An Introduction to Mechanical Engineering

449 Pages·2011·11.98 MB·English

by  Jonathan Wickert

An Introduction to
Mechanical Engineering
Third Edition
Jonathan Wickert
Iowa State University
Kemper Lewis
University at Buff alo—SUNY
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An Introduction to Mechanical © 2013, 2006 Cengage Learning
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D
EDICATION
To Karen and Rebecca for their patience and encouragement throughout
this project.
Jonathan Wickert
To the Lord for grace and to Laura, Kamryn, and Kaden for their
overwhelming patience, support, and love.
Kemper Lewis
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Contents
Student’s Preface xi
Instructor’s Preface xiii
About the Authors xxi
CHAPTER 1 THE MECHANICAL ENGINEERING PROFESSION 1
1.1 Overview 1
The Elements of Mechanical Engineering 1
1.2 What Is Engineering? 4
1.3 Who Are Mechanical Engineers? 10
Mechanical Engineering’s Top Ten Achievements 12
1.4 Career Paths 22
1.5 Typical Program of Study 24
Summary 28
Self-Study and Review 28
Problems 29
References 31
CHAPTER 2 MECHANICAL DESIGN 33
2.1 Overview 33
2.2 The Design Process 37
Requirements Development 41
Conceptual Design 42
Detailed Design 43
Production 47
2.3 Manufacturing Processes 50
2.4 Case Study in Conceptual Design:
Mousetrap-Powered Vehicles 57
First Concept: String and Lever Arm 58
Second Concept: Compound Geartrain 59
Third Concept: Sector-Shaped Gear 61
2.5 Case Study in Urban Power Infrastructures 62
Requirements Development 62
Conceptual Design 63
Detailed Design 65
v
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vi Contents
2.6 Case Study: Computer-Aided Design:
Noninvasive Medical Imaging 66
Summary 70
Self-Study and Review 71
Problems 72
References 76
CHAPTER 3 TECHNICAL PROBLEM-SOLVING AND COMMUNICATION
SKILLS 77
3.1 Overview 77
3.2 General Technical Problem-Solving Approach 82
3.3 Unit Systems and Conversions 84
Base and Derived Units 84
International System of Units 84
United States Customary System of Units 88
Converting Between the SI and USCS 91
3.4 Signifi cant Digits 96
3.5 Dimensional Consistency 98
3.6 Estimation in Engineering 107
3.7 Communication Skills in Engineering 112
Written Communication 113
Graphical Communication 115
Technical Presentations 116
Summary 120
Self-Study and Review 120
Problems 121
References 128
CHAPTER 4 FORCES IN STRUCTURES AND MACHINES 129
4.1 Overview 129
4.2 Forces in Rectangular and Polar Forms 131
Rectangular Components 132
Polar Components 133
4.3 Resultant of Several Forces 134
Vector Algebra Method 135
Vector Polygon Method 136
4.4 Moment of a Force 140
Perpendicular Lever Arm Method 140
Moment Components Method 142
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Contents vii
4.5 Equilibrium of Forces and Moments 148
Particles and Rigid Bodies 148
Free Body Diagrams 150
4.6 Design Application: Rolling-Element Bearings 158
Summary 166
Self-Study and Review 167
Problems 168
References 182
CHAPTER 5 MATERIALS AND STRESSES 183
5.1 Overview 183
5.2 Tension and Compression 185
5.3 Material Response 193
5.4 Shear 205
5.5 Engineering Materials 210
Metals and Their Alloys 211
Ceramics 212
Polymers 213
Composite Materials 214
5.6 Factor of Safety 218
Summary 222
Self-Study and Review 224
Problems 225
References 237
CHAPTER 6 FLUIDS ENGINEERING 238
6.1 Overview 238
6.2 Properties of Fluids 240
6.3 Pressure and Buoyancy Force 248
6.4 Laminar and Turbulent Fluid Flows 255
6.5 Fluid Flow in Pipes 259
6.6 Drag Force 266
6.7 Lift Force 275
Summary 281
Self-Study and Review 282
Problems 283
References 290
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viii Contents
CHAPTER 7 THERMAL AND ENERGY SYSTEMS 291
7.1 Overview 291
7.2 Mechanical Energy, Work, and Power 293
Gravitational Potential Energy 293
Elastic Potential Energy 294
Kinetic Energy 294
Work of a Force 295
Power 295
7.3 Heat as Energy in Transit 300
Heating Value 300
Specifi c Heat 302
Transfer of Heat 304
7.4 Energy Conservation and Conversion 313
7.5 Heat Engines and Effi ciency 318
7.6 Case Study 1: Internal-Combustion Engines 323
Four-Stroke Engine Cycle 325
Two-Stroke Engine Cycle 328
7.7 Case Study 2: Electrical Power Generation 330
7.8 Case Study 3: Jet Engines 339
Summary 342
Self-Study and Review 343
Problems 344
References 350
CHAPTER 8 MOTION AND POWER TRANSMISSION 351
8.1 Overview 351
8.2 Rotational Motion 353
Angular Velocity 353
Rotational Work and Power 355
8.3 Design Application: Gears 359
Spur Gears 360
Rack and Pinion 364
Bevel Gears 364
Helical Gears 364
Worm Gearsets 367
8.4 Speed, Torque, and Power in Gearsets 369
Speed 370
Torque 371
Power 372
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