Abstract
The object of research is a non-renewable system with a single sliding reservation. Such system consists of two main subsystems, one redundancy and two switching devices. While both main subsystems are operable, the spare subsystem is in an unloaded state. The redundancy system is designed to replace any major subsystem after its failure. Switching devices commute the main subsystems with a redundancy one. During the audit, it was revealed that the switching devices allow errors. In particular, a mistake of the first type, that is, they switch in advance, and a second type of error, that is, they pass the switching moment. This reduces the reliability of the system and leads to underutilization of the inherent resource. An approach is proposed that quantitatively takes into account the influence of errors of the first and second type on the probability of failure-free operation of the system under study during its design. The approach consists of two stages. At the first stage, the reliability of the system is mathematically described by the dynamic failure tree. At the second stage, based on the failure tree, a Markov model is formed. Applying it, it is possible to calculate the probabilistic characteristics of the system. The result is a mathematical relationship between the probability of trouble-free operation of the system and the parameters of the components of the system. In particular, the operating time to failure of the main and redundancy subsystems, as well as the parameters of switching devices that corresponds to errors of the first and second type. The form of presentation of the obtained results for the end user is a software product that automatically generates a family of graphs for reliability evaluation. Ignoring the errors of switching devices in the design of systems reduces their actual reliability, leads to underutilization of the reserve component resources, and also increases the probability of emergency situations. Using a more accurate mathematical model makes it possible to monitor the errors of switching devices during the design of the system. The simulation results will be useful for selecting the parameters of the switching devices.
Highlights
To increase the reliability of technical systems, structural redundancy is used
The dynamic fault tree of a non-renewable system with a single sliding redundancy and ideal swit ching devices was converted into a multi-terminal dynamic failure tree
It was possible to introduce into the model nine dynamic phenomena of mutual influence of components and switches, in particular, such phenomena as unauthorized switching of contacts and the operating time to the failure of the control system of switching devices
Summary
To increase the reliability of technical systems, structural redundancy is used. This redundancy is that redundant components are added to the structure of the system, which after the failure of the main components and subsequent switching take over the performance of their functions. When analyzing the reliability of systems with sliding redundancy, one of the principal factors is the consideration of the influence of switching devices This influence consists in the appear ance of errors of the first and second type. Under the error of the first type, we mean a false operation of the switching device This means that the main subsystems are functional, but the switching device decided that one of them is inoperable, and connected a redundancy. Under the second type of error, we understand the missed switching point of the switching device This means that one of the main subsystems refused, but the switching device decided that such subsystem is operable and did not connect a redundancy subsystem. This work is a continuation of this research, provided that the redundancy component is unloaded
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