Managing Functional Coupling Sequence to Decrease Complexity and Increase Modularity in Conceptual Design

Abstract

Conceptual design is the stage where the upstream objectives and downstream constraints meet, so both the ideality and practicality are important in conceptual design. Modularity supports designing complex system while the design can take advantages from the downstream resources. According to Axiomatic Design Theory (ADT), the design with the least complexity is the ideal design, and managing functional coupling sequence can lead to the minimal complexity of design concepts. In this paper, Design Coupling Sequence (DCS) was introduced to bridge the ADT and the modular design. The ‘precedence’ and ‘functional sets’ were defined in DCS to manage the coupled design concepts in order to support the modularity of the design concepts. The ‘precedence’ identified by the level of functional coupling helps realize the sequencing order. The two ‘functional sets’ were defined as the independent U-set: the collection of functionally dependent concepts, and the coupled C-set: the collection of the strongly coupled concepts. The faucet design case study shows how the DCS method and its strategy to decrease relative complexity and increase modularity, and the results between design by extra coupling elimination and design by the existing modules are compared. The DCS method bridges the design theory to design practice.

Building Numerical Design Matrix and Managing Functional Couplings for Concept Improvement of The Existing Product

“…After applying the adjusted DCS algorithm, the result of U-sets is U I : DP 2 U II : DP 4 U III : DP 6 U VI : DP 3 → DP 5 → DP 1 (10) Equation (10) is the same as Equation (8), and this shows that the proposed rating scale {0,1,3,9} is detailed enough in this case to provide the detailed execution sequence.…”

“…It is commonly known in product development practices that sequencing (or decoupling) functional couplings can improve upstream ideality (i.e., requirement driven) and modulating design concepts can achieve downstream practicality (i.e., manufacturability, cost, etc) [2,6,7,10]. DCS developed by Wang et al is an approach to manage functional coupling sequences and use functional sets to modularize design concepts [10]. Designers can use DCS to reach a desired level of balance between upstream objectives and downstream constraints at the same time.…”

“…For the functional sets-the completely independent Uset and the insolvably coupled C-set, the definitions are unchanged as it doesn't affect the check of functional coupling. Readers interested in more details of U-set and C-set are referred to DCS approach [10].…”

“…meet. In authors' prior work [10], the Design Coupling Sequence (DCS) method was developed to manage functional coupling sequences based on the binary DM to help designers achieve the desired balance between upstream and downstream requirements during concept improvement. However, uses of the binary DM, where X denotes nonnegligible relationships and O represents negligible relationships, has been criticised in many studies for lack of necessary details, and that the numerical DM would be better for product development practices [3,7,11].…”