Contents. 3 Load and Stress Analysis Introduction to Mechanical Engineering Design 3. Materiais 27

Transcription

1 Part 1 x Preface xv Basics 2 1 Introduction to Mechanical Engineering Design 3 Design 4 Mechanical Engineering Design 5 Phases and Interactions Process 5 of the Design Design Tools and Resources 8 The Design Engineer's Responsibilities 10 Standards and Codes 12 Economics 12 Professional Safety and Product Liability 15 Stress and Strength 15 Uncertainty 16 Design Factor and Factor of Safety 17 Reliability 18 Dimensions and Tolerances 19 Units 21 Calculations and Significant Figures 22 Power Transmission Specifications 22 Problems 24 Materiais 27 Case Study Material Strength and Stiffness 28 The Statistical Significance of Material Properties 32 Strength and Cold Work 33 Hardness 36 Impact Properties 37 Temperature Effects 39 Numbering Systems Sand Casting 41 Shell Molding 42 Investment Casting 42 Powder-Metallurgy Process 42 Hot- Working Processes 43 Cold-Working Processes 44 The Heat Treatment of Steel 44 Alloy Steels 47 Corrosion-Resistant Steels 48 Casting Materiais 49 Nonferrous Metais 51 Plastics 54 Composite Materiais 55 Materiais Selection 56 Problems 63 3 Load and Stress Analysis 67 Equilibrium Diagrams 68 and Free-Body Shear Force and Bending Moments in Beams 71 Singularity Functions 73 Stress 75 Cartesian Stress Components 75 Mohr's CircIe for Plane Stress 76 General Three-Dimensional Stress 82 Elastic Strain 83 Uniformly Distributed Stresses 84 Normal Stresses for Beams in Bending 85 Shear Stresses for Beams in Bending 90 Torsion 95 Stress Concentration 105 Stresses in Pressurized Cylinders 107 Stresses in Rotating Rings 110 Press and Shrink Fits 110

2 xi Part 2 Temperature Effects 111 Curved Beams in Bending 112 Contact Stresses 117 Summary 121 Problems Deflection and StiHness Spring Rates 142 Tension, Compression, and Torsion 143 DeftectionDue to Bending 1~4 Beam Deflection Methods 146 Beam Deflections by Superposition 147 Beam Deflections Functions 150 Strain Energy 156 by Singularity Castigliano's Theorem 158 Deflection of Curved Members 163 Statically Indeterminate Problems 168 Compression Members-General 173 Long Columns with Central Loading 173 lntermediate-length Columns with Central Loading 176 Columns with Eccentric Loading 176 Struts or Short Compression Members 180 Elastic Stability 182 Shock and Impact 183 Suddenly Applied Loading 184 Problems 186 Failure Prevention Failures Resulting from Static Loading 205 Static Strength 208 Stress Concentration 209 Failure Theories 211 Maximum-Shear-Stress for Ductile Materiais 211 Distortion-Energy Materiais 213 Theory Theory for Ductile Coulomb-Mohr Materiais 219 Theory for Ductile Failure of Ductile Materiais Summary 222 Maximum-Normal-Stress Materiais 226 Modifications Materiais 227 Failure of Brittle Materiais Summary 229 Theory for Brittle of the Mohr Theory for Brittle Selection of Failure Criteria 230 Introduction to Fracture Mechanics 231 Stochastic Analysis 240 Important Design Equations 246 Problems Fatigue Failure Resulting from Variable Loading 257 lntroduction to Fatigue in Metais 258 Approach to Fatigue Failure in Analysis and Design 264 Fatigue-Life Methods 265 The Stress-Life Method 265 The Strain-Life Method 268 The Linear-Elastic Method 270 The Endurance Limit 274 Fatigue Strength 275 Fracture Mechanics Endurance Limit Modifying Factors 278 Stress Concentration Sensitivity 287 and Notch Characterizing F1uctuating Stresses 292 Fatigue Failure Cri teria for Fluctuating Stress 295 Torsional Fatigue Strength Fluctuating Stresses 309 under Combinations of Loading Modes 309 Varying, Fluctuating Stresses; Cumulative Fatigue Damage 313 Surface Fatigue Strength 319 Stochastic Analysis 322 Roadmaps and Important Design Equations for the Stress-Life Method 336 Problems 340

3 xii Mechanical Engineering Design Part Design of Mechanical Elements Shafts and Shaft Components 347 Intraductian 348 Shaft Materiais 348 Shaft layaut 349 Shaft Design for Stress 354 Deflectian Cansideratians 367 Critical Speeds for Shafts 371 Miscellaneaus Shaft Campanents 376 Limits and Fits 383 Problems Screws, Fasteners, and the Design of Nonpermanent Joints 395 Thread Standards and Definitians 396 The Mechanics af Pawer Screws 400 Threaded Fasteners 408 Jaints-Fastener Stiffness 410 Jaints-Member Stiffness 413 Balt Strength 417 Tensian Jaints-The External Laad 421 Relating Balt Tarque ta Balt Tensian 422 Statically Prelaad 425 Laaded Tensian Jaint with Gasketed Jaints 429 Fatigue Laading af Tensian Jaints 429 Balted and Riveted Jaints Laaded in Shear 435 Problems Welding, Bonding, and the Design of Permanent Joints 457 Welding Symbals 458 Butt and Fillet Welds 460 Stresses in Welded Jaints in Tarsian 464 Stresses in Welded Jaints in Bending The Strength afwelded Jaints 471 Static Laading 474 Fatigue Laading 478 Resistance Welding 480 Adhesive Banding 480 Problems 489 Mechanical Springs 499 Stresses in Helical Springs 500 The Curvature Effect 501 Deflectian af Helical Springs 502 Campressian Springs 502 Stability 504 Spring Materiais 505 Helical Campressian for Static Service 510 Spring Design Critical Frequency af Helical Springs 516 Fatigue Laading Springs 518 Helical Campressian Laading 521 Extensian Springs 524 af Helical Campressian Spring Design for Fatigue Helical Cail Tarsian Springs 532 Belleville Springs 539 Miscellaneaus Springs 540 Summary 542 Problems Rolling-Contact Bearings 549 Bearing Types 550 Bearing Life 553 Bearing Laad Life at Rated Reliability 554 Bearing Survival: Reliability Life 555 versus Relating Laad, Life, and Reliability 557 Cambined Radial and Thrust Laading 559 Variable Laading 564 Selectian af Ball and Cylindrical Raller Bearings 568 Selectian af Tapered Raller Bearings 571 Design Assessment for Selected Ralling-Cantact Bearings 582

4 xiii Lubrication 586 Mounting and Enclosure 587 Problems 591 Lubrication and Journal Bearings 597 Types of Lubrication 598 Viscosity 599 Petroff's Equation 601 Stab1e Lubrication 603 Thick-Film Lubrication 604 Hydrodynamic Theory 605 Design Considerations 609 The Relations of the Variables 611 Steady-State Conditions in Self-Contained Bearings 625 Clearance 628 Pressure-Fed Bearings 630 Loads and MateriaIs 636 Bearing Types 638 Thrust Bearings 639 Boundary-Lubricated Bearings 640 Problems Force Analysis-Worm Gearing 694 Problems Spur and Helical Gears The Lewis Bending Equation 714 Surface Durability 723 AGMA Stress Equations 725 AGMA Strength Equations 727 Geometry Factors I and J (Z, and Y) 731 The Elastic Coefficient C p (ZE) 736 Dynamic Factor s, 736 Overload Factor Ko 738 Surface Condition Factor C J (ZR) 738 Size Factor K, 739 Load-Distribution Factor K", (KI-!) 739 Hardness-Ratio Factor C H 741 Stress Cycle Life Factors Y N and ZN 742 Reliability Factor K R (Y0 743 Temperature Factor KT (Yo) 744 Rim-Thickness Factor K B 744 Safety Factors SF and SH 745 Analysis 745 Design of a Gear Mesh 755 Problems Gears-General Types of Gear 654 Nomenclature 655 Conjugate Action 657 Involute Properties 658 FundamentaIs 658 Contact Ratio 664 Interference 665 The Forming of Gear Teeth 667 Straight Bevel Gears 670 Parallel Helical Gears 671 Worm Gears 675 Tooth Systems 676 Gear Trains 678 Force Analysis-Spur Gearing 685 Force Analysis-Bevel Gearing 689 Force Analysis-Helical Gearing Bevel and Worm Gears 765 Bevel Gearing-General 766 Bevel-Gear Stresses and Strengths 768 AGMA Equation Factors 771 Straight-Bevel Gear Analysis 783 Design of a Straight-Bevel Gear Mesh 786 Worm Gearing-AGMA Equation 789 Worrn-Gear Analysis 793 Designing a Worm-Gear Mesh 797 Buckingham Wear Load 800 Problems Clutches,Brakes, Couplings, and Flywheels 805 Static Analysis of Clutches and Brakes 807 Internal Expanding Rim Clutches and Brakes 812

5 xiv Mechanical Engineering Design External Contracting Rim Clutches and Brak:es 820 Band-Type Clutches and Brakes 824 Frictional-Contact Axial Clutches 825 Disk Brakes 829 Cone Clutches and Brak:es 833 Energy Considerations 836 Temperature Rise 837 Friction Materiais 841 Miscellaneous Clutches and Couplings 844 Flywheels 846 Problems 851 Flexible Mechanical Elements 859 Belts 860 Flat- and Round-Belt Drives 863 V Belts 878 Timing Belts 886 Roller Chain 887 Wire Rope 896 Flexible Shafts 904 Problems Power Transmission Case Study 913 Design Sequence for Power Transmission 915 Power and Torque Requirements 916 Gear Specification 916 Shaft Layout 923 Force Analysis 925 Shaft Material Selection 925 Shaft Design for Stress 926 Shaft Design for Deflection 926 Bearing Selection 927 Key and Retaining Ring Selection 928 Final Analysis 931 Problems 931 Part A B Analysis Tools 932 Finite-Element Analysis 933 The Finite-Element Method 935 Element Geometries 937 The Finite-Elernent Solution Process 939 Mesh Generation 942 Load Application 944 Boundary Conditions 945 Modeling Techniques 946 Thermal Stresses 949 Critical Buckling Load 949 Vibration Analysis 951 Summary 952 Problems 954 Statistical Considerations 957 Random Variables 958 Arithmetic Mean, Variance, and Standard Deviation 960 Probability Distributions 965 Propagation of Error 972 Linear Regression 974 Problems 977 Appendices Useful Tables 983 Answers to Selected Problems 1035 Index 1040