reliability modeling of phased mission systems subject to ageing andenvironmental shocks

Phased mission systems (pmss) have many applications to many areas ofscience and technology. a pms performs its mission in several phases that appearconsecutively and have not overlap. in addition to internal failures, external shocksmay cause the failure of components in a pms. in this paper, under this assumption,some compact expressions are given for the pmss reliability by using the concept ofsurvival signature in three scenarios: (a) the component failures occur only based oninternal failures (aging), (b) the component failures are only subject to external failures(fatal shocks) and (c) the components failures are subject to internal failures and externalshocks. finally, a numerical example is presented to explain the theoretical results.