1. Department of Mechanical & Marine Engineering, University of Plymouth 1 Formulating the Design Envelope The Role of Reflective Practice * Professor M Neil James * RS Adams, J Turns and CJ Atman (2003) Educating effective engineering designers: the role of reflective practice, Design Studies 24 275-294.

2. Department of Mechanical & Marine Engineering, University of Plymouth 2 What is the Design Envelope ? It is a means of describing the following aspects of the design: The various possible interactions between the design concept and the totality of its external environment – these:  Define design parameters  Constrain possible solutions  Affect material choice  Influence geometry and shape

3. Department of Mechanical & Marine Engineering, University of Plymouth 3 What is the Design Envelope ? It is a means of describing the following aspects of the design: The relationships among, and between, its various parts or components – these:  Influence function  Influence form and aesthetics  Confer operating characteristics

4. Department of Mechanical & Marine Engineering, University of Plymouth 4 What is the Design Envelope ? This description will contain text-based, graphical and numerical parts Through achieving inclusivity, it allows clearer identification of potential areas of innovation It forms the basis for rational choice between potential solutions It is performed for the overall concept and for sub-systems It allows for iteration between later and earlier stages in the design process

5. Department of Mechanical & Marine Engineering, University of Plymouth 5 What is the Design Envelope ? In simple terms a design envelope summarises: Requirements  Attributes that the solution must have to satisfy external or internal parameters  The more specific these become, reflecting better quantification of aspects of the problem, the better the potential solution choice and problem understanding e.g. “it must not be too heavy”, cf “it should weight less than 25 kg to meet COSH lifting guidelines

6. Department of Mechanical & Marine Engineering, University of Plymouth 6 What is the Design Envelope ? In simple terms a design envelope summarises: Constraints  Limitations on design characteristics imposed by external or internal parameters  The more specific these become, reflecting better quantification of aspects of the problem, the better the potential solution choice and problem understanding e.g. “it must operate quickly”, cf “it should have a response time of 10 s” (power implications etc)

7. Department of Mechanical & Marine Engineering, University of Plymouth 7 What is the Design Envelope ? In simple terms a design envelope summarises: Criteria  Critical design characteristics imposed by external or internal parameters  These are used to assess optimality of proposed solutions - very specific identification of these will assist greatly in choosing between various proposals e.g. “it must be failsafe in use”, cf “it must cut electrical power in 100ms if a short circuit occurs”

8. Department of Mechanical & Marine Engineering, University of Plymouth 8 What is the Design Envelope ? Requirements, constraints and criteria are interchangeable depending on the details of the design solution specification e.g. “it must operate quickly”  Could be a requirement of a design parameter  Could be a constraint on performance  Could be a criterion of paramount importance Careful thought as to the most appropriate category will amplify knowledge of the design ‘space’

9. Department of Mechanical & Marine Engineering, University of Plymouth 9 Formulating a Design Envelope Obtaining a fully specified design envelope is more involved than may initially be thought There are significant potential benefits  A good specification may enable greater innovation/cost savings  Advances in function  Advances in materials engineering  A more elegant solution may result  Better form/ergonomics; simpler operation

10. Department of Mechanical & Marine Engineering, University of Plymouth 10 Formulating a Design Envelope Obtaining a fully specified design envelope is more involved than may initially be thought It is a high level engineering skill  Innate embodiment of sum of knowledge  Achieved through ‘reflective practice’  Can be inculcated through understanding of reflective practice in design and project work It leads to ‘spider web’ linkages between design attributes

11. Department of Mechanical & Marine Engineering, University of Plymouth 11 Reflective Practice in Engineering Design Realising an engineering design encompasses 3 key stages: NEEDNEED – all design begins with a clearly defined need VISIONVISION – all designs arise from a creative response to a need DELIVERYDELIVERY – all designs result in a system, product or project that meets the need

12. Department of Mechanical & Marine Engineering, University of Plymouth 12 Reflective Practice in Engineering Design Consider the systems approach to design:

13. Department of Mechanical & Marine Engineering, University of Plymouth 13 Reflective Practice in Engineering Design Systems approach involves: ‘Deconstructing’ a particular problem in a sequential way into components, systems and actions prior to ‘constructing’ various potential solutions It also involves cross-linking and integrative processes between the various sub-sets of design activity This is done in a ‘virtual’ iterative and reflective way prior to prototype or final design production

14. Department of Mechanical & Marine Engineering, University of Plymouth 14 Reflective Practice in Engineering Design Another way of showing this reflective process in design activity terms is via an ‘iterative transition diagram’ – e.g. design of a playground

15. Department of Mechanical & Marine Engineering, University of Plymouth 15 Reflective Practice in Engineering Design The ‘iterative transition diagram’ is a model of the design process and summarises the key issues in reflective practice: Interactive framing of the problem Reflection on the outcome on these moves Inexperienced designers show a low level of iteration across design activities  Particularly the case later in the design activity sequence  Less willing to revisit earlier decisions

16. Department of Mechanical & Marine Engineering, University of Plymouth 16 Reflective Practice in Engineering Design What does reflective design practice entail ? Emphasis on problem-setting activities, as well as problem solving activities Reasoning about the problem  Experimentation with ideas/solutions  A variety of graphical and textual representations of problem aspects

17. Department of Mechanical & Marine Engineering, University of Plymouth 17 Reflective Practice in Engineering Design What does reflective design practice entail ? Interactive problem framing Iterative generation of ‘moves’ towards a solution Reflection on outcomes of this problem and solution framing

18. Department of Mechanical & Marine Engineering, University of Plymouth 18 Reflective Practice in Engineering Design Important features of this model of the design process are: Unpredictability (of final solution) Consequent surprise in the design process  Leads to innovation, novelty, uniqueness Reflection Unpredictability of complex design situations encourages ‘back-talk’

19. Department of Mechanical & Marine Engineering, University of Plymouth 19 Reflective Practice in Engineering Design ‘Back-talk’ isreflective interaction with aspects of the design and potential materials Aids in developing a deeper understanding of the design problem Experiment with solution to push boundaries  Irregularities in solution suggest further areas of clarification Iterative transitions between design activities represent such ‘back-talk’

20. Department of Mechanical & Marine Engineering, University of Plymouth 20 Reflective Practice in Engineering Design Iteration triggered by specific activities: Self-monitoring  Reviewing and evaluating progress  Checking understanding of problem  Searching for and being open to potential solution short-comings Clarifying  Interpret meaning of ambiguities or important criteria

21. Department of Mechanical & Marine Engineering, University of Plymouth 21 Reflective Practice in Engineering Design Iteration triggered by specific activities: Examining  Efforts to understand solution behaviour  Determine solution feasibility Iteration likely to result in: Redefining problem elements  More detail in design envelope Coupled revision to problem understanding and potential solutions

22. Department of Mechanical & Marine Engineering, University of Plymouth 22 Reflective Practice in Engineering Design Complex and ambiguous (open-ended) design tasks involve a paradox: Information cannot be gathered meaningfully unless the problem is understood Cannot understand the problem without gathering detailed information about it Iteration and reflection are essential to effective design practice