Failure Risk Analysis Of System Based On Weighted Fuzzy TOPSIS Method

Reliability is becoming more and more concerned by the design, manufacture and other industries. Due to the technology and equipment update quickly, so the performance requirements are also getting higher and higher and to ensure reliability, safety, reduce the risk of certain extent improves the performance.Because of the complexity andstability of modern systems, system data is not easy to get and it's difficult to analyze its reliability combined with the limit of running environment, technical requirements, cost and other factors.The research content and achievements of this paper are as follows:(1) Risk and reliability analysis of system based on FLT method. The paper begins with the fuzzy theory, combined with the specific calculation method of the failure rate, maintenance time, the average failure free operation time and other reliability parameters, using the theory of fuzzy cut set and expansion principle, the fuzzy data of the obtained parameters can be defuzzified to get the specificvalue, and the reliability analysis of the system is described.A sensitivity analysis method based on the change of working time variation is presented, which can solve the problem of incomplete and inaccurate data and makes the analysis result more scientific and reasonable. The results are favorable for the management to reasonable arrange the time of inspection and maintenance.(2)The risk research of system failure based on fuzzy TOPSIS.On the basis of the system's reliability obtained by the FLT method, the failure mode and effect analysis method which consists of the qualitative research and quantitative calculation is applied to analyze the reliability of the key nodes. In this paper, technique for order preference by similarity to ideal solution(TOPSIS) is mainly used for the failure mode and effect analysis(FMEA). The FMEA analysis model is constructed by using simple TOPSIS and fuzzy TOPSIS, respectively. The results illustrate the advantages of TOPSIS method than other methods, as well as the advantages of fuzzy TOPSIS than simple TOPSIS in the form of comparison. In the process of calculation, the weight of the risk factor is obtained by the entropy weight method and the expert evaluation method, respectively. Then, the closeness coefficient of each failure mode and its priority ranking are obtained and finally, a multi-level comparison result is given. In addition, the weight of each risk factor plays a very important role in the whole failure analysis. May be very small deviation will lead to the result is inconsistent. The sensitivity analysis of the failure modes about the priority order is carried out with the change of risk factor weight.(3) Failure risk model construction based on comprehensive weighted fuzzy TOPSIS. The paperproposes a fuzzy TOPSIS model based on the comprehensive weight of risk factors, which not only considers the subjective weight from the experts, but also measures the weight of the system itself. In addition, the fields of experts' research are different so they are assigned to the relative weights, which can reflect the actual situation. Then the application of the trapezoidal fuzzy number instead of triangular fuzzy number is used to calculate and the new method is applied to defuzzify. According to the weighted data, the distance between the failure mode and the positive and negative ideal solutions and the relative closeness coefficient of each failure mode are calculated. The ranking order will be obtained based on the closeness coefficient. The higher the priority is, the more important the potential failure mode is, or the more serious the failure occurs and the impact is. On the other hand, the lower the priority, the less important the potential failure mode is.According to the priority order of potential failure mode, the manager can give priority to the failure mode with high priority when the design or maintenance is carried out orprevent and maintain the important failure mode(easy to occur, more serious and difficult to detect), and reduce the possibility of failure by reasonable measures.Ensuring the reliability of each segment and reducing the failure ratecan ensure the safety and reliability of the whole system and also indirectly reduce the cost of system operation or maintenance.