A framework for conceptual design decision support
The decisions made at the conceptual design stage are crucial to the overall success of the product as they affect all the downstream phases of the product life cycle, the user satisfaction of the product and the environment that the product is used and disposed of. The consequences due to these design decisions could therefore be good or problematic. Due to the lack of availability of knowledge and understanding about the complexity of such knowledge spanning these different areas, designers find it difficult to know the implications of their decisions made at the conceptual stage on the product's life cycle, the user of the product and the environment in which the product operates. Reviews of existing methodologies reveal that there is a, need for a holistic view of knowledge in terms of the total context of the design problem under consideration to aid designers in their decision making at the conceptual design stage. This thesis addresses this problem by proposing, implementing and evaluating a computational framework for supporting decision making at the conceptual design stage. The need for considering the implications of design decisions on other life cycle stages of the product and using the whole context of the design problem lead to the characterization and formalization of the Design Context Knowledge into different groups and context knowledge categories. This structuring facilitates the creation of feasible design solutions composed of what is called Product Design Elements (PDEs) i.e. basic elements as a functional means to constitute a conceptual product design solution. The proposed Function to POE mapping model uses the aforesaid design context knowledge structured in different categories for reasoning and eliciting consequences, associated with selecting a particular design solution and determining its implications on the product's subsequent life cycle stages, user of the product and on the product itself. After developing a system architecture model based on the system requirements, the PROCONDES prototype system has been implemented for a sheet metal component design domain. An evaluation of PROCONDES performed by conducting a case study indicates the importance of design context knowledge in proactively supporting effective decision making during function to POE mapping process (i.e. conceptual design stage) by generating timely potential (good and problematic) consequences. However, further work is required to improve the model and its implementation to fully explore the approach and use of PROCONDES for real-time design scenarios.