Engineering design is a creative work that turns ideas into reality. It is an iterative process of designers and engineers, who not only need to apply their knowledge and inventiveness to create new products and solve the technical problems but should also adapt these solutions to fulfil the expectations of their clients and to meet certain restrictions (material, technology, environment, economy, etc.). In present days, several software tools are largely used to support the design and related analysis and simulation tasks; however, such tools lack in the representation of the design rationale, that is, the reasons why certain design solutions have been preferred in respect to others.
The research is aimed to define engineering ontologies, aimed to better support the representation of design rationale and design intent, in particular for CAD systems. An important aspect of the research is the role played by the geometrical information in the design process and on the relationships among elementary mechanical functions and components shapes.