Resilient System Design Using Cost-Risk Analysis With Functional Models

This paper presents a framework to compare the resiliency of different designs during the conceptual design, when information about implementation details is unavailable. We apply the Inherent Behavioral Functional Model (IBFM) tool to develop an initial functional model for a system and simulate the failure behavior. The simulated failure scenarios provide us the information on the unique failure propagation paths and the end state/final behavior of the system assigned to each failure. Each failure path is caused by injecting one or multiple simultaneous faults into the functional model. Within this framework, we generate a population of functional models from a baseline seed model, and evaluate its potential failure scenarios. We also develop a cost-risk model to compare resiliency of different designs, and produce a preference ranking. select the most resilient one, based upon the cost-risk objective. The risk is calculated based on the probability of having an undesired end state for each design, and a consequential cost is assigned to each failure to quantify the cost-risk for a given design. In this paper, we implement and demonstrate the proposed method on the design of a resilient mono-propellant system.