A novel reliability allocation method for uncertain random system based on structural importance

This paper proposes a novel reliability allocation method for uncertain random system based on belief reliability theory. Compared with the existing literature, systems that require reliability allocation in this paper are considered as uncertain random systems rather than random systems and the system reliability is measured by belief reliability theory for the first time. The uncertain random systems are composed of uncertain units whose reliability is mainly influenced by epistemic uncertainty and random units whose reliability is mainly influenced by aleatory uncertainty, and belief reliability theory is an advanced reliability theory for such uncertain random systems. Firstly, a logical decision diagram is established to decompose the actual system into uncertain units and random units. Next, an effective process is developed to allocate system reliability to these uncertain units and random units in terms of structural importance under the series assumption. Then the system reliability is calculated according to the actual system structure. To obtain the best economic effect, the unit reliability requirements are then adjusted according to the reliability improvement cost by using the simplex search method until system reliability exactly meets the requirement. Finally, a numerical example is given to demonstrate the method in detail.