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Design phases/stages

  1. Aug 23, 2013 #1
    Hello everyone!
    Could you please explain to me what design stages/phases exist?
    And in what order are they placed?
    Is it:
    - Conceptual Design
    - Preliminary Design
    - Final Deign

    What is "detail design" then and how is it different from the Final Design?

    After googling, I've got a lot of confusion about it all...
    Please, help me to put all these stages in the right places.

    Thank you!
  2. jcsd
  3. Aug 26, 2013 #2


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    Staff: Mentor

    In order to maintain ISO 900x certification, companies need to implement a PDP/QMS (Product Development Process / Quality Management System). This PDP/QMS will call out the stages of product development explicitly, and will generally include written checklists for each product development stage. Have a look at this document that we use at my workplace:


    The product development stages are described in the middle of the document:

    • Specifications
    • Investigation
    • Development
    • Beta Samples & Pilot Run
    • Design Changes
    • Release to Production
  4. Aug 27, 2013 #3
    Thank you.
  5. Aug 27, 2013 #4
    What if we are trying to develop something like a ship or a plane? Or at least an aircraft engine? I mean some sort of heavy machinery...
    I believe there is a well established practice with well defined stages, is not there?
  6. Aug 27, 2013 #5


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    Homework Helper

    In terms of ship design, a list of requirements or specifications is usually developed first. The requirements would list things like mission, max. speed, route of operation, max. cargo capacity, etc. Once the list of requirements is in hand, a preliminary design for the ship would be done to establish the basic size parameters of the hull. This is usually done parametrically, relying to a certain extent on previous designs for similar ships, if any exist. Once the basic size parameters of the hull are established then the detail design of the vessel can be undertaken. The lines for the hull are developed, a structural design is begun, a machinery arrangement is prepared, etc. Working all of these areas is part of the detailed design where the actual construction plans are developed. Other things like model testing to determine propulsive power and initial stability calculations are done. From these detailed design plans, actual preparation of construction material and ordering of machinery takes place. Once construction is complete, final stability and machinery tests are done, and the vessel is delivered.
  7. Aug 27, 2013 #6
    Thank you.
    You did not mention the conceptual design. Is it omitted in ship designing?
  8. Aug 27, 2013 #7


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    Conceptual design generally falls under the preliminary phase. After all, the ship has already been invented; the design phase is more adapting the ship concept to a new set of design requirements. New ship types have been developed over the years which differ somewhat from the conventional single-hull model (e.g., large catamarans and tri-marans, surface effect ships, submersibles, etc.), but the totally 'clean-sheet' design in this field is quite rare.

    In aircraft development, the fixed-wing concept branched into the rotary-wing concept, and these concepts have merged again into the tilt-rotor concept, which combines elements of both prior concepts.
  9. Aug 28, 2013 #8
    Ok. Thank you I got it.
  10. Aug 30, 2013 #9
    Engineer in the mining industry here:

    Generally major capital projects fall under 3-4 phases. In between each phase is a stopgate.

    First there is a Conceptual Study. Here the idea is laid out, possible solutions are put forward and compared based on value, cost, difficulty, schedule, permitting, etc.

    The pre-feasibility phase (or pre-design for product development) comes next, where one or several options are selected to investigate further. In this phase more detail is given into capital requirements, schedule, and operating costs. Generally at the end of this phase, one option is selected to move forward with.

    If approval is given to continue working on that option, the feasibility phase is started. In the pure version of this phase, it is only engineering design. All necessary equipment, materials, instruments, power requirements, permitting requirements, manpower, etc are laid out and specified. Here is where detailed calculations, equipment sizing, finalized fleet requirements, drawings, P&ID's, PFD's, etc are done and a much more accurate capital cost estimate is completed.

    This is the Final Design phase. As you can imagine, that is all costly stuff. Many companies will hedge their bets and assume that, as they've come this far, the end result is going to be a profitable design, so oftentimes since schedule is a concern long lead time items are purchased during this phase so that they can schedule the construction around the installation of these larger items.
  11. Aug 31, 2013 #10
    Thank you for such a detailed answer!
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