Machine Elements in Mechanical Design

by Mott, Robert; Mott, Robert L.

• ISBN13: 9780138414467
• ISBN10: 0138414467
• Edition: 3rd
• Format: Hardcover
• Copyright: 1999-01-01
• Publisher: Prentice Hall

Summary

For courses in Machine Design, Design of Machine Elements, Mechanical Design, and Product Design. Using an exceptionally readable, applied approach to the principles and practice of mechanical design, this text presents the concepts, procedures, data, and decision-analysis techniques students need to design safe, efficient, and workable machine elements and to effectively integrate them into total systems. Hands-on in nature, it features an abundance of thoroughly worked and explained examples and topic-specific and comprehensive integrative reality-based problems and projects. The use of spreadsheets and the latest computational tools and extensive appendices provide realistic up-to-date data and techniques for use in problem solutions and design projects.

Table of Contents

PART I Principles of Design and Stress Analysis	1	(220)
1 The Nature of Mechanical Design	2	(22)
The Big Picture	3	(1)
You Are the Designer	4	(1)
1-1 Objectives of This Chapter	4	(3)
1-2 The Mechanical Design Process	7	(2)
1-3 Skills Needed in Mechanical Design	9	(1)
1-4 Functions and Design Requirements	9	(1)
1-5 Criteria for Evaluating Machine Design Decisions	10	(1)
1-6 Example of the Integration of Machine Elements into a Mechanical Design	11	(2)
1-7 Computational Aids in This Book	13	(1)
1-8 Design Calculations	13	(1)
1-9 Preferred Basic Sizes, Screw Threads, and Standard Shapes	14	(6)
1-10 Unit Systems	20	(2)
1-11 Distinction among Weight, Force, and Mass	22	(1)
References	22	(1)
Problems	23	(1)
2 Materials in Mechanical Design	24	(43)
The Big Picture	25	(1)
You Are the Designer	26	(1)
2-1 Objectives of This Chapter	26	(1)
2-2 Properties of Metals	26	(7)
2-3 Classification of Metals and Alloys	33	(1)
2-4 Variability of Material Properties Data	34	(1)
2-5 Carbon and Alloy Steel	35	(3)
2-6 Conditions for Steels and Heat Treatment	38	(4)
2-7 Stainless Steels	42	(1)
2-8 Structural Steel	43	(1)
2-9 Tool Steels	43	(1)
2-10 Cast Iron	43	(2)
2-11 Powdered Metals	45	(1)
2-12 Aluminum	46	(1)
2-13 Zinc Alloys	47	(1)
2-14 Titanium	48	(1)
2-15 Copper, Brass, and Bronze	49	(1)
2-16 Nickel-based Alloys	50	(1)
2-17 Plastics	50	(2)
2-18 Composite Materials	52	(12)
References	64	(1)
Problems	65	(2)
3 Stress and Deformation Analysis	67	(45)
The Big Picture	68	(1)
You Are the Designer	68	(1)
3-1 Objectives of This Chapter	69	(1)
3-2 Philosophy of a Safe Design	69	(1)
3-3 Representing Streses on a Stress Element	69	(1)
3-4 Direct Stresses: Tension and Compression	70	(2)
3-5 Deformation under Direct Axial Loading	72	(1)
3-6 Direct Shear Stress	72	(2)
3-7 Relationship among Torque, Power, and Rotational Speed	74	(1)
3-8 Torsional Shear Stress	75	(2)
3-9 Torsional Deformation	77	(1)
3-10 Torsion in Members Having Noncircular Cross Sections	77	(2)
3-11 Torsion in Closed, Thin-walled Tubes	79	(1)
3-12 Open Tubes and a Comparison with Closed Tubes	80	(1)
3-13 Vertical Shearing Stress	81	(2)
3-14 Special Shearing Stress Formulas	83	(1)
3-15 Stress Due to Bending	84	(2)
3-16 Flexural Center for Beams	86	(1)
3-17 Beam Deflections	87	(2)
3-18 Equations for Deflected Beam Shape	89	(2)
3-19 Beams with Concentrated Bending Moments	91	(4)
3-20 Combined Normal Stresses: Superpostion Principle	95	(2)
3-21 Stress Concentrations	97	(3)
3-22 Notch Sensitivity and Strength Reduction Factor	100	(1)
References	101	(1)
Problems	101	(11)
4 Combined Stresses and Mohr's Circle	112	(28)
The Big Picture	113	(1)
You Are the Designer	113	(2)
4-1 Objectives of This Chapter	115	(1)
4-2 General Case of Combined Stress	115	(7)
4-3 Mohr's Circle	122	(6)
4-4 Mohr's Circle Practice Problems	128	(4)
4-5 Case When Both Principal Stresses Have the Same Sign	132	(3)
4-6 Mohr's Circle for Special Stress Conditions	135	(3)
4-7 Analysis of Complex Loading Conditions	138	(1)
Problems	139	(1)
5 Design for Different Types of Loading	140	(49)
The Big Picture	141	(1)
You Are the Designer	142	(1)
5-1 Objectives of This Chapter	143	(1)
5-2 Types of Loading and Stress Ratio	143	(6)
5-3 Endurance Strength	149	(1)
5-4 Factors Affecting the Endurance Strength	149	(5)
5-5 Estimating Actual Endurance Strength, S(n)	154	(3)
5-6 Design for Different Types of Loading	157	(1)
5-7 Predicitions of Failure	157	(2)
5-8 Design Factors	159	(1)
5-9 Methods of Computing Design Factor or Design Stress	160	(3)
5-10 General Design Procedure	163	(4)
5-11 Design Examples	167	(11)
References	178	(1)
Problems	178	(11)
6 Columns	189	(32)
The Big Picture	189	(1)
You Are the Designer	190	(1)
6-1 Objectives of This Chapter	190	(1)
6-2 Properties of the Cross Section of a Column	191	(1)
6-3 End Fixity and Effective Length	191	(2)
6-4 Slenderness Ratio	193	(1)
6-5 Transition Slenderness Ratio	193	(1)
6-6 Long Column Analysis: The Euler Formula	194	(4)
6-7 Short Column Analysis: The J.B. Johnson Formula	198	(2)
6-8 Column Analysis Spreadsheet	200	(3)
6-9 Efficient Shapes for Column Cross Sections	203	(1)
6-10 The Design of Columns	204	(5)
6-11 Crooked Columns	209	(1)
6-12 Eccentrically Loaded Columns	210	(6)
References	216	(6)
Problems	216	(5)
PART II Design of a Mechanical Drive	221	(378)
7 Belt Drives and Chain Drives	225	(31)
The Big Picture	226	(2)
You Are the Designer	228	(1)
7-1 Objectives of This Chapter	228	(1)
7-2 Types of Belt Drives	228	(2)
7-3 V-Belt Drives	230	(3)
7-4 V-Belt Drive Design	233	(8)
7-5 Chain Drives	241	(2)
7-6 Design of Chain Drives	243	(10)
References	253	(1)
Problems	254	(2)
8 Kinematics of Gears	256	(62)
The Big Picture	257	(4)
You Are the Designer	261	(1)
8-1 Objectives of This Chapter	262	(1)
8-2 Spur Gear Styles	262	(1)
8-3 Spur Gear Geometry: Involute-Tooth Form	263	(2)
8-4 Spur Gear Nomenclature and Gear-Tooth Features	265	(10)
8-5 Interference between Mating Spur Gear Teeth	275	(2)
8-6 Velocity Ration and Gear Trains	277	(7)
8-7 Helical Gear Geometry	284	(5)
8-8 Bevel Gear Geometry	289	(5)
8-9 Types of Wormgearing	294	(2)
8-10 Geometry of Worms and Wormgears	296	(3)
8-11 Typical Geometry of Wormgear Sets	299	(4)
8-12 Train Value for Complex Gear Trains	303	(2)
8-13 Devising Gear Trains	305	(7)
References	312	(1)
Problems	313	(5)
9 Spur Gear Design	318	(74)
The Big Picture	319	(1)
You Are the Designer	320	(1)
9-1 Objectives of This Chapter	320	(1)
9-2 Concepts from Previous Chapters	321	(1)
9-3 Forces on Gear Teeth	322	(3)
9-4 Gear Manufacture	325	(2)
9-5 Gear Quality	327	(1)
9-6 Allowable Stress Numbers	328	(2)
9-7 Gear Materials	330	(7)
9-8 Stresses in Gear Teeth	337	(9)
9-9 Selection of Gear Material Based on Bending Stess	346	(5)
9-10 Pitting Resistance of Gear Teeth	351	(4)
9-11 Selection of Gear Material Based on Contact Stress	355	(5)
9-12 Design of Spur Gears	360	(5)
9-13 Gear Design for the Metric Module System	365	(2)
9-14 Computer-aided Spur Gear Design and Analysis	367	(4)
9-15 Use of the Spur Gear Design Spreadsheet	371	(2)
9-16 Power-transmitting Capacity	373	(10)
9-17 Practical Considerations for Gears and Interfaces with Other Elements	383	(3)
References	386	(1)
Problems	387	(5)
10 Helical Gears, Bevel Gears, and Wormgearing	392	(41)
The Big Picture	393	(2)
You Are the Designer	395	(1)
10-1 Objectives of This Chapter	395	(1)
10-2 Forces on Helical Gear Teeth	395	(3)
10-3 Stresses in Helical Gear Teeth	398	(4)
10-4 Pitting Resistance for Helical Gear Teeth	402	(1)
10-5 Design of Helical Gears	403	(2)
10-6 Forces on Straight Bevel Gears	405	(3)
10-7 Bearing Forces on Shafts Carrying Bevel Gears	408	(4)
10-8 Bending Moments on Shafts Carrying Bevel Gears	412	(1)
10-9 Stresses in Straight Bevel Gear Teeth	412	(3)
10-10 Design of Bevel Gears for Pitting Resistance	415	(2)
10-11 Forces, Friction, and Efficiency in Wormgear Sets	417	(6)
10-12 Stress in Wormgear Teeth	423	(1)
10-13 Surfaces Durability of Wormgear Drives	424	(5)
References	429	(1)
Problems	430	(3)
11 Keys, Couplings, and Seals	433	(38)
The Big Picture	434	(1)
You Are the Designer	435	(1)
11-1 Objectives of This Chapter	435	(1)
11-2 Keys	436	(4)
11-3 Materials for Keys	440	(1)
11-4 Stress Analysis to Determine Key Length	440	(5)
11-5 Splines	445	(4)
11-6 Other Methods of Fastening Elements to Shafts	449	(5)
11-7 Couplings	454	(1)
11-8 Universal Joints	455	(4)
11-9 Retaining Rings and Other Means of Axial Location	459	(3)
11-10 Types of Seals	462	(3)
11-11 Seal Materials	465	(4)
References	469	(1)
Problems	469	(2)
12 Shaft Design	471	(44)
The Big Picture	472	(1)
You Are the Designer	473	(1)
12-1 Objectives of This Chapter	473	(1)
12-2 Shaft Design Procedure	473	(3)
12-3 Forces Exerted on Shafts by Machine Elements	476	(4)
12-4 Stress Concentrations in Shafts	480	(3)
12-5 Design Stresses for Shafts	483	(4)
12-6 Shafts in Bending and Torision Only	487	(2)
12-7 Shaft Design Example	489	(4)
12-8 Recommended Basic Sizes for Shafts	493	(1)
12-9 Additional Design Examples	494	(8)
12-10 Spreadsheet Aid for Shaft Design	502	(1)
References	503	(1)
Problems	504	(11)
13 Tolerances and Fits	515	(20)
The Big Picture	516	(1)
You Are the Designer	517	(1)
13-1 Objectives of This Chapter	517	(1)
13-2 Factors Affecting Tolerances and Fits	518	(1)
13-3 Tolerances, Production Processes, and Cost	518	(2)
13-4 Preferred Basic Sizes	520	(2)
13-5 Clearance Fits	522	(4)
13-6 Interference Fits	526	(2)
13-7 Transition Fits	528	(1)
13-8 Robust Product Design	528	(1)
13-9 Stresses for Forces Fits	529	(4)
References	533	(1)
Problems	533	(2)
14 Rolling Contact Bearings	535	(32)
The Big Picture	536	(1)
You Are the Designer	537	(1)
14-1 Objectives of This Chapter	538	(1)
14-2 Types of Rolling Contact Bearings	538	(4)
14-3 Thrust Bearings	542	(1)
14-4 Mounted Bearings	542	(2)
14-5 Bearing Materials	544	(1)
14-6 Load/Life Relationship	544	(1)
14-7 Bearing Manufacturers' Data	545	(4)
14-8 Design Life	549	(2)
14-9 Bearing Selection: Radial Loads Only	551	(1)
14-10 Bearing Selection: Radial and Thrust Loads Combined	552	(2)
14-11 Mounting of Bearings	554	(2)
14-12 Tapered Roller Bearings	556	(2)
14-13 Practical Considerations in the Application of Bearings	558	(4)
14-14 Importance of Oil Film Thickness in Bearings	562	(1)
14-15 Life Prediction under Varying Loads	563	(1)
References	564	(1)
Problems	565	(2)
15 Completion of the Design of a Power Transmission	567	(32)
The Big Picture	568	(1)
15-1 Objectives of This Chapter	568	(1)
15-2 Description of the Power Transmission to Be Designed	568	(2)
15-3 Design Alternatives and Selection of the Design Approach	570	(2)
15-4 Design Alternatives for the Gear-Type Reducer	572	(1)
15-5 General Layout and Design Details of the Reducer	572	(20)
15-6 Final Design Details for the Shafts	592	(3)
15-7 Assembly Drawing	595	(2)
References	597	(2)
PART III Design Details and Other Machine Elements	599
16 Plain Surface Bearings	600	(27)
The Big Picture	601	(2)
You Are the Designer	603	(1)
16-1 Objectives of This Chapter	603	(1)
16-2 The Bearing Design Task	603	(2)
16-3 Bearing Parameter, un/p	605	(1)
16-4 Bearing Materials	606	(2)
16-5 Design of Boundary-lubricated Bearings	608	(6)
16-6 Full-Film Hydrodynamic Bearings	614	(1)
16-7 Design of Full-Film Hydrodynamically Lubricated Bearings	615	(6)
16-8 Practical Considerations for Plain Surface Bearings	621	(1)
16-9 Hydrostatic Bearings	622	(3)
References	625	(1)
Problems	626	(1)
17 Power Screws and Ball Screws	627	(14)
The Big Picture	628	(1)
You Are the Designer	629	(1)
17-1 Objectives of This Chapter	630	(1)
17-2 Power Screws	630	(6)
17-3 Ball Screws	636	(3)
References	639	(1)
Problems	639	(2)
18 Fasteners	641	(14)
The Big Picture	642	(2)
You Are the Designer	644	(1)
18-1 Objectives of This Chapter	644	(1)
18-2 Other Types of Fasteners and Accessories	644	(2)
18-3 Bolt Materials and Strength	646	(2)
18-4 Thread Designations	648	(2)
18-5 Performance of Bolted Joints	650	(3)
18-6 Other Means of Fastening	653	(1)
References	654	(1)
Problems	654	(1)
19 Springs	655	(42)
The Big Picture	656	(1)
You Are the Designer	657	(1)
19-1 Objectives of This Chapter	657	(1)
19-2 Kinds of Springs	658	(3)
19-3 Helical Compression Springs	661	(9)
19-4 Stresses and Deflection for Helical Compression Springs	670	(2)
19-5 Analysis of Spring Characteristics	672	(2)
19-6 Design of Helical Compression Springs	674	(9)
19-7 Extension Springs	683	(4)
19-8 Helical Torsion Springs	687	(7)
References	694	(1)
Problems	695	(2)
20 Machine Frames, Bolted Connections, and Welded Joints	697	(22)
The Big Picture	698	(1)
You Are the Designer	699	(1)
20-1 Objectives of This Chapter	699	(1)
20-2 Machine Frames and Structures	699	(5)
20-3 Eccentrically Loaded Bolted Joints	704	(3)
20-4 Welded Joints	707	(8)
References	715	(1)
Problems	716	(3)
21 Electric Motors	719	(35)
The Big Picture	720	(1)
You Are the Designer	721	(1)
21-1 Objectives of This Chapter	721	(1)
21-2 Motor Selection Factors	722	(1)
21-3 AC Power and General Information about AC Motors	723	(1)
21-4 Principles of Operation of AC Induction Motors	724	(2)
21-5 AC Motor Performance	726	(1)
21-6 Three-Phase, Squirrel-Cage Induction Motors	727	(3)
21-7 Single-Phase Motors	730	(3)
21-8 AC Motor Frame Types and Enclosures	733	(3)
21-9 Controls for AC Motors	736	(8)
21-10 DC Power	744	(1)
21-11 DC Motors	745	(3)
21-12 DC Motor Control	748	(2)
21-13 Other Types of Motors	750	(1)
References	751	(1)
Problems	751	(3)
22 Motion Control: Clutches and Brakes	754	(35)
The Big Picture	755	(2)
You Are the Designer	757	(1)
22-1 Objectives of This Chapter	757	(1)
22-2 Descriptions of Clutches and Brakes	757	(2)
22-3 Types of Friction Clutches and Brakes	759	(4)
22-4 Performance Parameters	763	(2)
22-5 Time Required to Accelerate a Load	765	(2)
22-6 Inertia of a System Referred to the Clutch Shaft Speed	767	(2)
22-7 Effective Inertia for Bodies Moving Linearly	769	(1)
22-8 Energy Absorption: Heat-Dissipation Requirements	770	(1)
22-9 Response Time	771	(2)
22-10 Friction Materials and Coefficient of Friction	773	(1)
22-11 Plate-Type Clutch or Brake	774	(2)
22-12 Caliper Disc Brakes	776	(1)
22-13 Cone Clutch or Brake	776	(2)
22-14 Drum Brakes	778	(4)
22-15 Band Brakes	782	(2)
22-16 Other Types of Clutches and Brakes	784	(2)
References	786	(1)
Problems	786	(3)
23 Design Projects	789
23-1 Objectives of This Chapter	790	(1)
23-2 Design Projects	790
Appendices	A-1	(45)
Appendix 1 Properties of Areas	A-1	(2)
Appendix 2 Preferred Basic Sizes and Screw Threads	A-3	(3)
Appendix 3 Design Properties of Carbon and Alloy Steels	A-6	(2)
Appendix 4 Properties of Heat-treated Steels	A-8	(6)
Appendix 5 Properties of Stainless Steels	A-14	(1)
Appendix 6 Properties of Stainless Steel	A-15	(1)
Appendix 7 Properties of Structural Steels	A-16	(1)
Appendix 8 Design Properties of Cast Iron	A-17	(1)
Appendix 9 Typical Properties of Aluminum	A-18	(1)
Appendix 10 Typical Properties of Zinc Casting Alloys	A-19	(1)
Appendix 11 Properties of Titanium Alloys	A-20	(1)
Appendix 12 Properties of Bronzes	A-21	(1)
Appendix 13 Typical Properties of Selected Plastics	A-22	(1)
Appendix 14 Beam-Deflection Formulas	A-23	(9)
Appendix 15 Stress Concentration Factors	A-32	(4)
Appendix 16 Steel Structural Shapes	A-36	(6)
Appendix 17 Aluminum Structural Shapes	A-42	(2)
Appendix 18 Conversion Factors	A-44	(1)
Appendix 19 Hardness Conversion Table	A-45	(1)
Answers to Selected Problems	A-46
Index	I-1