Page 14 - Analysis and Design of Machine Elements

Contents
xii
9.3.4.2 Thermal Analysis 244
9.4 Design of Wormgear Drives 246
9.4.1 Introduction 246
9.4.2 Materials and Heat Treatments 246
9.4.3 Allowable Stresses 247
9.4.3.1 Allowable Contact Stresses 247
9.4.3.2 Allowable Bending Stresses 247
9.4.4 Design Criteria 249
9.4.5 Design Procedure and Guidelines 250
9.4.5.1 The Arrangement of Wormgear Drive and Selection of Accuracy Grade
Levels 250
9.4.5.2 The Selection of the Number of Worm Threads z and the Number of
1
Wormgear Teeth z 2 250
9.4.5.3 Design by Wormgear Strength 250
9.4.6 Design Cases 250
9.5 Structural Design of Wormgear Drives 253
9.6 Lubrication of Wormgear Drives 253
References 254
Problems 254

10 Shafts 259
10.1 Introduction 260
10.1.1 Applications, Characteristics and Structures 260
10.1.2 Types of Shafts 260
10.2 Working Condition Analysis 262
10.2.1 Force Analysis 262
10.2.2 Stress Analysis 262
10.2.3 Deflection and Rigidity 262
10.2.4 Rotating Shaft Dynamics 264
10.2.5 Potential Failure Modes 264
10.3 Load Carrying Capacities 264
10.3.1 Strength Analysis 264
10.3.1.1 Torsional Strength Analysis 265
10.3.1.2 Combination of Torsional and Bending Strength Analysis 265
10.3.1.3 Fatigue Strength Analysis 266
10.3.1.4 Static Strength Analysis 268
10.3.2 Rigidity Analysis 268
10.3.2.1 Bending Deflections and Slopes 268
10.3.2.2 Torsional Deflections 269
10.3.3 Critical Speed Analysis 270
10.4 Design of Shafts 271
10.4.1 Introduction 271
10.4.2 Materials and Heat Treatments 271
10.4.3 Design Criteria 272
10.4.4 Design Procedure and Guidelines 272
10.4.5 Structural Design of Shafts 273
10.4.5.1 Measures to Increase Shaft Strength and Rigidity 273