Engineering Design GE121 The Design Process (continued

1
Engineering DesignGE121The Design
Process(continued Part III)

• Lecture 8B

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Strategies/Methods/Meansin the Design Process

• Even formal prescriptive processes dont tell us
  HOW to Generate or Create Designs
• Will introduce
• Formal Design Methods
• Means of Acquiring Design Related Information
• Decision-support techniques and tools to explain
  HOW to design
• Describing thought processes or cognitive tasks

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Strategic Thinking in the Design Process

• Least Commitment
• Unwise to commit to a concept or configuration
  until forced to (exhausted information search /
  alternate designs)
• Never marry your first design
• Premature commitments can be dangerous and lead
  to sub-optimal designs
• Decomposition Divide and Conquer
• Break down / subdivide / decompose larger
  problems
• Smaller sub-problems or ideas easier to solve /
  handle
• Be careful sub-problems often interact
• How do you eat an elephant? .
• One bite at a time!

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Formal Methods for Design Process

• Objectives Trees
• Used to clarify and better understand Client
  Statement
• Tree-like structure
• Clustered by sub-objectives
• Have seen an example in the Case Study
• Will discuss in detail in section 3.1
• Pairwise Comparison Charts
• Used to rank-order Design Objectives
• Relatively simple
• Compare Objectives on a pair-by-pair basis
• Have seen an example in Case Study
• Will discuss in detail in section 3.3

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Formal Methods for Design Process (contd)

• Functional Analysis
• Black Box is the starting point clearly
  delineates boundaries between proposed device and
  its surroundings
• Decompose functions into sub-functions
• Track flow of material / signals through device
  detail what is needed to produce desired
  functions
• Have previously seen the Function-Means tree
• Detailed in section 4.1

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Formal Methods for Design Process (contd)

• Performance Specifications
• Elaboration of Design Specifications
• Solution independent attributes and performance
  specifications
• Hard numbers for both desired and required
  features
• Covered in section 5.2
• Morphological Charts
• Identify the Ways or Means that can be used to
  make the required functions happen
• Provides a framework for visualizing a design
  space of potential solutions
• Covered in sections 5.1 and 5.3

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Formal Methods for Design Process (contd)

• Quality Function Deployment
• More advanced tool
• Builds on Performance Specification, with goal of
  higher quality product
• Used widely in product manufacturing
• Charts client and user requirements and
  engineering attributes in matrix form relate
  and weight them, one against another
• Creates a House of Quality that exposes both
  positive and negative interactions
• Described briefly in section 8.5

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Means of Acquiring/Processing Design Knowledge

• Knowledge is a critical component of design
• Means for Acquiring Information
• Literature reviews
• Enhance understanding of potential users, clients
  and the design problem itself
• Prior and existing / competing solutions
• Physical properties during conceptual design
• Handbooks, codes, and part/component libraries in
  detailed design
• User surveys / questionnaires
• Market research
• Identify User understanding of problem
• Help Designer clarify / understand problem early
  on
• Can be used later during the selection process

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Means of Acquiring/Processing Design Knowledge
(contd)

• Focus groups
• Expensive
• Allow design team to observe response of selected
  users to potential designs
• Also involve knowledge/sophistication in
  psychology not often used by students
• Informal and structured interviews
• Informal Interviews should be focused so as not
  to waste the time of the interviewee helpful to
  send topics or questions ahead of time
• Structured Interviews combines focus of a
  survey with the flexibility of an informal
  interview to allow follow-up on areas of
  interest, or new areas

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Means of Acquiring/Processing Design Knowledge
(contd)

• Brainstorming
• Generate related or even unrelated ideas, without
  evaluation
• Free-wheeling
• Opens up new avenues, ideas
• Important for all members to maintain respect for
  the ideas of others
• Important to capture ALL ideas as they are
  offered
• Synectics
• Environment similar to brainstorming
• Explore relationships and similarities between
  relationships and ideas that initially seem
  unrelated
• Explore similar ideas/solutions (analogies) from
  different disciplines of engineering

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Means of Acquiring/Processing Design Knowledge
(contd)

• Benchmarking
• Take competitive products and use them as a
  benchmark, or reference, then try to make it
  better
• Reverse engineering
• Sometimes referred to as dissection
• Literally take it apart to try to determine
  design intent
• Find better ways to perform the same or similar
  sub-functions

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Means of Acquiring/Processing Design Knowledge
(contd)

• Means for Analyzing Information / Testing
  Outcomes
• Defining metrics is important we often need
  ways of determining a numeric value for metrics,
  or determine if a specification can be met
• Laboratory experiments
• May involve physical testing of a basic structure
  or component
• Prototyping
• Prototype or test unit is produced to verify
  functional operation
• May not look like final product, and may only
  have a subset of the key functions tested (saves
  money / time)

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Means of Acquiring/Processing Design Knowledge
(contd)

• Proof of concept testing
• Idea is to show that design can fulfill functions
  under certain prescribed conditions
• Tested unit may not survive, or perform stated
  function, but still may prove the concept
• Computer models
• Simulation software
• Discipline-specific CADD (Computer Aided Design
  and Drafting) software
• Means for Obtaining Feedback
• Regularly scheduled meetings with Users and
  Clients!!
• Formal Design Review (must learn give and take)
• Public Hearings
• Focus Groups
• Beta testing