Competing risk problems involving degradation failures are becoming increasingly common and important in practice. In this article, we will investigate the modeling of competing risk problems involving both catastrophic and degradation failures under accelerated conditions. Modeling the degradation process as a Brownian motion process for which the first passage time to a boundary is considered as the soft failure and modeling hard failures as a Weibull distribution enables us to model accelerated testing in a natural way, make inferences about the parameters of the degradation process and predict the reliability of products at the operating conditions. This methodology is demonstrated and validated using a real case study.

In addition to the basic gates defined in last month's Hotwire article, Overview of Fault Tree Gates (Part I), other gates exist in classical Fault Tree Analysis (FTA). These additional gates (e.g. Sequence Enforcing, Priority AND, etc.) are usually used to describe more complex redundancy configurations. However, we will introduce two new advanced gates that can be used to append to and/or replace classical fault tree gates.