Design structure matrix-based product representation for life-cycle process-based modularity.

摘要

Researchers have expanded the definition of product modularity from function-based modularity to life-cycle process-based modularity, and developed a measure of product modularity and validated a corresponding modular product design method. However, a correct modularity measure and modular design method are not enough to realize modular product design. How the measure and design method are used, especially the role of product representation, is an important aspect of modular design and imperative for realizing the promised cost savings of modularity.;This research starts from the development of a representation which includes similarity and dependency for manufacturing modularity. The manufacturing process-based component-component similarity matrix is used to cluster components with similar manufacturing processes into one module. Manufacturing process-based similarities are based on component processing codes that represent their manufacturing attributes. Clustering these manufacturing process-based similarities leads to cost savings through module-wide sharing of process plans, manufacturing tools, and equipment, and the reduction of manufacturing tool and equipment changes during manufacturing. The manufacturing process-based component-component dependency matrix is based on physical interactions among the components that affect the material, shape, size, surface finish of the components, and therefore affect the component manufacturing processes. If components are independent of other components not in the same module with respect to these physical interactions, the redesign of components in one module will not cause a cascade of design and manufacturing process plan changes for components not in the same module.;Then a representation which includes similarity and dependency for another common life-cycle process---assembly process is developed. The assembly process-based similarity representation is based on assembly cost factors including tool changes and fixture changes. The assembly process-based design dependency representation is based on the interactions of assembly interface that increase the difficulty of redesigning, updating, and assembling the module independently during the assembly process. A product is used to show the application of this representation in association with a modularity measure and modular design method.;The representation for retirement process has also been developed. The retirement process-based similarity is related to the similarity in components' post-life intents (recycling, reuse, disposal), or the degree of their material compatability if both of the components' end life intents are to be recycled, or their disassembly direction or tool if they have to be disassembled anyway. The retirement process-based dependency is developed based on the disassembly difficulty, which is also one aspect from the physical interactions between the components. Retiring the components with the difficult disassembly operation together as a module and reducing the disassembly difficulty between the modules can result in an increase of the efficiency of the retirement process.;Based upon the representation developments for these three processes, a generalized process of developing the product modularity representation for DSM-based modular product design that is derived from the most significant elements of product modularity across the life-cycle process is summarized. Similarity factors, which is developed based on processing cost factors, usually is pursued from the similarity of processing tooling or equipments. Sometimes, when the similarity in the processing tooling/equipment is difficulty to track due to the diversity of the tooling/equipments in that process, the similarity can be pursued in the processing attributes that will affect the choices of the tooling/equipment in that process. The development of a component-component similarity score is based on comparing the impact between the effects of the similarity factors on the components' processing time. This impact could be isolated from the existing cost models if possible. Or it could be estimated by the relative cost savings from sharing tooling and equipments and reducing tooling/equipment changeover time based on some processing attributes group technology existing in current literature. The dependency factors are developed based on interactions among the components during a life-cycle process that will increase difficulty in updating and processing the module independently. The dependencies are quantified based on the strength of the impact of those interactions and transform the result into a 0--1 scale to keep the consistency with similarity. Using these similarity and dependency representations as input to a DSM-based modular design method, would yield a design with a modular architecture that will reduce processing cost from sharing tooling/equipment and keeping redesign impact within the modules. Finally an application example of the generalized process of developing representation is shown on the design processes to guide the readers to develop the product modularity representations for their own purpose. This generalization process facilitates the consideration of a wide array of life-cycle processes in a key element of product architecture decision making---modular design early in the design process, which is, in essence, the goal of this research.