Page 8 - Analysis and Design of Machine Elements

Contents
vi
1.6 Standards and Codes 22
References 23
Problems 23
2 Strength of Machine Elements 25
2.1 Fluctuating Loads and Stresses 26
2.1.1 Service Factors and Design Loads 26
2.1.2 Types of Loads 26
2.1.3 Types of Stresses 28
2.1.3.1 Static Stress 28
2.1.3.2 Completely Reversed Stress 29
2.1.3.3 Repeated Stress 29
2.1.3.4 Fluctuating Stress 29
2.2 Static Strength 29
2.2.1 Static Strength for Uniaxial Stresses 30
2.2.2 Static Strength for Combined Stresses 30
2.2.2.1 Maximum Shear Stress Theory 30
2.2.2.2 Maximum Distortion Energy Theory 31
2.3 Fatigue Strength 32
2.3.1 The Nature of Fatigue 32
2.3.2 Stress-Life Diagrams 33
2.3.3 Endurance Limit Diagrams 34
2.3.3.1 The Endurance Limit Diagram of a Material 34
2.3.3.2 The Endurance Limit Diagram of an Element 35
2.3.4 Fatigue Strength for Uniaxial Stresses with Constant Amplitude 39
2.3.5 Fatigue Strength for Uniaxial Stresses with Variable Amplitude 41
2.3.5.1 Linear Cumulative Damage Rule (Miner’s Rule) 41
2.3.5.2 Prediction of Cumulative Fatigue Damage 42
2.3.6 Fatigue Strength for Combined Stresses with Constant Amplitude 43
2.3.7 Measures to Improve Fatigue Strength 44
2.3.8 Examples of Strength Analyses 44
2.4 Contact Strength 50
2.4.1 Hertzian Contact Stresses 50
2.4.2 Surface Fatigue Failure 51
References 52
Problems 53

Part II Design Applications 57

3 Detachable Joints and Fastening Methods 59
3.1 Introduction 60
3.1.1 Applications, Characteristics and Structures 60
3.1.2 Selection of Fastening Methods 60
3.2 Screw Threads 61
3.2.1 Types of Screw Threads 61
3.2.2 Standards and Terminology 62