The design process and a methodology for system integrity

Commonly used models of the design process do not reflect concurrent engineering, the influence of computer-assisted design on the design process, or the recursive divergent-convergent thinking processes at different levels of detail from whole system to subsystem to component design. Also, these models do not illustrate the process of establishing functional integrity in the design of multicomponent systems where multiple interdependencies are present. This paper outlines design model developments by the authors and introduces a methodology for designing for system integrity and minimizing risk from early in the conceptual phase, where uncertainty is high. The process involves probabilistic reasoning in propagating both qualitative and quantitative effects of changes or uncertainty in component or subsystem specifications through system models and determining the integrity of the design from multiple viewpoints.