Proceedings of ICAD2009 The Fifth International Conference on Axiomatic Design Campus de Caparica – March 25-27, 2009 ICAD-2009-XX Copyright © 2009 by ICAD2009 ABSTRACT Nowadays, due to its critical role regarding product cost and performance, as well as, time to market, product design is considered to be at the new frontiers for achieving competitive advantage. Therefore, to face today’s rapidly changing business environments, it is extremely important to adopt a systematic approach to product design, in order to avoid errors and consequently achieve shorter time-to market performances. In this context, we will describe a new approach to support product design, which links Axiomatic Design (AD) and Multidisciplinary Design Optimization (MDO), applied in an integrated way at the conceptual design and the detailed design stages, respectively. Firstly, the conceptual design stage is undertaken by AD, which is used to map Functional Requirements (FRs) with the corresponding Design Parameters (DPs). Even though we try to guarantee the Independence of FRs, as established by Axiom 1 of AD, if some remaining coupled relations subsist that is not prohibitive. Afterwards, the detailed design is carried out by MDO, considered to be an appropriate methodology to design complex systems through an adequate exploitation of interacting phenomena. The proposed approach is applied to the design of metallic moulds for plastic parts injection, since the mould makers sector involves constant design and production of unrepeatable moulds, where uncoupled designs solutions, mostly due to technological and time reasons, aren’t common (this sector is strongly influenced by customers who place enormous pressures on lead-time and cost reduction). This application points out the high potential of improvement that can be achieved through the simultaneous improvement of mould quality, reliability and time to market. Keywords: Axiomatic Design, Multidisciplinary Design Optimization, moulds design, coupled designs. 1 INTRODUCTION In general product development can be described, as an iterative process where some recursive and repetitive tasks, dominated by empirical knowledge, are performed until an acceptable solution is achieved. Due to today’s market pressure to reduce costs and time-to-market of products, as well as, to increase its quality, new design approaches must be adopted allowing faster and efficient product development. One of these methodologies is Axiomatic Design (AD), which establishes a systematic and scientific basis for product design process with the final goal of determining the best design solution [Suh, 1990]. The basic postulate of AD approach is that there are two fundamental axioms that must govern the design process: the Independence axiom and the Information axiom. The first axiom, states that the independence of Functional Requirements (FRs), which are the specific requirements translated from customer’s needs, must always be maintained. The second axiom establishes that the best design, amongst designed solutions that satisfy the independence axiom, is the one that has the smallest information content. In addition, AD establish that the design process must progress by mapping the FRs into Design Parameters (DPs), which characterized each design solution, in a top-down hierarchical manner. For each level of decomposition, the relationship between FRs and DPs can be described mathematically as a design matrix [A]. According to the structure of this matrix, there are three types of design: Uncoupled, Decoupled and Coupled. The Uncoupled design (most preferred) is characterized by a diagonal matrix, which indicates the independence of all FR-DP pairs [Jang, Yang et al., 2002]. The Decoupled design (second choice) is characterized by a triangular design matrix. Therefore, the FRs can be answered systematically from FR1 to FRn by considering only the first n DPs. Finally, the Coupled design (undesirable) is characterized by a design matrix with no specific structure. Therefore, a change in any DP may influence all FRs, simultaneously, meaning that the independence axiom is not accomplished. Although this type of design is not promoted by AD, because it does not guarantee the first axiom , some authors (e.g. [Crawley, Weck et al., 2004]) believe that there are some cases where it should be applied, especially when performance, efficiency and packaging constraints dominate, where uncoupled/decoupled solutions might not be feasible. This is the case of metallic moulds for plastic parts injection [Ferreira, Cabral et al., 2006], where, by technological and time reasons, mould designs are generally a coupled solution, or has at least some coupled areas. In this sense, Multidisciplinary Design Optimization (MDO), which is considered appropriate to design complex systems trough exploitation of interacting phenomena, can be A NEW AD/MDO APPROACH TO SUPPORT PRODUCT DESIGN Irene Ferreira. iferreira@estg.ipleiria.pt Centre for Rapid and Sustainable Product Development, INDEA, Campus 5 Rua das Olhalvas, 2414-016 Leiria, Portugal José A. Cabral jacabral@fe.up.pt Department of Industrial Engineering and Management, Faculty of Engineering, University of Porto Rua Dr. Roberto Frias, 4200-465 Porto, Portugal Pedro M. Saraiva pas@eq.uc.pt Department of Chemical Engineering, University of Coimbra, Pólo II - Pinhal de Marrocos, 3030-290 Coimbra, Portugal