Accelerated life tests at higher usage rates: a case study

Abstract

The life of some products is measured by usage, e.g., cycles and mileage. Such products are usually operated at a low usage rate in the field. Accelerated life testing of the products often involves the concurrent use of increased usage rate and other stresses. The effects of increasing the usage rate on usage to failure (life) are usually ignored. In fact, increasing the usage rate may shorten or prolong the life. A generic method for accelerated life tests at higher usage rates is described in Ref. 1. Using the method, this paper presents a case study on demonstrating the reliability of a type of compact relays, whose life testing uses increased switching rates. In particular, we develop the component-specific acceleration model, test method, and best compromise plan. Life data analysis using the maximum likelihood method concludes that the compact relays marginally meet the reliability requirement. In addition, this paper evaluates the significance of the switching rate effect and shows that the effect cannot be ignored