A physics/engineering of failure based analysis and tool for quantifying residual risks in hardware

Abstract

NASA Code Q is supporting efforts to improve the verification and validation and the risk management processes for spaceflight projects. A physics-of-failure based Defect Detection and Prevention (DDP) methodology previously developed has been integrated into a software tool and is currently being implemented on various NASA projects and as part of NASA's new model-based spacecraft development environment. The DDP methodology begins with prioritizing the risks (or failure modes, FMs) relevant to a mission which need to be addressed. These risks can be reduced through the implementation of a set of detection and prevention activities referred to herein as PACTs (preventative measures, analyses, process controls and tests). Each of these PACTs has some effectiveness against one or more FMs but also has an associated resource cost. The FMs can be weighted according to their likelihood of occurrence and their mission impact should they occur. The net effectiveness of various combinations of PACTs can then be evaluated against these weighted FMs to obtain the residual risk for each of these FMs and the associated resource costs to achieve these risk levels. The process thus identifies the project-relevant "tall pole" FMs and design drivers and allows real time tailoring with the evolution of the design and technology content. The DDP methodology allows risk management in its truest sense: it identifies and assesses risk, provides options and tools for risk decision making and mitigation and allows for real-time tracking of current risk status.