Basic Reliability Structures of Complex Technical Systems - New Contributions in Information Systems and Technologies - page 317

Fig. 2. Equivalence of different representation ways for the reliability structure of the
system; A) reliability block diagram; B) fault tree model; C) logical structural function
of the system (positive representation); D) logical structural function of the system (the
negative representation); E) set of minimal path-sets of the system; F) set of minimal
cut-sets of the system

In Fig. 2 the equivalence of different representation ways for the reliability
structure of the system is illustrated, where we can see: reliability block diagram,
fault tree model, positive and negative structural functions of the system, set of
minimal path-sets of the system or set of minimal cut-sets of the system.

4 Basic Reliability Structures

The basic reliability structures of multi-element systems include:

- simple structures: series, parallel or series-parallel and parallel-to-series;
- complex structures: bridge, linear, threshold and circuitous.

4.1 Simple Structures

Series reliability structure is the one in which the down state of any system
element causes the down state of the whole system. Graphic system model of
the series reliability structure of the elements (

E 1 ,E 2 , ..., E n )ispresentedin

Fig. 3.
For example, this structure corresponds to the centrifugal pump unit (Fig. 4).
In this system, each element (e.g.: shaft, impeller, frame, bearings, seals, clutch,
electric motor) is a serial reliability structure block.