment for vibration test, hydraulic shaking table can produce great vibration force and displacement of vibration, , widely applied in engineering field. In the test system of hydraulic shaking table, because of the existence of non-linearities, there exists higher harmonic in system response signal when the shaking table is excited by a sinusoidal signal, making the harmonic...
In this paper the external stray flux around a motor has been investigated as a possible new diagnostic instrument to detect generalized roughness. This very common bearing fault has been slightly considered in the literature so far. Stray flux was measured by two probes, one commercially available and one realized in laboratory; the diagnostic content of both signals has been compared also with the...
Harmonic wavelet analysis can extracts the singular components effectively in the non-stationary signals. Firstly, this paper elaborates on the structure and decomposition of the harmonic wavelet, and it also proposes an improved harmonic wavelet algorithm which based on the improvement of the harmonic wavelet frequency domain features and the change of the time domain signal instantaneous cutting...
Although detection of bearing faults from vibration signal has been extensively used, detection using electrical signal such as the stator current has also proven to be interesting and relevant, but improvements of the stator current spectrum are necessary so as to assist in a more readable signal. In this paper, two improvements have been proposed and discussed. Firstly, the proposition of a designed...
Current-based technique is an economic solution to detect bearing faults in drive-trains. Localized faults produce characteristic vibration frequencies. When an electric motor is supplied by a frequency-converter, the current response includes not only the fundamental and fault related frequencies but also higher harmonics from the inverter. This paper introduces a resonant filter to pick up frequency...
In order to prepare well for drawing Bode and Nyquist diagrams of vibration signals collected from rotor startup or shutdown process, a new Hilbert transform based calculation method is proposed. Experiment results show that the proposed method can smooth Bode and Nyquist diagrams, has more accuracy in amplitude and phase calculation, and also can not be affected by harmonic components of rotor vibration...
For a permanent magnet electrodynamic shaker (PMEDS), an LC filter is frequently connected in series to filter out the high-frequency voltage to avoid high-frequency harmonic acceleration of the PMEDS table. This paper use a simple current control loop to avoid high-frequency harmonic acceleration instead of an LC filter which may have large size and heavy weight in high-power applications. A cascade...
A current issue in human-computer interaction is the design of haptic stimuli. Recent studies reported that humans can successfully recognize various haptic stimuli, and thus suggest methods of designing distinguishable haptic stimuli. However, such methods have been complicated and inconsistent, indicating a need for exploring different parameters associated with human perception. Therefore we conducted...
Bearing is the most frequently used component in a wind turbine, and its' faults would lead to completely stall of a machine. Therefore, bearing Fault Diagnosis is an important part of condition monitoring in a wind turbine. This paper presented a High Frequency Resonance (HFR) method to implement bearing fault detection and fault diagnosis. This technique extracted the amplitude and frequency modulations...
In this paper, we show experimental results indicating that tactile mechanoreceptors have non-linear sensitivity to an applied vibration. We focus on the perceptual characteristic of high frequency amplitude-modulated (AM) vibration. It is known that humans can feel AM vibration even when its carrier frequency is higher than the perceivable range. Non-linearity of perception should be taken into consideration...
The most commonly used components in a wind turbine are bearings which failure could lead to malfunction and ultimately complete stall of a mission-critical equipment. Hence, bearing Fault Detection is an imperative part of preventive maintenance procedures of a wind turbine. This paper presents a Free Parameter method to implement bearing fault diagnosis. This method extracts the amplitude and frequency...
A novel signal processing algorithm was proposed here for vibration signal analysis in condition monitoring and health diagnosis of rolling bearings. Such technique required an envelope being extracted from vibration signal with a complex analytical band-pass filter which was designed for better efficiency in processing than Morlet wavelet and Harmonic wavelet. The principal periodic component in...
Wheel runout tolerance detection reflects the inaccuracy of wheel geometry. The inaccurate wheels not only intensify their own wear, but also bring the sources of vibration which bring insecurity for automobiles. By detecting runout tolerance, we can reject unqualified products in order to eliminate hidden dangers as early as possible and improve the quality of automobiles. By harmonic analysis, the...
The objective of this paper is to introduce Newland Harmonic wavelets and Richman -Moorman (2000) sample entropy are applied to detect singularity signal on worn tool. Because some weak vibration signals contained strong noises are very important for fault forecast. Based on harmonic wavelet mesh plot of the vibration signals, we can induce contours of the mesh map with log space, then, we offer the...
The total harmonic distortion (THD) is an important character of vibration transducer calibration system. A new method is proposed in this paper to reduce the THD, which is based on the open-loop frequency response analysis of the vibration transducer calibration system and harmonic compensation. The mathematic model of the motion of electric shaker is described. Results of simulations and experiments...
In order to adapt to high accuracy test requirement of dynamic balancing of Electric spindle. According to the harmonic wavelet phase locked, narrow-band analysis and the clear expression in time-domain, the method and algorithm of adaptive filtering based on harmonic wavelet was given. This method in accordance with the signal correlation, the dynamic unbalance signal was extracted by the relevant...
Considering the fault characteristic of rotating machinery, a novel approach was proposed by using harmonic wavelet filtering. Based on the fine refinement function of harmonic wavelet, the characteristic frequency components and other components were decomposed to independent frequency bands, without any overlapping or leaking. Then the characteristic frequency component would be extracted by the...
We propose a method using broadband tone burst excitation pulses with non-uniform sampling for Shearwave Dispersion Ultrasound Vibrometry (SDUV). The method allows long excitation pulses with a high PRF of detection pulses to induce a strong tissue motion and obtain strong detection signal. The method also simultaneously estimates all harmonics of tissue motion induced by the broadband excitation...
As an experimental tool for analyzing movement of chaos, we intend to introduce the correlation dimension for analyzing vibration signals of rotor system in this paper. For noise corruption existing in field-measured vibration signal, morphological filter is also introduced for de-noising the vibration signal. The analysis and comparison between the correlation dimensions of the noised and de-noised...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.