| The research of classical reliability theories is mostly concentrated in the static aspects of the system, which is difficult to describe the dynamic behavior and evolution of the system. Dynamic reliability aims to broaden the classical reliability methodologies, which can take into account the ordering and timing of events in the accident propagation, the dependence of transition rates and failure criteria on the process variable values, the human operator actions, etc.The methods for dynamic reliability include Markov analysis, Stochastic Petri Nets, Dynamic fault trees, Monte Carlo simulation and so on. Firstly this thesis presents a short description and comparison of the above methods. Then Stochastic Petri Nets is applied to modeling of a complicated hydraulic system. On the basis of the Petri Nets model, the dynamic characteristics of the system are analyzed and the reachability tree is established. During research of the Monte Carlo simulation, a fixed time interval method is proposed, which can be used to determine the failure number and failure time of fixed time intervals; The proposed method is applied to the reliability indices calculation of different maintenance hypotheses (good as new and basic repair); preventive maintenance strategies are established on avail of the dynamic reliability data. At the end of the thesis, a reliability analysis program is described. The program, developed under VC++6.0, combines the advantages of Stochastic Petri Nets and Monte Carlo simulation.The research results show that it is an effective method of analyzing the dynamic reliability of hydraulic system by modeling via SPN and calculating via Monte Carlo simulation. The fixed time interval method is reasonable and effective in determining reliability indices. The simulation results indicate that reliability indices change slightly under the good as new maintenance hypotheses, while greatly under basic maintenance hypotheses. The above conclusions have practical values.
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