ME2110 Topic 3 : Problem Understandingsinghose.marc.gatech.edu/courses/me2110...

ME2110

Topic 3 :

Problem Understanding

Phases of Design

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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

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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

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4

Example: CANSAT - Competition

Design Task

Coke-can satellite - CANSAT

Competition result – CANSAT is on-target, literally!

2. Customer Requirements

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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

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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

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• 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…”

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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)

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DT3 Example: Active-Safety Car Seat

Close, but not quite there…

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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

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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

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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

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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

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5. Quality Function Deployment

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Casual-wear in Japan [Photo from Dr. Singhose]

DT2 – House of Quality

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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

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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

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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

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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

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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

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Product: Car door

Customer requirements?

HoQ – Detailed Example

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Product: Car door

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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