  In this paper, a repairable multi-component system is studied where all the
components can be repaired individually within the system. The whole system is
inspected at inspection intervals and the failed components are detected and
replaced with a new one, while the other components continue functioning.
Replacing components individually within the system makes their initial age to
be different at each inspection time. Different initial age of all the
components have affect on the system reliability and probability of failure and
consequently the optimal inspection time, which is for the whole system not
individual components. A dynamic maintenance policy is proposed to find the
next inspection time based on the initial age of all the components. Two
competing failure processes of degradation and a shock process are considered
for each component. In our paper, there is a mutual dependency between the
degradation process and shock process. Each incoming shock adds additional
abrupt damages on the cumulative degradation path of all the components, and
the shock arrival process is affected by the system degradation process. A
realistic numerical example is presented to illustrate the proposed reliability
and maintenance model.
