me2110 topic 3 : problem understandingsinghose.marc.gatech.edu/courses/me2110...
TRANSCRIPT
ME2110
Topic 3 :
Problem Understanding
Phases of Design
© GIT2
A. Customer/Product Requirements
B. Design Specification
C. Conceptual Design
I. Concept Generation
II. Concept Evaluation
D. Detail Design
E. Prototyping
F. Design Finalization
I. Specification for Production
Manufacturing
Usable Life
End of Life
PR
OD
UC
T L
IFE
CY
CL
E
Start
End
Concurrent
NOT
Linear
DT 1&2: Understanding the Design Task
© GIT3
A. Customer/Product RequirementsProblem understanding, Initial Analysis
B. Design SpecificationTarget Performance Metrics, Design Constraints
C. Conceptual Design
I. Concept Generation
II. Concept Evaluation
D. Detail Design
E. Prototyping
F. Design Finalization
I. Specification for Production
DT1 – P.U.F DT2 – H.o.Q
DT4 – Design Spec. Sheet
DT3 – Function tree
1. Types of Design
© GIT
4
Example: CANSAT - Competition
Design Task
Coke-can satellite - CANSAT
Competition result – CANSAT is on-target, literally!
2. Customer Requirements
© GIT5
Review Class Notes
Key Concepts:
Customer side : Needs, Wants, Desires
Product side : Features, Benefits, Quality
Design process is most successful iff. customers’
“quality function” is embedded in the product
QFD - Quality Function Deployment:
Design process originated in Japan to rigorously
ensure customer-centric product development
Seeding questions: Where can I sell product?
What is target Market?, Why will people buy
it? Why is it important?
DT1 - Problem Understanding Form
© GIT6
Ensures evaluation of relative importance of Customer Requirements
Establishes relationships between Customer Requirements and Design
Requirements using Relationship Matrix
• Customer WHATS into Design HOWS
Analysis:
• Blank Row – customer requirement not met; Engineer doesn’t care
• Blank Column – design requirement that customer doesn’t want
• Be aware of intrinsic requirements
Relationship
Matrix
Design Requirements
Custo
mer
Requir
em
ents
1 nRelationship Weight
Strong 9
Medium 3
Weak 1
3. Product Functions
© GIT7
• Actions the product must be capable of DOING
• Abstract formulation of task
What is a Product Function?
Approach:
• Drill down to the “Hows”
What it is NOT:
• A specific solution path - eg. “Turn Light On”
• A Constraint – eg. “Be smaller than…”
8
DT3 Example: Active-Safety Car Seat
Consider the design of active-safety seats to
increase occupant safety
Use a Function Tree to establish/identify the
product functions
Conventional Car Seat Movie
(see ME 2110 Homepage)
Moving Car Seat Movie
(see ME 2110 Homepage)
© GIT
© GIT9
DT3 Example: Active-Safety Car Seat
Close, but not quite there…
© GIT10
Active Safety Car-Seat
Be
Comfortable
Provide
Active Safety
Maintain
cushioning
Conform to
User Shape
Constrain
occupant
Adjust Occ.
motion
Sense
Collision
Increase
head space
Increase
lower-leg
clearance
DT3 Example: Active-Safety Car Seat
Technically accurate, but not only solution
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DT3 Example: Pole-Vault Pole
© GIT
12
Shoot Athlete High
Into the Air
(Repeatedly)
Support Load Be Easy to Use Be Consistent
Spring BackBend LightweightFit Comfortably
in Hands
Maintain
Stiffness
Be Labeled
Properly
Pole-Vault Pole Functions
Warn
User
Alert
User
Inform
User
© GIT
© GIT13
4. Design Specifications
• Numerical target (TPM) or constraint
• Derived from Design Standard, Design
Constraint, or Design Analysis
What is a Design Specification
Specification Categories
• Geometric
• Kinematics
• Dynamics
• Energy
• Costs
• Material
• Signals
• Safety
• Ergonomics
• Schedules
• Assembly
• Transportation
• Operation
• Quality Control
• Recycling
© GIT14
DT4 – Design Specification Sheet/List
• List of Design Specifications, Source, Design responsibility
• Tracks versioning by including date of modification or spec change
• Specifications arranged by category
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For: A Pole Vault Pole
D/WChanges
Specification
Resp. SourceRequirements
USHSF
Standard
Shoot Idiot 3-6m into the air.
GeometryDiameter between 1-2”Length between 10'-17'6"
KinematicsDamping ratio < 0.1
ForcesBending Force ScalableBending angle > 180 deg.
MaterialsMoldableDurableDuctileNot temperature dependent
SafetyWill not fracture99% stiffness after 5k Bends
DesignTeam
Standard
USHSF
USHSF
Standard
D
D
D
DDD
D
W
W
W
W
D
DT4 Example – Pole Vault Pole
© GIT
5. Quality Function Deployment
© GIT16
Casual-wear in Japan [Photo from Dr. Singhose]
DT2 – House of Quality
© GIT17
Primary design tool in QFD
Ensures comprehensive
understanding of design task
and product requirements
Builds on P.U.F by adding
“rooms” for:
Design Trade-off & Analysis
Identification
Technical Importance
identifies key design
requirements for product
non-subjectively
Customer Competitive
Assessment
Technical Competitive
Assessment
Design Target Specification
Import
ance
Relationship
Matrix
Design Requirements
Custo
mer
Requir
em
ents
1 n
Correlation
Matrix
1 n RAbsolute
Relative 1/ R n/ R
TPMs
Custo
mer
Com
p.
Assessm
ent
Technical Competitive
Assessment
Import
ance
H.o.Q Matrices
© GIT18
Relationship Matrix:
• Relates Customer Requirements
to Design requirements
• WHATS to HOWS
• Symbolic Entries with larger
weighting scale
Relationship Symbol Weight
Strong 9
Medium 3
Weak 1
Correlation Matrix:
• Relates Design Requirements to
Design requirements
• Hows to HOWS
• Clearly identifies design trade-offs
• Demonstrates areas for
optimization efforts
Co-Relationship Symbol
Strong Positive
Positive
Negative
Strong Negative
H.o.Q Coffee Example
© GIT19
Product: A cup of coffee
Explicit Requirements:
Be Hot, Taste Good, Smell Good,
Stimulating, Look like Coffee, No
Grounds, Reasonable Cost
Intrinsic Requirements:
Non-Toxic
© GIT20
1 :
R
1/ R
Technical Importance
8*9 + 3*6 + 9*9 +10*1 = 181
181 + 132 + 54 + 99 + 18 +108 …
… + 90 = 682
181 / 682 = 0.27
Absolute
Relative
H.o.Q – Design Understanding Analysis
© GIT21
H.o.Q Analysis:
• Identify Blank rows and columns
• Compare customer vs technical competitive
surveys
• Identify and Resolve conflicts
• Identify advantages (marketing points)
• Confirm target performance metrics
• Identify areas for detailed design optimization
• Strong negative correlations
• Target direction indicators
House of Quality is a comprehensive summary of the
understanding of a design task.
HoQ exposes areas for detailed analysis and additional evaluation
HoQ – Detailed Example
© GIT22
Product: Car door
Customer requirements?
HoQ – Detailed Example
© GIT23
Product: Car door
© GIT24
Key Concepts
• Design is a Problem Solving Process
• Multiple Phases of Design
• Customer Requirements
• Intrinsic requirements
• Problem understanding Form
• Product Functions
• “drill down to the how's”
• Quality Function Deployment
• House of Quality