Dynamic Reliability Modeling And Simulating Research On Helicopter Power Transmission Systems Based On General Stochastic Petri Nets

As power transmission systems are key hardware systems of helicopters, the catastrophic failures and accidents are mainly caused by power transmission systems along with other mechanical systems. Aiming at the functional and structural characteristics of helicopter power transmission systems, this paper researched the dynamic reliability modeling methods and the simulating technique of complex mechanical systems.The hardware reliability, the human reliability, and the software reliability related to helicopter power transmission systems were analyzed in this dissertation from the systems engineering position; the reliability models were established and the availability of the subsystems and the total system were simulated. The main research contents and innovations of this thesis included:1. The dynamic reliability modeling methods of complex systems were studied and it's demonstrated that Petri nets were more appropriate than other methods in dynamic reliability modeling for helicopter power transmission systems.2. Aiming to deal with the existing shortage that traditional reliability modeling methods cannot describe the dynamic process of the complex system's states, according to relevant researches, The general stochastic Petri nets(GSPN) modeling method was applied to dynamic reliability modeling in respect that the process of failure and repair can be simulated by the timed transitions. Furthermore, the failures and their dynamic transfer processes were studied.3. Focusing at the functional and structural characteristics of helicopter power transmission systems, this paper analyzed hardware reliability, human reliability, and software reliability detailedly. The GSPN modeling method was used; the typical GSPN models of human system, software system, hardware system and the total system were established; the availability of subsystems and the total system were simulated.4. According to the logistic connections among the attributions of system availability, the thesis firstly puts forward a new calculational model of availability based on facilitation degree. Results showed that the caculational value of the formula is very close to the simulating value, and the new caculational model based on facilitation was proved to be correct.The modeling method and the simulating process aiming at helicopter power transmission systems in this paper were typical, which were applicable not only for different types of military or civil helicopters in the country, but also for the dynamic reliability modeling and simulating of the complex mechanical equipments'power transmission systems, such us carries, civil airplanes, submarines, etc. As a result, this dissertation has military meaning and academic value.