Papers by Author: Jing Cai

Abstract: The principle of gas path electrostatic circular sensor was discussed in this paper, in addition, a monitoring experiment with self-made circular sensor was carried out on turbojet engine, and electrostatic signals were collected successfully to verify the validity and feasibility of the sensor. According to the signals monitored over 131h, typical signals of 233-240 phases were analyzed. It was proved that the unusual particles were caused by carbon deposition from fuel spray nozzle. Therefore, under real-time monitoring of gas path changes with electrostatic circular sensor, early warning could be provided for initial fault condition as well as real-time reference for condition-based maintenance.

Abstract: This paper conducted a study on the comprehensive maintenance combined by time-based replacement and time-based detection. The sourse and policy of comprehensive maintenance were introduced in details. Based on availability and cost, comprehensive maintenance model were established respectively. For exponential distribution, optimized the modle, and finally through examples compared the advantages and disadvantages of the models.

Abstract: With the development of Condition-Based Maintenance, there is an urgent need for failure dependence of redundant components in parallel system. In this paper, Markov maintenance cost decision analysis based on failure dependence of components was put forward, moreover, maintenance cost optimal model of parallel system with cost rate was established, meanwhile, the minimum cost rate as well as corresponding optimal detection interval was obtained. Finally, failure dependence and dependent failure rate to parallel system maintenance cost optimal model were studied and realized to prove this theory.

Abstract: Modern fault diagnosis system always is a dynamic, flexible and uncertain complicated system, so many fault diagnosis methods are not effective to determine fault causes. Considering that abundant of fault diagnosis cases have been accumulated in daily maintenance work, a fault diagnosis method based on case-based reasoning (CBR) and rough set theory is proposed. Rough set theory is employed to process reduction on attributes and the weighting coefficient of case description attributes. This method makes full use of the advantage of" let the data speak". At last the method is testified by an example, and the result shows it is feasible and effective.

Abstract: The main purpose of this research is to find a solution for the coating/substrate of the wheel-slide which is the key component of civil aircraft flaps and slats, firstly, the simulation test is designed based on wheel-slide’ s working environment. Further, stress analysis of the coating/substrate is researched, and the results are as the input parameters of the finite element model. Then the finite element software, ANSYS, is applied to simulate the contact stress of coating/substrate in wheel-slide, and the stress’s distribution of coating/substrate are analyzed under different load, different coating thickness, different elastic modulus ratio of coating and other parameters. So the stress field characteristics are gained to guide the conduct of modeling experiments. The results can be applied to explore the failure of mechanism coating/substrate system, and provide theoretical guidance to design the coatings.

Abstract: Because mechanism always has the characteristic of high-reliability, long-life and small-sample, performance degradation theory is adopted to study the wear reliability of mechanism. So, firstly the degradation failure standard of mechanism is analyzed; then the distribution of performance parameters is verified by the K-S test; Furthermore, the failure probabilities are calculated based on degradation failure standard and distribution of performance parameters, in order to confirm the wear reliability distribution of mechanism; finally, an example is given to show the validity of this method.

Abstract: The slide rail of the airfoil is the key structural component of the aircraft, and its wear reliability has important impact to the aircraft security. The traditional method to the slide rail wear reliability analysis is based on time parameter to establish the reliability function. In fact, the actual operating and environmental parameters in the slide rails have an important impact on its reliability. The proportional hazards model (PHM) method is proposed to study the affecting factors of the slide rail’s wear reliability; the method of principal component is used to make a quantitative description to those affecting factors. and the slide rail’s reliability model of its failure function and life distribution function are obtained under many factors affecting. Finally, a study is made to the wear reliability of some regional jet’s slide rail with the PHM method; the wear reliability model is got under the contact stress, hardness and roughness three affecting factors which meet the fact. So the more accurate wear reliability models can be got by the PHM methods, and that has a practical significance to improve the overall reliability of the aircraft.