Comparison of expected failure times for several replacement policies

Planned replacement policies are used to reduce the incidence of system failures, or to return a failed system to work. New better than used aging classes are commonly used in reliability theory to model situations in which the lifetime of a new unit is "better" than the lifetime of a used one. The purpose of this paper is to establish comparisons of expected failure times of an age (block) replacement policy, and a renewal process with no planned replacements when the lifetime of the unit is NBUE. As we will see, age and block replacement policies improve the stochastic behavior compared with the renewal process with no planned replacements when the underlying distribution is NBUE. Some interpretations, applications, and a discussion about some related results are included.