Florian Misoc, 2010

ECET 4550:Alternate Energy

fall 2011Laboratory Topic:

The Design Process

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Announcement

• Third week in October (15-21): FE examination practice

• Contact Dr. John Krohn, Mechanical Engineering Department

• Suggestion: every graduating engineering student should take the FE exam (Fundamentals of Engineering)

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Chapter Objectives

• Description and Prescription• Strategies, Methods & Means• Managing the Design Process• Case Study & Examples

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Introduction

• Design Process ≠ “cooking” recipe• Design Process = Σ design tasks = task-1 +

task-2 + …. + task-n• Design Process = “framework”• Design process = process of questioning

“knowledge resides in the questions that can be asked and the answers that can be provided” Aristotle

Florian Misoc, 2010

Introduction

• Task # 1: Clarify what the client wants• Task # 2: Translate “want” into meaningful

objectives• Task # 3: Determine the constrains (limitations)

associated with client’s “want”• Task # 4: Establish the “function” of the future

system (what does it do?)

Florian Misoc, 2010

Introduction

• Task # 5: Establish set of requirements (specs)• Task # 6: Generate design alternatives• Task # 7: Model and analyze designs• Task # 8: Test and evaluate design alternatives• Task # 9: Refine and optimize the design• Task # 10: Document the design process• Task # 11: Communicate the completed design

Florian Misoc, 2010

Questions

• Task # 1: Clarify what the client wants:a. Why do you want another system, device, etc.?b. How it will have to work?c. How much can it cost?

• Task # 2: Translate “want”;i. What does “safe” means?ii. What would the system would be used for?

Florian Misoc, 2010

Questions

• Task # 3: Determine the constrains:1. What are the conditions of operations?2. What is the system impact on people’s safety?

• Task # 4: Establish the “function”:i. What is the weight, volume, mass distribution,

etc. that the system should accommodate?ii. Would the system operate indoors /outdoors?

Florian Misoc, 2010

Questions

• Task # 5: Establish set of requirements (specs)a. How much weight, voltage, current, should the

system withstand?b. What is the expected “breaking point”?

• Task # 6: Generate design alternativesi. Could the system be modular?ii. What are the alternative materials to be used?

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Questions

• Task # 7: Model and analyze designsa. What are the maximum stresses (weight,

current, etc.) on the system?b. How do stresses affect the material(s)

• Task # 8: Test and evaluate design alternativesi. Does the system meet OSHA requirements?ii. Can the system accommodate a wide

spectrum of users?

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Questions

• Task # 9: Refine and optimize the designa. Are there other methods of assembly?b. Can the amount of material/components used,

be reduced?

• Task # 10: Document the design processi. What are the justifications for choosing “this

design”?ii. What information is needed for manufacture?

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Design Process: Description and PrescriptionA. Describing the Design ProcessB. Prescribing the design ProcessC. Feedback from the ClientD. Iteration(s) in the design ProcessE. Opportunities and Limits

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Describing the Design Process

• Three-phase design process:1. Generation: designer generates various

design concepts2. Evaluation: designer tests the chosen design

against objectives and requirements3. Communication: designer communicates the

final design to the client and to the manufacturer

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Describing the Design Process

• Alternate three-phase design process:1. Research: designer reviews the existing

literature on the subject2. Creating: designer generates design prototype3. Implementing: designer implements & tests

design prototype

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Describing the Design Process

• Three stage linear model for design process

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Describing the Design Process

• Five stage linear model for design process

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Describing the Design Process

A. Problem Definition: • Pre-process stage• Frames the problem• Clarifies the client’s original problem statement

B. Design Communication:• Post-process stage• Identifies the work done• Presents final design & manufacture specs

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Prescribing the design Process

• Five-phase prescriptive model:

Client’s Problem Statement1. Problem Definition2. Conceptual Design3. Preliminary Design4. Detailed Design5. Design CommunicationDocumentation for Final Design

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1. Problem Definition

• Clarify objectives• Establish metrics for objectives• Identify constrains• Revise client’s Problem Statement

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2. Conceptual Design

• Establish functions• Establish requirements (specifications)• Establish means for functions• Generate design alternatives• Refine & apply metrics to design alternatives• Choose a design

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3. Preliminary Design

• Model design• Analyze design performance• Test chosen design• Evaluate chosen design: compare design

performances with specifications

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4. Detailed Design

• Refine & optimize chosen design: improve design performances

• Assign & fix design details

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5. Design Communication

• Document final design• Present chosen design performances to the

client• Emphasize design performance (vis-à-vis specs)• Present possible improvements (as a future

option)

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Feedback from the Client

• Design process: nonlinear, not sequential

• Required elements:a. Feedbackb. Iteration

NotePrimary focus: Conceptual Design

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a. Feedback

• Two (2) types:1. Internal feedback loops: tests & evaluation

results used to validate/verify design performances. Occurs during the design process

2. External feedback loops: results provided by the user(s) are used to validate the design. Occurs after the design reaches the market

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b. Iterations

• Definition: repeatedly applying a common method/technique at different points during the design/analysis

• It occurs at different levels of abstraction (different degrees of detail)

• More detail → less abstract

• Don’t loose focus on the original objectives!

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Opportunities and Limits

• Focus: Conceptual design

• Detailing: Broad themes, logical approaches

• Conceptual Design Tools: Not mathematical algorithms

• Problem Solving: Not necessarily “rigorous”

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Design Process: Strategies, Methods & Means

• Prescriptive design: No information on How to generate the design

• Formal Design Methods:a. Build “Objective Trees”b. Rank “Design Objectives’c. Establish “Metrics”d. Perform “Functional Analysis”e. Elaborate “Requirements/Specifications”

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Means for acquiring information

1. Literature review2. User survey & questionnaires3. Focus groups4. Informal interviews5. Structured interviews6. “Brainstorming”7. Benchmarking8. Reverse engineering

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Means for analyzing information

i. Develop metricsii. Undertake/design experimentsiii. Conduct proof-of-concept testingiv. Implement prototype developmentv. Conduct computer simulationsvi. Conduct computer numerical analysis

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Means for testing outcomes & feedback

I. Scheduled meetings (designer-client-user)II. Formal design review (present design to:

client, selected users, stakeholders), involves trade-off

III. Public hearings (expose the design for public review), increasingly the norm

IV. Focus groups (user input on problem definition), asses user reaction to design

V. Beta testing = almost-but-not-quite-finished version of the product

Florian Misoc, 2010

Managing the Design Process

• Four-phase process:I. Project definition: develop an initial

understanding of the problem to be solvedII. Project framing: develop & apply a design

planIII. Project scheduling: organize the design

plan/prioritizeIV. Project tracking / evaluation / control: keep

track of TIME, work, cost, etc.

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Managing the Design Process• Design: a social activity• Design: done by teams (seldom by individuals)• Requires: people with different talents, skills,

areas of expertise• Transition from group to functioning team:1. Forming2. Storming3. Norming4. Performing5. Adjourning

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Project Statements-1

Design of a container to deliver a children’s beverage

Designers: Dym, Little, Orwin and Spjut LLCClients: American Beverage Company (ABC)Users: Children living in the United StatesProblem Statement: Design a bottle for a new

children’s juice product

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Project Statements-2

Design a cooling air-flow system for spinal-fusion hydrostatic vest

Designers: Team of students at ATUClient: Memphis Trauma CenterUsers: Victims of accidents that sustained sever

spinal fracturesProject Statement: Design an air-flow cooling

system that will accommodate the existing spinal-fusion vests for patients who sustained severe spinal fractures

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References

• Engineering Design, A Project-Based Introduction, third edition

• Authors: Clive L. Dym, Patricl Little, Elizabeth J. Orwin, Erik R. Spjut

• ISBN: 978-0-470-22596-7• Pages: 18 - 45

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Assignment

• Due date: September 15th, 2010

• Exercises 2.1 – 2.4, page 45

• Case study 2.5.1: Design of a microlaryngeal surgical stabilizer

• Selected Project & team members for the project