A review of redundancy allocation problem for two decades: bibliometrics and future directions

Redundancy allocation problem (RAP) has attracted many researchers in recent years as it is very important aspect in the field of reliability and system engineering. It plays an important role in high-tech industries. Present paper conducts a comprehensive literature review to classify, analyze and intercept the existing studies related to the RAP with respect to different systems, system configuration, methodology, constraints. The previous literature related to the RAP problems have been invested by the researchers such as Tillman in 1980, Kuo in 2007 and Soltani from 2000 to 2014. The objective of this paper is to cover the study over the past two decades starting from 2000. The present research has reviewed approximately 280 papers which are segregated on the basis of exact and heuristic techniques, meta-heuristic and mathematical programming methods, stochastic and interval uncertainty, intuitionistic fuzzy and vague set, robust approach. Further, a classification has been done on the basis of objectives as single and multi-objective. Finally, insights regarding the future direction, challenges and limitations are given. Main aim of this research paper is to summurise the developments including recent, research gap and future directions in the field of reliability optimization.