Balancing load and performance for different failure models

In this article, we discuss an optimal loading for items with lifetimes described by failure models that are popular in reliability and statistics. The obtained results can be relevant, for example, for production/manufacturing systems. The expected productivity and the mission success probability are maximized with respect to the value of a load. It is shown that the optimal load for the considered settings is not necessarily the load that maximizes the production rate. The crucial function in our discussion is the production rate over the load. It is shown that, depending on the model, the optimal load can be equal, smaller or larger than the value of the load that achieves the maximum of this function. The accelerated life and the proportional hazards failure models are considered, as well as the additive hazards model. Illustrative examples confirm our theoretical findings.