《Experimental Stress Analysis and Motion Meassurement》

PART ⅠEXPERIMENTAL STRESS ANALYSIS1

CHAPTER 1.STRESS ANALYSIS BY STRAIN MEASUREMENT3

1-1Introduction3

1-2 Mechanical strain gages5

1-3 Optical strain gages9

1-4 Electrical strain gages13

1-5 Grid techniques18

1-6 Moiré fringe method21

1-7 Brittle coatings for strain indication31

1-8 References listed in Chapter 142

1-9 Problems43

1-10 Suggested laboratory experiments47

CHAPTER 2.VARIABLE-RESISTANCE STRAIN GAGES50

2-1Gage characteristics and types50

2-1a Gage factor51

2-1b Gage materials54

2-1c Method of gage construction and gage style-metal gages57

2-1d Method of gage construction and gage style-semiconductor gages63

2-1e Grid-backing materials67

2-1f Gage-bonding materials69

2-1g Mounting,wiring,moisture-proofing,and checking techniques71

2-2Circuitry for resistance strain gages76

2-2a Circuit analysis—metal strain gages77

2-2b Circuit analysis—semiconductor gages94

2-2c Calibrating strain-gage circuits98

2-2d Balancing strain-gage circuits103

2-2e Temperature compensation of strain-gage circuits106

2-2f Effect of leads,switches,and slip rings in strain-gage circuits117

2-2g Use of alternating current to power strain-gage circuits124

2-3 References listed in Chapter 2129

2-4 Problems130

2-5 Suggested laboratory experiments143

CHAPTER 3.INDICATING AND RECORDING EQUIPMENT FOR RESISTANCE STRAIN GAGES150

3-1Introduction150

3-2Indicators and multichannel recording equipment for static strains151

3-2a Unbalanced bridge systems151

3-2b Balanced bridge systems156

3-2c Reference bridge systems157

3-2d Constant-current strain indicators161

3-2e Multichannel recording systems163

3-3Equipment for recording dynamic strain166

3-3a Recorders utilizing galvanometers170

3-3b Recorders utilizing cathode ray oscilloscopes174

3-3c Magnetic tape recorders178

3-4 Telemetry systems191

3-5 References listed in Chapter 3193

3-6 Suggested laboratory experiments193

CHAPTER 4.SOME SPECIAL PROBLEMS ENCOUNTERED IN THE USE OF RESISTANCE STRAIN GAGES195

4-1Introduction195

4-2Unusual environments and applications196

4-2a Strain measurements over long periods196

4-2b Moistureproofing strain gages201

4-2c Strain gages subjected to nuclear radiation203

4-2d Strain measurements at high temperatures205

4-2e Strain measurements at low temperatures214

4-2f Magnetic effects215

4-2g Strain measurements at high pressures215

4-2h Measurement of strains on low-modulus materials and/or on thin sections217

4-2i Measurement of large strains221

4-2j Measurement of cyclic strains223

4-2k Measurement of transient strains225

4-2l Thermal-stress studies227

4-2m Measurement of strains at interior points232

4-3Additional special problems(abstracts and references)233

4-3a Use of strain gages on nonmetallic materials233

4-3b Use of strain gages in medical research236

4-3c Use of strain gages to measure residual stresses238

4-3d Use of strain gages in the construction of transducers239

4-4 References listed in Chapter 4240

CHAPTER 5.REDUCTION OF STRAIN-GAGE DATA242

5-1Introduction242

5-2 Effect of transverse sensitivity243

5-3Computing stresses from measured strains251

5-3a Rectangular rosettes252

5-3b Delta rosettes261

5-3c Two-element,90-degree rosettes262

5-3d Rosettes made from single-element gages265

5-3e Stress gages266

5-4 Summary272

5-5 Appendix A(Methods for determining transverse sensitivity)273

5-6 Appendix B(Stress-strain gage corrected for transverse sensitivity of the individual elements)280

5-7 References listed in Chapter 5281

5-8 Problems281

5-9 Suggested laboratory experiments285

CHAPTER 6.STRESS ANALYSIS BY PHOTOELASTICITY287

6-1Introduction287

6-2 Optical theory289

6-3 Stress-optical relationships297

6-4 Equipment and models303

6-5Static-stress analysis308

6-5a Two-dimensional model techniques308

6-5b Three-dimensional techniques322

6-6 Dynamic-stress analysis323

6-7 Thermal-stress analysis328

6-8 References listed in Chapter 6329

6-9 Problems332

6-10 Suggested laboratory experiments336

CHAPTER 7.STRESS ANALYSIS BY PHOTOELASTIC COATINGS338

7-1Surface-coating techniques338

7-2 Photoelastic strain gages347

7-3 References listed in Chapter 7355

7-4 Problems355

7-5 Suggested laboratory experiments358

PART ⅡMOTION MEASUREMENT361

CHAPTER 8.MEASUREMENT OF DISPLACEMENT,VELOCITY,AND ACCELERATION362

8-1Introduction362

8-2Motion measurement using a reference363

8-2a Measurement of displacement363

8-2b Measurement of velocity379

8-3Motion measurement using force transducers380

8-3a Measurement of angular velocity and acceleration380

8-3b Measurement of linear acceleration382

8-4 References listed in Chapter 8385

8-5 Suggested laboratory experiments385

CHAPTER 9.MOTION MEASUREMENT WITH NO REFERENCE-SEISMIC SYSTEMS388

9-1Basic seismic theory388

9-1a Steady-state response389

9-1b Transient response395

9-2 Seismic instruments401

9-3Circuitry for piezoelectric accelerometers414

9-3a Sensitivity considerations414

9-3b Low-frequency response considerations417

9-3c System components423

9-3d System frequency response427

9-4 References listed in Chapter 9430

9-5 Problems431

9-6 Suggested laboratory experiments433

CHAPTER 10.ACCELEROMETER CALIBRATION435

10-1Introduction435

10-2 Constant-acceleration methods436

10-3 Sinusoidal-motion methods438

10-4 Transient-motion methods440

10-5 Calibration by comparison to a standard444

10-6 Other kinds of calibration446

10-7Accelerometer system calibration448

10-7a Accelerometers capable of DC response448

10-7b Piezoelectric accelerometers454

10-8 References listed in Chapter 10468

10-9 Problems469

10-10 Suggested laboratory experiments473

CHAPTER 11.ACCELEROMETER PROBLEMS,DIFFERENTIATION AND INTEGRATION475

l1-1Humidity and dirt475

11-2 Temperature effects476

11-3 Nuclear-radiation effects478

11-4 Acoustical sensitivity479

11-5 Zero shift with piezoelectric accelerometers479

11-6 Mounting techniques481

11-7 Effect of accelerometer’s presence on the acceleration measured482

11-8 Differentiation and integration of motion measurements487

11-9 References listed in Chapter 11496

11-10 Problems496

11-11 Suggested laboratory experiments503

INDEX509