A decision support method for selecting design and manufacturing alternatives

One of the most important decisions which should be made at the early stage of the design process is to select one design alternative. Not only should the decision be made by tradeoffs between different conflicting criteria of the single stakeholder but also to aggregate different outcomes obtained by multiple stakeholders. This thesis represents a decision support tool for selecting design alternatives, in which a single choice has to be made between a number of alternatives in the presence of single or multiple stakeholders, multiple conflicting criteria, and resource limitation, based on two routes: using Analytic Hierarchy Process (AHP) alone and the combination of AHP with Zero-One Goal Programming (ZOGP). Using AHP-ZOGP allows the concept-concept and concept-specification approaches to be considered simultaneously in order to improve the process of concept design selections. Different outcomes obtained by using AHP alone, can be aggregated by two heuristic methods based on distance function, to generate an index for final single selection. The first method uses the final weights obtained by AHP, while the second method uses its detailed weights. AHP weights are then used to construct the ZOGP's objective function and constraints' parameters of intangible criteria for each individual stakeholder. Another ZOGP model can be constructed to aggregate the different outcomes, obtained by individual ZOGP's models, based on combining their objective functions. The advantages of using aggregated ZOGP models in comparison with heuristic methods are, not only ZOGP aggregated model is able to minimise the undesirable distances between sub-criteria and Product Design Specification (PDS), but also it can take into account the resource limitations explicitly. The case studies, which involved vehicle manufacturing technology selection, choosing a peristaltic pump, selection of a swivel joint design, and the justification of advanced manufacturing systems, possessed the characteristics of the type of problems this tool is intended to support. The case studies showed how it is possible to consider many criteria from different stakeholders to yield a single outcome that covers the requirements of those stakeholders.