SUMMARY
This paper presents an integrated fuzzy simulation-fuzzy data envelopment analysis (FDEA)-fuzzy analytic hierarchy process (FAHP) algorithm for optimization of flow shop facility layout design (FSFLD) problem with safety and ergonomics factors. Almost all FSFLD problems are solved and optimized without safety and ergonomics factors. At first, safety and ergonomics factors are retrieved from a standard questionnaire. Then, feasible layout alternatives are generated by a software package. Third, FAHP is used for weighting non-crisp ergonomics and safety factors in addition to maintainability, accessibility and flexibility (or qualitative) indicators. Fuzzy simulation is used consequently to incorporate the ambiguity associated with processing times in the flow shop by considering all generated layout alternatives with uncertain inputs. The outputs of fuzzy simulation or non-crisp operational indicators are average waiting time in queue, average time in system and average machine utilization. Finally, FDEA is used for finding the optimum layout alternatives with respect to ergonomics, safety, operational, qualitative and dependent indicators (distance, adjacency and shape ratio). The integrated algorithm provides a comprehensive analysis on the FSFLD problems with safety and ergonomics issues. The results have been verified and validated by DEA, principal component analysis and numerical taxonomy. The unique features of this study are the ability of dealing with multiple non-crisp inputs and outputs including ergonomics and safety factors. It also uses fuzzy mathematical programming for optimum layout alternatives by considering safety and ergonomics factors as well as other standard indicators. Moreover, it is a practical tool and may be applied in real cases by considering safety and ergonomics issues within FSFLD problems.