Function Based Risk Assessment: Mapping Function to Likelihood

Abstract

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.