Machine Design

Robert L. Norton earned undergraduate degrees in both mechanical engineering and industrial technology at Northeastern University and an MS in engineering design at Tufts University. He is a registered professional engineer in Massachusetts. He has extensive industrial experience in engineering design and manufacturing and many years’ experience teaching mechanical engineering, engineering design, computer science, and related subjects at Northeastern University, Tufts University, and Worcester Polytechnic Institute.   At Polaroid Corporation for 10 years, he designed cameras, related mechanisms, and high-speed automated machinery. He spent three years at Jet Spray Cooler Inc., designing food-handling machinery and products. For five years he helped develop artificial-heart and noninvasive assisted-circulation (counterpulsation) devices at the Tufts New England Medical Center and Boston City Hospital. Since leaving industry to join academia, he has continued as an independent consultant on engineering projects ranging from disposable medical products to high-speed production machinery. He holds 13 U.S. patents.   Norton has been on the faculty of Worcester Polytechnic Institute since 1981 and is currently the Milton P. Higgins II Distinguished Professor of Mechanical Engineering, Russell P. Searle Distinguished Instructor, Head of the Design Group in that department, and the Director of the Gillette Project Center at WPI. He teaches undergraduate and graduate courses in mechanical engineering with emphasis on design, kinematics, vibrations, and dynamics of machinery.   He is the author of numerous technical papers and journal articles covering kinematics, dynamics of machinery, cam design and manufacturing, computers in education, and engineering education and of the texts Design of Machinery, Machine Design: An Integrated Approach and the Cam Design and Manufacturing Handbook. He is a Fellow of the American Society of Mechanical Engineers and a member of the Society of Automotive Engineers. But, since his main interest is in teaching, he is most proud of the fact that, in 2007, he was chosen as U. S. Professor of the Year for the State of Massachusetts by the Council for the Advancement and Support of Education (CASE) and the Carnegie Foundation for the Advancement of Teaching, who jointly present the only national awards for teaching excellence given in the United States of America.

PART I FUNDAMENTALS 1

CHAPTER 1 INTRODUCTION TO DESIGN

1.1 Design

Machine Design

Introduction to Design

Machine

Iteration

1.2 A Design Process

1.3 Problem Formulation and Calculation

Definition Stage

Preliminary Design Stage

Detailed Design Stage

Documentation Stage

1.4 The Engineering Model

Estimation and First-Order Analysis

The Engineering Sketch

1.5 Computer-Aided Design and Engineering

Computer-Aided Design (CAD)

Computer-Aided Engineering (CAE)

Computational Accuracy

1.6 The Engineering Report

1.7 Factors of Safety and Design Codes

Factor of Safety

Choosing a Safety Factor

Design and Safety Codes

1.8 Statistical Considerations

1.9 Units

1.10 Summary

1.11 References

1.12 Web References

1.13 Bibliography

1.14 Problems

 

 

CHAPTER 2 MATERIALS AND PROCESSES

2.0 Introduction

2.1 Material-Property Definitions

The Tensile Test

Ductility and Brittleness

The Compression Test

The Bending Test

The Torsion Test

Fatigue Strength and Endurance Limit

Impact Resistance

Fracture Toughness

Creep and Temperature Effects

2.2 The Statistical Nature of Material Properties

2.3 Homogeneity and Isotropy

2.4 Hardness

Heat Treatment

Surface (Case) Hardening

Heat Treating Nonferrous Materials

Mechanical Forming and Hardening

2.5 Coatings and Surface Treatments

Galvanic Action

Electroplating

Electroless Plating

Anodizing

Plasma-Sprayed Coatings

Chemical Coatings

2.6 General Properties of Metals

Cast Iron

Cast Steels

Wrought Steels

Steel Numbering Systems

Aluminum

Titanium

Magnesium

Copper Alloys

2.7 General Properties of Nonmetals

Polymers

Ceramics

Composites

2.8 Selecting Materials

2.9 Summary

2.10 References

2.11 Web References

2.12 Bibliography

2.13 Problems

 

CHAPTER 3 LOAD DETERMINATION

3.0 Introduction

3.1 Loading Classes

3.2 Free-body Diagrams

3.3 Load Analysis

Three-Dimensional Analysis

Two-Dimensional Analysis

Static Load Analysis

3.4 Two-Dimensional, Static Loading Case Studies

Case Study 1A Bicycle Brake Lever Loading Analysis

Case Study 2A Hand-Operated Crimping-Tool Loading Analysis

Case Study 3A Automobile Scissors-Jack Loading Analysis

3.5 Three-Dimensional, Static Loading Case Study

Case Study 4A Bicycle Brake Arm Loading Analysis 94

3.6 Dynamic Loading Case Study

Case Study 5A Fourbar Linkage Loading Analysis

3.7 Vibration Loading

Natural Frequency

Dynamic Forces

Case Study 5B Fourbar Linkage Dynamic Loading Measurement

3.8 Impact Loading

Energy Method 107

3.9 Beam Loading

Shear and Moment

Singularity Functions

Superposition

3.10 Summary

3.11 References

3.12 Web References

3.13 Bibliography

3.14 Problems

 

CHAPTER 4 STRESS, STRAIN, AND DEFLECTION

4.0 Introduction

4.1 Stress

4.2 Strain

4.3 Principal Stresses

4.4 Plane Stress and Plane Strain

Plane Stress

Plane Strain

4.5 Mohr’s Circles

4.6 Applied Versus Principal Stresses

4.7 Axial Tension

x MACHINE DESIGN - An Integrated Approach

4.8 Direct Shear Stress, Bearing Stress, and Tearout

Direct Shear

Direct Bearing

Tearout Failure

4.9 Beams and Bending Stresses

Beams in Pure Bending

Shear Due to Transverse Loading

4.10 Deflection in Beams

Deflection by Singularity Functions

Statically Indeterminate Beams

4.11 Castigliano’s Method

Deflection by Castigliano’s Method

Finding Redundant Reactions with Castigliano’s Method

4.12 Torsion

4.13 Combined Stresses

4.14 Spring Rates

4.15 Stress Concentration

Stress Concentration Under Static Loading

Stress Concentration Under Dynamic Loading

Determining Geometric Stress-Concentration Factors

Designing to Avoid Stress Concentrations

4.16 Axial Compression - Columns

Slenderness Ratio

Short Columns

Long Columns

End Conditions

Intermediate Columns

Eccentric Columns

4.17 Stresses in Cylinders

Thick-Walled Cylinders

Thin-Walled Cylinders

4.18 Case Studies in Static Stress and Deflection Analysis

Case Study 1B Bicycle Brake Lever Stress and Deflection Analysis

Case Study 2B Crimping-Tool Stress and Deflection Analysis

Case Study 3B Automobile Scissors-Jack Stress and Deflection Analysis

Case Study 4B Bicycle Brake Arm Stress Analysis

4.19 Summary

4.20 References

4.21 Bibliography

4.22 Problems

 

CHAPTER 5 STATIC FAILURE THEORIES

5.0 Introduction

5.1 Failure of Ductile Materials Under Static Loading

The von Mises-Hencky or Distortion-Energy Theory

The Maximum Shear-Stress Theory

The Maximum Normal-Stress Theory

Comparison of Experimental Data with Failure Theories

5.2 Failure of Brittle Materials Under Static Loading

Even and Uneven Materials

The Coulomb-Mohr Theory

The Modified-Mohr Theory

5.3 Fracture Mechanics

Fracture-Mechanics Theory

Fracture Toughness Kc

5.4 Using The Static Loading Failure Theories

5.5 Case Studies in Static Failure Analysis

Case Study 1C Bicycle Brake Lever Failure Analysis

Case Study 2C Crimping Tool Failure Analysis

Case Study 3C Automobile Scissors-Jack Failure Analysis

Case Study 4C Bicycle Brake Arm Factors of Safety

5.6 Summary

5.7 References

5.8 Bibliography

5.9 Problems

CHAPTER 6 FATIGUE FAILURE THEORIES

6.0 Introduction

History of Fatigue Failure

6.1 Mechanism of Fatigue Failure

Crack Initiation Stage

Crack Propagation Stage

Fracture

6.2 Fatigue-Failure Models

Fatigue Regimes

The Stress-Life Approach

The Strain-Life Approach

The LEFM Approach

6.3 Machine-Design Considerations

6.4 Fatigue Loads

Rotating Machinery Loading

Service Equipment Loading

6.5 Measuring Fatigue Failure Criteria

Fully Reversed Stresses

Combined Mean and Alternating Stress

Fracture-Mechanics Criteria

Testing Actual Assemblies

6.6 Estimating Fatigue Failure Criteria

Estimating the Theoretical Fatigue Strength Sf’ or Endurance Limit Se’

Correction Factors to the Theoretical Fatigue Strength

Calculating the Corrected Fatigue Strength Sf

Creating Estimated S-N Diagrams

6.7 Notches and Stress Concentrations

Notch Sensitivity

6.8 Residual Stresses

6.9 Designing for High-Cycle Fatigue

6.10 Designing for Fully Reversed Uniaxial Stresses

Design Steps for Fully Reversed Stresses with Uniaxial Loading:

6.11 Designing for Fluctuating Uniaxial Stresses

Creating the Modified-Goodman Diagram

Applying Stress-Concentration Effects with Fluctuating Stresses

Determining the Safety Factor with Fluctuating Stresses

Design Steps for Fluctuating Stresses

6.12 Designing for Multiaxial Stresses in Fatigue

Frequency and Phase Relationships

Fully Reversed Simple Multiaxial Stresses

Fluctuating Simple Multiaxial Stresses

Complex Multiaxial Stresses

6.13 A General Approach to High-Cycle Fatigue Design

6.14 A Case Study in Fatigue Design

Case Study 6 Redesign of a Failed Laybar for a Water-Jet Power Loom

6.15 Summary

6.16 References

6.17 Bibliography

6.18 Problems

 

CHAPTER 7 SURFACE FAILURE

7.0 Introduction

7.1 Surface Geometry

7.2 Mating Surfaces

7.3 Friction

Effect of Roughness on Friction

Effect of Velocity on Friction

Rolling Friction

Effect of Lubricant on Friction

7.4 Adhesive Wear

The Adhesive-Wear Coefficient

7.5 Abrasive Wear

Abrasive Materials

Abrasion-Resistant Materials

7.6 Corrosion Wear

Corrosion Fatigue

Fretting Corrosion

7.7 Surface Fatigue

7.8 Spherical Contact

Contact Pressure and Contact Patch in Spherical Contact 438

Static Stress Distributions in Spherical Contact 440

Ch 00 4ed Final 12 7/26/09, 5:23 PM

7.9 Cylindrical Contact

Contact Pressure and Contact Patch in Parallel Cylindrical Contact

Static Stress Distributions in Parallel Cylindrical Contact

7.10 General Contact

Contact Pressure and Contact Patch in General Contact

Stress Distributions in General Contact

7.11 Dynamic Contact Stresses

Effect of a Sliding Component on Contact Stresses

7.12 Surface Fatigue Failure Models—Dynamic Contact

7.13 Surface Fatigue Strength

7.14 Summary

Designing to Avoid Surface Failure

7.15 References

7.16 Problems

 

CHAPTER 8 FINITE ELEMENT ANALYSIS

8.0 Introduction

Stress and Strain Computation

8.1 Finite Element Method

8.2 Element Types

Element Dimension and Degree of Freedom (DOF)

Element Order

H-Elements Versus P-Elements

Element Aspect Ratio

8.3 Meshing

Mesh Density

Mesh Refinement

Convergence

8.4 Boundary Conditions

8.5 Applying Loads

8.6 Testing the Model

8.7 Modal Analysis

8.8 Case Studies

Case Study 1D FEA Analysis of a Bicycle Brake Lever

Case Study 2D FEA Analysis of a Crimping Tool

Case Study 4D FEA Analysis of a Bicycle Brake Arm

Case Study 7 FEA Analysis of a Trailer Hitch

8.9 Summary

8.10 References

8.11 Bibliography

8.12 Web Resources

8.13 Problems

 

 

PART II MACHINE DESIGN

 

CHAPTER 9 DESIGN CASE STUDIES

9.0 Introduction

9.1 Case Study 8a Preliminary Design of a Compressor Drive Train

9.2 Case Study 9a Preliminary Design of a Winch Lift

9.3 Case Study 10a Preliminary Design of a Cam Dynamic Test Fixture

9.4 Summary 9.5 References

9.6 Design Projects

 

CHAPTER 10 SHAFTS, KEYS, AND COUPLINGS

10.0 Introduction

10.1 Shaft Loads

10.2 Attachments and Stress Concentrations

10.3 Shaft Materials

10.4 Shaft Power

10.5 Shaft Loads

10.6 Shaft Stresses

10.7 Shaft Failure in Combined Loading

10.8 Shaft Design

General Considerations

Design for Fully Reversed Bending and Steady Torsion

Design for Fluctuating Bending and Fluctuating Torsion

10.9 Shaft Deflection

Shafts as Beams

Shafts as Torsion Bars

10.10 Keys and Keyways

Parallel Keys

Tapered Keys

Woodruff Keys

Stresses in Keys

Key Materials

Key Design

Stress Concentrations in Keyways

10.11 Splines

10.12 Interference Fits

Stresses in Interference Fits

Stress Concentration in Interference Fits

Fretting Corrosion

10.13 Flywheel Design

Energy Variation in a Rotating System

Determining the Flywheel Inertia

Stresses in Flywheels

Failure Criteria

10.14 Critical Speeds of Shafts

Lateral Vibration of Shafts and Beams—Rayleigh’s Method

Shaft Whirl

Torsional Vibration

Two Disks on a Common Shaft

Multiple Disks on a Common Shaft

Controlling Torsional Vibrations

10.15 Couplings

Rigid Couplings 605

Compliant Couplings 606

10.16 Case Study

Case Study 8B Preliminary Design of Shafts for a Compressor Drive Train

10.17 Summary

10.18 References

10.19 Problems

 

CHAPTER 11 BEARINGS AND LUBRICATION

11.0 Introduction

11.1 Lubricants

11.2 Viscosity

11.3 Types of Lubrication

Full-Film Lubrication

Boundary Lubrication

11.4 Material Combinations in Sliding Bearings

11.5 Hydrodynamic Lubrication Theory

Petroff’s Equation for No-Load Torque

Reynolds’ Equation for Eccentric Journal Bearings

Torque and Power Losses in Journal Bearings

11.6 Design of Hydrodynamic Bearings

Design Load Factor—The Ocvirk Number

Design Procedures

11.7 Nonconforming Contacts

11.8 Rolling-element bearings

Comparison of Rolling and Sliding Bearings

Types of Rolling-Element Bearings

11.9 Failure of Rolling-element bearings

11.10 Selection of Rolling-element bearings

Basic Dynamic Load Rating C

Modified Bearing Life Rating

Basic Static Load Rating C0

Combined Radial and Thrust Loads

Calculation Procedures

11.11 Bearing Mounting Details

11.12 Special Bearings

11.13 Case Study

Case Study 10b Design of Hydrodynamic Bearings for a Cam Test Fixture

11.14 Summary

11.15 References

11.16 Problems

 

CHAPTER 12 SPUR GEARS

12.0 Introduction

12.1 Gear Tooth Theory

The Fundamental Law of Gearing

The Involute Tooth Form

Pressure Angle

Gear Mesh Geometry

Rack and Pinion

Changing Center Distance

Backlash

Relative Tooth Motion

12.2 Gear Tooth Nomenclature

12.3 Interference and Undercutting

Unequal-Addendum Tooth Forms

12.4 Contact Ratio

12.5 Gear Trains

Simple Gear Trains

Compound Gear Trains

Reverted Compound Trains

Epicyclic or Planetary Gear Trains

12.6 Gear Manufacturing

Forming Gear Teeth

Machining

Roughing Processes

Finishing Processes

Gear Quality

12.7 Loading on Spur Gears

12.8 Stresses in Spur Gears

Bending Stresses

Surface Stresses

12.9 Gear Materials

Material Strengths

AGMA Bending-Fatigue Strengths for Gear Materials

AGMA Surface-Fatigue Strengths for Gear Materials

12.10 Lubrication of Gearing

12.11 Design of Spur Gears

12.12 Case Study

Case Study 8C Design of Spur Gears for a Compressor Drive Train

12.13 Summary

12.14 References

12.15 Problems

 

CHAPTER 13 HELICAL, BEVEL, AND WORM GEARS

13.0 Introduction

13.1 Helical Gears

Helical Gear Geometry

Helical-Gear Forces

Virtual Number of Teeth

Contact Ratios

Stresses in Helical Gears

13.2 Bevel Gears

Bevel-Gear Geometry and Nomenclature

Bevel-Gear Mounting

Forces on Bevel Gears

Stresses in Bevel Gears

13.3 Wormsets

Materials for Wormsets

Lubrication in Wormsets

Forces in Wormsets

Wormset Geometry

Rating Methods

A Design Procedure for Wormsets

13.4 Case Study

Case Study 9B Design of a Wormset Speed Reducer for a Winch Lift

13.5 Summary

13.6 References

13.7 Problems

 

CHAPTER 14 SPRING DESIGN

14.0 Introduction

14.1 Spring Rate

14.2 Spring Configurations

14.3 Spring Materials

Spring Wire

Flat Spring Stock

14.4 Helical Compression Springs

Spring Lengths

End Details

Active Coils

Spring Index

Spring Deflection

Spring Rate

Stresses in Helical Compression Spring Coils

Helical Coil Springs of Nonround Wire

Residual Stresses

Buckling of Compression Springs

Compression-Spring Surge

Allowable Strengths for Compression Springs

The Torsional-Shear S-N Diagram for Spring Wire

The Modified-Goodman Diagram for Spring Wire

14.5 Designing Helical Compression Springs for Static Loading

14.6 Designing Helical Compression Springs for Fatigue Loading

14.7 Helical Extension Springs

Active Coils in Extension Springs

Spring Rate of Extension Springs

Spring Index of Extension Springs

Coil Preload in Extension Springs

Deflection of Extension Springs

Coil Stresses in Extension Springs

End Stresses in Extension Springs

Surging in Extension Springs

Material Strengths for Extension Springs

Design of Helical Extension Springs

14.8 Helical Torsion Springs

Terminology for Torsion Springs

Number of Coils in Torsion Springs

Deflection of Torsion Springs

Spring Rate of Torsion Springs

Coil Closure

Coil Stresses in Torsion Springs

Material Parameters for Torsion Springs

Safety Factors for Torsion Springs

Designing Helical Torsion Springs

14.9 Belleville Spring Washers

Load-Deflection Function for Belleville Washers

Stresses in Belleville Washers

Static Loading of Belleville Washers

Dynamic Loading

Stacking Springs

Designing Belleville Springs

14.10 Case Studies

Case Study 10C Design of a Return Spring for a Cam-Follower Arm 846

14.11 Summary

14.12 References

14.13 Problems

 

CHAPTER 15 SCREWS AND FASTENERS

15.0 Introduction

15.1 Standard Thread Forms

Tensile Stress Area

Standard Thread Dimensions

15.2 Power Screws

Square, Acme, and Buttress Threads

Power Screw Application

Power Screw Force and Torque Analysis

Friction Coefficients

Self-Locking and Back-Driving of Power Screws

Screw Efficiency

Ball Screws

15.3 Stresses in Threads

Axial Stress

Shear Stress

Torsional Stress

15.4 Types of Screw Fasteners

Classification by Intended Use

Classification by Thread Type

Classification by Head Style

Nuts and Washers

15.5 Manufacturing Fasteners

15.6 Strengths of Standard Bolts and Machine Screws

15.7 Preloaded Fasteners in Tension

Preloaded Bolts Under Static Loading

Preloaded Bolts Under Dynamic Loading

15.8 Determining the Joint Stiffness Factor

Joints With Two Plates of the Same Material

Joints With Two Plates of Different Materials

Gasketed Joints

15.9 Controlling Preload

The Turn-of-the-Nut Method

Torque-Limited Fasteners

Load-Indicating Washers

Torsional Stress Due to Torquing of Bolts

15.10 Fasteners in Shear

Dowel Pins

Centroids of Fastener Groups

Determining Shear Loads on Fasteners

15.11 Case Study

Designing Headbolts for an Air Compressor

Case Study 8D Design of the Headbolts for an Air Compressor

15.12 Summary

15.13 References

15.14 Bibliography

15.15 Problems

 

CHAPTER 16 WELDMENTS

16.1 Welding Processes

Types of Welding in Common Use

Why Should a Designer Be Concerned with the Welding Process?

16.2 Weld Joints and Weld Types

Joint Preparation

Weld Specification

16.3 Principles of Weldment Design

16.4 Static Loading of Welds

16.5 Static Strength of Welds

Residual Stresses in Welds

Direction of Loading

Allowable Shear Stress for Statically Loaded Fillet and PJP Welds

16.6 Dynamic Loading of Welds

Effect of Mean Stress on Weldment Fatigue Strength

Are Correction Factors Needed For Weldment Fatigue Strength?

Effect of Weldment Configuration on Fatigue Strength

Is There an Endurance Limit for Weldments?

Fatigue Failure in Compression Loading?

16.7 Treating a Weld as a Line

16.8 Eccentrically Loaded Weld Patterns

16.9 Design Considerations for Weldments in Machines

16.10 Summary

16.11 References

16.12 Problems

 

CHAPTER 17 CLUTCHES AND BRAKES

17.0 Introduction

17.1 Types of Brakes and Clutches

17.2 Clutch/Brake Selection and Specification

17.3 Clutch and Brake Materials

17.4 Disk Clutches

Uniform Pressure

Uniform Wear

17.5 Disk Brakes

17.6 Drum Brakes

Short-Shoe External Drum Brakes

Long-Shoe External Drum Brakes

Long-Shoe Internal Drum Brakes

17.7 Summary

17.8 References

17.9 Bibliography

17.10 Problems

APPENDIX A MATERIAL PROPERTIES

APPENDIX B BEAM TABLES

APPENDIX C STRESS- CONCENTRATION FACTORS

APPENDIX D ANSWERS TO SELECTED PROBLEMS

INDEX