instrumentation for engineering measurements-dally jw, rile wf

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  • INSTRUMENTATION FOR ENGINEERING MEASUREMENTS

    Second Edition

    JAMES W. DALLY University of Maryland

    WILLIAM F. RILEY KENNETH G. McCONNELL Iowa State University

    JOHN WILEY & SONS, INC. New York Chichester Brisbane Toronto Singapore

  • CONTENTS

    LIST OF SYMBOLS xv i i

    CHAPTER 1 APPLICATIONS OF ELECTRONIC INSTRUMENT SYSTEMS 01

    1.1 INTRODUCTION 01 1.2 THE ELECTRONIC INSTRUMENT SYSTEM 02 1.3 ENGINEERING ANALYSIS 03 1.4 PROCESS CONTROL 04

    1.4.1 PROCESS CONTROL DEVICES 06 1.5 EXPERIMENTAL ERROR 12

    1.5.1 ACCUMULATION OF ACCEPTED ERROR 13 1.5.2 IMPROPER FUNCTIONING OF

    INSTRUMENTS 14 1.5.3 EFFECT OF THE TRANSDUCER ON THE

    CHAPTER

    1.6 1.7

    R 2 2.1 2.2 2.3 2.4

    2.5 2.6 2.7

    2.8 2.9

    PROCESS 1.5.4 DUAL SENSITIVITY ERRORS 1.5.5 OTHER SOURCES OF ERROR

    MINIMIZING EXPERIMENTAL ERROR SUMMARY REFERENCES EXERCISES

    ANALYSIS OF CIRCUITS INTRODUCTION AND DEFINITIONS BASIC ELECTRICAL COMPONENTS KIRCHHOFF'S CIRCUIT LAWS DIODES, TRANSISTORS, AND GATES

    2.4.1 DIODES 2.4.2 TRANSISTORS 2.4.3 GATES

    DC CIRCUITS PERIODIC FUNCTIONS AC CIRCUITS

    2.7.1 IMPEDANCE FREQUENCY RESPONSE FUNCTION SUMMARY REFERENCES EXERCISES

    15 17 18 19 20 20 21

    24 24 26 28 29 29 29 31 33 34 38 40 42 44 45 45

    vii

  • CONTENTS

    CHAPTER 3 3.1 3.2

    3.3

    3.4

    3.5

    3.6

    CHAPTER 4 4.1 4.2 4.3 4.4 4.5

    4.6

    4.7 4.8 4.9

    4.10 4.11 4.12

    ANALOG RECORDING INSTRUMENTS INTRODUCTION GENERAL CHARACTERISTICS OF RECORDING INSTRUMENTS VOLTMETERS FOR STEADY-STATE MEASUREMENTS

    3.3.1 D'ARSONVAL GALVANOMETER 3.3.2 AMMETER 3.3.3 DC VOLTMETERS 3.3.4 VOLTMETER LOADING ERRORS 3.3.5 AMPLIFIED VOLTMETERS 3.3.6 POTENTIOMETRIC VOLTMETERS

    VOLTMETERS FOR SLOWLY VARYING SIGNALS

    3.4.1 STRIP-CHART RECORDERS 3.4.2 X-Y RECORDERS

    VOLTMETERS FOR RAPIDLY VARYING SIGNALS

    3.5.1 OSCILLOGRAPH RECORDERS 3.5.2 TRANSIENT RESPONSE

    OF GALVANOMETERS 3.5.3 PERIODIC SIGNAL RESPONSE

    OF GALVANOMETERS 3.5.4 OSCILLOSCOPES 3.5.5 MAGNETIC TAPE RECORDERS

    SUMMARY REFERENCES EXERCISES

    DIGITAL RECORDING SYSTEMS INTRODUCTION DIGITAL CODES CONVERSION PROCESSES DIGITAL-TO-ANALOG CONVERTERS ANALOG-TO-DIGITAL CONVERTERS

    4.5.1 SUCCESSIVE-APPROXIMATION METHOD

    4.5.2 INTERGRATION METHOD 4.5.3 PARALLEL OR FLASH METHOD

    DATA DISTRIBUTION 4.6.1 BUS STRUCTURES

    INTERFACES DIGITAL VOLTMETERS DATA-LOGGING SYSTEMS DATA-ACQUISITION SYSTEMS PC-BASED DATA-ACQUISITION SYSTEMS DIGITAL OSCILLOSCOPES

    49 49

    49

    54 54 55 56 57 57 58

    59 59 60

    61 61

    62

    68 73 77 81 82 82

    86 86 86 88 89 92

    92 94 97 98 99 101 102 108 109 112 112

  • CONTENTS ix

    4.13 WAVEFORM RECORDERS 4.14 ALIASING

    4.14.1 ANTIALIASING FILTERS 4.15 SUMMARY

    REFERENCES EXERCISES

    CHAPTER 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9

    10 11 12 13 14

    CHAPTER 6 6.1 6.2

    6.3

    6.4

    6.5 6.6

    6.7 6.8

    SENSORS FOR TRANSDUCERS INTRODUCTION POTENTIOMETERS DIFFERENTIAL TRANSFORMERS RESISTANCE STRAIN GAGES CAPACITANCE SENSORS EDDY-CURRENT SENSORS PIEZOELECTRIC SENSORS PIEZORESISTIVE SENSORS PHOTOELECTRIC SENSORS

    5.9.1 VACUUM-TUBE DETECTORS 5.9.2 PHOTOCONDUCTIVE CELLS 5.9.3 SEMICONDUCTOR PHOTODIODES

    RESISTANCE TEMPERATURE DETECTORS THERMISTORS THERMOCOUPLES CRYSTAL OSCILLATORS SUMMARY REFERENCES EXERCISES

    SIGNAL CONDITIONING CIRCUITS INTRODUCTION POWER SUPPLIES

    6.2.1 BATTERY SUPPLIES 6.2.2 LINE VOLTAGE SUPPLIES

    POTENTIOMETER CIRCUIT (CONSTANT VOLTAGE) POTENTIOMETER CIRCUIT (CONSTANT CURRENT) WHEATSTONE BRIDGE (CONSTANT VOLTAGE) WHEATSTONE BRIDGE (CONSTANT CURRENT) AMPLIFIERS OPERATIONAL AMPLIFIERS

    6.8.1 INVERTING AMPLIFIER 6.8.2 DIFFERENTIAL AMPLIFIER 6.8.3 VOLTAGE FOLLOWER 6.8.4 SUMMING AMPLIFIER

    116 117 119 119 120 120

    124 124 124 126 129 135 137 139 142 144 146 149 149 151 152 153 155 157 157 158

    162 162 162 162 165

    166

    169 170

    173 176 181 181 184 186 187

  • x CONTENTS

    6.8.5 INTEGRATING AMPLIFIER 188 6.8.6 DIFFERENTIATING AMPLIFIER 189

    6.9 FILTERS 189 6.9.1 HIGH-PASS RC FILTER 190 6.9.2 LOW-PASS RC FILTER 191 6.9.3 ACTIVE FILTER 193

    6.10 AMPLITUDE MODULATION AND DEMODULATION 194

    6.11 TIME-MEASURING CIRCUITS 197 6.11.1 BINARY COUNTING UNIT 197 6.11.2 GATES IN COUNTER APPLICATIONS 198 6.11.3 TRIGGERS 198 6.11.4 COUNTING INSTRUMENTS 199

    6.12 SUMMARY 202 REFERENCES 205 EXERCISES 206

    CHAPTER 7 RESISTANCE-TYPE STRAIN GAGES 211 7.1 INTRODUCTION 211 7.2 ETCHED-FOIL STRAIN GAGES 212 7.3 STRAIN-GAGE INSTALLATION 212 7.4 WHEATSTONE BRIDGE SIGNAL CONDITIONING 214 7.5 RECORDING INSTRUMENTS FOR STRAIN

    GAGES 219 7.5.1 DIRECT-READING STRAIN INDICATOR 220 7.5.2 NULL-BALANCE BRIDGES 220 7.5.3 STRAIN-GAGE SIGNAL CONDITIONERS 222 7.5.4 WHEATSTONE BRIDGE AND

    OSCILLOSCOPE 222 7.5.5 WHEATSTONE BRIDGE AND

    OSCILLOGRAPH 224 7.6 CALIBRATION METHODS 227 7.7 EFFECTS OF LEAD WIRES, SWITCHES, AND

    SLIP RINGS 229 7.7.1 LEAD WIRES 229 7.7.2 SWITCHES 232 7.7.3 SLIP RINGS 234

    7.8 ELECTRICAL NOISE 234 7.9 TEMPERATURE-COMPENSATED GAGES 236

    7.10 ALLOY SENSITIVITY, GAGE FACTOR, AND CROSS-SENSITIVITY FACTORS 238

    7.11 DATA-REDUCTION METHODS 241 7.11.1 THE UNIAXIAL STATE OF STRESS 241 7.11.2 THE BIAXIAL STATE OF STRESS 242 7.11.3 THE GENERAL STATE OF STRESS 242

    7.12 HIGH-TEMPERATURE STRAIN MEASUREMENTS 244

  • CONTENTS xi

    7.13 SUMMARY REFERENCES EXERCISES

    245 248 249

    CHAPTER 8 FORCE, TORQUE, AND PRESSURE MEASUREMENTS

    8.1 INTRODUCTION 8.2 FORCE MEASUREMENTS (LOAD CELLS)

    8.2.1 LINK-TYPE LOAD CELL 8.2.2 BEAM-TYPE LOAD CELL 8.2.3 RING-TYPE LOAD CELL 8.2.4 SHEAR-WEB-TYPE LOAD CELL

    8.3 TORQUE MEASUREMENT (TORQUE CELLS) 8.3.1 TORQUE CELLS - DESIGN CONCEPTS 8.3.2 TORQUE CELLS-DATA TRANSMISSION

    8.4 COMBINED MEASUREMENTS OF FORCE AND MOMENTS OR TORQUES

    8.4.1 FORCE-MOMENT MEASUREMENTS 8.4.2 FORCE-TORQUE MEASUREMENTS

    8.5 PRESSURE MEASUREMENTS (PRESSURE TRANSDUCERS)

    8.5.1

    8.6

    8.7

    8.9

    DISPLACEMENT-TYPE PRESSURE TRANSDUCER DIAPHRAGM-TYPE PRESSURE TRANSDUCER PIEZOELECTRIC-TYPE PRESSURE TRANSDUCER

    MINIMIZING ERRORS IN TRANSDUCERS 8.6.1 DUAL SENSITIVITY

    ZERO SHIFT WITH TEMPERATURE CHANGE BRIDGE BALANCE SPAN ADJUST SPAN CHANGE WITH TEMPERATURE

    FREQUENCY RESPONSE OF TRANSDUCERS 8.7.1 RESPONSE OF A FORCE TRANSDUCER TO

    A TERMINATED RAMP FUNCTION 8.7.2 RESPONSE OF A FORCE TRANSDUCER TO

    A SINUSOIDAL FORCING FUNCTION CALIBRATION OF TRANSDUCERS SUMMARY REFERENCES EXERCISES

    8.5.2

    8.5.3

    8.6.2

    8.6.3 8.6.4 8.6.5

    253 253 253 254 256 258 260 262 262 264

    268 268 271

    271

    272

    272

    275 276 277

    279 280 280 280 280

    282

    285 286 288 289 290

    CHAPTER 9 DISPLACEMENT, VELOCITY, AND ACCELERATION MEASUREMENTS

    9.1 INTRODUCTION 9.2 THE SEISMIC TRANSDUCER MODEL

    293 293 294

  • xii CONTENTS

    9.3 DYNAMIC RESPONSE OF THE SEISMIC MODEL 295

    9.3.1 SINUSOIDAL EXCITATION 295 9.3.2 TRANSIENT EXCITATIONS 298

    9.4 SEISMIC MOTION TRANSDUCERS 299 9.4.1 SEISMIC DISPLACEMENT

    TRANSDUCERS 300 9.4.2 SEISMIC VELOCITY TRANSDUCERS 301 9.4.3 SEISMIC ACCELERATION

    TRANSDUCERS 301 9.5 PIEZOELECTRIC FORCE TRANSDUCERS 305 9.6 PIEZOELECTRIC SENSOR CIRCUITS 306

    9.6.1 CHARGE SENSITIVITY MODEL 306 9.6.2 VOLTAGE-FOLLOWER CIRCUIT 308 9.6.3 CHARGE-AMPLIFIER CIRCUIT 311 9.6.4 BUILT-IN VOLTAGE FOLLOWERS 313

    9.7 RESPONSE OF PIEZOELECTRIC CIRCUITS TO TRANSIENT SIGNALS 317

    9.8 ACCELEROMETER CALIBRATION 320 9.9 DYNAMIC CALIBRATION OF FORCE

    TRANSDUCERS 323 9.9.1 FORCE TRANSDUCER CALIBRATION

    BY IMPACT 325 9.10 OVERALL SYSTEM CALIBRATION 327 9.11 SOURCES OF ERROR WITH PIEZOELECTRIC

    TRANSDUCERS 328 9.12 DISPLACEMENT MEASUREMENTS IN A

    FIXED REFERENCE FRAME 331 9.12.1 DISPLACEMENT MEASUREMENTS WITH

    RESISTANCE POTENTIOMETERS 331 9.12.2 DISPLACEMENT MEASUREMENTS WITH

    MULTIPLE-RESISTOR DEVICES 335 9.12.3 PHOTOELECTRIC DISPLACEMENT

    TRANSDUCERS 336 9.13 OPTICAL DISPLACEMENT MEASUREMENTS 337

    9.13.1 OPTICAL TRACKER SYSTEM 337 9.13.2 VIDEO CAMERA MOTION

    ANALYSIS 338 9.14 VELOCITY MEASUREMENTS 339

    9.14.1 LINEAR-VELOCITY MEASUREMENTS 340

    9.14.2 ANGULAR-VELOCITY MEASUREMENTS 342

    9.14.3 LASER-DOPPLER SYSTEM 343 9.15 SUMMARY 344

    REFERENCES 345 EXERCISES 347

  • CONTENTS xiii

    CHAPTER 10 ANALYSIS OF VIBRATING SYSTEMS 356 10.1 INTRODUCTION 356

    10.1.1 TEMPORAL MEAN 358 10.1.2 TEMPORAL MEAN SQUARE

    AND ROOT MEAN SQUARE 358 10.2 SINUSOIDAL SIGNAL ANALYSIS 358 10.3 CHARACTERISTICS OF SIGNALS 3 61

    10.3.1 PERIODIC SIGNALS 362 10.3.2 TRANSIENT SIGNALS 363 10.3.3 RANDOM SIGNALS 366

    10.4 LUMPED MASS-SPRING VIBRATION MODELS 368

    10.4.1 UNDAMPED NATURAL FREQUENCY AND MODE SHAPE 369

    10.4.2 FORCED VIBRATION RESPONSE (DIRECT SOLUTION) 370

    10.4.3 FORCED VIBRATION RESPONSE (MODAL SOLUTION) 370

    10.5 CONTINUOUS VIBRATION MODELS 373 10.5.1 FUNDAMENTAL EQUATION

    OF MOTION 373 10.5.2 STEADY-STATE MODAL SOLUTION 374

    10.6 THE LINEAR INPUT-OUTPUT MODEL 376 10.6.1 IMPULSE RESPONSE 377 10.6.2 RANDOM INPUT-OUTPUT

    RELATIONSHIPS 379 10.7 BASICS OF A DIGITAL FREQUENCY

    ANALYZER 380 10.7.1 TIME SAMPLING PROCESS 380 10.7.2 CONVOLUTION 381 10.7.3 FILTER LEAKAGE 385 10.7.4 BLOCK DIAGRAM 387

    10.8 USING A DIGITAL FREQUENCY ANALYZER 387 10.8.1 RELATIONSHIPS FOR FREQUENCY

    ANALYZERS 388 10.8.2 FILTER CHARACTERISTICS 390 10.8.3 FOUR COMMON WINDOW

    FUNCTIONS 392 10.8.4 UNCERTAINTY IN THE MAGNITUDE