Machine elements : Life and design

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CRC Press

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Library of Congress Cataloging-in-Publication Data

Klebanov, Boris M.

Machine elements : life and design / Boris M. Klebanov, David M. Barlam, Frederic E. Nystrom.

p. cm. -- (Mechanical engineering series)

Includes bibliographical references and index.

ISBN 0-8493-9563-1 (alk. paper)

1. Machine parts. 2. Machine design. I. Barlam, David. II. Nystrom, Frederic E. III. Title.

TJ243.K543 2007

621.8’2--dc22 2006051883

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Table of Contents

PART I Deformations and Displacements ............................... 1

Chapter 1 Deformations in Mechanisms and Load Distribution over the Mated

Surfaces of Parts...........................................................................................................3

Reference............................................................................................................................................9

Chapter 2 Movements in Rigid Connections and Damage to the Joint Surfaces......................11

2.1 Interference-Fit Connections (IFCs) ......................................................................................11

2.1.1 IFCs Loaded with a Torque .......................................................................................11

2.1.2 IFCs Loaded with Bending Moment .........................................................................12

2.2 Bolted Connections (BCs)......................................................................................................14

2.2.1 Forces in Tightened BC under Centrically Applied Load.........................................16

2.2.2 Forces in Tightened BC under an Eccentrically Applied Load ................................18

2.3 Damage to the Mating Surfaces in the Slip Area..................................................................19

References ........................................................................................................................................20

Chapter 3 Deformations and Stress Patterns in Machine Components .....................................21

3.1 Structure and Strength of Metals ...........................................................................................21

3.2 Deformations in the Elastic Range ........................................................................................24

3.3 Elastoplastic Deformation (EPD) of Parts.............................................................................32

3.4 Surface Plastic Deformation (SPD) .......................................................................................36

References ........................................................................................................................................39

PART II Elements and Units of Machines.............................. 41

Chapter 4 Shafts ..........................................................................................................................43

4.1 Selecting the Basic Shaft Size ...............................................................................................43

4.2 Elements of Shaft Design.......................................................................................................46

4.3 Hollow Shafts .........................................................................................................................53

4.4 Selection of a Loading Layout for Strength Analysis...........................................................54

4.5 Analysis of Shaft Deformations.............................................................................................58

References ........................................................................................................................................65

Chapter 5 Shaft-to-Hub Connections..........................................................................................67

5.1 General Considerations and Comparison...............................................................................67

5.1.1 Interference-Fit Connections (IFCs) ..........................................................................67

5.1.2 Key Joints ...................................................................................................................69

5.1.3 Splined Joints (SJs) ....................................................................................................70

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5.2 Strength Calculation and Design of IFCs..............................................................................71

5.2.1 Calculation for Total Slippage ...................................................................................71

5.2.1.1 Surface Pressure..........................................................................................72

5.2.1.2 Coefficient of Friction.................................................................................74

5.2.2 Design of IFCs ...........................................................................................................77

5.3 Design and Strength Calculation of Key Joints.....................................................................79

5.3.1 Role of IFC in the Key Joint .....................................................................................79

5.3.2 Strength of Keys.........................................................................................................85

5.3.3 Strength of the Shaft Near the Keyway.....................................................................86

5.3.4 Strength of Hub Near the Keyway ............................................................................88

5.3.5 Round Keys ................................................................................................................92

5.4 Splined Joints .........................................................................................................................93

5.4.1 SJs Loaded with Torque Only....................................................................................94

5.4.2 SJs Loaded with Torque and Radial Force................................................................97

5.4.3 Allowable Bearing Stresses in SJs...........................................................................100

5.4.4 Lubrication of SJs ....................................................................................................101

References ......................................................................................................................................102

Chapter 6 Supports and Bearings..............................................................................................103

6.1 Types and Location of Supports ..........................................................................................103

6.2 Rolling Bearings (RBs) ........................................................................................................108

6.2.1 Design of RBs ..........................................................................................................108

6.2.2 Stresses and Failures in RBs....................................................................................111

6.2.3 Design of Supports with Rolling Bearings..............................................................115

6.2.4 Choice and Arrangement of Supports......................................................................121

6.2.5 Fits for Bearing Seats...............................................................................................123

6.2.6 Requirements for Surfaces Adjoined to RBs...........................................................131

6.2.7 Elastic Deformation of RBs under Load .................................................................133

6.2.8 RBs with Raceways on the Parts of the Mechanism...............................................135

6.2.9 Lubrication of RBs...................................................................................................137

6.3 Sliding Bearings (SBs).........................................................................................................138

6.3.1 Friction of Lubricated Surfaces................................................................................138

6.3.2 Types of SBs.............................................................................................................140

6.3.3 Materials Used in SBs..............................................................................................141

6.3.4 Design of Radial SBs ...............................................................................................144

6.3.5 Design of Thrust SBs ...............................................................................................149

6.3.6 Surfaces Connected with SBs: Features Required ..................................................151

6.3.7 Oil Supply to SBs.....................................................................................................153

References ......................................................................................................................................158

Chapter 7 Gears.........................................................................................................................159

7.1 Geometry and Kinematics of Gearing ...............................................................................160

7.2 Forces in Spur Gearing and Stresses in Teeth...................................................................167

7.3 Kinds of Tooth Failure .......................................................................................................170

7.4 Contact Strength (Pitting Resistance) of Teeth..................................................................174

7.5 Bending Strength (Breakage Resistance) of Gear Teeth ...................................................181

7.6 Unevenness of Load Distribution across the Face Width (Factor KW) .............................187

7.7 Dynamic Load in the Gear Mesh and Factor Kd ...............................................................195

7.8 Load Distribution in Double-Helical Gears (Factor KWh) .................................................197

7.9 Backlash in the Gear Mesh ................................................................................................198

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7.10 Lubrication of Gears...........................................................................................................200

7.11 Cooling of Gears ................................................................................................................208

References ......................................................................................................................................213

Chapter 8 Gear Design..............................................................................................................215

8.1 Gear and Shaft: Integrate or Separate?................................................................................215

8.2 Spur and Helical Gears ........................................................................................................217

8.3 Built-up Gear Wheels...........................................................................................................224

8.4 Manufacturing Requirements and Gear Design ..................................................................235

8.5 Bevel Gears...........................................................................................................................238

8.6 Design of Teeth ....................................................................................................................239

References ......................................................................................................................................240

Chapter 9 Housings ...................................................................................................................241

9.1 The Function of Housings....................................................................................................241

9.2 Materials for Housings.........................................................................................................243

9.3 Design of Housings ..............................................................................................................248

9.3.1 Housings Split through the Axes of Shafts..............................................................248

9.3.1.1 Design of Mounting Feet..........................................................................250

9.3.1.2 Design of Lifting Elements.......................................................................251

9.3.2 Housings Split at Right Angle to the Axes of the Shafts........................................251

9.3.3 Nonsplit Housings ....................................................................................................253

9.4 Deformations and Stiffness Problems..................................................................................254

9.5 Housing Seals .......................................................................................................................255

9.5.1 Sealing of Rigid Connections (Static Seals)............................................................255

9.5.2 Sealing Movable Joints ............................................................................................262

9.5.2.1 Noncontact Seals.......................................................................................262

9.5.2.2 Contact Seals.............................................................................................264

9.5.2.3 Combined Seals.........................................................................................274

References ......................................................................................................................................275

Chapter 10 Bolted Connections (BCs)........................................................................................277

10.1 Load Distribution between the Bolts .................................................................................278

10.1.1 Load Distribution in Bolted Joints Loaded in Shear ...........................................282

10.1.2 Load Distribution in Bolted Joints Loaded in Tension .......................................287

10.2 Tightening of Bolts.............................................................................................................292

10.2.1 Tightening Accuracy .............................................................................................292

10.2.2 Stability of Tightening ..........................................................................................295

10.2.2.1 Self-Loosening of Bolts ......................................................................295

10.2.2.2 Plastic Deformation of Fasteners and Connected Parts .....................295

10.2.3 Locking of Fasteners.............................................................................................300

10.3 Correlation between Working Load and Tightening Force of the Bolt ............................302

10.3.1 Load Normal to Joint Surface ..............................................................................302

10.3.2 Shear Load ............................................................................................................305

10.3.3 Bending Load........................................................................................................311

10.4 Strength of Fasteners ..........................................................................................................313

10.4.1 Static Strength.......................................................................................................313

10.4.2 Fatigue Strength ....................................................................................................317

References ......................................................................................................................................319

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Chapter 11 Connection of Units .................................................................................................321

11.1 Housing Connections..........................................................................................................321

11.2 Shaft Connections...............................................................................................................329

11.2.1 Alignment of Shafts..............................................................................................329

11.2.2 Rigid Couplings ....................................................................................................334

11.2.3 Resilient Couplings...............................................................................................336

11.2.4 Gear Couplings .....................................................................................................342

References ......................................................................................................................................352

PART III Life Prediction of Machine Parts .......................... 355

Chapter 12 Strength of Metal Parts ............................................................................................357

12.1 Strength of Metals ..............................................................................................................359

12.1.1 Strength at a Static Load ......................................................................................359

12.1.2 Fatigue Strength (Stress Method).........................................................................363

12.1.3 Limited Fatigue Life under Irregular Loading (Stress Method)..........................374

12.1.4 Fatigue Life (Strain Method)................................................................................376

12.2 Strength of Machine Elements...........................................................................................386

12.2.1 Surface Finish .......................................................................................................387

12.2.2 Dimensions of the Part .........................................................................................387

12.2.3 Stress Concentration .............................................................................................388

12.2.4 Use of Factors KS, Kd, and Ke...............................................................................389

12.3 Comparative Calculations for Strength..............................................................................390

12.4 Real Strength of Materials .................................................................................................395

References ......................................................................................................................................396

Chapter 13 Calculations for Strength..........................................................................................397

13.1 Characteristics of Stresses in the Part................................................................................397

13.1.1 Estimation of External Loads ...............................................................................397

13.1.2 Determination of Forces Applied to the Part .......................................................398

13.1.3 Estimation of Stresses in the Part.........................................................................403

13.2 Safety Factors .....................................................................................................................404

13.3 Errors Due to Inappropriate Use of FEM..........................................................................405

13.3.1 Design Principles and Precision of FEM.............................................................405

13.3.2 Design of Model for FEM Computation..............................................................407

13.3.3 Interpretation of Boundary Conditions.................................................................409

13.3.4 Is the Computer Program Correct? ......................................................................412

13.3.5 More about Simplified Analytical Models ...........................................................412

13.3.6 Consideration of Deformations.............................................................................416

13.4 Human Error.......................................................................................................................416

13.4.1 Arithmetic .............................................................................................................416

13.4.2 Units (Dimensions) ...............................................................................................417

13.4.3 Is This Formula Correct?......................................................................................418

References ......................................................................................................................................419

Chapter 14 Finale ........................................................................................................................421

Index ..............................................................................................................................................423

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Preface

This book describes the behavior of some machine elements during action, based on our under￾standing accumulated over many decades of machine design. We have sought to describe the

mechanisms of interaction between the motion participants in as much detail and depth as the scope

of our knowledge and the volume of the book allow.

Our understanding is based in many respects on the work of others, and we have made reference

to all authors and publications known to us. But the literature of mechanical engineering is vast,

and we welcome notification by any author inadvertently omitted to enable us to amend this

omission in the future.

Chapter 1 to Chapter 11 were written mainly by Boris M. Klebanov. Chapter 12 was written

mainly by David M. Barlam, who also performed all the calculations using the finite element

method (FEM) that appears in the book. Chapter 13 was written jointly by Boris M. Klebanov and

David M. Barlam. Frederic E. Nystrom edited the entire work, including the text, tables, and

illustrations.

This work is dedicated to our teachers.

Boris M. Klebanov

David M. Barlam

Frederic E. Nystrom

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Authors

Dr. Boris Klebanov has spent all 48 years of his professional life in the design of diesel engines

and drive units for marine and land applications, reduction gears, hydraulic devices, and mine

clearing equipment. His Ph.D. thesis (1969) was on the strength calculation and design of gears.

He is the author of many articles and coauthor of two books in the field of machinery.

Dr. Klebanov worked from 1959 to 1990 in St. Petersburg, Russia, as a designer and head of

the gear department in a heavy engine industry, and then he worked until 2001 at Israel Aircraft

Industry (IAI) as a principal mechanical engineer. Currently, he is a consultant engineer at Israel

Aircraft Industry.

Dr. David Barlam is a leading stress engineer and a senior researcher at Israel Aircraft Industry

(IAI), specializing in stress and vibration in machinery — the field in which he has accumulated

37 years of experience in the industry and seven years in academia. He is an adjunct professor at

Ben-Gurion University. Dr. Barlam’s current industrial experience, since 1991, includes dealing

with diversified problems in aerospace and shipbuilding. Prior to that, he worked as a stress analyst

and head of the strength department in heavy diesel engine industry in Leningrad (today’s St.

Petersburg). David Barlam received his doctoral degree (1983) in finite element analysis.

Dr. David Barlam is coauthor of the book Nonlinear Problems in Machine Design (CRC Press,

2000), and numerous papers on engineering science.

Frederic Nystrom has since 1997 held the position of senior project engineer at Twin Disc, Inc.

(Racine, WI). He is responsible for management of both R&D projects and new concept develop￾ment, focusing on marine propulsion machinery for both commercial and military applications.

Prior to that, beginning in 1989, he worked as a senior engineer at Electric Boat Corp., Groton,

CT (a division of General Dynamics).

While at Electric Boat he accumulated wide experience in the design of propulsion systems,

product life cycle support, and manufacturing support for U.S. Navy surface ships and nuclear

submarines. He currently holds U.S. Patent No. 6,390,866, “Hydraulic cylinder with anti-rotation

mounting for piston rod,” issued May 2002.

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