| This dissertation examines methods for designing product families. Tools are developed for aiding designers in making commonality and modularity decisions given requirements for a set of products.; Product platforms enable rapid enrichment of a product portfolio to meet changing market needs while keeping design and manufacturing cycle times and costs low. A product platform can be summarized as a collection of the common elements implemented across a range of products. The product platform is the set of parts, interfaces, and manufacturing systems that are shared among a set of products and allows the development of derivative products with cost and time savings. In this manner, it is emphasized that a platform does not only refer to common physical components but also to a common manufacturing and assembly system. Product modularity enables quick redesign of existing products into new products. Modules with regard to the product itself are the set of components that when interchanged produce variety. Likewise, products may be based on modular manufacturing or assembly systems.; Designing a family of product variants that share some components usually requires a compromise in performance relative to the individually optimized variants, due to the constraints on commonality. Choosing components for sharing may depend on what performance losses can be tolerated. This thesis presents methodologies for choosing product components to be shared without exceeding user-specified bounds on performance. This enables the designer to control tradeoffs and obtain optimal product family designs for maximizing commonality at different levels of acceptable performance.; The product family design methodology is extended to formulations for hierarchical system design. The all-at-once formulations are modified to accommodate the presence of shared assemblies, subsystems, components and/or variables with local design specifications. Hierarchical formulations associated with each product variant are combined to formulate the product family design problem, and common subproblems are identified based on the shared elements (i.e., the platform).; Several examples are shown to demonstrate the methods including design of automotive body structures, engines, and vehicle chassis/suspension. |
