Applied Mechanical Design E-Book

Ammar Grous

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 471

Veröffentlichungsjahr: 2018

Beschreibung

This book is the result of lessons, tutorials and other laboratories dealing with applied mechanical design in the universities and colleges.  In the classical literature of the mechanical design, there are quite a few books that deal directly and theory and case studies, with their solutions. All schools, engineering colleges (technical) industrial and research laboratories and design offices serve design works. However, the books on the market remain tight in the sense that they are often works of mechanical constructions. This is certainly beneficial to the ordinary user, but the organizational part of the functional specification items is also indispensable.

Leseprobe

Applied Mechanical Design

Ammar Grous

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd

27-37 St George’s Road

London SW19 4EU

UK

www.iste.co.uk

John Wiley & Sons, Inc.

111 River Street

Hoboken, NJ 07030

USA

www.wiley.com

© ISTE Ltd 2018

The rights of Ammar Grous to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Control Number: 2017962687

British Library Cataloguing-in-Publication Data

A CIP record for this book is available from the British Library

ISBN 978-1-84821-822-2

Table of Contents

Cover

Title

Copyright

Preface

Introduction

1 Case Study-based Design Methodology

1.1. Methodology for designing a project product

1.2. Main players involved in the design process

1.3. Conceptualization and creativity

1.4. Functional analysis in design: the FAST method

1.5. Functional specifications (FS)

1.6. Failure Mode Effects and Criticality Analysis

1.7. PERT method

1.8. The Gantt method (Henry Gantt’s graph, devised 1910)

1.9. Principal functions of a product

1.10. Functional analysis in mechanical design

1.11. Scientific writing on a project

1.12. Esthetics of materials in mechanical design

1.13. Conclusion

2 Materials and Geometry in Applied Mechanical Design, Followed by Case Studies

2.1. Introduction to materials in design

2.2. Optimization of mass in mechanical design

2.3. Case study of modeling based on the material–geometry couple

2.4. Geometry by standard sections in strength of materials

2.5. Case study of design of multi-purpose items

2.6. Case study of superposed bimetallic materials

2.7. Curving and incurvate elements by sweeping of sheet metals

2.8. Conclusion

3 Geometrical Specification of GPS and ISO Products: Case Studies of Hertzian Contacts

3.1. Introduction

3.2. Dimensional and geometrical tolerances in design

3.3. Envelopes and cylinders under pressure (for R/e < 20)

3.4. Case study

3.5. Rotating cylinders with a full round cross-section: flywheel

3.6. Press fit and thermal effects through bracing

3.7. Case study applied to bolted tanks

3.8. Case studies applied to contact stresses (Hertz) in design

3.9. Conclusion

4 Design of Incurvate Geometries by Sweeping

4.1. Introduction

4.2. Case studies

4.3. Conclusion

5 Principles for Calculations in Mechanical Design: Theory and Problems. Strength of Materials in Constructions

5.1. Essential criteria of constructions in design

5.2. Principles of calculations for constructions in design

5.3. Pressurized recipients and/or containers

5.4. Calculation principles and solution method for compound loading

5.5. Buckling of elements of machines, beams, bars, shafts and stems

5.6. Design of stationary and rotating shafts

5.7. Power transmission elements: gear systems and pulleys

5.8. Sizing and design of couplings

5.9. Design of beams and columns

5.10. Case studies using the Castigliano method

5.11. Conclusion

6 Noise and Vibration in Machine Parts

6.1. Noise and vibration in mechanical systems

6.2. Case study 1

6.3. Vibration of machines in mechanical design

6.4. Case studies with a numerical solution

6.5. Critical speeds of shafts in mechanical systems

6.6. Conclusion

7 Principles of Calculations for Fatigue and Failure

7.1. Mechanical elements of failure through fatigue

7.2. Analysis of materials and sizing in applied design

7.3. Sizing of pivot joints with bearings

7.4. Faults of form and position of ranges on the operating clearance fit

7.5. Friction and speed of bearings

7.6. Sizing of bearing pivot joints and lifetime

7.7. Case study: statement of the problem

7.8. Biaxial stresses combined with shear for ductile materials in concrete application

7.9. Fundaments of sizing in mechanical design. Soderberg equations in fatigue of ductile materials

7.10. Welding and fatigue

7.11. Limits of performance and of strength in the elastic domain

7.12. Proposed project: outboard motor for a small boat

7.13. Conclusion

8 Friction, Brakes and Gear Systems

8.1. Friction, materials and design of assembled systems

8.2. Buttressing of mechanical connections

8.3. Case study: principles of calculations for brakes

8.4. Principles of calculations of a gear system or gear disc

8.5. Flywheels and rims (discs and rims)

8.6. Conclusion

9 Sizing of Creations

9.1. Elastic machine elements and bolted assemblies

9.2. Dimensions (sizing) of bolted assemblies

9.3. Fatigue, shocks and endurance of bolted assemblies

9.4. Springs in mechanical design

9.5. Simple blade and spiral blade springs

9.6. Main expressions of design calculations for Belleville washers

9.7. Power transmission. Case study: hoist

9.8. Case study on couplings

9.9. Case study on power transmission: external spring clutch

9.10. Couplings and machine elements subjected to stress at high speeds

9.11. Design of spring rings

9.12. Principle of calculations for a Belleville washer: case study

9.13. Determination of the pressing moment for a bolted assembly

9.14. Power transmission by epicyclic gear system

9.15. Conclusion

10 Design of Plastic Products

10.1. Calculations for the design of plastic parts

10.2. Jointing of a ball bearing in a metal casing

10.3. Cylindrical clip of PP (e.g. blinds): force exerted

10.4. Types of clip fitting: counter-cylindrical cantilever

10.5. Configuration of strips: two-dimensional spline interpolation

10.6. Press assembly

10.7. Reduction of stress relaxation: bolts and self-tapping screws

10.8. Case study: piping link

10.9. Assembly by forced jointing

10.10. Stress and thermal swelling in assembled materials

10.11. Capacity and reliability of roller bearings (plastic and otherwise)

10.12. Safe stress of the appropriate material for a plastic clutch system

10.13. Case study: plastic ball bearings

10.14. Limits of performances of polymer design

10.15. Case study: fan with plastic blades

10.16. Conclusion

11 Mechanical Design Projects

11.1. Proposed projects in mechanical design

11.2. Case studies of hoisting and handling devices

11.3. Projects design proposal for a lifting winch

11.4. Calculation and design of a bolted assembly

11.5. Yield of power transmission of a screw mechanism

11.6. Project 2: case studies: scooter

11.7. Project 3: dental hygiene dummy

Conclusion: Recap and Reflections on Applied Mechanical Design

Appendix: Lexicon, Glossary and Standards

A.1. Introduction

A.2. Abbreviations used in this book

A.3. A few international standards on surface state and metrology

A.4. Recap of some calculation formulae used in design

A.5. Properties of regular sections

A.6. Glossary and definitions of mechanical characteristics of plastic materials

Bibliography

Index

End User License Agreement

Guide

Cover

Table of Contents

Begin Reading

Pages

C1

iii

iv

v

xiii

xiv

xv

xvi

xvii

xviii

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

467

468

469

471

472

473

474

G1

G2

G3

G4

G5

G6

G7

G8

G9

e1

Preface

This book is designed for students in specialized schools and in science and technology universities, and also for professionals in the industrial sector. Its content is based on case studies with given solutions, which are targeted and discussed. This content is drawn from the author’s own classes in applied mechanical design. It gives an overview of all the necessary elements of knowledge, and the methods for analyzing and selecting materials. The book is written as a didactic tool to guide readers in their approach to design, making heavy reference to industry.

The construction of the book is founded primarily on intuition where Arts and Industry are concerned. University courses in Technology offer solutions to the problems arising in design, but do not always present an exhaustive list of the numerous steps that need to be followed at the implementation stage. Sometimes, solutions put forward in mechanical design refer to diagrams without saying anything of the “how”, the “why” or the “where”… The thought process surrounding design is far more subtle, much deeper and, in many respects, considerably more complex than it might, at first glance, appear to be. The approach to design must begin with concise methods which enable us to:

– clearly set out the problem (or problems) at hand;

– compare succinct analytical solutions;

– make informed, and duly documented, choices and selections.

In this book, we examine a protocol which qualifies and quantifies the requirements, beginning with a clearly written set of Functional Specifications (FS). The methods and analyses herein aim to satisfy the expressed need.

In particular, it is absolutely crucial to have, at our disposal, mathematical and physical tools to calculate the mechanical resistance of materials. Knowledge of how materials behave is fundamentally important to enlightened design; in other words, the results of calculations, even fairly accurate, constitute simple pedagogical mathematical exercises which have no bearing on the final decision taken on a project. The case studies presented here are the result of the author’s research and targeted work in mechanical design. They are taken directly from the author’s teaching materials which have, in turn, given rise to manuals and a wide range of publications, including manufacturer catalogs on an international scale.

At the end of the book, readers will find case studies which have previously been discussed in the author’s classes, with a view to finding solutions. They are invited to make use of these materials for an appropriate illuminating study, in keeping with the workshop tools and lab tools available to them. In applied mechanical design, there is no single solution, but instead a range of possible solutions in view of the means and methods being used.

Ammar GROUS

December 2017

Introduction

In design, modeling is an indispensable step. In the preliminary stages of a design project, it is essential to make sketches (outlines), and combine these with a rough graphic-analytical model. When the preliminary sketches appear viable, we move on to other factors of progressive design. The principles of the calculations include combinations of properties to find the best possible performances that the project can deliver. The mathematical model is founded on exact values of the stresses at work, and of the strains undergone by the components, bounded by the operational limitations. In this book, we present concrete examples with different geometrical properties, under stress from a variety of types of loading. Beams, bars, discs and cylinders (to mention only a few classic forms) already have working hypotheses concerning their use, set out in specialized publications. It is wise to draw upon this pre-existing body of work in putting together real-world projects. The important thing is to be aware that the information is out there, and that judicious use can be made of it. The formulae presented herein are taken from the specialist literature, cited in the bibliographies at the end of each chapter. The tables, standards, formulae and other are presented here as an illustrative guide. Under no circumstances should this book be thought of as exhaustive; readers must refer, for more detailed information, to the aforementioned specialized publications.

Historically, the design of products such as mechanisms and machines has been at the heart of engineering sciences and techniques. The development of computer tools and computer-aided design (CAD) has greatly contributed, with the help of the standards brought into force, to better presentation of the graphical results of sketches of definitions and products. Optimization methods, new workflow schemes and mathematical tools employed in mechanical construction can easily be used by project designers. On the basis of a clear set of technical specifications, the designer can achieve their objectives in the shortest possible time and with the lowest possible material cost. A clearly presented preliminary project is a good guarantee for the production of a safe, well-documented design.

There is no reproducible, prefabricated “recipe” for a good design of mechanical systems. Instead, there are step-by-step, incremental methods which are optimized to deliver the desired results. The current book is founded on experience both in industry and in teaching. It discusses indispensable tools which orientate and guide designers in their search for solutions. It uses a skill-based pedagogical approach, and thus presents the target vectors, including:

1)

Methodology

: Readers of this book will follow the steps, from needs analysis to the hunt for mutually acceptable solutions (agreed between the client and the designer), right through to the presentation of the documented preliminaries for the project. Technical specifications, creative design methods (including FAST: Function Analysis System Technique), Gantt charts and FMECA (Failure Modes, Effects and Criticality Analysis) are used here.

2)

Principles behind the calculations

: The elements of analysis and calculations traditionally employed in construction are the preserve of the mathematical and applied physics tools. The novel aspect of this book is that it brings in a clearly documented pedagogical approach. The analytical approach follows the principles of the calculations. The materials and processes, which are subjects close to mechanical systems, are clearly documented.

3)

Graphical-analytical tools

: The graphical and/or analytical methods discussed herein are used in such a way that engineers, technicians and students can, themselves, use them or draw inspiration from them for their own projects. Logically, the fundamentals of computer-assisted design are examined using the software tools recommended in the industry.

4)

Pedagogical and industrial case studies

: The solved examples given here are taken from the author’s own experience in industry and in a university setting. These examples cover a wide range of fields in manufacturing industry (recreational equipment, lifting devices and forms of transport, pedagogical demonstrative mechanisms, etc.). The studies also look at how to make the right choice of materials and structures for the projects at hand.

This book, which is devoted to applied mechanical design, draws on case studies taken from the author’s own experience in the professional and university spheres. It is based on a methodology and pedagogical approach which are deliberately painstaking, because they are being used instead of pure mathematics and applied physics to present the subject. It is an arduous task to present a mechanical design book, owing to the multidisciplinarity of the field and the computer tools which are crucially important to run the design calculations quickly. Design is not a singular subject: a complete design project will inevitably require the coming together of a multitude of technical, scientific and technological disciplines, in addition to clarity in the drafting of the dossiers making up the studies.

The first chapter discusses the organization of workflow for projects. Its purpose is to guide the projector–designer through the entire organizational process, from the first general overview sketch to the launch of the idea based on the technical specifications. This part tackles the search for practical solutions which can orientate the projects. This, in a manner of speaking, is the art of conducting a design project.

Chapter 2 sets out the main design tasks, with emphasis being placed on the judicious use of materials and geometric form. Throughout the book’s eleven chapters, we present case studies with worked solutions as a didactic approach.

Next, the third chapter presents the principles underpinning the calculations for the elements of machines, materials and structures. It is here that calculation tools prove indispensable for the design analysis. This chapter discusses the need for process analysis and materials analysis. It is also at this stage that the issue of sizing comes into play, and that geometry (GPS: Geometrical Product Specifications) takes on its demonstrative part. We also look at the theory of Hertz contact stress.

Chapter 4 is given over to the particular geometric forms used in applied mechanical design: profiled and incurvate parts (we look at the NURBS method: Non-Uniform Rational Basis Spline).

We move on, in our fifth chapter, to the appropriate use of the principles of calculations for the elements of machines employed in mechanical construction. We touch upon cases of material resistance and give further case studies, with solutions, which can serve as concrete examples to be used in tutorials and other applied mechanical design workshops.

The sixth chapter presents case studies devoted to the noise and vibrations produced by mechanical elements and machine supports. The solution sets demonstrated here could be used to devise other projected cases for tutorials.

Chapter 7 offers further context about a number of cases commonly encountered in welded structures, and presents the calculations used to determine the fatigue of stationary parts and bearings.

The eighth chapter then presents case studies on the brakes and clutch systems used in applied mechanical design.

In the ninth chapter, we discuss bolted mechanical structures, such as spring washers and axles.

Chapter 10 is devoted specifically to the principles underlying the calculations for machine elements made of plastic materials.

The eleventh chapter presents concrete projects that have actually been tackled in the author’s classes and tutorials, and the resulting commentated sets of solutions also offered.

The Conclusion and Appendix provide a brief summary, containing a glossary, and tables of reference pertaining to the standards in force in construction and mechanical design. Having come to the end of the above sections of the discussion, this final chapter presents a number of recommendations regarding the drafting and final presentation of projects.