A synthesis strategy for mechanical devices

Abstract

Good mechanical designs are often composed of highly integrated, tightly coupled components in which the interactions among the components are essential to the function and economic execution of the design. This assertion runs counter to design methodologies in other engineering fields, such as software design and circuit design, that advocate designs in which each component fulfills a single function with minimal interaction. Because of the geometry, weight, and cost of mechanical components, converting a single functional requirement into a single component is usually not practical. Each component may contribute to the performance of more than one function, and the performance of each function may be distributed over many components. In fact, most mechanical components perform not only the desired function, but also have many additional, unintended behaviors. In good mechanical designs, these additional behaviors often are exploited.

We describe a synthesis strategy to utilize these behaviors by transforming design specifications in a function-preserving manner to obtain function structures which correspond closely to collections of available components. This strategy is elaborated in the context of simple gearbox design.

We feel that design strategies derived from characteristics of good designs will foster improved design practice and facilitate the development of computer-based assistance to the designer.