Senior Design
Fall 2005, Week 3
Notes are based on “Engineering
Design and Design for Manufacturing –
A Structured Approach” by John R.
Dixon and Corrado Poli
Lecture Overview
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Groups
Projects
Conceptual Design Overview
Formulating the problem
– Customer Attributes
– Engineering Characteristics
– Engineering Design Specification
Groups
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Group 1 (Energy 1 – project presented by Dr.
Fletcher)
Richelle Atienza
Holman Chua
Jason Garner
Jason Harrington
Joshua Severance
Group 2 (ASME 1)
William Berry
Nicholas Fonder
Jason Kardos
James Martini
Group 3 (Energy 2 – project to be discussed
with Dr. Fletcher)
Sean Mochocki
Evan McNay
Lince Philip
Richard Thompson
Stephen Thompson
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Group 4 (ASME 2)
Justin Caudle
Luke Delaney
Joshua Isaacson
Peter Vergenz
Group 5 (Extruder – Project presented by Dr.
Adewale or a modification to the project)
Anthony Barletta
Daniel Jones
Parineeta Nayyar
Spencer Schwab
Engineering Conceptual
Design
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The Goal
– Determine the physical concept of the designed object
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Information about the physical principles by which the object
will achieve its principal functions
An abstract physical description of the object called the
embodiment
– Embodiment: Abstract physical description with few details
provided
 Beam is long and slender member of uniform cross section
but we don’t know the exact cross sectional shape or
dimensions
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The process of decomposition
Guided Iteration
The process of
decomposition
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It is necessary to “decompose” the design into
more manageable sub-assemblies/components.
Helps in finding creative solutions and ultimately
generating a superior design
Two primary approaches of conceptual
decomposition are used
– Direct decomposition
– Function-First decomposition
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Will need to include the couplings between
subsystems
– How are forces transferred? Energy transfer?
Direct Decomposition
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A product is composed of the subsidiary
components (the design is not really
decomposed)
Ex: An automobile is decomposed into its
engine, drive train, body, suspension
system, steering system.
Then you work on each of the decomposed
systems and find the best design for each.
This decomposition method minimizes
creative new ideas.
Direct Decomposition
continued
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Often used by Mechanical Engineers
A sketch is commonly used identifying the
embodiment
Ex: For a bicycle we would identify the
handle bar (but for what function)
Ex: Design a breaking system for an
automobile
– Foot pedal, hydraulic system, and brake shoes
and drums.
Function-First
Decomposition
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First the functions are identified
without any embodiments assumed
Then embodiments are identified to
fulfill the functional needs
This process often helps identify
creative solutions
Abstract way of thinking.
Overview of Guided Iteration
Applied to Engineering
Conceptual Design
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Formulating the Engineering Conceptual Deisgn Problem: The Engineering Design
Specification
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The Engineering Design Specification is used during the conceptual design stage and through the
rest of the design stages.
Should be a written document
Convert the vague, qualitative, and incomplete information that is generally available at the
beginning of the conceptual design stage into a set of specific, quantitative, complete
performance requirements
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Generating Alternatives in Engineering Conceptual Design Problems
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Will use Quality Function Deployment (more to come…)
Ex: Should be easy to carry  the weight should be less than 20lb
The selection of the best possible conceptual design is crucial in obtaining the best possible final
design solution.
Mistakes at the conceptual design stage are extremely costly if you must backtrack when in the
configuration, parametric, and detailed design stages.
Evaluating Alternatives in Engineering Conceptual Design
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Alternatives are rated and compared
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Illuminate the specific characteristics of proposed alternatives that are weak and strong.
Is the design “good-enough”?
Guided Redesign
Summary of guided iteration methods
(Engineering Conceptual Design)
Steps in GI process
Methods
Problem formulation
Quality
Generation of Alternatives
Search
Evaluation of alternatives
Pugh’s
Redesign, Guided by the evaluation
and physical reasoning
Modify
Function Deployment and
House of Quality
Engineering Design Specification
for alternatives physical laws
and effects
Techniques for creativity
Memory Search
Analogous Problems
Literature searches
method
Dominic’s Method
Pahl and Beitz Method
Existing Alternatives
New alternatives
Formulating the Problem: The
Engineering Design Specification
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Includes statements
– In-use purposes, and
– Functional requirements
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Some information may be available from marketing
and industrial design stage
Most information available at this stage is typically
qualitative, incomplete, and/or approximate
The Engineering Design Specification will be used in
future design stages so care should be put into
making it as detailed and complete as possible.
Overview: Engineering
Design Specification (Specs)
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in-use purposes
Primary Purpose
Unintended Purpose
Special Purpose
Functional Requirements
Product performances
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Functional Performance Requirements
Complementary Performance
Environmental and other conditions
Economic issues
Physical attributes
Process technologies
Aesthetics
Product development time and cost
Before developing the Specs it is best to understand the customer needs.
House of Quality
Quality Function
Deployment (QFD) and the
House of Quality (HoQ)
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QFD: term used to describe a strategy
for focusing engineering design
attention on quality issues as
perceived by customers
HoQ: A technique used for structuring
information commonly used to
implement QFD.
House of Quality
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Matrix that relates the customers wants (Customer Attributes)
to the technical product characteristics (Engineering
Characteristics)
Customer Attributes (CA)
– Generally qualitative
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Fast, smooth, easy
– The Customer Attributes are listed to the left of the rows (also
grouped – functions, features)
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Engineering Characteristics (EC)
– Qualitative
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Weight in pounds
– The Engineering Characteristics are listed at the top of the
columns (grouped by categories)
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HoQ is also used for competitive benchmarking
House of Quality
Coffee Maker Example
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Customer Attributes  Good coffee
– Nice looking coffee maker
– Easy to clean
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Engineering Characteristics
– Goodness of coffee (in measurable quantities)
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Functional requirements
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Temperature
Flow rate of water
Time the water takes to flow through the grounds
Temperature when poured into the cup
EC will include requirements such as the electrical resistance to the heater, the
size of the tube supplying the hot water to the coffee grounds, and other
factors having to do with geometry and materials.
Since there are yet no proposed designs there are no engineering
characteristics yet.
Determine the Customer Attributes, then write the Specs and then
return to the Engineering Characteristics
CD protective portable
carrying case
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Customer Attributes
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Protects the discs
Attractive
Inexpensive
Can identify the contents
Stays closed
Easy to open
Can’t be used as a coaster for
coffee cups
Holds at least 6 CDs
Doesn’t pop open on its own
Won’t break if dropped
Compact
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Eliminate redundancies
Organize the list hierarchically
– Protects the discs
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Stays closed
Won’t break if dropped
Can’t be used as a coaster for
coffee cups
– Convenient to use
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Easy to Open
Ca identify the contents
Compact
– Attractive
– Holds at least six CDs
– Inexpensive
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Often priorities are assigned to
the customer attributes that
total 100 units
Assignment of priorities
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Stays closed
20
Won’t break if dropped
14
Can’t be used as a coaster for coffee cups
5
Easy to Open
20
Can identify the contents
10
Compact
7
Attractive
5
Holds at least six CDs
7
Inexpensive
10
Total
100
Content of the Engineering
Design Specification
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Develop the Specs after the Customer
Attributes have been identified
The Specs should include
– In-use purposes
– Functional Requirements
In-use purposes
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Primary Intended Use By Customers
– Examples
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To make coffee
To convert electrical to rotating energy
To aid in the catching of a baseball and to protect the hand when doing so
– Some products have multiple uses
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Baseball glove example
Hammer: Drive and pull nails
Predictable Unintended Uses
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Wrenches are used as hammers
Screw drivers as chisels
Shelves and chairs as step ladders
People standing (and jumping) on top of the washing machine
People driving with the windshield sun protector???? Remove when
driving. UNF parking tag….
– NOT enough to use warnings. Must design with unintended uses in
mind. Legal and common sense reasons.
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Design the wrench such that it is reasonable safe to use as a hammer
In-use purposes
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Special Purpose Features
– Features that enhance the product
Rechargeable electric shaver that can be
directly plugged into the outlet rather than
having an inconvenient cord.
 Redial button on your telephone
 No-drip tops on laundry detergents
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– May rate the special purpose features as
essential, important, or desirable
Functional Requirements
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Product performances
– Functional Performance Requirements
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Capacity (energy or material flow rate, force, …)
Input and output conditions (temperature, energy, pressures, flows,
power, deflections, forces)
Efficiency
Accuracy and sensitivity
– Complementary Performance
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Useful life
Reliability
Robustness
Safety
Noise
Legal requirements
Maintenance requirements
Requirements on users (skills, speed, knowledge, …)
Functional Requirements
Continued
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Environmental and other conditions
– Temperature, humidity, corrosive elements, noise, dirt, vibration, electric
or magnetic field.
– Extremes of variations
– How product will be disposed, how it will influence the environment,
design for dis-assembly.
– Is pollution a problem?
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Economic issues
– Tooling cost, initial product cost, maintenance costs, return on
investment, cash flow, break even time
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Physical attributes
– Weight, size, shape, surface finish, …
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Aesthetics
– Style, uniqueness, …
– Work with marketing team
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Product development time and cost
Process technologies
– restrictions on manufacturing processes
Expressing Functional
Requirements
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Qualitatively
– Verbal statement (high, low, moderate, fast, slow, …)
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As extremum goals, with or without limits
– Mass should be as low as possible
– Mass should be as low as possible but no higher than 10 lb
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As target values with tolerance
– The power output of an engine should be 5 Hp +/- 0.25
Hp
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As ranges
– Length must be between 3.7 and 4.8 inches
Completeness and
Invariability of the
Engineering Design
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The Specs should never be though of
as complete or invariable at any stage
in the design process.
Specifications should be as complete
as possible on what the designed
object is to do. They should say as
little as possible about how the
requirements are to be met.
Example: A Portable Wind
Chill Meter
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In-purpose use
– Primary Intended Use
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For skiers and winter hikers: to be able to determine
the so-called “wind chill” factor easily and conveniently
– Unintended Uses:
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Non anticipated
– Special Features
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Indicate temperature, wind velocity seperately as well
as the combined wind chill
Example continued
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Functional requirements
– Performance requirements
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Functional Performance requirements
– Indicated reading should be accurate within one degree
using U.S. Weather Bureau formula for the wind chill
– The meter should provide a reading after no more than
20 seconds for reaching equilibrium with the outdoor
environment
– The meter should perform with the above accuracy from
32 F to 50 F, and from wind velocities from 10 mph to
60 mph. Accuracy should not be affected by misorientation with the wind direction up to 20 degree
angle
Example continued
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Functional requirements
– Performance requirements
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Complementary performance requirements:
– The expected life in normal use should be at least 10
years
– The reliability should be such that no more than one in
1000 sold will be returned for repairs or replacement
during the 1st year of use.
– Must be able to withstand shocks and pressure without
damage when carried in jacket pockets
– Hiker or skier should not be cut by the device if (s)he
falls.
– No maintenance should be required (except battery
replacement – if used)
Example continued
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Environmental conditions
– Use at previously mentioned conditions
– Survive summer shipping storage up to 120 F
and 80% humidity
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Economic issues
– $10 (for a volume of 5000)
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Physical Attributes
– To be carried in a ski or hiking jacket pocket
– No more than 16 oz
– 3 x 5 x ¾ in3
Example continued
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Process Technologies
– None
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Aesthetics
– Should look like a rugged, reliable, accurate device
compatible with the quality equipment needed by skiers
and hikers
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Product development time and cost
– The product should be designed and prototyped by
<specific date>. Design and development cost, including
engineering , model shop, and laboratory should not
exceed <specified amount>
Assignment for next week
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Meet with your group
– Define a project leader
– Determine times when you will work on the
project as a groups each week
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At least 2 times (Beginning of the week discuss
the tasks, split and work independently, regroup)
Define the Customer Attributes with
priorities
Start discussing the Specs