Maintenance Versus Individual and Overarching Protections for Parallel Systems

A parallel system consisting of components with different characteristics is studied. The components can be unavailable due to internal failures or external impacts. Each component has an increasing failure rate and is subjected to external impacts that can occur with fixed frequency. In order to increase the system availability, three measures can be taken: 1. Increase of the components replacement frequency; 2. Overarching protection of the system; 3. Individual component protection. The external impact must penetrate both the overarching protection and the individual component protection in order to destroy a component. The optimal resource allocation strategy which minimizes the total cost of maintenance, protection and damage caused by unsupplied demand is studied. The proposed approach is based on a universal generating function technique and a genetic algorithm.