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Gearboxes are important parts of mechanical transmission systems, so that it is very pivotal for avoiding future catastrophic failures to detect faults in gearboxes at the early stage. Various vibration analysis techniques have been proposed and successfully applied to detect faults in gearboxes. The outputs of these techniques are used to identify the signal changes caused by defects. Because of...
This paper introduces a new idea of bearing fault diagnosis, which is to use the Multipoint Optimal Minimum Entropy Deconvolution Adjusted (MOMEDA) Technique to filter the vibration signal, getting the output signal and directly to do spectral analysis, then to observe the fault characteristics for fault diagnosis. MOMEDA technique is an improved MED algorithm proposed by McDonald in 2016, which can...
In condition monitoring systems, condition indicators(CIs) are usually used to describe health state of equipment. Usually, detailed fault isolation is conducted by various diagnoses model, threshold alarming is used to detect exceptions. However, how to set threshold that performs best become a problem. Based on ROC analysis, a condition indicator threshold optimization method is proposed in this...
The general methods of health indicators extraction for planetary gearbox are based on the vibration signals which acquired by sensors equipped on the casing of the gearbox and sampled in the frame of Shannon sampling theory. Therefore, it is necessary to sample and save abundant original vibration data in the process of uninterrupted monitoring, and this will generate masses of original data which...
Condition indicators are significant elements in condition monitoring systems. A condition indicator (CI) performance assessment method would help users to select effective CIs and improve fault diagnosis performance of condition monitoring system (CMS). Investigating of measurement influence factors shows that CIs obey normal distribution. Taking advantage of signal detection theory, a CI assessment...
A fault implantable signal model could be helpful for researchers to develop fault diagnosis methods of planetary gearboxes. Considering meshing regularity between given planet gear tooth and ring gear, as well as AM effect caused by rotating of carrier, fault implantable signal model is established. The theoretical derivations are validated through spectrum analysis of simulation signal. Furthermore,...
Broken rotor bar is one of the main causes of induction motor fault. The method for detecting the existence of sideband frequency component in stator phase current when the rotor bars broken by motor current signature analysis (MCSA) technology has been widely used. However, there are obvious limitations with the incipient fault, the amplitude of fault signature frequency is much smaller than the...
Motor current signature analysis has been investigated widely for diagnosing faults of induction motors. However, most of these studies are based on open loop drives. This paper examines the performance of diagnosing motor stator faults under both open and closed loop operation modes. It examines the effectiveness of conventional diagnosis features in both motor current and voltage signals using spectrum...
To deal with the lack of good quality and commonly accepted fault data of large-scale equipments, simulation based strategy is calling for more and more attention. This paper focuses on the real-time fault injection method in the simulation model of mechanic-electronic-hydraulic control system. First, simulation model of a ship steering system was built in AMESim. And then, several typical faults...
Multi-loop model of asynchronous motor contains lots of parameters, which leads to problems such as complex calculations, difficulty in equations solution and so on. In this paper, a simplified asynchronous motor model is set up on the basis of MATLAB®/Simulink environment to imitate health states of stator inter-turn short and broken rotor bars by simulating and studying their asymmetric fault features...
One of the major obstacles in developing Health Management System (HMS), by using intelligent technologies for diagnosis, prognosis, maintenance and health management of aerospace, is the correct description of knowledge. The work proposed in this paper suggests a normative knowledge representation frame based on ontology to integrate Knowledge related to Health Management of Aerospace (AHMK). In...
According to the dynamic evaluation of performance reliability of the key components of Propellant Filling System, a model simulating the filling procedure is built with AMESim. According to FMEA for the system, especially the deterioration mechanism of pneumatic ball valves, the degradation states of pneumatic ball valve are simulated, and a number of evaluation models of the degradation degree based...
According to the abnormal state detection without enough priori knowledge and fault samples, a new detector generation method with step radiuses is proposed. The method separates abnormal state space into several regions, and then sets different detector radius for them according to actual situations, has great flexibility and higher coverage rate to space. Artificial immune real-valued negative selection...
Based on the principle of Stochastic Resonance (SR), two models of weak signals detection — coupled array of stochastic resonance and uncoupled array of stochastic resonance are built. Through numerical simulation and computation, the influence of every parameter on system capability is analyzed. In addition, two models are compared with each other on signal-to-noise ratio gain. Simulation results...
Propellant filling system is one of the key components of liquid rocket engine test bed and improving its reliability and security is very necessary. However because of the shortage of failure data and high expense and risk of test experiments, modeling and fault simulation are urgently needed. Based on the modular modeling, a new method using the objected-oriented language Modelica in Dymola is proposed...
Turbopump is a high-fault-rate component in Liquid Rocket Engine (LRE). In this paper, the reasons of the typical fault of turbopump rotor blade abruption and abscission are analyzed. And, by the method of dynamic analysis, the vibration features of the fault are studied to select the frequency features diagnosing effectively the fault. Then, the extraction method of the features is researched. By...
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