Considering Modified Criticality Factor and Functional Dependency for Reliability Allocation Purposes

摘要

Reliability allocation is a very critical step for setting targets during product design and development process. Recently, many researchers have used information generated during failure modes and effects analysis (FMEA) such as risk priority number (RPN) to provide more authentic basis for reliability allocation. The RPN or criticality numbers are derived by multiplying severity, occurrence and/or detection ratings under the assumption of linearity of these rating scales. Additionally, most functions of a system are accomplished by cooperation of different subsystems. The functional dependency of subsystems should be considered when it comes to system improvements and modifications. In this research we attempt to explain this nonlinear behavior of these rating scales and propose a modified criticality factor for reliability allocation purpose. In addition, the modified criticality measure and the system functional dependency are combined to capture the system improvement. An example is provided to demonstrate the applicability of the proposed method.