Use of functional representation diagram for reliability improvement

This paper presents a functional hierarchy approach that can be used to develop a functional representation diagram of a complicated system. This functional representation identifies, successively, the system main functions and their associated subfunctions. The equipment (components, assemblies, subsystems) and calibration strategy software needed to accomplish these functions/subfunctions can also be tied to their corresponding level in the diagram. The potential benefits of this approach are many. In addition to providing an enhanced understanding of the system and interactions among the various functions, subfunctions, subsystems, assemblies and components, it can also be used by design engineers to focus more on the most effective design to achieve the basic functions. Other possible applications include providing a better framework for identification of the effects of potential failures, evaluation of possible impact from design/production changes, devising tests that focus more on the verification of important functions, development of engineering specifications (e.g., functional, interfaces, and equipment), etc. Collectively, these benefits can result in an improved design with better reliability and reduced field.