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Windings' deformation is one of the most common transformer faults. The paper proposes a new method of Vibration frequency response analysis (VFRA) in order to effectively detect the deformation. A series of experiments have been conducted on a large power transformer to validate its efficiency by testifying its repetitiveness and sensitivity. The first series of experiments used VFRA on phase A under...
A new gearbox fault prognosis scheme based on continuous hidden Markov model (CHMM) and support vector machine (SVM) is developed. Based on the features which are the energies of intrinsic mode functions (IMFs) decomposed by empirical mode decomposition (EMD) extracted from normal gearbox vibration signal, a CHMM is trained to model the normal condition. The logarithm of the probability of this CHMM...
Crack of crankshaft and scuff of bearing have been the bottleneck for the development of large-scale reciprocating compressor. To solve such problems, modal and dynamic response analyses are performed for the crankshaft system. Torsional model shapes and stress status are obtained, which shows that the crack of original crankshaft results from fatigue damage and slight torsional vibration, and two...
Through analyzing the statistical properties of measured vibratory data for X-type aircraft, it confirms that non-Gaussian or nonstationary vibration environment exist in transportation and employment of equipments. The deficiencies of the existing vibration test methods and standard are pointed out, and the vibration test methods and flow chart based on measured data are proposed, which can effectively...
In today's global environment, accelerated life testing is becoming a competitive advantage when time spent from conceptual stage to the final product development needs to be minimized (project costs and development time) in order to be successful. Using accelerated life testing techniques for mechanical and structural applications have strong challenges when defining the actual operational loading...
Information fusion arises in a surprising number of fault diagnosis applications. In this paper, common faults are designed in the experiment according to the gear pump vibration mechanism. Fault signal is collected from vibration sensors of different positions, and wavelet packet energy percentage and RMS are extracted as features of the signal. RBF neural network is adopted to fuse thiese features...
Rolling element bearing is one of the most important and common components in rotary machines, whose failures can cause both personal damage and economic loss. This paper focuses on condition monitoring and fault diagnosis of rolling element bearing in order to detect the failure ahead of time and estimate the fault location accurately when failure occurs. Wavelet energy entropy is introduced into...
This paper presents an incipient machine degradation assessment method based on multifractal theory and Mahalanobis-Taguchi system (MTS), which help to differentiate the incipient fault stage and assess the degradation degree as well. According to different machine degradation states, the feature parameters from multifractal aspects are first calculated and further optimized by a MTS statistical method,...
In order to solve the issue of unsteadiness of coordinator belonging to a transfer system and master the natural frequency and deformation of coordinator, calculations of natural frequency were performed by the method of theory calculation and FEM software ANSYS. Accuracy of the model was tested and the natural frequency and deformation were studied according to comparing the data obtained by the...
In order to process the non-stationary vibration signals such as speed up or speed down, a new method combined computed order tracking method with the ARMA model analysis to analyze the instantaneously signals in the rotate mechanism is explored. Firstly, the vibration signals at start-up in the gearbox are sampled at constant time increments in time-domain, and then the data are to resampled with...
Permutation entropy and fractal theory are new methods which are used to study irregularity and nonlinearity of a complex system in nature. Principle of Permutation Entropy (PE) and Correlation Dimension (CD) is introduced in this paper firstly, their differences in describing the complexity of vibration signal were analyzed and the selection methods of algorithm parameters were put forward, then...
Reciprocating compressor is the key equipment in the process of industry production such as oil refinery, chemical plants and so on. The traditional maintenance management model is the fire type which results in the lower reliability, lower availability and lower safety. In this paper, in order to reduce the uncertainty of maintenance, the number of system failures and failure effects, as well as...
There are many studies on materiel readiness presently, but there is no unity recognition on the relation between operational availability and materiel readiness. This paper expatiates to the concepts of availability and materiel readiness, and has a theory derivation of their relation. Otherwise, has an experiment on this model used MATLAB, and discussed the model of the real operational availability...
To monitor the initial failure of cooling fan's rolling bearing, this paper reviews the theory of autoregressive (AR) model and the minimum entropy deconvolution (MED) filtering technique. The AR method can remove the deterministic components of the original signal, and the MED filter could reduce the effect of the transmission path. These two filtering techniques were combined in this paper to pre-process...
Modern self-propelled artilleries compose weapons parts and chassis parts. Its chassis is walking part of self-propelled artilleries and the chassis engine is the heart of the walking part. Technical state of the engine directly influences the condition of artillery technology. Thus, the research on fault diagnosis of the chassis engine of artilleries is very important. Fault diagnosis of the engine...
Because of the advantage of gear, gearbox was used widely. But its fault also brought many losses of the production and society. It was necessary to research and analysis on the dynamical behavior of the gear system. One kind of gear fault was numerically simulated so that the influence of gear fault to change of vibration state was studied theoretically, and the symptom generated by faults was found...
A gear vibration model involving tooth backlash and time-varying stiffness is investigated here, which is exposed to nonstationary excitation. The investigation is explored by the time domain method, and the reliability analysis is based on the first passage problem of the displacement amplitude. As to the multi-dimensional problem, the dimensional decomposition method is used to simplify the calculation...
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