Notes

5. Solution Process
   As mentioned earler, working through the solution process involves working through sub-states of knowledge from the initial state to the goal state. The process we will consider in what follows are applicable only to those where the initial state is at the conceptual level or higher as discussed above. Further, the implication is that we consider engineering design to be synthesis rather than analysis problems.
   Ullman suggests four components of a design process as being essential to characterizing a design:

   1. Plans
      Planning the design, deciding on the approach.
   2. Processing Actions
      Putting the plans (above)into effect
   3. Effects
      How the processing affects the designs
   4. Failure Actions
      What to do when the goal criterion is not met.

   Note the similarity in these 4 parts of a design process to the parts of a management process in E&J (p60). Also these closely parallel the steps in quality improvement processes by Deming, namely his PDCA process Plan-Do-Check-Act. All of these are loop processes being done over and over, until the goal criterion is met.
   The selected portion of Ullman's taxonomy can then be summarized as in Figure C2. The following sections will expand the taxonomy to give more specific process and problem descriptions suitable for this course .

4. Design Process
   1. Problem Statement
      Whatever the type of design problem being addressed or if the problem is only a task within larger effort, a clear and unambiguous statement of the problem must be established and understood by all involved, before any other action is taken. Based upon our previous discussions a Problem Statement should completely define the Initial State and will include any initial state constraints or design requirements,
      

      Management

      Once the problem description is established and understood a planning or management phase is essential, whether one or many designers are involved. Specific tasks here would include

      1. Information collection
      2. Objective analysis
      3. Task establishment
      4. Resource management
      5. Team assignments
      6. Scheduling

      A more detailed approach is summarized under "Plan" and "Direct" in Figure 2.3 of E&J.

      Solution

      The search for a solution can begin transforming our knowledge from the initial state to the goal state through a set of intermediate levels.

      1. Approach (Plans)
      2. Modeling (Processing Actions)
         1. Physical Model
         2. Design Criteria
         3. Mathematical Model
         4. Constraint Establishment
      3. Nominal Solution (Effects)
         1. Analysis
         2. Feasibility Assessment
         3. Criteria Assessment
      4. Evaluation & Decision (Failure Actions)
         1. Design Space Studies
            Design Space Extent
            Sensitivity Study

            Trade-off Studies

            Iteration

            Assess Concepts

            Parameters Choice

            Reassess Criteria

      Presentation

      Throughout the design process communication is essential to an efficient operation which minimizes misunderstandings. This normally includes written status reports and of course always a final report. If there is no reporting, there is no design. Communications are generally one or more of the following types and depend upon management requirements and the end artifact being produced.

      1. Graphical
      2. Text
      3. Numerical
      4. Verbal
      5. Physical model

      A format for written reports for this course is included below.

5. A Design Methodology
   We are now prepared to set up a methodology which can serve as a guide in proceeding with an engineering design problem. It is not our intent to stifle creativity by forcing an approach but we do need uniformity for communicating with each other in a course like this one. The approach leaves quite a bit of flexibility and will aid you in understanding the language of design as used by modern designers.
   It is important to understand that we have not delineated between a large multi-tasked project and a small project which might be a task or sub-task of a major project. So whether you are the Chief Engineer, a Team Leader, a Team Member, or a Consulting Engineer, this methodology is applicable. Some of the parts will be modified of course, depending upon the task level.
   The steps of the methodology are (loosely) related to the problem knowledge levels and the taxology in Figure E1. An outline is given in the table below.

6. Morphology of Design
   1. Conceptual Design (E&J p10,11)
      Conceptual design is normally performed by very experienced design engineers in a company. They are creative people with a well-developed background of knowledge, but willing to be open-minded. As mentioned above (Section C.1) this process should take the problem from and initial state of recognized need or specified function to one or more concepts which will satisfy the need.
      The 4 parts of the process of Section D above are still followed as in preliminary design. The Problem Statement is the Need Statement (D1) and Management is much as in D2.
      The solution process (D3)for conceptual design is usually a group effort and should be unstructured so as not to restrict ideas and creativity. A commonly used process is "brainstorming". The purpose of brainstorming is to make sure all possibilities are considered. Even if ideas have no apparent merit they may lead others to a new productive train of thought.
      Brainstorming goals and rules might be as follows:

      OBJECTIVE:

      • generate many ideas and concepts
        
      • minimize personal bias and expand viewpoints by working in a group

      RULES:

      • criticism and judgement are not allowed
      • the more the better
      • think far out

      ORGANIZATION:

      • No leader
      • No recording secretary preferably, use tape recorder

      How do you think up new concepts? You must of course rely on things you already know, and attempt to apply this knowledge to a new situation. The way most of us would do this is by developing in our minds, images of analogous (similarly behaving things) that we already understand, and apply them to the problem at hand.

      Finally (D4), the presentation will be in the form of a Problem Statement and sketch for each concept to be studied for feasibility. The problem statement should include a discussion of important goals and criteria.

      CONTINUED