Analysis and Design of Machine Elements

Incorporating Chinese, European, and International standards and units of measurement, this book presents a classic subject in an up-to-date manner with a strong emphasis on failure analysis and prevention-based machine element design. It presents concepts, principles, data, analyses, procedures, and decision-making techniques necessary to design safe, efficient, and workable machine elements. Design-centric and focused, the book will help students develop the ability to conceptualize designs from written requirements and to translate these design concepts into models and detailed manufacturing drawings. Presents a consistent approach to the design of different machine elements from failure analysis through strength analysis and structural design, which facilitates students' understanding, learning, and integration of analysis with design Fundamental theoretical topics such as mechanics, friction, wear and lubrication, and fluid mechanics are embedded in each chapter to illustrate design in practice Includes examples, exercises, review questions, design and practice problems, and CAD examples in each self-contained chapter to enhance learning Analysis and Design of Machine Elements is a design-centric textbook for advanced undergraduates majoring in Mechanical Engineering. Advanced students and engineers specializing in product design, vehicle engineering, power machinery, and engineering will also find it a useful reference and practical guide Cover 1 Title Page 5 Copyright 6 Contents 7 Preface 19 About the Companion Website 21 Part I Fundamentals of Design and Strength Analysis 23 Chapter 1 An Overview of Machine Design 25 1.1 Introduction 25 1.1.1 Machines and Machine Elements 25 1.1.2 The Scope of Machine Design 26 1.2 Machine Design 27 1.2.1 Machine Design Considerations 27 1.2.2 Machine Design Process 29 1.3 Machine Element Design 31 1.3.1 Machine Element Design Considerations 31 1.3.2 Common Failure Modes in Machine Elements 32 1.3.3 Design Criteria 33 1.3.3.1 Strength Criteria 33 1.3.3.2 Rigidity Criteria 34 1.3.3.3 Life Criteria 34 1.3.3.4 Wear Criteria 35 1.3.4 Machine Element Design Process 35 1.4 Materials and Their Properties 37 1.4.1 Types of Materials 37 1.4.1.1 Steels and Alloys 37 1.4.1.2 Cast Irons and Cast Steels 39 1.4.1.3 Nonferrous Alloys 39 1.4.1.4 Polymers 40 1.4.1.5 Composite Materials 40 1.4.2 Material Properties 40 1.4.3 Heat Treatments 41 1.4.4 Material Selection 42 1.5 Unit Systems 43 1.6 Standards and Codes 44 References 45 Problems 45 Chapter 2 Strength of Machine Elements 47 2.1 Fluctuating Loads and Stresses 48 2.1.1 Service Factors and Design Loads 48 2.1.2 Types of Loads 48 2.1.3 Types of Stresses 50 2.1.3.1 Static Stress 50 2.1.3.2 Completely Reversed Stress 51 2.1.3.3 Repeated Stress 51 2.1.3.4 Fluctuating Stress 51 2.2 Static Strength 51 2.2.1 Static Strength for Uniaxial Stresses 52 2.2.2 Static Strength for Combined Stresses 52 2.2.2.1 Maximum Shear Stress Theory 52 2.2.2.2 Maximum Distortion Energy Theory 53 2.3 Fatigue Strength 54 2.3.1 The Nature of Fatigue 54 2.3.2 Stress‐Life Diagrams 55 2.3.3 Endurance Limit Diagrams 56 2.3.3.1 The Endurance Limit Diagram of a Material 56 2.3.3.2 The Endurance Limit Diagram of an Element 57 2.3.4 Fatigue Strength for Uniaxial Stresses with Constant Amplitude 61 2.3.5 Fatigue Strength for Uniaxial Stresses with Variable Amplitude 63 2.3.5.1 Linear Cumulative Damage Rule (Miner's Rule) 63 2.3.5.2 Prediction of Cumulative Fatigue Damage 64 2.3.6 Fatigue Strength for Combined Stresses with Constant Amplitude 65 2.3.7 Measures to Improve Fatigue Strength 66 2.3.8 Examples of Strength Analyses 66 2.4 Contact Strength 72 2.4.1 Hertzian Contact Stresses 72 2.4.2 Surface Fatigue Failure 73 References 74 Problems 75 Part II Design Applications 79 Chapter 3 Detachable Joints and Fastening Methods 81 3.1 Introduction 82 3.1.1 Applications, Characteristics and Structures 82 3.1.2 Selection of Fastening Methods 82 3.2 Screw Threads 83 3.2.1 Types of Screw Threads 83 3.2.2 Standards and Terminology 84 3.3 Threaded Fastening Methods 86 3.3.1 Types of Threaded Fastening Methods 86 3.3.2 Threaded Fasteners 87 3.3.3 Tightening Torque and Preloading 88 3.3.4 Fastener Loosening and Locking 88 3.4 Force Analysis of Multiply Bolted Joints 89 3.4.1 Multiply Bolted Joints Subjected to Symmetric Transverse Loads 89 3.4.2 Multiply Bolted Joints Subjected to a Torque 90 3.4.3 Multiply Bolted Joints Subjected to a Symmetric Axial Load 91 3.4.4 Multiply Bolted Joints Subjected to an Overturning Moment 92 3.5 Strength Analysis 93 3.5.1 Potential Failure Modes 93 3.5.2 Strength Analysis for Shear Bolts 93 3.5.3 Strength Analysis for Tension Bolts 94 3.5.3.1 Tension Bolts Subjected to Axial Loads Only 94 3.5.3.2 Preloaded Tension Bolts Subjected to Transverse Loads 94 3.5.3.3 Preloaded Tension Bolts Subjected to Combined Preload and Static Axial Loads 95 3.5.3.4 Preloaded Tension Bolts Subjected to Combined Preload and Variable Axial Loads 96 3.5.4 Measures to Improve Fatigue Strength of Bolted Joints 97 3.6 Design of Bolted Joints 98 3.6.1 Introduction 98 3.6.2 Materials and Allowable Stresses 98 3.6.3 Design Criteria 100 3.6.4 Design Procedure and Guidelines 100 3.6.5 Structural Design 101 3.6.6 Design Cases 101 References 105 Problems 106 Chapter 4 Detachable Fastenings for Shaft and Hub 113 4.1 Keys 113 4.1.1 Applications, Characteristics and Structure 113 4.1.2 Types of Keys 114 4.1.3 Strength Analysis 116 4.2 Splines 118 4.3 Pins 119 References 120 Problems 121 Chapter 5 Permanent Connections 127 5.1 Riveting 127 5.1.1 Applications, Characteristics and Structure 127 5.1.2 Types of Rivets 127 5.1.3 Strength Analysis 128 5.1.4 Design of Riveted Joints 129 5.2 Welding 131 5.2.1 Applications, Characteristics and Structure 131 5.2.2 Types of Welded Joints and Types of Welds 132 5.2.3 Strength Analysis 132 5.2.3.1 Butt Welds 133 5.2.3.2 Fillet Welds 133 5.2.4 Design of Welded Joints 134 5.3 Brazing, Soldering and Adhesive Bonding 135 5.3.1 Applications, Characteristics and Structure 135 5.3.2 Types of Adhesive and Their Selection 135 5.3.3 Analysis and Design of Adhesive Joints 136 References 137 Problems 137 Chapter 6 Belt Drives 141 6.1 Introduction 142 6.1.1 Applications, Characteristics and Structures 142 6.1.2 Types of Belts 143 6.1.3 V‐Belts 145 6.1.3.1 Terminology and Dimensions of V‐Belts 145 6.1.3.2 Types of V‐Belts 145 6.1.3.3 V‐Belt Construction 145 6.2 Working Condition Analysis 146 6.2.1 Geometrical Relationships in Belt Drives 146 6.2.2 Force Analysis 147 6.2.2.1 Force Analysis of an Element of Belt 148 6.2.2.2 Relations Between Tight Tension F1, Slack Tension F2, Initial Tension F0 and Effective Tension Fe 148 6.2.2.3 Critical or Maximum Effective Tension, Fec 149 6.2.2.4 Centrifugal Tension, Fc 150 6.2.3 Kinematic Analysis 150 6.2.3.1 Elastic Creep 150 6.2.3.2 Slippage of Belts 151 6.2.3.3 Speed Ratio 151 6.2.4 Stress Analysis 152 6.2.4.1 Tensile Stress in Tight Side, σ1, and Slack Side, σ2 152 6.2.4.2 Centrifugal Stress, σc 152 6.2.4.3 Bending Stress, σb 152 6.2.5 Potential Failure Modes 153 6.3 Power Transmission Capacities 153 6.3.1 The Maximum Effective Tension 153 6.3.2 Power Transmission Capacity of a Single V‐Belt 154 6.3.2.1 The Basic Power Rating of a Single Standard V‐Belt, P0 154 6.3.2.2 The Actual Power Rating of a Single V‐Belt, Pr 154 6.4 Design of Belt Drives 157 6.4.1 Introduction 157 6.4.2 Design Criteria 157 6.4.3 Design Procedure and Guidelines 157 6.4.3.1 Compute Design Power, Pca 158 6.4.3.2 Specify Suitable Belt Types 158 6.4.3.3 Determine the Sheave Size 158 6.4.3.4 Confirm the Centre Distance, a and Belt Datum Length, Ld 158 6.4.3.5 Compute Contact Angle on the Small Sheave, α1 159 6.4.3.6 Compute the Number of Belts Required to Carry the Design Power 159 6.4.3.7 Decide Initial Tension, F0 159 6.4.3.8 Compute the Force Acting on the Sheave Shaft, FQ 160 6.4.4 Design of V‐Belt Sheaves 160 6.4.5 Design Cases 160 6.5 Installation and Maintenance 162 References 163 Problems 163 Chapter 7 Chain Drives 169 7.1 Introduction 170 7.1.1 Applications, Characteristics and Structures 170 7.1.2 Types of Chains 170 7.2 Working Condition Analysis 173 7.2.1 Geometrical Relationships in Chain Drives 173 7.2.2 Kinematic Analysis 173 7.2.2.1 Speed Ratio 173 7.2.2.2 Angular Velocity Ratio 174 7.2.2.3 Chordal Action 175 7.2.3 Force Analysis 176 7.2.3.1 Tension in Tight Side 176 7.2.3.2 Tension in Slack Side 176 7.2.3.3 Dynamic Forces 176 7.2.4 Potential Failure Modes 177 7.3 Power Transmission Capacities 177 7.3.1 Limiting Power Curves 177 7.3.2 Actually Transmitted Power 178 7.4 Design of Chain Drives 179 7.4.1 Introduction 179 7.4.2 Materials 179 7.4.3 Design Criteria 179 7.4.4 Design Procedure and Guidelines 180 7.4.4.1 Tentatively Select the Number of Sprocket Teeth z and Speed Ratio i 180 7.4.4.2 Determine the Required Power Rating of a Single‐Strand Chain, P0 181 7.4.4.3 Select Types of Chain and Pitch, p 181 7.4.4.4 Determine the Centre Distance Between the Sprocket Shafts, a and Chain Length, Lp 182 7.4.4.5 Select an Appropriate Lubrication According to the Speed of Chain 182 7.4.4.6 Forces Acting on the Shaft 182 7.4.5 Design Cases 183 7.5 Drive Layout, Tension and Lubrication 185 7.5.1 Drive Layout 185 7.5.2 Tensioning 185 7.5.3 Lubrication 186 References 187 Problems 187 Chapter 8 Gear Drives 193 8.1 Introduction 195 8.1.1 Applications, Characteristics and Structures 195 8.1.2 Types of Gear Drives 195 8.1.3 Geometry and Terminology 197 8.2 Working Condition Analysis 200 8.2.1 Kinematic Analysis 200 8.2.1.1 Speed Ratio and Pitch Line Velocity 200 8.2.1.2 Contact Ratio 200 8.2.2 Design Loads 201 8.2.3 Potential Failure Modes 203 8.3 Strength Analysis for Spur Gears 204 8.3.1 Forces on Spur Gear Teeth 204 8.3.2 Tooth Surface Fatigue Strength Analysis 206 8.3.2.1 Hertz Formula 206 8.3.2.2 Contact Stress Calculation 207 8.3.2.3 Contact Strength Analysis 208 8.3.3 Tooth Bending Strength Analysis 208 8.3.3.1 Bending Stress Calculation 209 8.3.3.2 Bending Strength Analysis 210 8.4 Strength Analysis for Helical Gears 210 8.4.1 Geometry and Terminology 211 8.4.1.1 The Geometry of a Helical Gear 211 8.4.1.2 Contact Ratio 213 8.4.1.3 Virtual Number of Teeth 214 8.4.2 Forces on Helical Gear Teeth 214 8.4.3 Tooth Surface Fatigue Strength Analysis 216 8.4.3.1 Contact Stress Calculation 216 8.4.3.2 Contact Strength Analysis 217 8.4.4 Tooth Bending Strength Analysis 217 8.4.4.1 Bending Stress Calculation 217 8.4.4.2 Bending Strength Analysis 218 8.5 Strength Analysis for Bevel Gears 218 8.5.1 Geometry and Terminology 218 8.5.2 Forces on Straight Bevel Gear Teeth 221 8.5.3 Tooth Surface Fatigue Strength Analysis 222 8.5.3.1 Contact Stress Calculation 222 8.5.3.2 Contact Strength Analysis 223 8.5.4 Tooth Bending Strength Analysis 223 8.5.4.1 Bending Stress Calculation 223 8.5.4.2 Bending Strength Analysis 224 8.6 Design of Gear Drives 224 8.6.1 Introduction 224 8.6.2 Materials and Heat Treatments 224 8.6.2.1 Commonly Used Gear Materials 225 8.6.2.2 Heat Treatments 225 8.6.3 Gear Manufacturing and Quality 225 8.6.4 Allowable Stresses 226 8.6.5 Design Criteria 229 8.6.6 Design Procedure and Guidelines 229 8.6.6.1 Select Gear Type, Materials, Accuracy Grades, Heat Treatments and Manufacturing Methods 229 8.6.6.2 Initial Selection of Design Variables 229 8.6.6.3 Design by Gear Strength 230 8.6.6.4 Geometrical Calculation 231 8.6.7 Design Cases 232 8.7 Structural Design of Gears 246 8.8 Lubrication and Efficiency 247 References 247 Problems 248 Chapter 9 Wormgear Drives 255 9.1 Introduction 256 9.1.1 Applications, Characteristics and Structures 256 9.1.2 Types of Wormgear Drives 256 9.1.2.1 Cylindrical Wormgear Drives 257 9.1.2.2 Toroidal Wormgear Drives 257 9.1.2.3 Spiroid Wormgear Drives 257 9.1.3 Geometry and Terminology 257 9.1.3.1 Module m and Pressure Angle a 258 9.1.3.2 The Worm Diameter d1 and Worm Diameter Factor q 258 9.1.3.3 The Number of Threads of Worm z1 and the Number of Wormgear Teeth z2 259 9.1.3.4 Worm Lead Angle γ and Wormgear Helix Angle β 259 9.1.3.5 Profile Shift Coefficient x 259 9.1.3.6 Centre Distance a 259 9.2 Working Condition Analysis 261 9.2.1 Kinematic Analysis 261 9.2.1.1 Speed Ratio i and Gear Ratio u 261 9.2.1.2 Sliding Velocity Analysis 261 9.2.2 Forces on Worm and Wormgear Teeth 262 9.2.3 Potential Failure Modes 263 9.3 Load Carrying Capacities 264 9.3.1 Tooth Surface Fatigue Strength Analysis 264 9.3.2 Tooth Bending Strength Analysis 265 9.3.3 Rigidity Analysis 265 9.3.4 Efficiency and Thermal Capacity 266 9.3.4.1 Efficiency of Wormgear Drives 266 9.3.4.2 Thermal Analysis 266 9.4 Design of Wormgear Drives 268 9.4.1 Introduction 268 9.4.2 Materials and Heat Treatments 268 9.4.3 Allowable Stresses 269 9.4.3.1 Allowable Contact Stresses 269 9.4.3.2 Allowable Bending Stresses 269 9.4.4 Design Criteria 271 9.4.5 Design Procedure and Guidelines 272 9.4.5.1 The Arrangement of Wormgear Drive and Selection of Accuracy Grade Levels 272 9.4.5.2 The Selection of the Number of Worm Threads z1 and the Number of Wormgear Teeth z2 272 9.4.5.3 Design by Wormgear Strength 272 9.4.6 Design Cases 272 9.5 Structural Design of Wormgear Drives 275 9.6 Lubrication of Wormgear Drives 275 References 276 Problems 276 Chapter 10 Shafts 281 10.1 Introduction 282 10.1.1 Applications, Characteristics and Structures 282 10.1.2 Types of Shafts 282 10.2 Working Condition Analysis 284 10.2.1 Force Analysis 284 10.2.2 Stress Analysis 284 10.2.3 Deflection and Rigidity 284 10.2.4 Rotating Shaft Dynamics 286 10.2.5 Potential Failure Modes 286 10.3 Load Carrying Capacities 286 10.3.1 Strength Analysis 286 10.3.1.1 Torsional Strength Analysis 287 10.3.1.2 Combination of Torsional and Bending Strength Analysis 287 10.3.1.3 Fatigue Strength Analysis 288 10.3.1.4 Static Strength Analysis 290 10.3.2 Rigidity Analysis 290 10.3.2.1 Bending Deflections and Slopes 290 10.3.2.2 Torsional Deflections 291 10.3.3 Critical Speed Analysis 292 10.4 Design of Shafts 293 10.4.1 Introduction 293 10.4.2 Materials and Heat Treatments 293 10.4.3 Design Criteria 294 10.4.4 Design Procedure and Guidelines 294 10.4.5 Structural Design of Shafts 295 10.4.5.1 Measures to Increase Shaft Strength and Rigidity 295 10.4.5.2 Locating and Fastening Elements on a Shaft 296 10.4.5.3 Machinability and Assemblability of Shafts 297 10.4.6 Design Cases 299 References 306 Problems 306 Chapter 11 Rolling Contact Bearings 313 11.1 Introduction 314 11.1.1 Applications, Characteristics and Structures 314 11.1.2 Characteristic Factors of Rolling Contact Bearings 315 11.1.2.1 Internal Clearance 315 11.1.2.2 Contact Angle α 316 11.1.2.3 Angular Deviation θ 316 11.1.3 Types of Rolling Contact Bearings and Their Selection 317 11.1.3.1 Classification of Rolling Contact Bearings 317 11.1.3.2 Types of Rolling Contact Bearings 317 11.1.3.3 Bearing Type Selection 318 11.1.4 Designation of Rolling Contact Bearings 319 11.2 Working Condition Analysis 320 11.2.1 Kinematic Analysis 320 11.2.2 Force Analysis 321 11.2.2.1 Thrust Bearings (50000, 290000) 321 11.2.2.2 Radial Bearings (60000, 10000, 20000, N, NA) 321 11.2.2.3 Angular Contact Bearings (70000, 30000) 321 11.2.3 Stress Analysis 325 11.2.4 Potential Failure Modes 326 11.3 Life Expectancy and Load Carrying Capacities 327 11.3.1 Life Prediction under Constant Loads 327 11.3.1.1 Relations Between Bearing Load and Bearing Life 327 11.3.1.2 Modification of Life Prediction 328 11.3.1.3 Rated Life at Different Reliability 329 11.3.2 Life Prediction under Variable Loads 330 11.3.3 Static Strength Analysis 331 11.4 Design of Bearing Support Systems 332 11.4.1 Introduction 332 11.4.2 Bearing Selection 332 11.4.3 Design Procedures and Guidelines 333 11.4.4 Practical Considerations in the Application of Bearings 333 11.4.4.1 Assembly and Disassembly 333 11.4.4.2 Axial Positioning 333 11.4.4.3 Axial Retaining 335 11.4.4.4 Axial Adjustment 336 11.4.4.5 Rolling Bearing Fits 336 11.4.4.6 Preloading 336 11.4.4.7 Lubrication 336 11.4.4.8 Sealing 337 11.4.5 Design Cases 338 References 343 Problems 344 Chapter 12 Sliding Bearings 351 12.1 Introduction 352 12.1.1 Applications, Characteristics and Structures 352 12.1.2 Types of Sliding Bearings 353 12.2 Working Condition Analysis 354 12.2.1 Friction 354 12.2.2 Wear 356 12.2.3 Lubrication 357 12.2.3.1 Newton's Law of Viscous Flow 357 12.2.3.2 Viscosity of Lubricants 358 12.2.4 Formation of Hydrodynamic Lubrication in a Journal Bearing 359 12.2.4.1 Formation of Hydrodynamic Lubrication in Plates 359 12.2.4.2 Formation of Hydrodynamic Lubrication in a Journal Bearing 361 12.2.5 Potential Failure Modes 362 12.3 Load Carrying Capacities 362 12.3.1 Boundary‐Lubricated Bearings 362 12.3.2 Hydrodynamically Lubricated Bearings 363 12.3.2.1 Reynolds Equation 363 12.3.2.2 Hydrodynamic Lubrication in a Journal Bearing 366 12.3.3 Heat Balance Analysis 369 12.4 Design of Sliding Bearings 371 12.4.1 Introduction 371 12.4.2 Materials for Sliding Bearings 371 12.4.2.1 Property Requirements for Sliding Bearing Materials 371 12.4.2.2 Commonly Used Bearing Materials 372 12.4.3 Lubricants, Their Properties and Supply 373 12.4.3.1 Lubricants 373 12.4.3.2 Lubricant Properties and Their Selection 374 12.4.3.3 Lubricant Supply 374 12.4.4 Design Criteria 375 12.4.5 Design Procedures and Guidelines 376 12.4.5.1 Design of Boundary‐Lubricated Bearings 376 12.4.5.2 Design of Hydrodynamically Lubricated Bearings 376 12.4.6 Design Cases 377 References 382 Problems 382 Chapter 13 Couplings and Clutches 387 13.1 Introduction to Couplings 388 13.1.1 Applications, Characteristics and Structures 388 13.1.2 Shaft Misalignments 388 13.1.3 Types of Couplings 389 13.2 Design and Selection of Couplings 397 13.2.1 Coupling Type Selection 397 13.2.1.1 The Characteristics of Operation Conditions 397 13.2.1.2 Reliability and Operating Environments 398 13.2.1.3 Manufacturing, Installation, Maintenance and Cost Considerations 398 13.2.2 Coupling Size Selection 398 13.3 Introduction to Clutches 399 13.3.1 Applications, Characteristics and Structures 399 13.3.2 Types of Clutches 399 References 404 Problems 404 Chapter 14 Springs 409 14.1 Introduction 410 14.1.1 Applications and Characteristics 410 14.1.2 Types of Spring and Structures 410 14.1.2.1 Helical Coil Springs 411 14.1.2.2 Belleville Springs 413 14.1.2.3 Spiral Springs 413 14.1.2.4 Leaf Springs 414 14.2 Working Condition Analysis 414 14.2.1 Geometry and Terminology 414 14.2.2 Spring Characteristic Curves 416 14.2.3 Storage and Dissipation of Energy 417 14.2.4 Potential Failure Modes 418 14.3 Load Carrying Capacities 418 14.3.1 Analysis of Helical Compression Springs 418 14.3.1.1 Load‐Deflection Relationship 418 14.3.1.2 Force Analysis 420 14.3.1.3 Strength Analysis 420 14.3.1.4 Rigidity Analysis 423 14.3.1.5 Buckling Analysis 424 14.3.1.6 Critical Frequency Analysis 425 14.3.2 Analysis of Helical Extension Springs 426 14.3.3 Analysis of Helical Torsion Springs 427 14.3.3.1 Load‐Deflection Relationship 427 14.3.3.2 Force Analysis 427 14.3.3.3 Strength Analysis 427 14.3.3.4 Rigidity Analysis 428 14.4 Design of Springs 428 14.4.1 Introduction 428 14.4.2 Materials and Allowable Stresses 429 14.4.3 Design Criteria 431 14.4.4 Design Procedures and Guidelines 431 14.4.5 Design Cases 432 References 437 Problems 438 Index 441 EULA 457