Preliminary hazard analysis for the design alternatives based on fuzzy methodology

A fuzzy logic approach is adopted in order to add more power features and update a classic hazard assessment methodology. Fuzzy logic provides an easy tool for directly manipulating the linguistic terms used in the risk assessment. Based on the findings for the four-stroke diesel engine safety assessment there are five metrics of the consequences categories defined as follows: Cost and Equipment Damage, Operability, Maintainability, Personnel Death/Injury and Environmental Impact. There are four likelihood categories defined by the linguistic expressions as follows: likely, may occur, not likely and very unlikely. The quantitative ranges of the consequences and likelihood categories are adopted to create the universe of discourse for the fuzzy sets. The Risk Ranking Matrix is adopted to create the fuzzy sets rules for each combination of severity of consequence and likelihood for five metrics. This study has confirmed that fuzzy methodology is one technique that is particularly appropriate for processing the choice of best alternative in the early stage of the design. The fuzzy method shows clearly the advantages of the fuzzy ranking matrix in comparison with the previous analysis performed by classic hazard assessment methodology.