Function Based Risk Assessment: Mapping Function to Likelihood

Risk assessments are necessary to anticipate and prevent accidents from occurring or repeating. This paper focuses specifically on the relationship between function and risk by presenting a mathematical mapping from product function to risk likelihood. This type of mapping will aid designers by removing the subjectivity of the likelihood value from a risk element, provide three key risk element properties (design parameter, failure mode, and likelihood) for numerous risk elements with one simple mathematical calculation, and provide a means for inexperienced designers to effectively address risk in the conceptual design phase. In addition, the level of detail a functional model should be written in to produce adequate likelihood risk assessments is examined. Three case studies are used to validate the proposed mapping: A spacecraft orientation subsystem, a subsystem to guide science instruments on an extraterrestrial, and subsystems from a Bell 206 rotorcraft. The work described in this paper continues is part of ongoing research relating function to failure