A Plug-and-Contract Mechanism for a Robust Assessment of Design Concepts Available to Purchase

Starting from a need and a set of functional requirements (FRs), a designer is often perplexed to assess the potential of a given concept to fit these requirements. He is even more perplexed when several concepts are candidates. This paper proposes a definition of a concept in a practical way as a parameterized model linking a set of design variables (DVs) to a set of performance variables (PVs). This set of PVs is supposed to be the same for any concept candidate to fulfill a need. This is why our model propose to “plug” a card of FRs into candidate concepts in order to lead concurrent reasonings on competing concepts until one or several of them appear to be of poor interest. The plugging mechanism is implemented by constraint programming techniques (evolved interval arithmetics) that immediately contract the performance and design variable domains to provide an outer approximation of the solution (or design) space. Two sets of comparison operators between solution spaces are proposed: operators for comparing the relative potential of two concepts submitted to the same FRs, and operators for comparing two successive stages of solution spaces of a given concept. These last operators provide the way to tackle the robustness of design decision making under uncertainty. All the mentioned features: plugging mechanism, contraction of domains and design space representation, comparison operators and robustness considerations have been experimented on an example of a pair of candidate concepts of truss structures.