Value Driven Design : a methodology for value-oriented decision making in preliminary design

Sammanfattning: Making design decisions during preliminary design of a complex product, such as an aircraft, is a difficult activity. Numerous teams, acting on a global scale, take part in such design activities, approaching the problem from different perspectives and at different levels of granularity. Based on their position in the supply chain, design teams can focus either on the product as a whole, on its service-related aspects, or on the design of specific components of the product itself. The complexity of the design causes design teams to often base decisions on flawed or incomplete information, since stakeholders’ needs and perceptions are difficult to predict and communicate among teams. Such situations make it problematic for the developers to understand which design concept would be the most valuable to develop.Through collaboration with major European aerospace manufacturers, this research has highlighted the limits of current product development practices in addressing the promotion of more value-oriented design decisions in preliminary design This thesis has investigated the meaning of value in preliminary design decision-making and proposed a way forward towards its assessment and communication, introducing a value-oriented perspective to decision-making. This thesis builds on the Value Driven Design (VDD) concept increasingly discussed in the aerospace industry. VDD, in its original formulation, promotes the use of the mathematical optimization of a value function to select the most valuable design concepts. VDD is debated in literature, and an established VDD theory is not present. Contributing to such debate, this thesis proposes a Value Driven Design methodology for decision making in preliminary design that goes beyond the concept of mathematical optimization of a single value function. It considers the value of a design concept as encompassing stakeholders’ needs that are not always quantitatively quantifiable in a mathematical function, giving up with the idea of obtaining an absolute numerical measurement for value. The methodology takes the standpoint of an aircraft sub-system manufacturer. It merges concepts available in literature (i.e. Value Creation Strategy, Knowledge Maturity, Customer-Oriented Design Analysis) with the approaches developed from the findings of the empirical study. The methodology is based on correlating value aspects at different supply chain levels, assessing the maturity of the knowledge and computing the value of a design alternative compared to a baseline and a target. The use of colored features in CAD models to enhance the communication of value-related information is also proposed, and preliminary tested.Finally, guidelines for value assessment and visualization in preliminary design are provided, and the contributions to the VDD field are discussed together with the industrial implications of the methodology.