Product success is a major goal of designing and design research. Designing involves developing systems. A system interacts with its environment to satisfy its requirements. Therefore, designing should involve developing the concept of both the system and its surrounding. Depending on how the concept of the system changes will impinge on the concept of the environment, and vice-versa; design must co-evolve the concepts of both the system and its environment to adapt them to each other. A comprehensive review of literature on designing to explore the use of system-environment view in designing revealed that while the concept of systems is used by many design models, implicitly or explicitly, the concept of environment is rarely used as an evolvable construct in designing. Activities, outcomes, requirement-solution and system-environment views play a significant role in product success. Thus, it is important to explicitly address these views in designing. Further, integration of these views is important for explaining various complex characteristics of designing such as requirement-solution co-evolution and system-environment co-evolution. Integration of views is important also for mapping the steps in design models using these views, so as to be able to characterize design models, or benchmark one design model against another. Literature has been reviewed to identify the constructs in these views that are essential for representing the design process. Srinivasan and Chakrabarti [2010] had earlier developed a model of designing by integrating three of these views: activities, outcomes, and requirement-solution. However, this model did not incorporate the system-environment view. In this thesis, a system-environment view is developed, with both the system and environment as explicit and evolvable constructs in designing. The thesis then proposed an extended, integrated model of designing which combines the constructs of the identified views of activities, outcomes, requirement-solution and system-environment. The proposed model is empirically validated using protocols from six design sessions; the sesessions had been undertaken well before the proposed model was developed.Validation involved checking whether or not instances of all the constructs in the model are naturally present in these design sessions, and whether or not every event in these design sessions could be described using the constructs of the proposed model. Further, the explanatory power of the proposed model is illustrated by explaining how system-environment co-evolution and requirement-solution co-evolution occur during the design sessions captured in the protocols. Also, a standard prescriptive approach to designing –Pahl and Beitz approach – is used to demonstrate how a design model can be mapped using the constructs of the proposed model–the first step to characterizing or benchmarking design models.

Current design models, approaches and theories are highly fragmented, have seldom been compared with one another, and rarely attempted to be consolidated. Novelty is a measure of creativity of engineering products and positively influences product success. Using physical laws and effects for designing can improve the chances of creativity but they cannot be used directly owing to their inadequate current representations. It is important to address activities, outcomes, requirements and solutions in designing. Conceptual design is an early phase in engineering design and needs to be supported better. A systematic approach for designing often increases effectiveness and efficiency. Thus, the broad objective of this thesis is to develop and validate a comprehensive understanding of how designing occurs during the conceptual phase of engineering design, and to support variety and novelty of designs during this phase. The approach followed is: (a) formulate and validate an understanding of novelty and its relationships to the designing constructs, in current designing, and(b)develop and validate a support, founded on the current designing, to improve novelty. The understanding and the support are addressed, respectively, through an integrated model and a systematic framework for designing; the model and the framework comprise activities, outcomes(including laws and effects), requirements and solutions. An integrated model of designing, GEMS of SAPPhIRE as req-sol is developed by combining activities(Generate, Evaluate, Modify, Select– GEMS), outcomes (State change, Action, Parts, Phenomenon, Input, oRgans, Effect–SAPPhIRE), requirements (req) and solutions (sol), identified from a comprehensive survey of existing design models and approaches. Validation of SAPPhIRE model with existing systems indicates that the model can be used to describe analysis and synthesis, both of which together constitute designing. Validation of the integrated model using existing videos of design sessions, to check if all its constructs are naturally used in designing, reveals that:(a) all the constructs are naturally used;(b) not all the outcomes are explored with equal intensity;(c) while high numbers of action and parts are observed, only low numbers of phenomenon, effects and organs are found. Empirical study using another set of design sessions to study the relationships between novelty and the outcomes reveals that novelty of a concept space depends on the variety of the concept space, which in turn depends on the variety of the idea space explored. Novelty and variety of a concept space also depend on the number of outcomes explored at each abstraction level. Thus, phenomena and effects are also vital for variety and novelty. Based on the above, GEMS of SAPPhIRE as req-sol framework for designing is proposed. The framework is divided into: Requirements Exploration Stage(RES) and Solutions Exploration Stage(SES). In RES and SES, requirements and solutions respectively at all the abstraction levels including SAPPhIRE are generated, evaluated, modified and selected. The framework supports task clarification, conceptual and early embodiment phases of designing, and provides process knowledge. Comparison of the framework against existing design models, theories and approaches reveals that:(a) not all existing models, theories and approaches address activities, outcomes, requirements and solutions together;(b) those that address all these constructs together do not make a distinction between requirements and solutions; and(c) no model or approach explicitly addresses novelty. The usability of the framework and Idea-inspire is assessed by applying them in an industrial project for designing novel concepts of lunar vehicle mobility system. The use of this combined support enables identification of critical requirements, development of a large variety of ideas and concepts. One of these concepts is physically and virtually modelled, and tested, and is found to satisfy all the requirements. A catalogue of physical laws and effects is developed using SAPPhIRE model to provide assistance to designers, especially for phenomena, effects and organs. Observations found during this development are reported. A comparative validation of the framework and the catalogue for their support to design for variety and novelty is done using comparative observational studies. Results from the observational studies reveal that the variety and the novelty of concept space improve with the use of the framework, or with the frame work and the catalogue, as compared to variety and novelty with no support.