This thesis addresses the problem of achieving better convergence between different phases (here design and manufacturing) of the product development cycle. The use of liaison has been proposed to better integrate the product and assembly process. Two facets of integration have been addressed in this thesis. One is concurrent evolution of the process model with the product model and the second is associativity between product model and process model. A liaison data structure has been proposed, which is set of geometric entities, associated with one or more assembly process that acts as an interface between the product model and process model. As the liaison data is not available explicitly in the product model, a set of algorithms have been developed and implemented to identify and extract the geometric entities defined in the liaison data structure from assembly model. The proposed algorithms can identify and extract liaisons for riveting, welding, bolt fastening, screw fastening, adhesive bonding (gluing) and blind fastening. The developed algorithms have been implemented and tested. The process model needs to evolve with the product model concurrently so that any mistakes or infeasibility in the process model can be flagged right away. The use of liaison enables the construction of process model as the product model is fleshed out. A framework based on liaison has been proposed and implemented to demonstrate the concurrent evolution of product and process model. Linking the changes in the product model to flag the changes (or at least identify the need for changes) in the process model forms the associativity problem. The liaison has been used for maintaining associativity between the product and process model. A framework has been proposed for maintaining associativity between product model and process model that makes use of expert knowledge or tribal knowledge to track impact of changes in product model or process model. An aircraft wing box has been used as an example to illustrate and validate the proposed approaches. Finally the thesis concludes by summarizing contributions of the research and outlining future work.

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Semantic interoperability (SI) of a product model refers to automatic exchange of meaning associated with the product data, among applications/domains throughout the product development cycle. In the product development cycle, several applications (engineering design, industrial design, manufacturing, supply chain, marketing, maintenance etc.) and different engineering domains (mechanical, electrical, electronic etc.) come into play making the ability to exchange product data with semantics very significant. With product development happening in multiple locations with multiple tools/systems, SI between these systems/domains becomes important. The thesis presents a feature-based framework for shape model to address these SI issues when exchanging shape models. Problem of exchanging semantics associated with shape model to support the product lifecycle has been identified and explained. Different types of semantic interoperability issues pertaining to the shape model have been identified and classified. Features in a shape model can be associated with volume addition/subtraction to/from base-solid, deformation/modification of base-sheet/base surface, forming of material of constant thickness. The DIFF model has been extended to represent, classify and extract Free-Form Surface Features (FFSFs) and deformation features in a part model. FFSFs refer to features that modify a free-form surface. Deformation features are created in constant thickness part models, for example, deformation of material (as in sheet-metal parts) or forming of material (as in injection molded parts with constant thickness), also referred to as constant thickness features. Volumetric features covered in the DIFF model have been extended to classify and represent volumetric features based on relative variations of cross-section and PathCurve. Shape feature ontology is described based on unified feature taxonomy with definitions and labels of features as defined in the extended DIFF model. Features definitions are used as intermediate and unambiguous representation for shape features. The feature ontology is used to capture semantics of shape features. The proposed ontology enables reasoning to handle semantic equivalences between feature labels, and is used to map shape features from a source to target applications. Reasoning framework for identification of semantically equivalent feature labels and representations for the feature being exchanged across multiple applications is presented and discussed. This reasoning framework is used to associate multiple construction paths for a feature and associate applicable meanings from the ontology. Interface is provided to select feature label for a target application from the list of labels which are semantically equivalent for the feature being exchanged/mapped. Parameters for the selected feature label can be mapped from the DIFF representation; the feature can then be represented/constructed in the target application using the feature label and mapped parameters. This work shows that product model with feature information (feature labels and representations), as understood by the target application, can be exchanged and maintained in such a way that multiple applications can use the product information as their understandable labels and representations. Finally, the thesis concludes by summarizing the main contributions and outlining the scope for future work.

There is a noticeable lack of production of indigenously engineered and manufactured products in Less Developed Countries (LDC's). Few products developed in these LDC's could be viable in competitive markets or even sold as components and supplies to other manufacturers of competitive goods. Assumintg that these less developed countries do not innovate and manufacture because they cannot, the next logical question to ask is why can they not? This thesis looks at the problems of manufacture and design in LDC's from the standpoint of Product Development. It begins by looking at development theories, namely top down and bottom up and assessing the difficulties encountered with either approach. It then looks at literature on product development, covering four areas: appropriate technolotgy, Product Development Cycle, QFD, and finally Design for X. These areas are analyzed for their usefulness in solving the development problem. The environment is considered and a linkage is developed between the Product Development Cycle and the environment. This is found to happen by way of Enterprise Needs which are needs that a product must fulfill to make it a viable option for manufacture. Finally, a process is outlined and demonstrated to form Enterprise Needs and take them into account within a traditional concept selection process. Environment was found to play a part in the Product Development Cycle. By clarifying Enterprise Needs as well as Customer Needs or Functional Needs, a more balanced approach can be taken to the concept selection process choosing the best concept, not only for the customer, but for the company as well.