Integrating product and process design through decision analysis
With fast moving markets and increasingly global competition, companies now recognise that every aspect of a product, through its development and beyond, must be considered when making design decisions. Design for X tools are a popular way of doing this, providing information on how design choices affect subsequent lifephases or important virtues of the product. However, each DfX tool imposes a preference structure on the designers by giving precedence to a single virtue or lifephase, and offering no way of reconciling trade-offs with others. This thesis demonstrates that decision analysis - a technique for evaluating alternatives against conflicting objectives - can resolve this problem by incorporating DfX information in design decisions without imposing a preference structure. As many DfX techniques are available, attention is restricted to the context of integrated product and process design, where design decisions include the implications of manufacturing. Eight characteristics are proposed, taken from concurrent engineering principles and decision analysis, for successful integrated product and process design decisions. A relationship is shown to exist between DfX and decision analysis, and this relationship is embodied as a methodology for decision-making in integrated product and process design. Three Design Experiments and two Case Studies demonstrate that this methodology is feasible, and exhibits the desired characteristics in practice. Further work is necessary to determine whether these findings generalise to other DfX and whether this is an appropriate method of combination. Then future DfX tools could be developed based on decision analysis principles that can analyse designs systematically against multiple virtues and lifephases. By demonstrating the relationship between Design for X and decision analysis, and showing that it can be used in practice, this thesis provides the first step along this path.