Engineering system safety analysis and synthesis using the fuzzy rule-based evidential reasoning approach

The main objective of this paper is to propose a framework for modelling, analysing and synthesizing system safety of engineering systems or projects on the basis of a generic rule-based inference methodology using the evidential reasoning (RIMER) approach. The framework is divided into two parts. The first one is for fuzzy rule-based safety estimation, referred to as a fuzzy rule-based evidential reasoning (FURBER) approach. The second one is for safety synthesis using the evidential reasoning approach. In the FURBER framework, parameters used to define the safety level, including failure rate, failure consequence severity and failure consequence probability are described using fuzzy linguistic variables; a fuzzy rule base designed on the basis of a belief structure is used to capture uncertainty and nonlinear relationships between these three parameters and the safety level; and the inference of the rule-based system is implemented using the evidential reasoning algorithm. Then the following steps involve synthesizing safety at higher levels of an engineering system to integrate all possible causes to a specific technical failure, or estimates made by a panel of experts. The synthesis is also based on the evidential reasoning approach. The final step describes the analysis and interpretation of the final synthesized safety of a system. The above framework has been applied to modelling system safety of an offshore and marine engineering system: the floating production storage offloading (FPSO) system. A series of case studies of collision risk between a FPSO and a shuttle tanker due to technical failure during a tandem offloading operation is used to illustrate the application of the proposed model.