Study on improving reliability of complex engineering system with an allocation method based on fuzzy theory

In complex engineering systems, many effective factors are in fuzzy form. by using fuzzy theory, the fuzzy factors affected significantly on reliability allocation of the system were analyzed and quantized. Calculation method of weighting coefficient matrix for effects of fuzzy factors on reliability allocation and subordinate function matrix of the fuzzy factors were given. The relative proportional relation, satisfied in reliability allocation consideration among the subsystems, was derived, then the model of fuzzy allocation of system reliability was given. The reliability allocation for the cascade system with six subsystems and six fuzzy factors as an example was considered. The numerical results have shown that the fuzzy allocation method is simple and practical.