Design engineers : An introductory text

DESIGNING ENGINEERS

AN INTRODUCTORY TEXT

SUSAN McCAHAN

University of Toronto

PHILIP ANDERSON

University of Toronto

MARK KORTSCHOT

University of Toronto

PETER E. WEISS

University of Toronto

KIMBERLY A. WOODHOUSE

Queen’s University

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vPreface

Preface

This book provides an introduction to the basic principles of engineering design in

a way that is accessible and appropriate for first- or second-year undergraduate stu￾dents, who do not yet have any discipline-specific expertise. It uses a first-principles

approach, with an emphasis on problem definition and scoping, and a creative solution

process, and is less concerned with rigorous, code-based design practice. However, it

is also quite comprehensive, and includes significant material on communications,

team strategies, and project management. This should allow instructors to pick and

choose the components that they want as a custom print or digital text. The approach

is based on the premise that “design thinking” can and should be introduced from the

very beginning of an engineering education in order to frame the remainder of the

subject area studies and motivate the students.

The past 15 years have seen a transformation of engineering design instruction.

Historically, engineering education often consisted of two fundamental parts: a

strong foundation of math, physics, and chemistry and a technical depth in one of

the traditional disciplines. Although many programs included a final-year “capstone”

design course, there was little formal education in design thinking and methodology

leading up to this. Students were expected to learn how to design things during the

often short and intense capstone experience.

Two forces have fomented change in this traditional approach. First, industry and

accreditation groups have strongly indicated that this was not enough: That engineers

needed to be further along in a full set of design skills. Second, design itself became

recognized as a basic and significant engineering skill, with many commonalities

across disciplines.

In recent years, a more formal introduction to engineering design thinking has

been introduced in many undergraduate programs, often beginning in the first year

of studies.

At the University of Toronto, Engineering Strategies and Practice (ESP) was intro￾duced on a pilot basis in 2003 and rolled out to the full class of about 900 first-year

students in 2005. We incorporated extensive material on communication, team, and

professional developments into this first-year design course. We have now delivered

this course to more than 8000 students, and we have been able to convey the impor￾tant aspects of engineering design using a combination of lectures and progressively

more complex design tutorials, leading up to community-service design projects in

the second term.

There are many textbooks on engineering design, and they span a wide range of

approaches. At one end, there are simplified, generic, and often shorter books on the

basics of problem definition and creative solution methods. At the other end, there

are comprehensive discipline-specific texts based in industry practice for individual

fields. After more than a decade of teaching freshman design, we see a need for a text

that sits between these extremes: a more comprehensive and flexible text that spans

more topics, in more detail than some of the generic introductory texts, but does so

in a way that is accessible and therefore useful for first- and second-year students.

The result is this text, Designing Engineers: An Introductory Text.

viPreface

Our course, and this text, strives to teach a structured, planned approach to the

design process, but one that is flexible based on results, insights, and reflection. It is an

iterative approach that considers the understanding that design solutions are never

perfect, but engineers work to provide a solution that best balances various aspects in

the context of the design, including emerging technology, economic and environmen￾tal concerns, and the interests of the client, team, users, and other members of society

who may be affected by the design.

This text is organized as a set of small relatively independent modules, organ￾ized into clusters, which are further organized into sections. The sections differenti￾ate major areas of engineering design knowledge, such as “Implementing a Project.”

Clusters associate information about specific areas of the section, such as “Working

on a Team.” The modules are the smallest text unit, covering a specific topic, such as

“Organizing Teams.” While the modules are not generally intended to be read sequen￾tially, links at the start of each module indicate which modules would normally be

read before the module, which modules can be read along with this module to supple￾ment the information, and which modules would normally follow this module.

The text is conceived primarily as an electronic resource, something that an indi￾vidual instructor can customize for a particular course and something that an individ￾ual student can read in a nonsequential manner, considering the student’s individual

needs. Although you may be holding in your hands a print form, you should look at it

as you would a Web page or online encyclopedia. There are multiple focal points and

most of these can be taken in any order. We strongly recommend that you use most of

the core design process modules because these cover the essential foundation of the

engineering design process, but after that, the text should be customized as needed,

according to the demands of the design course and your own design projects.

There are six types of modules:

r
narrative modules, which explain concepts and their context;

r
navigation modules, which link modules and help the reader move from one to

another;

r
process modules, which enable application of a systematic design process;

r
skill/tools modules, which provide specific techniques that support a systematic

design process;

r
resource modules, with complementary material to back up design learning; and

r
review/reflection modules, which provide a summary and support reflective

practice.

Some modules give the basic information needed to proceed with a project or a

part of a project and that may be enough information for you at that given point.

Other modules provide more detail and can be easily found, when you want to fill out

your knowledge.

The material in the module is followed by a list of key terms and questions and

activities that help you determine how well you have grasped the concepts in the

module. In an electronic version, the key terms may be linked to the definitions in

the glossary, and hashtags can take you to the sections of the text where a particular

concept is dealt with in some depth.

viiPreface

Acknowledgments

Many colleagues have contributed to the development of our ideas over the years. We

are particularly indebted to

r
Members of the Engineering Strategies and Practice teaching team over the

years. This dedicated team of instructors, staff, and graduate students has

contributed enormously to our understanding of engineering design teaching.

r
Our students, who provide invaluable feedback and inspiration.

r
Maegan Chang, who developed the case studies for the text.

r
Chirag Variawa, who developed a bibliography that identified the need for this text.

r
Our editors at Wiley.

In addition, we would like to acknowledge the valuable feedback we received from

the many people who reviewed early versions of the manuscript for the text:

Dr. Nadia Bhuiyan—Concordia University

Dr. Peter Byrne—University of South Alabama

Dr. Mauro Caputi—Hofstra University

Dr. Glenn Ellis—Smith College

Dr. Robert Fleisig—McMaster University

Dr. Robert Gettens—Western New England University

Dr. Hayden Griffin—East Carolina University

Dr. Margaret Harkins—University of North Carolina at Charlotte

Dr. Allen Hoffman—Worcester Polytechnic Institute

Dr. Jean Kampe—Michigan Tech University

Dr. Paul Kurowski—University of Western Ontario

Dr. Pierre Larochelle—Florida Institute of Technology

Dr. Stephanie Ludi—Rochester Institute of Technology

Dr. John Meech—University of British Columbia at Vancouver

Dr. J. Carson Meredith—Georgia Institute of Technology

Dr. Janice Miller-Young—Mount Royal University

Dr. Ibrahim Nisanci—University of Arkansas at Little Rock

Dr. Arun Srinivasa—Texas A&M University

Dr. Marlee Walton—Iowa State University

Dr. William Wild—SUNY Buffalo

Dr. Yuelei (James) Yang—University of Ontario Institute of Technology

Dr. Yih-Choung Yu—Lafayette College

viiiContents

Contents

Preface v

PART 1 How Engineers Design 0

Introduction 1

Design Process Overview 5

Project Phases 10

Communicating throughout the Process 14

What Engineers Design 18

How Engineering Projects Are Initiated 22

Navigating the Engineering Design Process 27

Engineering School Projects 32

PART 2 Design Process 34

Requirements

Introduction to Requirements 35

Functions 43

Objectives 50

Constraints 56

Documenting the Context 61

Describing Stakeholders 69

Describing Users, Operators, and Clients 76

Characteristics of Good Requirements 83

Summary: Putting It All Together 92

Functional Basis 96

Multi-use Design Tools

Black Box Method 101

Decomposition 104

Information Gathering 108

Benchmarking 115

Pairwise Comparison 122

Idea Generation

Introduction to Idea Generation 125

Brainstorming 128

Creativity Methods 134

Morphological Charts, Analogy, and TRIZ 140

Decision-making

Design Evaluation and Selection 144

Selecting a Design Solutiona 150

Decision Methods for Teams 160

Iterating

Stages in Iteration: Generate, Select, Reflect 163

Suggested Iteration Process 167

Reflection Considerations for Iteration 173

Investigating Ideas

Using Metrics 177

Investigating Ideas through Models and

Prototypes 180

Feasibility Checking 185

Routine Design 189

Post-Conceptual Design

Intermediate Design 194

Final Design 202

Post-Final Design Engineering 213

PART 3 Implementing a Project 218

Working in Teams

Introduction to Teamwork 219

Organizing 225

Tools for Organizing 230

Producing 237

Managing Teams 240

Management Strategies 247

Sample Team Documents 253

Project Management

Introduction to Project Management 261

Project Management Concepts 267

Creating a Project Plan 273

Estimating Cost and Time 279

Project Cycle (see www.wiley.com/college/mccahan)

Monitoring a Project (see www.wiley.com/college/mccahan)

Project Analysis (see www.wiley.com/college/mccahan)

Advanced Tools and Methods

(see www.wiley.com/college/mccahan)

Personal Management (see www.wiley.com/college/mccahan)

MS Project Instructions 284

Client Interaction

Client Meetings (see www.wiley.com/college/mccahan)

Asking Questions and Listening

(see www.wiley.com/college/mccahan)

Critical Thinking

Basic Concepts 293

Critical Thinking in Design Documents 300

Making and Supporting Statements Effectively 306

Skeptical Thinking 313

Communication

Engineering Communication 318

Organizing Communication 323

Contents

ix

Putting Together an Engineering Report

(see www.wiley.com/college/mccahan)

Diagrammatic Elements 330

Using Pictures and Photographs 339

Influencers of Communication 344

Organizing Presentations 349

Effective Slides 354

PART 4 Design for X 360

Durability

Design for Durability 361

The Environment

Design for the Environment:

Introduction 365

Life Cycle Assessment (LCA) 369

LCA Goal Definition and Scoping 375

LCA Inventory Analysis 382

LCA Impact and Improvement 388

Sustainability 396

Flexibility

Design for Flexibility: Introduction 401

Managing Flexibility 408

Human Factors

Design for Human Factors: Introduction 413

Task Analysis 420

Use Case Method 426

Concept of Operations 433

Intellectual Property

Design for Intellectual Property: Introduction 438

Principles of Patentability 444

Intellectual Property in the Design

Process 449

Frisbee Patents 454

Manufacture

Design for Manufacture: Introduction 460

Manufacturing Process Choices 468

Safety

Design for Safety: Introduction 475

Identifying Hazards 481

Safety in the Design Process 486

Workplace Safety 495

Testing & Maintenance

Design for Testing and Maintenance

(see www.wiley.com/college/mccahan)

PART 5 Resources 498

Principles and Problem Solving

Problem Spectrum: Open, Constrained, and

Closed (see www.wiley.com/college/mccahan)

Solving Closed Problems (see www.wiley.com/college/mccahan)

Writing up a Problem Solution

(see www.wiley.com/college/mccahan)

Significant Figures (see www.wiley.com/college/mccahan)

Conservation of Mass and Energy

(see www.wiley.com/college/mccahan)

Estimation

Introduction to Estimation 499

Estimation Techniques 504

Estimating Cost and Labor 515

Estimation Confidence 518

Probability & Statistics

Introduction to Probability and Statistics

(seewww.wiley.com/college/mccahan)

Discrete Distributions (see www.wiley.com/college/mccahan)

Continuous Distributions (see www.wiley.com/college/mccahan)

Fitting a Line (see www.wiley.com/college/mccahan)

Uses (see www.wiley.com/college/mccahan)

Economics

Introduction to Economics 523

Time and Money Calculations 528

Project Decisions 532

Types of Costs and Revenues 540

Payback 546

Failure & Risk

Introduction to Failure and Risk 550

Handling Risk 555

Why Things Fail 563

PART 6 Case Studies 570

Aerial Photography 571

The Razor Sole Skate (see www.wiley.com/college/mccahan)

A Video Titler for Sewer Inspection

(see www.wiley.com/college/mccahan)

The Steam Whistle Brewery

(see www.wiley.com/college/mccahan)

Selling Flowers (see www.wiley.com/college/mccahan)

Sample Design Briefs (see www.wiley.com/college/mccahan)

Historic Design Failures (see www.wiley.com/college/mccahan)

Glossary 577

Index 601

1

How

Engineers

Design

Introduction

H O W E N G I N E E R S D E S I G N > 1

1

#narrative module: #introduction

Learning outcomes

By the end of this module, you should demonstrate the ability to:

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Recommended reading

After this module:

ìHow Engineers Design > 2. Design Process Overview

1. Introduction

Welcome to “Designing Engineers: An Introduction.” Th is text, which is written in concise

units, covers an engineering design process from developing an understanding of the

problem to be solved, through idea generation, developing a detailed design, and imple￾mentation. Th e emphasis is on the fi rst stages of a design process, in particular defi ning

the project requirements, generating solution ideas, and evaluating the ideas. You will

cover more specifi cs of the design process and the design of discipline-specifi c tech￾nologies in your upper-year courses. In this text we will discuss some of the common

aspects of the design process across disciplines (e.g., the iterative nature of the process),

and the need for modeling and testing. Also, we will compare and contrast the detailed

design and implementation phases of the design process across project types.

Th e text is written in short units that are connected by recommended readings

at the beginning of each unit, links, and a glossary. Terms that are bold and italicized

throughout the text are linked to defi nitions and can be found in the glossary. Your

instructor may use all the text or parts of it depending on how he or she wishes to

teach design. Each unit will also contain the learning outcomes. Th ese are things that

you should be able to demonstrate by the time you fi nish the unit.

Introduction 1

2

HOW ENGINEERS DESIGN > 1

HOW ENGINEERS DESIGN

1.1. Introduction to the Engineering Process

There are many types of design. We will be focusing on engineering design, which

serves the essential purpose of engineering: turning science into useable systems.

Designing simple things generally does not require any special process, and many peo￾ple can design simple things without learning how to design. In fact, we humans are

very good at finding creative solutions to simple problems (see Figure 1).

However, as engineers you will generally be called upon to solve much more com￾plex problems that require consideration from multiple perspectives. The problems

engineers are asked to solve often involve specialized knowledge, regulations, or

codes, and the resulting technology can have far-reaching consequences, including

the health and safety of the public. Engineering work often involves finding solutions

that must function well from many different points of view; the design must function

well for the user, it must minimize impact on the environment, and it must be easy

to construct and maintain. As the complexity of these problems grows, it becomes

FIGURE 1 The informal design process: Designing a simple thing for your own use might not require any

special design process.

3Introduction

H O W E N G I N E E R S D E S I G N > 1

increasingly difficult to organize all of the information, balance the trade-offs success￾fully, and still find creative, effective solutions. As the complexity grows there is also a

need for larger design teams.

A more formal engineering design process is used to help large teams manage the

information that will be part of complex engineering problems, and to help engineers

develop solutions that have the best chance of being effective from these many differ￾ent perspectives. For example, the discipline of formulating the problem as a full set

of requirements gives designers a means

for comparing and prioritizing the differ￾ent goals of the project. Requirements are

a formal description of what is required of

the design. Formulating a complete set of

requirements is a way of making sure that

as the work progresses, which may take

years for a complex system, nothing essen￾tial to the project is forgotten or missed.

Furthermore, engineers as a profession

are required to carefully and fully docu￾ment a project. To document a project

means to explain what has been done in

writing, pictures (i.e., graphical communi￾cation and drawings), and orally (in pres￾entations, conversations, and meetings).

The act of documenting the work also

helps engineers develop ideas and clarify

their thinking and it. This documentation,

and the work it describes (the engineer’s

design work), will be the basis for deci￾sions. People will decide whether to fund

a project or not, whether to implement a

design or not, based on the quality of the

process that was used and the credibility

of the documentation developed.

It may not seem necessary to use a formal process for the relatively easy design

problems you will be given in the first few years of engineering school, or even for the

more difficult term projects you will do for your courses in upper years. However, like

learning any skill, it is valuable to learn the process in the context of simpler work

so that as the complexity of the problems increases you have developed habits and

learned tools that help you to be successful. In this regard learning design is much

like learning to play a musical instrument or some other complex skill that combines

thinking and doing. You start with simpler pieces of music, learn the basic process

and techniques, so that you can successfully tackle increasingly complex works. Tech￾niques for playing that work for a simple piece of music will not suffice for faster, more

complex pieces later. The same approach applies to engineering problem solving and

design. Being a good engineering designer requires both knowledge and practice.

There is no single universal engineering design process. Design processes vary

from discipline to discipline and even from company to company. And design pro￾cesses are changing as engineering tasks become more complex and more finely