Nodal Framework Modeling for System-Level Reliability Analysis

Reliable systems are crucial to ensure a design’s operational lifespan meets the needs of an application. This is done by identifying the various degradation and failure modes associated with a system and taking steps to mitigate their effects. By performing experimental life cycle tests to assess the reliability of a system’s design function, making changes based on the ways in which the system failed, and iterating on this process, more reliable and robust system designs can be found. However, experimental life-cycle testing can often be costly, so various modeling efforts have been developed to reduce expenses and speed up this design process. Commonly used reliability modeling techniques including reliability block diagrams, fault tree analysis, and Markov chain, each come with strengths and weaknesses with regards to ease of use, model complexity, and calculation approach. In this article, a new reliability analysis technique is presented with a state-space hierarchical structure, referred to as a nodal reliability framework. The structure of this modeling approach is outlined, and a simple case study is presented for the application of this technique on a single component fin-and-tube heat exchanger. Critical aspects of the implementation are discussed along with the differences for single component and system-level modeling.