Basic Reliability Tools for SHM Protocols

This chapter details the existing models, tools and methodologies existing for commercial-off-the-shelf new emerging technologies. It explains why and how the concept of activation energy is an Eyring model related to the stress and temperature applied, and the use of an approximated constant activation energy can no longer be considered as a constant to extrapolate some experiments under high stress to a nominal mission operation profile. The chapter presents hypotheses, baselines and definitions of reliability parameters through the prism of transition state theory in order to show how the multi-dimensional stress environment can be simply modeled. It addresses the transition state reliability model and reliability Physics-of-Healthy defined as the probability of a product performing its intended function for a given amount of time and mission profile. The entropic approaches are expected to develop in order to apply them in practical reliability analyses and prognoses.