Dynamic Fault Tree Analysis Method Research Articles

Multi-dimensional T-S dynamic fault tree analysis method involving failure correlation

The lack of effective failure correlation analysis is one main reason for the gap between the reliability models and the actual complex systems with mixed static and dynamic characteristics. Takagi and Sugeno (T-S) dynamic fault tree is one powerful tool to analyze the static and dynamic failure logic relationship but it assumes the failure probability of the event is independent. Therefore, this paper proposes a multi-dimensional T-S dynamic fault tree analysis method involving failure correlation. The method integrates the failure probability distribution function of basic events with multi-factors and the multi-dimensional copula function, and the important measure of this method is also deduced. The reliability model expression for systems with failure correlations, both in series and in parallel, is discussed and verified. Compare the proposed method with the assumption that the probability of a failure event is independent. This method solves the problem of a large error when ignoring the failure correlation between parts and the degree of the correlation between variables can be characterized. The reliability analysis can be conducted on complex systems affected both by multi-factors and failure correlations. The proposed method is applied to the reliability analysis of a hydraulic height adjustment system and the correctness and superiority of the method are verified.

Research on Failure Diagnosis Method of a Rocket Borne Micro Electro-Mechanical Systems Recorder Based on Fault Tree

With the complexity and diversification of rocket launch tasks, more stringent requirements are put forward for MEMS electronic equipment, which is closely related to the stability and security of rocket. The key components of the rocket-borne electronic system are composed of discrete components, integrated components and corresponding connected fixed components. The selection, welding and board level connection of each electronic element determine the reliability of the MEMS component. In this paper, the fault tree analysis method is applied to the reliability analysis of the rocket-borne recorder, and the dynamic fault tree analysis method is introduced to compensate the deficiency of the traditional static fault tree analysis method, finally the simulation comparison with Monte-Carlo analysis method is carried out to verify the effectiveness and feasibility of the proposed method. The work of this paper is of great significance for establishing the reliability theory of the system and mastering the experience of quick failure diagnosis.

A New Dynamic Fault Tree Analysis Method of Electromagnetic Brakes Based on Bayesian Network Accompanying Wiener Process

Product fault diagnosis has always been the focus of quality and reliability research. However, a failure–rate curve of some products is a symmetrical function, the fault analysis result is not true because the failure period of the products cannot be judged accurately. In order to solve the problem of fault diagnosis, this paper proposes a new Takagi-Sugeno (T-S) dynamic fault tree analysis method based on a Bayesian network accompanying the Wiener process. Firstly, the top event, middle event, and bottom event of the product failure mode are determined, and the T-S dynamic fault tree is constructed. Secondly, in order to form the Bayesian network diagram of the T-S dynamic fault tree, the events in the fault tree are transformed into nodes, and the T-S dynamic gate is also transformed into directed edges. Then, the Wiener process is used to model the performance degradation process of the stationary independent increment of the symmetric function distribution, and the maximum likelihood estimation method is applied to estimate the unknown parameters of the degradation model. Next, the product residual life prediction model is established based on the concept of first arrival time, and a symmetric function of failure–rate curve is obtained by using the product failure probability density function. According to the fault density function derived from the Wiener process, the reverse reasoning algorithm of the Bayesian network is established. Combined with the prior probability of the bottom event, the posterior probability of the root node is calculated and sorted as well. Finally, taking the insufficient braking force of electromagnetic brakes as an example, the practicability and objectivity of the new method are proved.

Reliability Analysis of Tape Winding Hydraulic System Based on Continuous-Time T-S Dynamic Fault Tree

It is necessary to make the tape winding system have good reliability. Because the power system usually is a pneumatic or hydraulic system, the static reliability analysis lacks the ability to describe the dynamic state transfer, component fault correlation, and propagation effect of the system; it is difficult to accurately reflect the actual behavior of the complex system. Most of the existing research results lack the situation that the importance of bottom events changes with time; only a single number cannot express the impact of bottom events on top events at different times. Therefore, this study uses the dynamic reliability analysis method to quantitatively analyze the reliability of the tape winding power hydraulic system. Firstly, the dynamic reliability model of hydraulic system is established by using the continuous-time T-S dynamic fault tree to solve the fault rate of the system. Secondly, the results are compared with the traditional Markov chain analysis method of dynamic fault tree. The feasibility and advantages of the continuous-time T-S dynamic fault tree analysis method are verified. Finally, the probability importance and key importance of the system unit are calculated, and the law of importance changing with time is expressed. According to the importance of different time, it can help the regular maintenance and fault diagnosis of equipment.

Research on Reliability Analysis Method Based on Dynamic Fault Tree

Due to the development of digital technology, digital I&C systems have replaced analog I&C systems and become the mainstream I&C systems for nuclear power plants and marine nuclear power plants. However, there is still a lack of effective and recognized analysis methods for the reliability analysis of digital I&C systems. Based on the commonly used dynamic fault tree analysis method for dynamic system reliability analysis, this paper uses Markov transition matrix to achieve quantitative analysis. Reliability analysis of the digital I&C system, through the improved dynamic fault tree analysis method, provides an effective analysis method for the reliability analysis of the digital I&C system.

Reliability assessment of the hydraulic system of wind turbines based on load-sharing using survival signature

The hydraulic system is one of the most critical subsystems of wind turbines. It is used to reset the aerodynamic brakes. Because of this, the reliability of the hydraulic system is important to the functioning of the entire wind turbine. To realistically assess the reliability of the hydraulic system, we propose in this article the load-sharing based reliability model using survival signature to conduct system reliability assessment. In addition, due to the uncertainty of the failure rates, it is difficult to conduct accurate reliability analysis. The Markov-based fuzzy dynamic fault tree analysis method is developed to solve this issue for reliability modeling considering dynamic failure characteristics. Following this, we explore the reliability importance and the reliability sensitivity of redundant components. The relative importance of the components with respect to the system reliability is evaluated and ranked. Then the reliability sensitivity with respect to the distribution parameters of redundant components is studied. The results of the reliability sensitivity analysis investigate the effects of the distribution parameters on the entire system’s reliability. The effectiveness and feasibility of the proposed methodology are demonstrated by the successful application on the hydraulic system of wind turbines.

Continuous-time T-S Dynamic Fault Tree Analysis Method

Continuous-time T-S Dynamic Fault Tree Analysis Method

Reliability Evaluation of NPP’s Power Supply System Based on Improved GO-FLOW Method

NPP’s power supply system is repairable and there is common cause failure between the components. The repair rate is introduced and total signaling is considered in the improved GO-FLOW method, aimed at reliability analysis for NPP’s power supply system. Traditional GO-FLOW operators’ algorithms are improved. Comprehensively considering the effect of total signaling flow in the power supply system, the equivalent reliability parameter model and common cause failure probability model of multimodal repairable components are constructed. The improved GO-FLOW model of NPP’s power supply system is set up. Based on the proposed model, components’ reliability parameters are computed. The failure probability time-varying trend in thirty years, respectively, of NPP’s offsite power source and power supply system, is simulated and analyzed. Compared with calculation results of dynamic fault tree analysis method, the validity and the simplicity of the improved GO-FLOW method are verified. The effectiveness and applicability of the improved GO-FLOW model for NPP’s power supply system are proved by simulation examples.

Reliability Analysis of Relay Protection Based on the Fuzzy-Markov Model

Relay protection and safety device are regarded as the sentry of safe and reliable operation of the power grid. It plays a very important role in the power grid, and can determine whether the normal operation of the power system. This article considers the influence of the fuzzy uncertainty of relay protection failure rate to power system on the basis of Markov model, and researches the dynamic fault tree analysis method in the case of fuzzy failure parameter. A dynamic fault model has been built. The triangular fuzzy numbers are used to express the failure rate of the components and system, after which the fuzzy Markov model has been established based on the dynamic fault tree model obtained before. The fuzzy reliability curve and fuzzy failure probability on given degree of membership could be obtained. Finally, the fuzzy Markov model based dynamic fault tree analysis method is used for reliability modeling and analysis of relay protection. The results show that this method can conduct reliability modeling and quantitative assessment effectively for systems which have dynamic failure characteristics and uncertainty of failure rate.

Dynamic fault tree analysis based on continuous-time Bayesian networks under fuzzy numbers

In the calculation of dynamic fault trees, the existing state space–based methods, such as Markov chain method, are basically global-state models, which make the solution procedure very complex. Bayesian networks have become a popular tool to build probability models and conduct inference for reliability design and analysis in various industry fields. The “state explosion” problem can be alleviated by Bayesian networks. Furthermore, to obtain sufficient failure data sets in real engineering systems is extremely difficult and thus causes the parametric uncertainty in failure data. To address these issues, a novel dynamic fault tree analysis method based on the continuous-time Bayesian networks under fuzzy numbers is proposed in this article. The probability distributions under fuzzy numbers for the output variable of dynamic logic gates are determined. The calculation of fuzzy failure probability of a system is presented. Finally, an example is given to demonstrate the effectiveness of the proposed method.

Reliability Analysis of Plug Door System Based on Dynamic Fault Tree

The plug door system is an important guarantee of the safe operation of the emu, since it has structural redundancy, correlation function and fault dynamic characteristics, this paper uses the dynamic fault tree analysis method for reliability analysis. In deep understanding of the basis of the structure and working principle of the plug door, dynamic fault tree model is established by the way of structure ontology, Module iteration is introduced , and the Markov method is adopted to solve the reliability. At the last, we obtained the equipment failure rate and the reliability of the whole system.

Fuzzy Dynamic Fault Tree Analysis for the Solar Array Drive Assembly

Solar array drive assembly, as an important part of the spacecraft, the research on its reliability is very important for fault occurs frequently. The fault tree of the solar array drive assembly is established based on the structure and principle of solar array drive assembly. Taking into account the both failure phenomenon of solar array drive assembly and many uncertainties exist in the fault status and fault reasons, fuzzy sets theory is introduced into dynamic fault tree. The failure parameters of bottom events for solar array drive assembly are modeled by triangular fuzzy numbers. Furthermore, the fuzzy dynamic fault tree analysis method for solar array drive assembly based on combination cut set theory and interval arithmetic is proposed. The system weak parts and key components can be found easily according to the fuzzy probability importance which is comes from the fuzzy probability of system top event and fuzzy probability importance of bottom events. The results show that the bearings and harmonic drive are key components for the solar array drive assembly.

Analysis on Dynamic Fault Tree Based on Fuzzy Set

In case of fault tree analysis of large complex system, the probability of bottom event in dynamic fault tree is uncertain in some cases. To address the problem, the paper presented a dynamic fault tree analysis method based on fuzzy set computation. The method separates logic attributes and timing attributes of dynamic logic gates. It can convert dynamic fault tree into static fault tree not considering timing constraints and obtain minimum cut set of static fuzzy fault tree with set operations, then the concept of minimum cut set is extended to dynamical minimum cut sequence. Thus, the dynamic fault tree was analyzed in both qualitative and quantitative aspects, which solve the problem that it is difficult to assign value of event probability in previously process.