Optimal block replacement policies with multiple choice at failure

In this article the authors consider block replacement policies where the operating item is replaced by a new one at times kT, k=1,2,..., independently of its failure history. At failure the item is either replaced by a new or a used one or remains inactive until the next planned replacement. The mathematical model is defined and general analytical results are obtained. Computations are carried out for the case where the underlying life distribution is gamma or Weibull.