Transcript Slide 1
IMPORTANCE OF PROPER PROBLEM DEFINITION 100 80 60 40 20 0 Specification Development Conceptual Design Detailed design
Time
After specifications phase, we have already committed ~40% of product cost!
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Gantt charts CPM CONCEPTUAL DESIGN PHASE
1. Specification Development / Planning Phase
Determine need, customer and engineering requirements Develop a project plan Customer surveys Customer interviews QFD
2. Conceptual Design Phase
Generate and evaluate concepts Select best solution
3. Detail Design Phase
Documentation and part specification Prototype evaluation
4. Production Phase
Component manufacture and assembly Plant facilities / capabilities
5. Service Phase
Installation, use , maintenance and safety
6. Product Retirement Phase
Length of use, disposal, and recycle 2
CONCEPT GENERATION Concept - is an idea that can be represented in a rough sketch or with notes of what might someday be a product.
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CONCEPT GENERATION If you generate one idea it will probably be a poor idea if you generate twenty ideas then you might have one good idea 4
CONCEPT GENERATION So how do we generate those concepts?
Basic philosophy for generating concepts: Form follows function Creativity must be controlled by engineering judgment / expertise / experience 5
CONCEPT GENERATION AND SELECTION SUMMARY Need QFD Functional Decomposition Morphological Analysis Required functionality Ideation Brainstorming Patents Reference (Books, Trade Journals) Experts ’ help Concept 1 Concept 2 Concept 3 … Concept n Feasibility judgment Technology readiness Go/no go screening Decision matrix method Final concept 6
SOURCES FOR CONCEPT IDEAS 1.
Ideation
2.
Brainstorming
- a group oriented technique 3.
Patents
- extensive patent search may be required. (Note: there are over 5 million patents in the U.S.) 4.
Reference books and trade journals
- most reference books give analytical techniques and few design ideas (Trade journals are a good source, but generally are targeted at specific disciplines).
5.
Experts to help generate concepts
- a good source of information are manufacturers catelogues (check the Thomas Registry).
6.
Functional decomposition and morphological analysis
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IDEATION
1. Get a general idea of the design problem and develop different ways to tackle it
Do not worry about practicality Do not refine ideas
2. Find feasible ideas
If only some elements of an idea work, extract them for inclusion in the next iteration
3. Pick, choose and recombine ideas
Using useful elements from all ideas
4. Refine
List three concepts and add elements you really need in the finished product 8
BRAINSTORMING
Fundamental Principles of Brainstorming
1.
Criticism is not allowed
- any attempt to analyze, rejecty, or evaluate ideas is postponed until after the brainstorming session.
2.
All ideas brought forth should be picked up by the other people
others.
- participants should seek ways of improving the ideas of 3.
Participants should divulge all ideas that enter their mind
wilder the idea, the better.
- the 4.
Provide as many ideas as possible within a relatively short time
- the greater the number of ideas, the more likelihood of useful results.
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BRAINSTORMING Brainstorming is an organized approach for producing creative ideas by letting the mind think without interruption. Brainstorming can be done either individually or in a group; in group brainstorming sessions, the participants are encouraged, and often expected, to share their ideas with one another as soon as they are generated. The key to brainstorming is not to interrupt the thought process. As ideas come to the mind, they are captured and stimulate the development of better ideas. An essential element of brainstorming is putting criticism 'on hold'. Instead of immediately stating what might be wrong with an idea, the participants focus on extending or adding to it, reserving criticism for a later 'critical stage' of the process.
By suspending judgment, you create a supportive atmosphere where participants feel free to generate unusual ideas.
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BRAINSTORMING
Procedure for a typical brainstorming session
A meeting room is equipped with a flipchart, blackboard, or overhead projector placed in a prominent location. Between
six and twenty people
with an interest in the subject (although not necessarily experts) are invited to participate.
Write on the flipchart (or blackboard) a statement of the subject or problem that will be discussed. This is often presented as a question.
Choose one person to write down the ideas
generated. Ideas should be written concisely but without paraphrasing. The recorder should state the idea in the words she has written to ensure that it expresses the meaning intended by the originator.
Choose one person to facilitate the process
. This involves encouraging participation by everyone and maintaining a criticism free, uninhibited atmosphere. Encourage even wild and seemingly ridiculous ideas.
After 5 to 20 minutes the facilitator ends the session
Review the list from top to bottom to ensure everyone understands the ideas. Eliminate from the list any duplications. Remove any obviously ridiculous suggestions. 11
PATENTS In the 1920s, engineers at Sperry Gyroscope Company developed a clever design for a bearing that would hold the end of the gyro shaft in position with great accuracy both axially and laterally, would support the gyro, and would have low friction.
– It was patented and put into service with great success.
– However, in 1965 the same basic design was discovered in a notebook belonging to Leonardo da Vinci dating from about 1500.
A low friction bearing from da Vinci's notebook.
[Ullman 1992] 12
SOURCES FOR CONCEPT IDEAS REFERENCE BOOKS AND TRADE JOURNALS http://www.machinedesign.com/ http://www. sae.org/ 13
SOURCES FOR CONCEPT IDEAS – EXPERT HELP 14
FUNCTIONAL DECOMPOSITION TECHNIQUE
Step 1:
Find the overall function that needs to be accomplished.
Goal
is to generate a single statement of the overall function based on the customer requirements. All design problems have one or two "
most important
" functions. These must be stated in a single concise sentence.
Example:
portable kayak
Design a kayak that can be folded into a package small enough to fit in a trunk of a car Step 2:
Decompose the function into subfunctions (perform functional decomposition). Goal is to refine the overall function statement as much as possible.
Guidelines:
1.
Document
what
not
how
.
2.
3.
4.
5.
Use standard methods and notations whenever possible for describing subfunctions.
Consider the logical relationships between the functions to determine their sequence.
Match inputs and outputs in the functional decomposition.
Break the main function down as finely as possible using a
block diagram
.
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FUNCTIONAL DECOMPOSITION TECHNIQUE Foldable kayak Customer requirements unpack Use unpacked pack Allows reduction in size when transported and stored Product functions satisfying customer requirements 16
First level decomposition
FUNCTIONAL DECOMPOSITION TECHNIQUE unpack Use unpacked pack
Second level decomposition
Unfold skeleton unpack Pump up Assemble form smaller components
Third level decomposition ...
Pump up
...
...
Decomposing top level function into subfunctions 17
FUNCTIONAL DECOMPOSITION TECHNIQUE AND MORPHOLOGICAL ANALYSIS*
Functional decomposition
is used to identify the necessary product functionality
Morphological analysis
is used to explore alternative means and combinations of achieving that functionality. For each element of product function, there may be a number of possible solutions. The morphological chart is prepared and used to develop alternative combinations of means to perform functions and each feasible combination represents a potential solution.
* Morphology:
The science of the form and structure 18
DEVELOPING CONCEPTS FOR EACH FUNCTION
Goal
is to generate as many concepts as possible for each of the functions identified in the
Functional Decomposition
process.
If there is a function for which only one conceptual idea exists, then this function needs to be reexamined because there are very few functions that can be fulfilled by only one concept).
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DEVELOPING CONCEPTS FOR EACH FUNCTION Steps:
List product functions
(functional decomposition)
List the possible 'means' for each function
(morphological analysis)
Chart functions and means and explore combinations
Unfold skeleton unpack Pump up Assemble form smaller components 20
Functional decomposition of a wood splitter – in class exercise 21
COMBINING CONCEPTS INTO SINGLE CONCEPTUAL DESIGN
hold on ice secure
Concept 1 Concept 2 Concept 3 Concept 4 Concept 1 Concept 2 Concept 3 Concept 4
Function Design concept
Goal is to select one concept for each function and combine those selected into a single complete conceptual design.
Abstract concepts must now take some form, most often the form of sketches and comments.
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SKETCHES AND COMMENTS
Terminal cover assembly
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SKETCHES AND COMMENTS
Assistive writing device.
– Rough sketches made in the design notebook provide a clear record of the development of the concept and the product.
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SKETCHES AND COMMENTS
Initial sketches and final design for a reusable syringe.
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SOME THOUGHTS ON CREATIVITY
1. Develop a confident attitude.
[Buhl 1968] 26
SOME THOUGHTS ON CREATIVITY
2. Unlock your imagination.
[Buhl 1968] 27
SOME THOUGHTS ON CREATIVITY [Buhl 1968]
3. Be persistant.
"Invention is 95% perspiration and 5% inspiration" T. Edison
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SOME THOUGHTS ON CREATIVITY
4. Develop an open mind.
[Buhl 1968] 29
SOME THOUGHTS ON CREATIVITY
5. Suspend your judgement.
[Buhl 1968] 30
SOME THOUGHTS ON CREATIVITY
6. Set problem boundaries.
[Buhl 1968] 31
TECHNIQUES FOR EVALUATING CONCEPTUAL DESIGN
Type of Comparison Technique
Numerous Concepts
Basis of Comparison
Feasibility Judgment
Gut Feeling Absolute
Technology Readiness Assessment Go/no-go Screening
State of Art Customer Requirements Relative
Decision Matrix Method
BEST CONCEPTS
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EVALUATION BASED ON FEASIBILITY* JUDGMENT What we think about it?
Understanding + Experience
* Feasibility: The quality of being doable
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EVALUATION BASED ON TECHNOLOGY READINESS ASSESSMENT Objective - is to determine the readiness of the technologies that may be used in the design concept. Immature technology will lead to a poor-quality product or cancellation of a project due to cost overruns.
Time-Line for Technology Readiness Technology
Powered human flight Photographic cameras Radio Television Radar Xerography Atomic bomb Transistor Digital camera High temperature super conductor ? Electric car …..
17 6 5 30 403 112 35 12 15
Development Time
(1500 – 1903) (1727 – 1839) (1867 – 1902) (1922 – 1934) (1925 – 1940) (1938 – 1955) (1939 – 1945) (1948 – 1953) 1965 - 2004 1987 - ?
1900 - ?
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EVALUATION BASED ON TECHNOLOGY READINESS ASSESSMENT
Six measures to determine if a technology is mature:
1. Can the technology be manufactured with known processes?
2. Are the critical parameters that control the function identified ?
3. Are the safe operating parameters known ?
4. Have the failure modes been identified ?
5. Does hardware exist that demonstrates positive answers to the above four questions ?
6. Is the technology controllable throughout the product's life cycle ?
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EVALUATION BASED ON TECHNOLOGY READINESS ASSESSMENT
Displacement on Demand
has been in works for the last 25 years…..
finally: GM announces that the 2005 model year GMC Envoy XL, Envoy XUV and Chevrolet trailblazer EXT will be the first vehicles to showcase its innovative
Displacement on Demand
fuel-saving technology, which enhances fuel economy without compromising performance or the ability to carry heavy loads. Displacement on Demand is to be a standard feature in the vehicles' optional Vortec 5300 V-8 engine. The technology, which boosts the Vortec engine's fuel efficiency by 8 percent, is also to be introduced in other GM engines in the 2006 model year. 36
EVALUATION BASED ON TECHNOLOGY READINESS ASSESSMENT 2000
Hybrid car
2010 37
EVALUATION BASED ON TECHNOLOGY READINESS ASSESSMENT http://www.veva.bc.ca/enfield/enfield1.jpg
2004 http://www.dieselstation.com/pics/2011-Holden-Volt-car-pics.jpg
2010
Electric car
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EVALUATION BASED ON TECHNOLOGY READINESS ASSESSMENT Film camera Digital camera 39