Experimental Mechanics: An Introduction

Description

The book presents in a clear, simple, straightforward, novel  and unified manner the most used methods of experimental mechanics of solids for the determination of displacements, strains and stresses. Emphasis is given on the principles of operation of the various methods, not in their applications to engineering problems. The book is divided into sixteen chapters which include strain gages, basic optics, geometric and interferometric moiré, optical methods (photoelasticity, interferometry, holography, caustics, speckle methods, digital image correlation), thermoelastic stress analysis, indentation, optical fibers, nondestructive testing, and residual stresses. The book will be used not only as a learning tool, but as a basis on which the researcher, the engineer, the experimentalist, the student can develop their new own ideas to promote research in experimental mechanics of solids. Preface Contents About the Author 1 Electrical Resistance Strain Gages 1.1 Introduction 1.2 Basic Principles 1.3 Bonded Resistance Strain Gages 1.4 Transverse Sensitivity and Gage Factor 1.5 Electrical Circuits 1.5.1 Introduction 1.5.2 The Potentiometer Circuit 1.5.3 The Wheatstone Bridge 1.6 Strain Gage Rosettes Further Readings 2 Fundamentals of Optics 2.1 Introduction 2.2 Historical Overview 2.3 Light Sources, Wave Fronts, and Rays 2.4 Reflection and Mirrors 2.4.1 Reflection 2.4.2 Plane Mirrors 2.4.3 Spherical Mirrors 2.5 Refraction 2.6 Thin Lenses 2.7 The Wave Nature of Light—Huygens’ Principle 2.8 Electromagnetic Theory of Light 2.9 Polarization 2.10 Interference 2.10.1 Introduction 2.10.2 Interference of Two Linearly Polarized Beams 2.10.3 Young’s Double-Slit Experiment 2.10.4 Multi-slit Interference 2.10.5 Interference of Two Plane Waves 2.10.6 Change of Phase upon Reflection—Thin Films 2.10.7 Dispersion 2.11 Diffraction 2.11.1 Introduction 2.11.2 Single Slit Diffraction 2.11.3 Two-Slit Diffraction 2.11.4 The Diffraction Grating 2.11.5 Diffraction by a Circular Aperture 2.11.6 Limit of Resolution 2.11.7 Fraunhofer Diffraction as a Fourier Transform 2.11.8 Optical Spatial Filtering 2.12 Camera Further Readings 3 Geometric Moiré 3.1 Introduction 3.2 Terminology 3.3 The Moiré Phenomenon 3.4 Mathematical Analysis of Moiré Fringes 3.5 Relationships Between Line Grating and Moiré Fringes 3.6 Moiré Patterns Formed by Circular, Radial and Line Gratings 3.7 Measurement of In-Plane Displacements 3.8 Measurement of Out-Of-Plane Displacements 3.9 Measurement of Out-Of-Plane Slopes 3.10 Sharpening of Moiré Fringes 3.11 Moiré of Moiré Further Readings 4 Coherent Moiré and Moiré Interferometry 4.1 Introduction 4.2 Superposition of Two Diffraction Gratings 4.3 Moiré Patterns 4.4 Optical Filtering and Fringe Multiplication 4.5 Advantages Offered by Coherent Moiré 4.6 Moiré Interferometry 4.6.1 Introduction 4.6.2 Optical Arrangement 4.6.3 The Method 4.6.4 Determination of Strains Further Readings 5 Moiré Patterns Formed by Remote Gratings 5.1 Introduction 5.2 Geometric Moiré Methods 5.3 The Coherent Grading Sensor (CGS) Method 5.3.1 Introduction 5.3.2 Experimental Arrangement 5.3.3 Governing Equations 5.4 Comparison of the Geometric Moiré and the CGS Method Further Readings 6 The Method of Caustics 6.1 Introduction 6.2 General Equations for Reflecting Surfaces 6.3 The Ellipsoid Mirror 6.4 Intensity Distribution of Light Rays Reflected or Transmitted by a Transparent Specimen 6.5 Stress-Optical Equations 6.6 Crack Problems 6.6.1 Introduction 6.6.2 Principle of the Method 6.6.3 Opening-Mode Loading 6.6.4 Mixed-Mode Loading 6.6.5 Anisotropic Materials 6.6.6 The State of Stress Near the Crack Tip 6.6.7 Comparison of the Method of Caustics and Photoelasticity Further Readings 7 Photoelasticity 7.1 Introduction 7.2 Plane Polariscope 7.3 Circular Polariscope 7.4 Isoclinics 7.5 Isochromatics 7.6 Isochromatics with White Light 7.7 Properties of Isoclinics 7.8 Properties of Isochromatics 7.9 Compensation Methods 7.9.1 Introduction 7.9.2 The Tension/Compression Specimen 7.9.3 Babinet and Babinet-Soleil Compensators 7.9.4 Sernarmont Compensation Method 7.9.5 Tardy Compensation Method 7.10 Determination of the Photoelastic Constant fs 7.11 Stress Separation 7.12 Fringe Multiplication and Sharpening 7.13 Transition From Model to Prototype 7.14 Three-Dimensional Photoelasticity 7.15 Photoelastic Coatings 7.15.1 Introduction 7.15.2 Transfer of Stresses From Body to Coating 7.15.3 Determination of Stresses 7.15.4 Reinforcing Effect 7.15.5 Photoelastic Strain Gages Further Readings 8 Interferometry 8.1 Introduction 8.2 Interferometers 8.3 Analysis of Interferometers 8.3.1 Introduction 8.3.2 The Mach–Zehnder Interferometer 8.3.3 The Michelson Interferometer 8.3.4 The Fizeau-Type Interferometer 8.3.5 Other Interferometers 8.3.6 A Generic Analysis of Interferometers Further Readings 9 Holography 9.1 Introduction 9.2 Recording and Reconstruction Processes 9.3 Holographic Interferometry 9.3.1 Introduction 9.3.2 Real-Time Holographic Interferometry 9.3.3 Double-Exposure Holographic Interferometry 9.3.4 Sensitivity Vector 9.4 Holographic Photoelasticity 9.4.1 Introduction 9.4.2 Isochromatic-Isopachic Patterns 9.4.3 Generic Interpretation Further Readings 10 Optical Fiber Strain Sensors 10.1 Introduction 10.2 Optical Fibers 10.2.1 Introduction 10.2.2 Structure 10.2.3 Principle of Operation 10.2.4 Applications 10.2.5 Advantages and Disadvantages 10.3 Fiber Optic Sensors (FOS) 10.3.1 Architecture of a FOS 10.3.2 Classification of FOSs 10.3.3 Interferometric FOSs 10.3.4 Fiber Bragg Grating Sensors (FBGSs) 10.3.5 Multiplexing 10.3.6 Advantages and Disadvantages of FOSs 10.3.7 Applications of FOSs Further Readings 11 Speckle Methods 11.1 Introduction 11.2 The Speckle Effect 11.3 Speckle Photography 11.3.1 Introduction 11.3.2 Point-by-Point Interrogation of the Specklegram 11.3.3 Spatial Filtering of the Specklegram 11.4 Speckle Interferometry 11.5 Shearography 11.6 Electronic Speckle Pattern Interferometry (ESPI) Further Readings 12 Digital Image Correlation (DIC) 12.1 Introduction 12.2 Steps of DIC 12.3 Speckle Patterning 12.4 Image Digitization 12.5 Intensity Interpolation 12.6 Image Correlation—Displacement Measurement 12.7 2-D DIC 12.8 3-D DIC 12.9 Volumetric Digital Image Correlation (V-DIC) Further Readings 13 Thermoelastic Stress Analysis (TSA) 13.1 Introduction 13.2 Thermoelastic Law 13.3 Infrared Detectors 13.4 Adiabaticity 13.5 Specimen Preparation 13.6 Calibration 13.7 Stress Separation 13.8 Applications Further Readings 14 Indentation Testing 14.1 Introduction 14.2 Contact Mechanics 14.3 Macro-indentation Testing 14.3.1 Brinell Test 14.3.2 Meyer Test 14.3.3 Vickers Test 14.3.4 Rockwell Test 14.4 Micro-indentation Testing 14.4.1 Vickers Test 14.4.2 Knoop Test 14.5 Nanoindentation Testing 14.5.1 Introduction 14.5.2 The Elastic Contact Method 14.5.3 Nanoindentation for Measuring Fracture Toughness Further Readings 15 Nondestructive Testing (NDT) 15.1 Introduction 15.2 Dye Penetrant Inspection (DPI) 15.2.1 Principle 15.2.2 Application 15.2.3 Advantages and Disadvantages 15.3 Magnetic Particles Inspection (MPI) 15.3.1 Principle 15.3.2 Advantages and Disadvantages 15.4 Eddy Currents Inspection (ECI) 15.4.1 Principle 15.4.2 Advantages and Disadvantages 15.5 X-ray Diffraction (XRD) 15.5.1 Introduction 15.5.2 X-rays 15.5.3 X-ray Diffraction 15.5.4 Measurement of Strain 15.5.5 Instrumentation 15.6 Ultrasonic Testing (UT) 15.6.1 Introduction 15.6.2 Operation 15.6.3 Advantages and Disadvantages 15.7 Acoustic Emission Testing (AET) 15.7.1 Introduction 15.7.2 Acoustic Emission Testing 15.7.3 Advantages and Disadvantages Further Readings 16 Residual Stresses—The Hole-Drilling Method 16.1 Introduction 16.2 Hole-Drilling Method 16.3 Uniaxial Residual Stresses 16.4 Biaxial Residual Stresses 16.5 Variation of Residual Stresses Through the Thickness 16.6 Nondestructive Methods for Measuring Residual Stresses Further Readings Index