Degree of Modularity in Engineering Systems and Products with Technical and Business Constraints

Abstract

There is consensus that modularity has many benefits from cost savings due to increased commonality to enabling a higher variety of products. Full modularity is, however, not always achievable. How engineering systems and products whose design is heavily influenced by technical constraints, such as weight or size limitations, tend to exhibit rather integral architectures is shown in this study. For this, two metrics are defined on the basis of a binary design structure matrix (DSM) representation of a system or product. The non-zero fraction (NZF) captures the sparsity of the interrelationships between components between zero and one, while the singular value modularity index (SMI) captures the degree of internal coupling, also between zero and one. These metrics are first developed using idealized canonical architectures and are then applied to two different product pairs that are functionally equivalent, but different in terms of technical constraints. Empirical evidence is presented that the lightweight variant of the same product tends to be more integral, presumably to achieve higher mass efficiency. These observations are strengthened by comparing the results to another, previously published, modularity metric as well as by comparing sparsity and modularity of a set of 15 products against a control population of randomly generated architectures of equivalent size and density. The results suggest that, indeed, some products are inherently less modular than others due to technological factors. The main advantage of SMI is that it enables analysis of the degree of modularity of any architecture independent of subjective module choices.

Pareto-optimization of complex system architecture for structural complexity and modularity

“…Several modularity metrics of first kind are introduced over time. Examples include singular value-based metric proposed by Holtta- Otto and de Weck (2007), coupling-based metric proposed by Martin and Ishii (2002), design interface-based metric proposed by Sosa et al (2003) and the minimum description metric (MDL) proposed by Yu et al (2007), which measures the sum of model description length and mismatched data description of the architecture. Second category of metric measures the similarity of modules in the system.…”

Visual Product Architecture Modelling for Structuring Data in a PLM System

“…This approach takes a starting point in the decomposition of a product into components/systems and an identification of interfaces/relations among these [18] [19].…”

Investigating tradeoffs between performance, cost and flexibility for reconfigurable offshore ships

“…Hölltä et al (2005) use several metrics to quantify the degree of modularity for products that face both technical and business-related constraints, finding that technical constraints limit the degree to which a design should be modularized. In a more thorough study, Hölttä-Otto and de Weck (2007) find that designs driven by technical constraints in fact often exhibit integral architectures, compared to less constrained designs. These results are in partial opposition to the independence axiom of Suh (1990), and the notion that modularization is always a positive.…”