هادی قلی نژاد

One of the key criteria for assessing the durability of a system is evaluating the probability of its performance over a specified time period, which is refered to as reliability. This probability depends on the performance of the system's components, and the failure rate of each component impacts this issue significantly. In most related studies, it is assumed that the failure rates of components remain constant over time; however, this rate is often not constant due to various factors. A common pattern for changes in failure rates over time is known as the bathtub curve, where the failure rate is initially high, decreases over a period, and then eventually increases again. The early life period, during which the failure rate of components is initially high and then decreases, can lead to early failures and a reduction in the probability of component performance. By conducting controlled experiments before the practical use of a system, this initial period can be eliminated, thereby preventing early failures, which in turn can lead to improved system reliability. This paper examines the impact of eliminating the early life period on system reliability. The results indicate that the elimination of this period does not necessarily lead to improved reliability under all conditions, as it depends on specific parameters. This paper will analyze the sensitivity of these parameters and the conditions under which eliminating the early life period can improve reliability.