Engineering Design Engineering Design CIVE

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Engineering Design Engineering Design CIVE Powered By Docstoc
					Engineering Design
       CIVE 4312
      Hanadi Rifai
           What is an Engineer?

Engineers apply science and technology to
develop solutions to practical problems–problems
that need to be solved for the benefit of humanity.
               ABET Definition

“Engineering is the profession in which a knowledge of
the mathematical and natural sciences, gained by study,
experience, and practice, is applied with judgment to
develop ways to utilize, economically, the materials and
forces of nature for the benefit of mankind”
           Working Definition
Engineering as an activity:

An innovative and methodical application of scientific
knowledge and technology to produce a device, system
or process, which is intended to satisfy human needs.
          Are Engineers Inventors?
   Inventors:                      Engineers:
    • Seek to develop a new          • Seek to solve a specific
      idea                             technical problem
    • Do not necessarily apply       • Always applies scientific
      scientific knowledge and         knowledge and follows
      follow methodical                methodical approach

         Many engineers are also inventors
          Attributes of an Engineer
   Problem solving skills
   Effective communication skills
   Highly ethical and professional behavior
   An open mind and positive attitude
   Proficiency in math and science
   Technical skills
   Motivation to continue learning
   Knowledge of business strategies and management
   Computer literacy
   Understanding of world affairs and cultures
Engineering Design Process

    Implementation           Needs

   Analysis                   Formulation

              And Synthesis
 Writing Technical
Reports, Letters, and
The Need to Communicate Effectively

           Engineers must be able to
           convey ideas effectively in
           formal reports
            Top 10 Problems
   Poor organization
   Spelling and capitalization
   Grammar and punctuation
   Misused words
   Redundancy
   Hedging
   Lengthy paragraphs
   Passive language
   Inappropriate tone
      Key Message for Design
   Engineering design proposals, technical
    reports, etc. should avoid the top 10
   Be of professional caliber, reflect careful
    thought and preparation
   Well written/organized presentation leads to
    implementation of a design concept
   Poorly written reports has the opposite effect
    regardless of how good the design is
   Goes without saying: design concept must
    have intrinsic merit and value in of itself
          General Guidelines
   Purpose: what is the purpose of the
     Write one sentence statement focusing on
      the problem to be solved, the task to be
      performed or the response that is sought
      from the intended audience
     Generate enough interest in the reader so
      they will continue reading
     Briefly describe the situation, the
      problems to be solved, and the proposed
          General Guidelines
   Audience: what do they need to know
    and understand
     Is presentation accessible to readers
     Is language too technical so as to be
      obscure to readers
     A technical presentation must be “lappy”,
      i.e., land into the reader’s lap
             General Guidelines
   Organization: prepare an outline
       Evaluate your outline to make sure it flows
       Are paragraphs linked in meaningful and logical
       Transitions between paragraphs and sections
       Signposts: subheadings, bold, italic fonts to guide
       Tables, figures, diagrams should be self-
        explanatory and useful
       Conclusions must be supported by the data and
          General Guidelines
   Grammar, syntax and punctuation:
    spell-checking is a must
     Not all spelling errors show up on spell-
      check. Examples: form instead of from,
      affect instead of effect, there instead of
      their etc.
     Syntax and grammar must be corrected

     Ask other team members to edit your
          General Guidelines
   Rewrite: edit, edit, edit…..
     Winston Churchill (famous for very
      eloquent and meaningful speeches)re-
      wrote his speeches at least seven times!
     Ideas must be fully developed and clearly
      expressed in clear, easily understood
             Technical Reports
   Front-end                    Technical content:
    materials:                       Introduction
       Title page                   Background info
       Contents                     Methodology
                                     Alternative solutions
       List of figures               developed
       List of tables               Final design solution
       Abstract or Summary          Conclusions
                                     Recommendations
                                     Bibliography
                                     Appendices
Other Written Communication Tools

   Cover letters
   Memoranda
   Progress Reports
Defining the Problem
A specific problem should be formulated if
One is to develop a specific solution.

A problem statement should focus on the

  Example: Designing a better ink pen
  • Need fast-drying ink
  • Need uniform flow
  Solution: ball-point ink pens!
Formulating the Real Problem
   Engineering is an iterative process,
     Assumptions
     Decisions
     Conclusions

   Initial problem statement may be
    vague, ill-conceived or incorrect
   Incorrect problem statement unlikely
    to lead to optimal solution
     Methods for Problem Formulation

1.   Statement-Restatement Technique
2.   Source and Cause – Why-Why
3.   Revision Method
4.   Present State and Desired State –
     Dunker Diagrams
5.   What is wrong with it?
6.   Benchmarking and Best Practices
7.   Fresh Eye Approach
 Statement-Restatement Technique

State and restate the problem in
  different and innovative ways:
 Determine the “real” problem

 Determine the actual constraints

 Identify meaningful goals

 Identify inputs, outputs, unknowns
    Determining “Real” problem
   Varying the emphasis on words in
    problem statement
   Substituting explicit definitions of
   Changing positive terms to negatives
   Replacing persuasive and/or implied
    words with reasoning behind them
   Expressing words in graphical or
    mathematical form
      Determining Constraints
   Relax constraints
   Quantitative not
   Eliminate perceived
    or imagined
Identifying Meaningful Goals

                   Qualitative
                   Prioritized
                   Focus on most
                    critical ones
Identifying Input, Output, Unknowns

   What is desired output or benefit?
   What are inputs? people, equipment,
   What is unknown?
Design Goals and
 The Need to Structure Your
    Search for a Solution
•An exhaustive search for possible solutions
 is neither practical nor wise.
•One should not seek to generate and
 evaluate every possible solution
•Engineers work within deadlines and search
for solutions within rigid constraints
            Engineer’s Role
Design and Develop Solutions in an Efficient Manner

      Current                      Final
      Problem       STRATEGY
       State                       State

      Strategy must guarantee success
    Designing Search Strategy
   Eliminate paths that do not fit goals or
   Design tasks to provide most
   Use attributes of final solution state to
    guide decision-making
        General Design Goals
   Safety
   Environmental Protection
   Public Acceptance
   Reliability
   Performance
   Ease of Operation
   Durability
   Use of Standard parts
   Minimum Cost
   Minimum Maintenance and Ease of
     Specific Design Goals
Seatbelt Design Problem:
o Before impact - cannot restrict user

o During impact - operate effectively
  and automatically
o After impact - cannot restrict user
  from quick exit
          Design Specs
 Physical
 Functional or operational

 Environmental

 Economic

 Legal

 Human Factors/Ergonomics
Engineering Design Process

    Implementation           Needs

   Analysis                   Formulation

              And Synthesis
    Problem Formulation

Formulating                  Design Goals
Real Problem                 and Specifications

               ABET Considerations
               •Health and Safety
    ABET Design Considerations
• Economic – cost (capital and O&M)
• Constructability – can it be built?
• Social – serves the need?
• Political – solution acceptable to
• Environmental – effects on people or
• Health and Safety – dust levels, light,
• Sustainability – tomorrow?
        Science and Engineering
   Technical knowledge begins with
    understanding of scientific principles
       Example: jet planes based on Newton’s
        first law “for every action there is an equal
        and opposite reaction”
        Sources of Technical
   Other individuals
   Engineering journals
   Textbooks
   Magazines
   Reference manuals/Handbooks
   Newspapers
   Manufacturer catalogs
   Internet
            Protected Sources of
            Technical Knowledge
   Intellectual property (ideas, concepts,
    product names, art, music, etc.)
       Ownership legally protected by:
         Trade secrets (formula for Coke)
         Trademarks (Kleenex/Xerox)

         Copyrights (journal articles)

Abstraction and
   Engineers must be creative
   Engineers must develop alternative
    design solutions
   During abstraction the goal is to get a
    conceptual perspective or vision of the
    problem and its possible solutions
   Abstraction requires models to
    represent possible design solutions
         Example of Abstraction
   Design a method for
    transporting people
       Propel
       Carry
       Attract/repel
       Sink/drop
       Lift
       Slide
       Float
       Pull
Modeling in Design
            Engineers use
             models to develop
             and evaluate their
                Organize data
                Structure thoughts
                Describe
                Analyze proposed
            A model can be
   working scaled miniature
   Abstract set of equations
   Computerized simulation and animation
   2- or 3-D graphical description of a
   Any other purposeful representation of
    a process, object or system
Purpose of models
            Obtain greater
             insight and
            Abstraction of a
             problem and its
             possible solutions
            Elucidate
             relationships and
             among system
             components and
             Model Types
   Iconic - visually equivalent: resemble
    process or system (e.g., maps, globes,
    physical models)
   Analogic - functionally equivalent:
    behave like the physical process or
    system (e.g., miniature airplanes in
    wind tunnels)
   Symbolic - equations
            Modeling Tools
   Sketching
   Functional graphs and charts
   Finite element, process simulation, and
    solids models
   System and Process models:
    deterministic and stochastic
Synthesis in Design
          What is Synthesis?
   Formation of a whole from a set of
    building blocks or parts
   Creative thinking is distinguished in
    engineering by its ability to synthesize,
    or combine ideas into new and
    meaningful forms
   “Constrained creativity”
        Barriers to Synthesis
   Knowledge blocks
   Perceptual blocks
   Emotional blocks
   Cultural blocks
   Expressive blocks
         Creativity Simulation
   Brainstorming
   Brainwriting
   Bionics
   Checklisting
   Synectics
   Analogies, Adaptation,and Duplicated Design
   Fresh Perspective
   Inversion
   Idea Diagrams
   Group of people
    work on problem for
    a limited time
   Generate max no. of
   Ideas not evaluated
Design Analysis
Engineering Design Process

    Implementation           Needs

   Analysis                   Formulation

              And Synthesis
    Evaluating Alternative Designs
   Prioritize or weight design goals
   Formulate scheme for ratings
   Combine the prioritized weightings of
    the goals with the ratings given to the
    designs to generate a score for each
   Compare total scores to select best
   Re-evaluate best solution to anticipate
    Rank-Ordering Design Goals
   Example for a computer system
     Performance
     Minimum maintenance
     Aesthetics
     Minimum Cost
     Availability of Parts
     Ease of use
     Versatility
     Portability
Assigning Weighting Factors
      to Design Goals
                                       100 Versatility
                                       95 Portability
• Decide range of values    Critical   85
                                       75 Cost
• Separate range into
  categories                           70
• Evaluate each goal and               60 Ease of Use
                            Import.    50
  assign weighting factor
                                       40 Low Maint.

                            Option. 10 Aesthetics
    Rating Alternative Designs
   Use measurable parameters to
    estimate success or failure in
    achieving goal, e.g., cost
   For “unquantifiable goals, use rating
                 10   Excellent
                 8    Good
                 6    Satisfactory
                 4    Mediocre
                 2    Unacceptable
                 0    Failure
              Decision Matrix
                        Cost Maint. Perf.
                        Weighting Factors
    Design               100        80       60      Total
    Model 1             7/700     8/640    7/420     1760

    Model 2             4/400     6/480    7/420     1300

    Model 3             6/600     9/720    4/240     1560

    Model 4             9/900     7/560    6/360     1520

            Rating Factor

Decision Factor = Weighting Factor x Rating Factor
    Decision Matrix for 4312 Project

   Must include:
     Economic
     Environmental

     Health and safety

     Constructability

     Sustainability

     Political

     Social

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