Abstract
In general, the vague lambda-tau methodology based on interval arithmetic operation is used to analyze the reliability of repairable system. The reliability analysis of complex systems based on the interval arithmetic operations are not effectively assessed under the vague environment. Therefore, in order to overcome the above mentioned limitation, this research adopts the weakest t-norm based arithmetic operations over vague lambda-tau methodology. The proposed arithmetic operations provide control on fuzzy spread during complicated calculation of complex system under the vague environment and also it effectively preserve the original shape of a membership function. An example of gas turbine system is given to demonstrate the methods described in this paper.