Degradable systems:a survey of multistate system theory

Abstract

The vast majority of reliability analyses assume that ccmponents and system are in either of two states: functioning or failed. However, in many real life situations we are actually able to distinguish among various 'Ilevels of performance" for both system and components. For such situations, the existing dichotomous model is a gross oversimplification and so models assuming degradable (multistate) systems and components are preferable since they are closer to reality.We present a survey of recent papers which treat the more I sophisticated and more realistic models in which components and systems may assume many states ranging from perfect functioning to complete failure. Our survey updates and complements a previous survey by El-Neweihi and Proschan (1980). Some new results are included.