Design Phases/Stages - Order & Explanation

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Discussion Overview

The discussion revolves around the various stages or phases of design in engineering, particularly in the context of product development and specific applications such as ship and aircraft design. Participants seek clarification on the order of these stages and the distinctions between terms like "detail design" and "final design." The conversation touches on both general practices and industry-specific methodologies.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose a sequence of design phases including Conceptual Design, Preliminary Design, and Final Design, while questioning the role of Detail Design.
  • One participant mentions the necessity of a Product Development Process/Quality Management System (PDP/QMS) for maintaining ISO 900x certification, outlining specific stages such as Specifications, Investigation, Development, and Release to Production.
  • Another participant inquires about the established practices for designing heavy machinery like ships or aircraft, suggesting that there are well-defined stages in these fields.
  • A participant describes the ship design process, emphasizing the importance of requirements specification, preliminary design, and detailed design, including model testing and construction planning.
  • There is a discussion about whether conceptual design is omitted in ship design, with some arguing it falls under the preliminary phase due to the adaptation of existing designs to new requirements.
  • An engineer from the mining industry outlines a different approach involving phases such as Conceptual Study, Pre-feasibility, Feasibility, and Final Design, highlighting the detailed calculations and specifications involved in the later phases.

Areas of Agreement / Disagreement

Participants express varying views on the specific stages of design and their definitions, indicating that multiple competing models exist. The discussion remains unresolved regarding the exact order and terminology used across different industries.

Contextual Notes

Participants reference different industry practices and may rely on specific definitions that could vary by context. There is an acknowledgment of the complexity and variability in design processes across fields.

Who May Find This Useful

This discussion may be of interest to engineers, project managers, and students involved in product development, particularly in sectors such as aerospace, maritime, and mining engineering.

Jack8rkin
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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!
 
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Jack8rkin said:
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 Design

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!

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:

http://www.google.com/url?sa=t&rct=...6TxhbXwvU-WQGYGzOmBfoog&bvm=bv.51156542,d.cGE

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

  • Specifications
  • Investigation
  • Development
  • Beta Samples & Pilot Run
  • Design Changes
  • Release to Production
 
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Thank you.
 
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?
 
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.
 
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Thank you.
You did not mention the conceptual design. Is it omitted in ship designing?
 
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.
 
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Ok. Thank you I got it.
 
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.
 
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  • #10
Thank you for such a detailed answer!
 

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