The Bonded Electrical Resistance Strain Gage: An Introduction

Contents......Page 10
1.1 Introduction......Page 16
1.2 Characteristics Desired in a Strain Gage......Page 17
1.3 General Considerations......Page 18
1.4 Analysis of Strain Sensitivity in Metals......Page 27
1.5 Wire Strain Gages......Page 37
1.6 Foil Strain Gages......Page 42
1.7 Semiconductor Gages......Page 45
1.8 Some Other Types of Gages......Page 46
1.9 Brittle Lacquer Coatings......Page 49
2.1 Introduction......Page 55
2.2 Basic Concepts of Stress......Page 56
2.3 Biaxial Stresses......Page 58
2.4 Mohr\'s Circle for Stress......Page 67
2.5 Basic Concepts of Strain......Page 74
2.6 Plane Strain......Page 75
2.7 Mohr\'s Circle for Strain......Page 81
2.8 Stress–Strain Relationships......Page 85
2.9 Application of Equations......Page 90
2.10 Stress and Strain Invariants......Page 94
3.1 Introduction......Page 103
3.2 Constant-Voltage Circuit......Page 104
3.3 Constant-Current Circuit......Page 107
3.4 Advantages of the Constant-Current Circuit......Page 109
3.5 Fundamental Laws of Measurement......Page 110
4.1 Introduction......Page 113
4.2 Circuit Equations......Page 114
4.3 Analysis of the Circuit......Page 119
4.4 Linearity Considerations......Page 132
4.5 Temperature Effects......Page 142
4.6 Calibration......Page 154
5.1 Introduction......Page 159
5.2 Elementary Bridge Equations......Page 162
5.3 Derivation of Elementary Bridge Equations......Page 170
5.4 General Bridge Equations......Page 185
5.5 Effect of Lead-Line Resistance......Page 193
5.6 Circuit Calibration......Page 206
5.7 Comments......Page 208
6.1 Introduction......Page 218
6.2 Analysis of Single Gage Desensitization......Page 220
6.3 Analysis of Half-Bridge Desensitization......Page 231
6.4 Analysis of Full-Bridge Sensitivity Variation......Page 240
7.1 Significance of Strain Sensitivity and Gage Factor......Page 247
7.2 Basic Equations for Unit Change in Resistance......Page 249
7.3 Determination of Gage Factor and Transverse Sensitivity Factor......Page 255
7.4 Use of Strain Gages Under Conditions Differing from those Corresponding to Calibration......Page 259
7.5 Indication from a Pair of Like Strain Gages Crossed at Right Angles......Page 261
8.2 Stress Fields......Page 266
8.3 Rosette Geometry......Page 269
8.4 Analytical Solution for the Rectangular Rosette......Page 271
8.5 Analytical Solution for the Equiangular or Delta Rosette......Page 280
8.6 Rosettes with Four Strain Observations......Page 288
8.7 Graphical Solutions......Page 294
9.2 Two Identical Orthogonal Gages......Page 304
9.3 Two Different Orthogonal Gages......Page 307
9.4 Three-Element Rectangular Rosette......Page 309
9.5 The Equiangular or Delta Rosette......Page 314
10.2 The Normal Stress Gage......Page 323
10.3 The SR-4 Stress–Strain Gage......Page 329
10.4 Electrical Circuit for Two Ordinary Gages to Indicate Normal Stress......Page 333
10.5 The V-Type Stress Gage......Page 334
10.6 Application of a Single Strain Gage to Indicate Principal Stress......Page 339
10.7 Determination of Plane Shearing Stress......Page 340
11.2 Basic Considerations of Temperature-Induced Strain......Page 350
11.3 Self-Temperature-Compensated Strain Gages......Page 356
11.4 Strain Gage–Test Material Mismatch......Page 362
11.5 Compensating Gage......Page 366
12.1 Introduction......Page 373
12.2 Axial-Force Transducers......Page 376
12.3 Simple Cantilever Beam......Page 381
12.4 Bending Beam Load Cells......Page 385
12.5 Shear Beam Load Cell......Page 388
12.6 The Torque Meter......Page 391
12.7 The Strain Gage Torque Wrench......Page 393
12.8 Pressure Measurement......Page 395
13.1 General Considerations......Page 403
13.2 Strain Gage Alloys......Page 404
13.3 Grid Backing Materials......Page 406
13.4 Gage Length, Geometry, and Resistance......Page 407
13.5 Adhesives......Page 409
13.6 Bonding a Strain Gage to a Specimen......Page 411
Answers to Selected Problems......Page 415
D......Page 418
P......Page 419
S......Page 420
W......Page 421