engineering design exam prep

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engineering design exam prep
2013-12-10 18:52:15
engineering design exam prep
engineering design exam prep
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  1. design process
    • Not one process, many processes which have common
    • characteristics

    • Start off uncertain, don’t know exactly what final product
    • will look like

    As you continue, final product becomes more and more evident

    • It is good to go outside of comfort zone (e.g. mech. eng.
    • doing chem.)
  2. 8 steps in design process
    • Problem Identification,
    • Idea Generation,
    • Idea Selection,
    • Detailed Design,
    • Design Validation,
    • Implementation,
    • End of Life
  3. RussianDolls:
    • Problems within problems, processes within processes, not evident in the
    • beginning
  4. Problem Identification
    • Make sure you are solving the correct problem, be aware of
    • what you are actually aiming to do

    This allows to find a more efficient solution

    • E.g. Hotel Elevator: Slow elevators, instead of speeding them
    • up they just added mirrors (pass time)

    • junior engineers: … sometimes not your role to change
    • problem?

    Good engineers do start off a little uncertain/confused
  5. Opportunity Identification
    In contrast, not always a problem, sometimes you have an innovative idea (IPAD)

    • After you have identified the problem/opportunity, information gathering is
    • important

    • Figure out what kind of words people in that field use, get
    • to know users, other solutions to the same problem someone else might have,
    • file a patent

    After problem identification, make objectives (long and short term)

    • Scope: How far and deep you plan to go, how much impact will
    • your idea provide

    • Identify what you are NOT going to do, don’t want to solve
    • all problems at the same time

    To do this, you need constraints
  6. Constraints
    Hard Constraints: Legal, by law things you must follow

    • Soft Constraints: Still constraints because you decided you
    • MUST have it

    • They should be well
    • written and should be able to be assessed pass/fail, yes/no

    • ALL constraints must be satisfied for your project to be
    • complete, for your solution to be acceptable

    • Over constrained: Constraints that oppose each other (E.g.
    • building must be taller than 6 feet but shorter than 5 feet)

    • May be less obvious, but basically things that are near
    • impossible to do together
  7. Criteria:
    • similar to constraint, things you want to include in your
    • final solution/product

    • But they are not necessary, and only even think about them
    • if your constraint is met

    • E.g. our car should be fast (criteria), but the priority is
    • for it to even work (constraint)

    Criteria is measured, you want to maximize or minimize it

    • Criteria often controls the decision made, because all
    • solutions are going to satisfy constraints

    • You want a balance among criteria, and remember importance
    • of one criteria vs. another

    • E.g. speed vs. looks, which is more important to you/to the
    • overall goal of the item
  8. Idea Generation
    • This is a very preliminary step, design with an extremely open mind here
    • There is more than one solution to any problem, find them, choose best one
    • Transportation A to B (Many options, walk, run, drive)
    • Communication (Talk, text, email, etc.)
    • Techniques for idea generation, brainstorming
  9. Feasibility
    • First filter stage, first check which ideas even meet the constraints
    • Try and pick best candidates to minimize analysis effort (which requires time + money)
    • *Most innovative ideas usually get lost here, need to use experience and open mindedness to judge
    • Make sure good ideas don’t get thrown out at this stage
    • This is the least depth of analysis, but perhaps most important, most judgement required here
    • After the feasibility you should have a few ideas left
    • One is too few (too many constraints or not enough effort on idea stage)
    • A lot is too much (use another filtration process)
    • 90% decisions, 90% cost quote slide ?
    • Not only decision stages, decisions are happening all the time
  10. Idea Development
    • Consists of 3 main things:
    • Multiple, parallel (happening at same time) activities complimenting each other
    • Analysis of all the parts of the idea, synthesizing and pulling them all together into one solution
    • Virtual and physical prototyping, calculations/computer simulations (solid works) and prototypes, scale models
    • Find things that are right/wrong about the different ideas, further analyze and decide which are best
    • Synthesize, put best ideas into one solution
    • *Challenges: Hard to do an analysis for ALL ideas you initially had, this is why filteration process/feasibility is so important
  11. Preliminary Design
    • Ideas at this point are pretty raw, start putting another layer of effort/detail
    • Main goal here is to decide upon best idea and move forward
    • Very decision driven, try to differentiate one idea from another
    • Performance vs. criteria, may want to start relating back to constraints again
    • enough depth slide??
    • Also figure out budget in a little more detail
    • initial Budget estimation: capital cost (estimate big main parts), operation costs (estimate what it'll take to keep it running), end of life cost (what is going to cost to remove/dispose)
    • Pretty much continuous throughout prelim design and idea development
    • Usually very informal and subjective
    • When making formal/important decisions, you want to be objective, third person point of view
    • Perhaps use decision matrix (use weighted criteria, score out of 10, choose best one statistically)
    • *Make sure weighting isn't subjective (don’t weight speed most because you like speed), look at it all objectively, what is most important to solving solution/problem, remember purpose of object
    • Final decision: Don’t just trust decision matrix, look at results (maybe there are two close solutions)
  13. Detailed Design/ Design Validation
    • At this point you have one idea, but this idea can continue to evolve and grow and be shaped
    • Now you can afford to invest a lot more time and money
    • Work out all of the details (e.g. specifications, exact size, number of nuts and screws, etc)
    • It should theoretically be able to be built at this point
    • This one final chosen design should make complete and total sense with respect to the constraints
    • Its contribution to all the criteria is evident
    • It is the best that it can be, does not have to be perfect obviously
    • LOT S of virtual/physical design effort should be put in at this point
    • Engineering models, 3D sketches, equations of the system/product
    • Create prototypes, full scale if possible, run crash tests, make sure it is user proof
    • "optimization", maximize/minimize what you want
    • heuristic optimization ?
  14. Implementation
    • Manufacturing, make sure it is going to be built how you designed it
    • Process and buildings, be ready for errors and challenges that arise at this point, surprises
    • E.g. There are alpha and beta trials with all software, but bugs and problems persist
    • Recalls are sometimes a solution to this
  15. End of Life
    • Waste, how will you deal with it
    • What are the costs of disposal, what will it cost you, is environment a concern
    • Next version designs, now you see strengths and weaknesses of the product (large scale trial and error)