RELIABILITY OF REDUNDANT SYSTEMS WITH DEPENDENT FAILURES.

The authors adopt a dependent failure model proposed by B. V. Gnedenko and M. L. Shooman and analyze the system reliability for a one-stage parallel redundancy with the assumption of dependent failures among components. The failure correlation coefficient is defined to express the dependency of failures, and its critical limit within which the redundant system is effective is clarified. It is found that when the failure correlation coefficient exceeds a critical value, the adoption of a redundant system rather reduces the system redundancy. Further, from the comparison of reliability of component redundancy with dependent failure and reliability of system redundancy in the multistage system, it is clarified that the system redundancy has higher reliability than the component redundancy.