Relational computer-aided design

One of the established benefits of computer aided design (CAD) systems is the ability to change the attributes of a component within the design model. For example, changing the length of a component or changing its position within the model are normally simple operations. However, it is likely that changing one component will have implications for other components in the model. For example, changing the length of one component may require that the length of another component is altered. These implied changes may in turn imply further changes are required. Hence the process of implementing what may have seemed a simple change can quickly become a complex task. Supporting change is an important issue as it is widely accepted that design is an iterative process (J.C. Jones, 1980; A.J. Medland, 1986; B. Lawson, 1991). The paper demonstrates that traditional approaches to CAD systems do not support change, in that they are unable to deduce the implications of a change. It is argued that design intent could be used to better facilitate change