Introduction to the Design and Behavior of Bolted Joints : Non-Gasketed Joints

The fully updated Fifth Edition of John H. Bickford's classic work, updated by Michael Oliver, provides a practical, detailed guide for the design threaded bolted joints, the tightening of threaded joints, and the latest design procedures for long-term life. New sections on materials, threads, and their strength have been added, and coverage of FEA for design analysis is now included. Referencing the latest standards, this new edition combines fastener materials, explanation of how fasteners are made, and how fasteners fit together, supplementing the basic design coverage included in previous versions of this authoritative text. Introduction to the Design and Behavior of Bolted Joints: Non-Gasketed Joints will be of interest to engineers involved in the design and testing of bolted joints. Cover Half Title Title Page Copyright Page Dedication Contents Preface Acknowledgments Authors Chapter 1: Basic Concepts 1.1. Two Types of Bolted Joints 1.2. Bolt's Job 1.2.1. Tensile Joints 1.2.2. Shear Joints 1.3. The Challenge 1.3.1. Assembly Process 1.3.2. The Complexity of Tightening the Bolt 1.3.3. In-Service Behavior 1.3.3.1. Joints Loaded in Tension 1.3.3.2. Shear Joints 1.4. Failure Modes 1.5. Design 1.5.1. In General 1.5.2. Specific Goals of the Designer 1.5.3. Final Thought 1.6. Layout of the Book Exercises References Chapter 2: Materials 2.1. Properties That Affect the Clamping Force 2.1.1. Magnitude of the Clamping Force 2.1.2. Stability of the Clamping Force 2.1.2.1. Thermal Expansion or Contraction 2.1.2.2. Corrosion 2.1.2.3. Fatigue Rupture 2.1.2.4. Loss of Strength with Temperature 2.1.2.5. Loss of Clamping Force with Temperature 2.1.2.6. Elastic Stiffness of the Parts 2.1.2.7. Change in Stiffness with Temperature 2.1.2.8. Brittle Fracture 2.1.3. Miscellaneous Properties 2.2. Fastener Standards 2.3. Selecting an Appropriate Standard 2.4. Bolting Materials 2.5. Tensile Strength of Bolting Materials 2.5.1. General Purpose/Automotive Group 2.5.2. Structural Steel Group 2.5.3. Petrochemical/Power Group 2.5.4. Metric Group 2.5.5. Extreme-Temperature Materials 2.5.5.1. American Society for Testing and Materials (ASTM) F2281 Materials 2.5.5.2. Traditional High-Temperature Materials 2.5.6. Corrosion-Resistant Group 2.5.7. ASTM Bolting Standards 2.5.7.1. Room Temperature Strengths of ASTM F2281 and F2282 Materials 2.6. Metric Fasteners 2.7. Equivalent Materials 2.7.1. Steel Designation 2.8. Some Comments on the Strength of Bolting Materials 2.8.1. In General 2.8.2. Shear Strength 2.8.3. Bearing Yield Strength 2.8.4. Hardness Versus Strength 2.9. Nut Selection 2.10. Effects of Temperature on Material Properties 2.10.1. Thermal Expansion 2.10.2. Miscellaneous Temperature Problems 2.11. Other Material Factors to Consider 2.11.1. Fatigue Properties 2.11.2. Corrosion 2.11.3. Miscellaneous Considerations 2.12. Joint Materials 2.13. The Affect of Material Hardness on the Development of Preload 2.14. The Manufacturing of Threaded Fasteners 2.14.1. Creating the Threaded Fastener 2.14.2. Microstructure Exercises References Chapter 3: Stress and Strength Considerations 3.1. Types of Strength 3.1.1. Tensile Strength 3.1.2. Thread-Stripping Strength 3.1.3. Shear Strength 3.1.4. Brittle Fracture Strength 3.1.5. Strengths at High and Low Temperatures 3.1.6. Fatigue Strength 3.1.7. Stress Corrosion Cracking Strength 3.2. Bolt in Tension 3.2.1. Elastic Curves for Bolts in Tension 3.2.2. Elastic Curves Under Repeated Loading 3.2.3. Stress Distribution Under Tensile Load 3.2.4. Stress Concentrations 3.2.5. Magnitude of Tensile Stress 3.2.6. Load Distribution and Stress in the Nut 3.3. Strength of a Bolt 3.3.1. Proof Strength 3.3.2. Tensile Stress Area 3.3.3. Other Stress Area Equations 3.3.4. Stress Areas—Metric Threads 3.3.5. Strength of the Bolt Under Static Loads 3.3.6. Static Failure of the Bolt 3.4. Strength of the Joint 3.4.1. Contact Stress between Fastener and Joint 3.4.2. Stresses within and between the Joint Members 3.4.3. Static Failure of the Joint 3.5. Other Types of Load on a Bolt 3.5.1. Strength under Combined Loads Exercises References Chapter 4: Threads and Their Strength 4.1. Thread Forms 4.1.1. Thread Forms in General 4.1.2. Inch Series Thread Forms 4.1.3. Metric Thread Forms 4.2. Thread Series 4.2.1. Inch 4.2.2. Metric 4.3. Thread Nomenclature: Diameters, Allowance, Tolerance, and Class 4.3.1. Diameters 4.3.1.1. Tolerance and Allowance 4.3.1.2. Allowance 4.3.1.3. Tolerance 4.3.1.4. Thread Class 4.3.2. Metric Threads 4.3.2.1. Tolerance Position (Allowance) 4.3.2.2. Tolerance Grade (Tolerance) 4.3.2.3. Tolerance Class (the Class) 4.3.3. Inch Series and Metric Thread Classes, Compared 4.3.4. Formulas for Tolerance and Allowance 4.3.5. Coating Allowances 4.3.6. Tolerances for Abnormal Lengths of Engagement 4.4. Thread Inspection 4.4.1. Inspection Levels 4.4.2. Gaging 4.4.3. Thread Errors 4.4.4. Actual Inspecting 4.5. Thread Call-Outs or Identification on Drawings 4.5.1. Inch Series 4.5.2. Metric Thread 4.5.3. The Drawing 4.6. Coarse- Versus Fine- Versus Constant-Pitch Threads 4.6.1. Coarse-Pitch Threads 4.6.2. Fine-Pitch Threads 4.6.3. Constant-Pitch Threads 4.6.4. Miscellaneous Factors Affecting Choice 4.7. 3D Modeling of Threads 4.8. The Strength of Threads 4.8.1. Basic Considerations 4.8.2. Thread Strength Equations 4.8.3. Thread Strength Computations When LE = D 4.8.4. Basic Procedure—An Example 4.8.5. Thread Strength Calculations When LE ≠ D 4.8.6. Other Stress Area Formulas 4.9. What Happens to Thread Form Under Load? 4.10. Things that Modify the Static Strength of Threads 4.10.1. Common Factors 4.10.2. Which Is Usually Stronger—Nut or Bolt? 4.10.3. Tables of Tensile Stress and Shear Areas 4.11. Other Factors Affecting Strength 4.11.1. Pitch Diameter 4.11.2. Other Thread Parameters Exercises References Chapter 5: Stiffness and Strain Considerations 5.1. Bolt Deflection 5.1.1. Basic Concepts 5.1.2. Change in Length of the Bolt 5.1.2.1. Effective Length 5.1.2.2. Cross-Sectional Areas of the Bolt 5.1.3. Computing Change in Length of the Bolt 5.2. Bolt Stiffness Calculations 5.2.1. Basic Concepts 5.2.2. Example 5.2.3. Actual versus Computed Stretch and Stiffness 5.2.4. Stiffness of Bolt–Nut–Washer System 5.2.5. Alternative Expression for Bolt Stiffness 5.2.6. Energy Stored in the Bolt 5.3. The Joint 5.3.1. Basic Concepts 5.3.2. Computing Joint Stiffness 5.3.2.1. Stiffness of Concentric Joints 5.3.2.2. Stiffness of Eccentric Joints 5.3.3. Stiffness in Practice 5.3.3.1. A Quick Way to Estimate the Stiffness of Non-Gasketed Steel Joints 5.4. Gasketed Joints 5.5. An Alternate Way to Compute Joint Stiffness 5.6. Joint Stiffness Ratio or Load Factor 5.7. Stiffness—Some Design Goals 5.7.1. Energy Stored in the Joint Members 5.7.2. Relationship between Stiffness and Stored Energy 5.7.3. Stiffness Ratio 5.8. Experiments in Stiffness Exercises References Chapter 6: Introduction to Assembly 6.1. Initial versus Residual Preload 6.2. Speaking of Torque 6.3. Starting the Assembly Process 6.3.1. Assembling the Parts 6.3.2. Tightening the First Bolt 6.4. Bolt Preload versus Clamping Force on the Joint 6.4.1. Effects of Hole Interference 6.4.2. Resistance from Joint Members 6.5. Continuing the Snugging Pass 6.6. Short-Term Relaxation of Individual Bolts 6.6.1. Sources of Short-Term Relaxation 6.6.1.1. Poor Thread Engagement 6.6.1.2. Thread Engagement Too Short 6.6.1.3. Soft Parts 6.6.1.4. Bending 6.6.1.5. Non-perpendicular Nuts or Bolt Heads 6.6.1.6. Fillets or Undersized Holes 6.6.1.7. Oversized Holes 6.6.1.8. Conical Makeups 6.6.2. Factors Affecting Short-Term Relaxation 6.6.2.1. Bolt Length 6.6.2.2. Belleville Washers 6.6.2.3. Number of Joint Members 6.6.2.4. Simultaneous Tightening of Many Fasteners 6.6.2.5. Bent Joint Members 6.6.3. Amount of Relaxation To Expect 6.6.4. Torsional Relaxation 6.7. The Effect of Tightening Speed on Preload Generation 6.8. Elastic Interactions Between Bolts 6.9. The Assembly Process Reviewed 6.10. Optimizing Assembly Results Exercises References Chapter 7: Torque Control of Preload 7.1. Importance of Correct Preload 7.1.1. Problems Created by Incorrect Preload 7.1.2. How Much Preload? 7.1.3. Factors That Affect the Working Loads on Bolts 7.2. Torque versus Preload—The Long-Form Equation 7.3. Things That Affect the Torque–Preload Relationship 7.3.1. Variables That Affect Friction 7.3.2. Geometric Variables 7.3.3. Strain Energy Losses 7.3.4. Prevailing Torque 7.3.5. Weight Effect 7.3.6. Hole Interference 7.3.7. Interference Fit Threads 7.3.8. The Mechanic 7.3.9. Tool Accuracy 7.3.10. Miscellaneous Factors 7.3.11. Lubrication 7.4. Torque versus Preload—The Short-Form Equation 7.5. Nut Factors 7.5.1. Some General Comments 7.5.2. Nut Factor Examples and Case Histories 7.5.3. Coefficient of Friction versus Nut Factor 7.6. Torque Control in Practice 7.6.1. What Torque Should I Use? 7.6.2. Initial Preload Scatter 7.6.3. Low Friction for Best Control 7.6.4. The Lines Aren't Always Straight 7.6.5. Other Problems 7.7. Some Tools for Torque Control 7.7.1. Some Generalities 7.7.2. Reaction Forces Created by the Tool 7.7.2.1. Shear Loads Created by Torque Wrenches 7.7.2.2. Reaction Torques 7.7.3. In the Beginning—A Search for Accuracy 7.7.3.1. Manual Torque Wrenches 7.7.4. More Torque for Large Fasteners 7.7.4.1. Torque Multipliers and Geared Wrenches 7.7.4.2. Hydraulic Wrenches 7.7.5. Toward Higher Speed 7.7.5.1. Impact Wrenches 7.7.5.2. Pulse Tools 7.7.5.3. Nut Runners 7.7.6. Add Torque Calibration or Torque Monitoring 7.7.7. Add Torque Feedback for Still Better Control 7.7.8. For More Information 7.8. Chatter 7.8.1. Background 7.8.2. Torque and Preload 7.8.3. Under-Head and Thread CoF 7.8.4. How to Fix the Chatter 7.8.5. Chatter Conclusion 7.9. Fasteners that Limit Applied Torque 7.9.1. The Twist-Off Bolt 7.9.2. The Frangible Nut 7.10. Is Torque Control Any Good? 7.11. Testing Tools 7.12. The Influence of Torque Control on Joint Design 7.13. Using Torque to Disassemble a Joint Exercises References Chapter 8: Torque and Turn Control 8.1. Basic Concepts of Turn Control 8.2. Turn versus Preload 8.2.1. Common Turn–Preload Relationship 8.2.2. Other Turn-Preload Curves 8.2.2.1. Sheet Metal Joint 8.2.2.2. Gasketed Joint 8.3. Friction Effects 8.4. Torque and Turn in Theory 8.4.1. Torque, Turn, and Energy 8.4.2. Torque–Turn–Preload Cube 8.4.3. The Broader View 8.5. Turn-of-Nut Control 8.5.1. The Theory 8.5.2. The Practice 8.5.2.1. Structural Steel 8.5.2.2. Turn-of-Nut Procedure in Production Operations 8.5.2.3. Turn-of-Nut Procedure in Aerospace Assembly 8.6. Production Assembly Problems 8.7. Popular Control Strategies 8.7.1. Torque–Angle Window Control 8.7.2. Torque–Time Window Control 8.7.3. Hesitation and Pulse Tightening 8.7.4. Yield Control 8.7.5. Turn-of-Nut Control 8.7.6. Prevailing Torque Control 8.7.7. Plus—Permanent Records 8.7.8. Meanwhile, Out in the Field 8.8. Monitoring the Results 8.9. Problems Reduced by Torque–Angle Control 8.10. How to Get the Most Out of Torque–Angle Control Exercises References Chapter 9: Other Ways to Control Preload 9.1. Stretch Control: The Concept 9.2. Problems of Stretch Control 9.2.1. Dimensional Variations 9.2.2. Change in Temperature 9.2.3. Plastic Deformation of the Bolt 9.2.4. Bending and Non-perpendicular Surfaces 9.2.5. Grip Length 9.3. Stretch Measurement Techniques 9.3.1. Micrometer Measurements 9.3.1.1. Irregular Measurement Surfaces 9.3.1.2. Operator Feel 9.3.1.3. Measurement Accuracy Required 9.3.1.4. Depth Micrometers 9.3.2. Other Techniques 9.3.2.1. Dial Gages 9.3.2.2. Commercially Available Gage Bolt 9.3.2.3. Other Gage Measurements 9.4. How Much Stretch? 9.5. Problems Reduced by Stretch Control 9.6. How to Get the Most Out of Stretch Control 9.7. Direct Preload Control—An Introduction 9.7.1. Strain-Gaged Bolts 9.7.2. Strain-Gaged Force Washers 9.7.3. Direct Tension Indicators 9.7.4. Squirter Self-Indicating DTIs 9.7.5. Twist-Off Tension-Control Bolts 9.7.6. Alternative-Design Fasteners 9.8. Bolt Tensioners 9.8.1. The Hardware 9.9. Bolt Heaters 9.10. Problems Reduced by Direct Preload Control 9.10.1. Direct Tension Indicators 9.10.2. Twist-Off Bolts 9.10.3. Hydraulic Tensioners 9.10.4. Bolt Heaters 9.11. Getting the Most Out of Direct Preload Control 9.11.1. Twist-Off Bolts and DTI Washers 9.11.2. Bolt Tensioners 9.11.3. Bolt Heaters 9.12. Ultrasonic Measurement of Stretch or Tension 9.12.1. In General 9.12.2. Principle of Operation 9.12.3. How It's Used 9.12.4. Calibration of the Instrument 9.12.5. Presently Available Instruments 9.13. Ultrasonic Measurements Using Plasma—Coated, Thin Film Transducers 9.14. Fiber Optic Strain Measurement 9.14.1. Principle of Operation 9.14.2. How It's Used 9.14.3. Installation 9.14.4. Calibration 9.14.5. Performance Exercises References Chapter 10: Theoretical Behavior of the Joint under Tensile Loads 10.1. Basic Joint Diagram 10.1.1. Elastic Curves for Bolt and Joint Members 10.1.2. Determining Maximum and Minimum Residual Assembly Preload 10.1.2.1. The Equations 10.1.2.2. An Example 10.1.3. Joint Diagram for Simple Tensile Loads 10.1.4. The Parable of the Red Rolls Royce 10.1.5. Back to the Joint Diagram—Simple Tensile Load 10.1.6. Finite Element Analysis Support 10.2. Details and Variations 10.2.1. Changing the Bolt or Joint Stiffness 10.2.2. Critical External Load 10.2.3. Very Large External Loads 10.2.4. Another Form of Joint Diagram 10.3. Mathematics of the Joint 10.3.1. Basic Equations 10.3.2. Continuing the Example 10.4. Loading Planes 10.4.1. Tension Applied to Interface of Joint Members 10.4.2. Mathematics of a Tension Load at the Interface 10.4.3. Significance of the Loading Planes 10.4.4. Loading Planes within the Joint Members 10.4.5. Modifying Our Example to Include the Effects of Internal Loading Planes 10.5. Dynamic Loads on Tension Joints 10.6. The Joint Under a Compressive Load 10.7. A Warning Exercises References Chapter 11: Behavior of the Joint Loaded in Tension: A Closer Look 11.1. Effect of Prying Action on Bolt Loads 11.1.1. Definition of Prying 11.1.2. Discussion of Prying 11.1.3. Prying Is Non-Linear 11.1.4. Prying via Fea 11.2. Mathematics of Prying 11.2.1. In General 11.2.2. VDI's Analytical Procedure 11.2.3. Critical Loads and the Preloads Required to Prevent Joint Separation 11.2.4. Bending Stress in the Bolt Before Liftoff 11.2.5. Effects of Very Large External Loads 11.3. Other Non-Linear Factors 11.3.1. Nut-Bolt System 11.4. Thermal Effects 11.4.1. Change in Elasticity 11.4.2. Loss of Strength 11.4.3. Differential Thermal Expansion 11.4.4. Stress Relaxation 11.4.5. Creep Rupture 11.4.6. Compensating for Thermal Effects 11.5. Joint Equations That Include the Effects of Eccentricity and Differential Expansion 11.5.1. The Equations 11.5.2. An Example Exercises References Chapter 12: In-Service Behavior of a Shear Joint 12.1. Bolted Joints Loaded in Axial Shear 12.1.1. In General 12.1.2. Friction-Type Joints 12.1.2.1. Bolt Load in Friction-Type Joints 12.1.2.2. Stresses in Friction-Type Joints 12.1.3. Bearing-Type Joints 12.1.3.1. Stresses in Bearing-Type Joints 12.2. Factors That Affect Clamping Force in Shear Joints 12.3. Response of Shear Joints to External Loads 12.4. Joints Loaded in Both Shear and Tension 12.5. Present Definitions—Types of Shear Joint Exercises References Chapter 13: Introduction to Joint Failure 13.1. Mechanical Failure of Bolts 13.2. Missing Bolts 13.3. Loose Bolts 13.4. Bolts Too Tight 13.5. Which Failure Modes Must We Worry About? 13.6. Concept of Essential Conditions 13.7. Importance of Correct Preload 13.7.1. Corrosion 13.7.2. Stress Corrosion Cracking 13.7.3. Fatigue Failure 13.7.4. Mechanical Failure 13.7.5. Self-Loosening of Fastener 13.7.6. Leakage 13.8. Load Intensifiers 13.9. Failure of Joint Members 13.10. Galling 13.10.1. Discussion 13.10.2. Removing Galled Studs Exercises References Chapter 14: Self-Loosening 14.1. The Problem 14.2. How Does a Nut Self-Loosen? 14.3. Loosening Sequence 14.4. Junker's Theory of Self-Loosening 14.4.1. The Equations 14.4.2. The Long-Form Equation in Practice 14.4.3. The Equation When Applied Torque Is Absent 14.4.4. Why Slip Occurs 14.4.5. Other Reasons for Slip 14.4.6. Other Theories of Self-Loosening 14.5. Testing For Vibration Resistance 14.5.1. NAS Test 14.5.2. Junker Test 14.6. To Resist Vibration 14.6.1. Maintaining Preload and Friction 14.6.1.1. Conventional Wisdom 14.6.2. Preventing Relative Slip between Surfaces 14.6.3. Countering Back-Off Torque 14.6.3.1. Prevailing Torque Fasteners 14.6.3.2. DISC-LOCK® Washers and Nuts 14.6.3.3. In General 14.6.4. Double Nuts 14.6.5. Mechanically Locked Fasteners 14.6.5.1. Lock Wires and Pins 14.6.5.2. Welding 14.6.5.3. Stage 8 Fastening System 14.6.5.4. Huck Lockbolt 14.6.5.5. Honeybee Robotics 14.6.5.6. A-Lock Bolt and Nut 14.6.5.7. Omni-Lok Fasteners 14.6.6. Chemically Bonded Fasteners 14.6.6.1. Rust 14.6.6.2. Anaerobic Adhesives 14.6.7. Vibration-Resistant Washers 14.6.7.1. Washers That Maintain Tension in the Fastener 14.6.7.2. Toothed Washer 14.6.7.3. Helical Spring Washer 14.6.7.4. DISC-LOCK® Washer 14.6.8. Comparison of Options Exercises References Chapter 15: Fatigue Failure 15.1. Fatigue Process 15.1.1. Sequence of a Fatigue Failure 15.1.1.1. Crack Initiation 15.1.1.2. Crack Growth 15.1.1.3. Crack Propagation 15.1.1.4. Final Rupture 15.1.2. Types of Fatigue Failure 15.1.3. Appearance of the Break 15.2. What Determines Fatigue Life? 15.2.1. S–N Diagrams 15.2.2. Material versus “The Part” 15.2.3. Summary 15.3. Other Types of Diagram 15.3.1. Constant Life Diagram 15.3.2. Center Portion of Constant Life Diagram 15.3.3. Approximate Constant Life Diagram 15.3.4. Endurance Limit Diagram 15.3.5. Fatigue Life Data for Fasteners 15.4. Influence of Preload and Joint Stiffness 15.4.1. Fatigue in a Linear Joint 15.4.2. Non-Linear Joints 15.4.3. What Is the Optimum Preload? 15.4.4. Fatigue and the VDI Joint Design Equations 15.5. Minimizing Fatigue Problems 15.5.1. Minimizing Stress Levels 15.5.1.1. Increased Thread Root Radius 15.5.1.2. Rolled Threads 15.5.1.3. Fillets 15.5.1.4. Perpendicularity 15.5.1.5. Overlapping Stress Concentrations 15.5.1.6. Thread Run-Out 15.5.1.7. Thread Stress Distribution 15.5.1.8. Bending 15.5.1.9. Corrosion 15.5.1.10. Flanged Head and Nut 15.5.1.11. Surface Condition 15.5.2. Reducing Load Excursions 15.5.2.1. Prevent Prying 15.5.2.2. Proper Selection of Preload 15.5.2.3. Control of Bolt-to-Joint Stiffness Ratios 15.5.2.4. Achieving the Correct Preload 15.6. Predicting Fatigue Life or Endurance Limit 15.7. Fatigue of Shear Joint Members 15.8. Case Histories 15.8.1. Transmission Towers 15.8.2. Gas Compressor Distance Piece Exercises References Chapter 16: Corrosion 16.1. Corrosion Mechanism 16.1.1. Galvanic Series 16.1.2. Corrosion Cell 16.1.3. Types of Cells 16.1.3.1. Two-Metal Corrosion 16.1.3.2. Broken Oxide Film 16.1.3.3. Stress Corrosion Cracking 16.1.3.4. Crevice Corrosion 16.1.3.5. Fretting Corrosion 16.2. Hydrogen Embrittlement 16.2.1. Brittle Cracking and Fracture 16.2.2. General Description of Hydrogen Embrittlement 16.2.3. Hydrogen Damage Mechanism 16.2.4. Fracture Morphology 16.2.5. Conditions at the Tip of a Crack 16.2.6. Conditions for Hydrogen Embrittlement Failure 16.2.6.1. Root Cause and Triggers for Hydrogen Embrittlement Failure 16.2.7. Material Susceptibility 16.2.7.1. General 16.2.7.2. Defects and Other Conditions Causing Abnormal Material Susceptibility 16.2.7.3. Methodology for Measuring HE Threshold Stress 16.2.8. Tensile Stress 16.2.9. Atomic Hydrogen 16.2.9.1. Sources of Hydrogen 16.2.9.2. Internal Hydrogen 16.2.9.3. Environmental Hydrogen 16.2.10. Case-Hardened Fasteners 16.2.11. Hot Dip Galvanizing and Thermal Up-Quenching 16.2.12. Stress Relief Prior to Electroplating 16.2.13. Fasteners Thread Rolled after Heat Treatment 16.2.14. Hydrogen Embrittlement Test Methods 16.2.15. Baking 16.3. Hydrogen Embrittlement and Stress Corrosion Cracking—A Fracture Mechanics Approach 16.3.1. The Concept of KISCC 16.3.2. Factors Affecting KISCC 16.3.2.1. Bolt Material 16.3.2.2. The Environment 16.3.2.3. Bolt Strength or Hardness 16.3.2.4. Type of Electrolyte 16.3.2.5. Temperature 16.3.2.6. Bolt Diameter and Thread Pitch 16.3.3. Combating SCC 16.3.3.1. Susceptibility of the Material 16.3.3.2. Eliminating the Electrolyte 16.3.3.3. Keeping Stress Levels below a Threshold Limit 16.3.4. Surface Coating or Treatment 16.3.5. Detecting Early SCC Cracks 16.4. Minimizing Corrosion Problems 16.4.1. In General 16.4.2. Detailed Techniques 16.5. Fastener Coatings 16.5.1. In General 16.5.2. Organic Coatings 16.5.2.1. Paints 16.5.2.2. Phos-Oil Coatings 16.5.2.3. Solid-Film Organic Coatings 16.5.3. Inorganic or Metallic Coatings 16.5.3.1. Electroplated Coatings 16.5.3.2. Hot-Dip Coatings 16.5.3.3. Mechanical Plating 16.5.3.4. Miscellaneous Coating Processes 16.5.4. Composite Coatings 16.5.5. Rating Corrosion Resistance 16.5.6. Substitutes for Cadmium Plate Exercises References Chapter 17: Selecting Preload for an Existing Joint 17.1. How Much Clamping Force Do We Need? 17.1.1. Factors to Consider 17.1.1.1. Joint Slip 17.1.1.2. Self-Loosening 17.1.1.3. Pressure Loads 17.1.1.4. Joint Separation 17.1.1.5. Fatigue 17.1.2. Placing an Upper Limit on the Clamping Force 17.1.2.1. Yield Strength of the Bolt 17.1.2.2. Thread-Stripping Strength 17.1.2.3. Design-Allowable Bolt Stress and Assembly Stress Limits 17.1.2.4. Torsional Stress Factor 17.1.2.5. Shear Stress Allowance 17.1.2.6. Stress Cracking 17.1.2.7. Combined Loads 17.1.2.8. Damage to Joint Members 17.1.2.9. Distortion of Joint Members 17.1.2.10. Gasket Crush 17.1.3. Summarizing Clamping Force Limits 17.2. Simple Ways to Select Assembly Preloads 17.2.1. Best Guide: Past Experience 17.2.2. Second Best: Ask the Designer 17.2.3. Unimportant Joint: No Prior Experience 17.2.4. When More Care Is Indicated 17.2.5. If Improvements Are Required 17.2.6. Selecting Preload for Critical Joints 17.3. Estimating the In-Service Clamping Force 17.3.1. Basic Assumptions 17.3.2. Combining the Scatter Effects 17.4. Relating Desired to Anticipated Bolt Tensions 17.5. Which Variables to Include in the Analysis 17.5.1. In General 17.5.2. Possible Factors to Include 17.5.3. Which Should We Include? 17.6. ASTM F16.96. Subcommittee on Bolting Technology 17.7. A More Rigorous Procedure (Final Equations, 3D Solid Modeling, FEA, and Testing) 17.7.1. The Equations 17.7.1.1. Minimum Clamping Force—Some Examples 17.7.1.2. Maximum Bolt Tension 17.8. 3D Solid Modeling 17.9. Finite Element Analysis 17.9.1. The Math 17.9.2. Analysis or Table 17.9.3. Prepare the Simulation 17.10. Physical Testing 17.10.1. Why Test 17.10.2. Fastener Test Equipment 17.10.3. Fastener Tests 17.11. NASA's Space Shuttle Preload Selection Procedure 17.11.1. Calculating Maximum and Minimum Preloads 17.11.2. Confirming the Preload Calculations 17.11.3. Discussion Exercises References Chapter 18: Design of Joints Loaded in Tension 18.1. A Major Goal: Reliable Joints 18.1.1. Checklist for Reliable Bolted Joints 18.2. Typical Design Steps 18.2.1. Initial Definitions and Specifications 18.2.2. Preliminary Design 18.2.3. Load Estimates 18.2.4. Review Preliminary Layouts: Define the Bolts 18.2.5. Clamping Force Required 18.2.5.1. Minimum Clamp 18.2.5.2. Maximum Clamp 18.3. Joint Design in the Real World 18.4. VDI Joint Design Procedure 18.4.1. Terms and Units 18.4.2. Design Goals 18.4.3. General Procedure 18.4.4. Estimating Assembly Preloads: Preliminary Estimate of Minimum and Maximum Assembly Preloads 18.4.5. Adding the Effects of the External Load 18.4.6. Is the Required Force Good Enough? 18.4.7. Further Considerations 18.4.7.1. Static Strength of the Bolt 18.4.7.2. Fatigue 18.4.7.3. Bearing Stress 18.4.7.4. Shear Stress 18.4.7.5. Bending Stress 18.4.7.6. Eccentric Loading 18.4.8. Revised Bolt Specifications 18.5. An Example 18.5.1. Inputs 18.5.2. Calculations 18.5.2.1. Maximum and Minimum Assembly Preloads 18.5.2.2. Static Strength of the Bolts 18.5.2.3. Fatigue Strength 18.5.2.4. Contact Stress 18.6. Other Factors to Consider When Designing a Joint 18.6.1. Thread Strength 18.6.2. Flexible Bolts 18.6.3. Accessibility 18.6.4. Shear versus Tensile Loads 18.6.5. Load Magnifiers 18.6.6. Minimizing Embedment 18.6.7. Differential Expansion 18.6.8. Other Stresses in Joint Members 18.6.9. Locking Devices 18.6.10. Hole Interference 18.6.11. Safety Factors 18.6.12. Selecting a Torque to Be Used at Assembly Exercises References Bibliography Chapter 19: Design of Joints Loaded in Shear 19.1. An Overview 19.2. The VDI Procedure Applied to Shear Joints 19.3. How Shear Joints Resist Shear Loads 19.3.1. In General 19.3.2. Concept of Slip-Critical Joints 19.4. Strength of Friction-Type Joints 19.4.1. In General 19.4.2. Allowable Stress Procedure 19.4.3. Other Factors to Consider 19.4.4. Slip Coefficients in Structural Steel 19.4.5. An Example 19.4.5.1. Minimum Preload Required to Prevent Slip 19.4.5.2. Alternate Using the Allowable Stress Procedure 19.5. Strength of Bearing-Type Joints 19.5.1. Shear Strength of Bolts 19.5.1.1. Distribution of Load among the Bolts 19.5.1.2. Shear Strength Calculations 19.5.2. Tensile Strength of Joint Plates 19.5.3. Bearing Stress 19.5.4. Tearout Strength 19.5.5. Summary 19.5.6. Clamping Force Required by a Bearing-Type Joint 19.6. Eccentrically Loaded Shear Joints 19.6.1. Rotation about an Instant Center 19.6.2. Rotation About the Centroid of the Bolt Group 19.6.2.1. Find the Centroid of the Bolt Group 19.6.2.2. Estimating the Shear Stress on the Most Remote Bolt 19.7. Allowable Stress versus Load and Resistance Factor Design Exercises References Appendix A: Units and Symbol Log Appendix B: Glossary of Fastener and Bolted Joint Terms Appendix C: Sources of Bolting Information and Standards Appendix D: English and Metric Conversion Factors Appendix E: Tensile Stress Areas for English and Metric Threads with Estimated “Typical” Preloads and Torques for As-Received Steel Fasteners Appendix F: Basic Head, Thread, and Nut Lengths Index "The fully updated Fifth Edition of this classic work provides a practical, detailed guide for the design threaded bolted joints, the tightening of threaded joints, and the latest design procedures for long-term life. New sections on Materials, and Threads and Their Strength, have been added, and coverage of FEA for design analysis is now included. The 5th Edition of John H. Bickford's classic Introduction to the Design and Behavior of Bolted Joints: Non-Gasketed Joints, updated by Michael Oliver, provides a thorough guide for the design of threaded bolted joints, the tightening of threaded joints, and latest design procedures for long-term life. Sections on Materials, and Threads and their Strength, have been added, and coverage of FEA for design analysis is now included. Referencing the latest standards, this new edition combines fastener materials, explanation of how fasteners are made, and how fasteners fit together, supplementing the basic design coverage included in previous versions of this authoritative text. The book will be of interest to engineers involved in the design and testing of bolted joints"-- Provided by publisher