Digital Photoelasticity: Advanced Techniques and Applications

ISBN-13: 9783642640995 / Angielski / Miękka / 2013 / 410 str.

K. Ramesh

Opis

Rapid strides have been made in the use of digital image processing tech niques for data acquisition in photoelasticity in the last two decades. Techniques such as fringe thinning, fringe clustering, fringe tracing, phase shifting, polarization stepping and Fourier transform methods have significantly contributed to the automation of data acquisition. The recent developments in colour image processing and development of tricolour light source have added a new dimension. The use of time delay and integration (TDI) camera techniques has extended digital photoelasticity for dynamic analysis. Now the field of Digital Photoelasticity has matured to a level where it could be used to solve problems in industries. Apart from developments in data acquisition techniques, several methods have also come into existence for efficient processing of experimental data. Extensive use of computer graphics has found a unique place in presenting the experimental results in a meaningful way. Though there has been significant developments in data processing and data acquisition in the last two decades, there is no book available yet to present these developments in a comprehensive way. The motivation for this book is based on the experience of teaching the course on Experimental Methods in Stress Analysis at lIT Kanpur for the last 10 years. I have always felt a need for introducing Digital Image Processing in an appropriate way, which will be useful for an experimentalist."

Recenzje

Excerpts from the Reviews of the book on Digital Photoelasticity(Pattern I)

The author has produced a first class text book that should find widespread use among students, researchers, and design engineers in many branches of engineering.....

Applied Mechanics Reviews 55(4) B69-B71 JUL 2002

The book is accompanied by a CD-ROM of the C source code of the programs referred to in the text along with some photoelasticity simulations and some hardware-specific code. The text is supported by ample end-of-chapter tutorial questions.....

Strain 38 85-86 2002

Bible of digital photoelasticity., 17 February, 2001

Not only beginners and students but also researchers, engineers and inspectors should read this book as a bible of photoelasticity.

http://www.amazon.co.uk/exec/obidos/ASIN/3540667954/qid%3D1050727743/202-1368056-3855028

....This is the first monograph in its field and forms a useful contribution...

Meas. Sci. Technol. 11 (December 2000) 1826-1827

Spis treści

1 Transmission Photoelasticity.- 1.1 Introduction.- 1.2 Physical Principle Used in Photoelasticity.- 1.3 Nature of Light.- 1.4 Polarization.- 1.5 Passage of Light Through Isotropic Media.- 1.6 Passage of Light Through a Crystalline Medium.- 1.7 Light Ellipse.- 1.8 Retardation Plates and Wave Plates.- 1.9 Stress-Optic Law.- 1.10 Plane Polariscope.- 1.10.1 Analysis by Trigonometric Resolution.- 1.11 Jones Calculus.- 1.11.1 Rotation Matrix.- 1.11.2 Retardation Matrix.- 1.11.3 Representation of a Retarder.- 1.11.4 Polarizer.- 1.11.5 Quarter-Wave Plate.- 1.12 Analysis of Plane Polariscope by Jones Calculus.- 1.13 Circular Polariscope.- 1.14 Use of White Light.- 1.15 Determination of Isoclinic and Isochromatic Fringe Order at a Point.- 1.15.1 Ordering of Isoclinics.- 1.15.2 Ordering of Isochromatics.- 1.16 Tardy’s Method of Compensation.- 1.17 Calibration of Photoelastic Model Materials.- 1.17.1 Stress Field in a Circular Disc Under Diametral Compression.- 1.17.2 Conventional Method.- 1.17.3 Sampled Linear Least Squares Method.- Need for a better methodology.- Use of whole field data to evaluate material fringe value.- 1.17.4 Theoretical Reconstruction of Fringe Patterns.- 1.18 Further Comments on Fringe Ordering.- 1.18.1 Properties of Isochromatic Fringe Field.- 1.18.2 Properties of Isoclinic Fringe Field.- 1.18.3 Use of Fringe Field Properties to Identify Fringe Ordering.- 1.18.4 Role of Principles of Solid Mechanics in Fringe Ordering.- 1.19 Determination of the Sign of the Boundary Stresses.- 1.20 Resolving the Ambiguity on the Principal Stress Direction.- 1.21 Introduction to Three-Dimensional Photoelasticity and Integrated Photoelasticity.- 1.21.1 Conventional Three-Dimensional Photoelasticity.- 1.21.2 Principle of Optical Equivalence.- 1.22 Model to Prototype Relations.- 1.23 Closure.- Exercises.- References.- 2 Reflection Photoelasticity.- 2.1 Introduction.- 2.2 Reflection Polariscope.- 2.3 Stress and Strain-Optic Relations for Coatings.- 2.4 Coating and Specimen Stresses.- 2.5 Correction Factors for Photoelastic Coatings.- 2.6 Poisson’s Ratio Mismatch.- 2.7 Coating Materials.- 2.8 Bonding the Coating.- 2.9 Selection of the Coating Thickness.- 2.10 Calibration of the Coating Material.- 2.11 Data Collection and Analysis.- 2.12 Application of Photoelastic Coatings.- 2.13 Closure.- Exercises.- References.- 3 Digital Image Processing.- 3.1 Introduction.- 3.2 Image Sampling and Quantization.- 3.2.1 Pictures as Functions.- 3.2.2 Uniform Sampling and Quantization.- 3.3 Video Standards.- 3.4 Image Sensors.- 3.5 Image Display.- 3.6 Image Perception.- 3.7 Image Storage.- 3.8 Some Basic Relationships and Mathematical Operations Between Pixels.- 3.8.1 Neighbours of a Pixel.- 3.8.2 Arithmetic and Logic Operations.- 3.8.3 Neighbourhood Oriented Operations.- 3.9 Basic Steps in Image Processing.- 3.10 Typical Image Processing Systems for Digital Photoelasticity.- 3.11 Software Structure and Design.- 3.12 Image Acquisition.- 3.13 Tools for Image Understanding.- 3.13.1 Pseudo Colouring.- 3.13.2 Histogram.- 3.13.3 Two-Dimensional and Three-Dimensional Intensity Plots.- 3.14 Filtering in Spatial Domain.- 3.14.1 Low Pass Spatial Filtering.- 3.14.2 Median Filtering.- 3.15 Image Enhancement.- 3.15.1 Contrast Stretching.- 3.15.2 Histogram Equalisation.- 3.16 Image Segmentation.- 3.16.1 Thresholding.- Global thresholding.- Semi thresholding.- Dynamic thresholding.- 3.16.2 Edge Detection.- Edge detection by convolution filters.- Edge detection by non-convolution filters.- Edge detection by thresholding.- 3.17 Morphological Filters.- 3.18 Further Discussions on Image Sensors.- 3.18.1 Operation of CCD Arrays.- 3.18.2 Interline Transfer CCD.- 3.18.3 Linearity and Dynamic Range.- 3.18.4 Sources of Noise.- 3.19 Digitisation of the Camera Video Signal.- 3.20 Resolution of an Image Processing System.- 3.21 Gamma Compensation.- Exercises.- References.- 4 Fringe Multiplication, Fringe Thinning and Fringe Clustering.- 4.1 Introduction.- 4.2 Fringe Multiplication.- 4.3 Half Fringe Photoelasticity (HFP).- 4.4 DIP Methods for Fringe Thinning.- 4.5 Algorithms Based on Considering the Fringe Patterns as a Binary Image.- 4.6 Mask-Based Algorithms for Skeleton Extraction Using Intensity Variation within a Fringe.- 4.7 Global Identification of Fringe Skeletons Based on Intensity Variation.- 4.7.1 Edge Detection.- 4.7.2 Fringe Skeletonization.- Row-Wise scanning algorithm.- Algorithm for fringe skeleton extraction for arbitrarily shaped fringes.- 4.7.3 Applications of the Algorithm to Actual Experimental Conditions.- 4.8 Further Improvements on the Global Thinning Algorithm.- 4.9 Performance Evaluation of Various Fringe Thinning Algorithms.- 4.9.1 Comparison of the Skeleton Extraction.- Computer generated test images.- Images recorded from actual experimental situations.- 4.9.2 Comparison of the Computational Effort.- 4.10 Use of Tiling to Improve Information in Stress Concentration Zones.- 4.11 Fringe Tracing Algorithm.- 4.12 Ordering of Fringes.- 4.13 Closure.- Exercises.- References.- 5 Phase Shifting, Polarization Stepping and Fourier Transform Methods.- 5.1 Introduction.- 5.2 Early Attempts for Automated Polariscopes.- 5.3 Phase Shifting in Photoelasticity.- 5.4 Intensity of Light Transmitted for a Generic Arrangement of a Plane Polariscope.- 5.5 Intensity of Light Transmitted for a Generic Arrangement of a Circular Polariscope.- 5.6 Evaluation of Fractional Fringe Order along an Isoclinic Contour.- 5.7 Whole Field Evaluation of Photoelastic Data by Using a Plane Polariscope.- 5.8 Whole Field Evaluation of Photoelastic Data by Using a Circular Polariscope.- 5.8.1 The Generic Procedure.- 5.8.2 Calculation and Representation of Whole Field Data.- 5.8.3 Parameters Affecting the Generation of Phase Map and its Solution.- Influence of local oscillations of isoclinic parameter on fractional retardation calculation.- Importance of isoclinic parameter representing either ?1 or ?2 direction over the domain.- Ambiguity in experimentally evaluating the isoclinic parameter.- Interactive approach to obtain a good phase map.- 5.9 Error Sources and Methods to Minimise Their Influence.- 5.9.1 Influence of Error in Measuring Intensities.- 5.9.2 Errors Due to Mismatch of Quarter-Wave Plates.- 5.10 Evaluation of Isoclinic Value by Phase Shifting Technique.- 5.10.1 Use of Two Loads to Get Continuous Isoclinic Contours.- 5.10.2 Use of Multiple Wavelengths to Get Continuous Isoclinic Contours.- 5.11 Polarization Stepping for Isoclinic Determination.- 5.12 Fourier Transform Methods for Photoelastic Data Acquisition.- 5.12.1 Use of Carrier Fringes.- 5.12.2 Use of Multiple Polarization Stepped Images.- 5.12.3 Use of Load Stepping.- 5.13 Comparative Evaluation of Phase Shifting, Polarization Stepping and Fourier Transform Techniques.- 5.14 Closure.- Exercises.- References.- 6 Phase Unwrapping and Optically Enhanced Tiling in Digital Photoelasticity.- 6.1 Introduction.- 6.2 Boundary Detection.- 6.3 Noise Removal in Phase Maps.- 6.4 Algorithm for Phase Unwrapping.- 6.5 Representation of the Unwrapped Phase.- 6.5.1 Three-Dimensional Plots.- 6.5.2 Total Fringe Order Viewing on the Image.- 6.6 Parameters Affecting Phase Unwrapping.- 6.6.1 Influence of the Selection of the Phase Unwrapping Threshold.- 6.6.2 Influence of the Location of the Primary Seed Point.- 6.7 Use of Tiling Procedure for Phase Unwrapping.- 6.8 Digital Magnification of High Fringe Density Zones.- 6.8.1 Replication.- 6.8.2 Linear Interpolation.- 6.8.3 Higher Order Interpolation.- 6.9 Optically Enhanced Tiling (OET).- 6.10 Cementing of a Tile.- 6.11 OET Applied to a Circular Disc Under Diametral Compression.- 6.12 OET Applied to a Ring Under Diametral Compression.- 6.13 Closure.- Exercises.- References.- 7 Colour Image Processing Techniques.- 7.1 Introduction.- 7.2 Colour Models.- 7.2.1 RGB Model.- 7.2.2 HSI Model.- 7.3 Colour Image Processing Systems.- 7.3.1 Hardware.- Transmission Photoelasticity.- Reflection Photoelasticity.- 7.3.2 Software.- 7.4 Typical Spectral Response of a Colour Camera.- 7.5 Intensity of Light Transmitted in White Light for Various Polariscope Arrangements.- 7.6 Three Fringe Photoelasticity (TFP).- 7.6.1 Calibration.- 7.6.2 Methodology.- 7.6.3 Application to the Problem of a Circular Disc Under Diametral Compression.- 7.7 Green Image Plane as a Green Filter.- 7.8 Phase Shifting in Colour Domain.- 7.8.1 Transmission Photoelasticity.- 7.8.2 Reflection Photoelasticity.- 7.9 Spectral Content Analysis (SCA).- 7.10 Digital Spectral Content Analysis (DSCA).- 7.11 Hybrid Techniques.- 7.11.1 Polarization Stepping in Colour Domain.- 7.12 Tricolour Photoelastic Method.- 7.13 Closure.- Exercises.- References.- 8 Evaluation of Contact Stress Parameters and Fracture Parameters.- 8.1 Introduction.- 8.2 Basic Data Required and its Digital Acquisition.- 8.2.1 Conversion of Pixel Co-ordinates to Model Co-ordinates.- 8.2.2 Rotational Transformation.- 8.3 Stresses in Terms of Contact Length and Geometrical and Elastic Properties of the Bodies in Contact.- 8.4 Evaluation of Contact Stress Parameters by Least Squares Analysis.- 8.4.1 Validation for Hertzian and Non-Hertzian Contact.- 8.5 Developments in the Description of the Stress Field Equations in the Neighbourhood of a Crack-tip.- 8.5.1 Mode-I Stress Field Equations.- 8.5.2 Mixed-Mode (Combination of Mode-I and Mode-II) Stress Field Equations.- 8.5.3 Equivalence Between the Multi-Parameter Stress Field Equations.- 8.6 Developments in SIF Evaluation Methodology.- 8.7 Evaluation of Mixed-Mode Stress Field Parameters Using Least Squares Technique.- 8.8 Experimental Validation of the Methodology.- 8.8.1 Mode-I Loading.- 8.8.2 Mixed-Mode Loading.- 8.9 Contact Stress and Fracture Analysis of a Spur Gear.- 8.9.1 Loading Frame Design.- 8.9.2 Evaluation of Contact Parameters.- Measurement of radius of curvature at the point of contact.- Experimental results.- 8.9.3 Evaluation of Fracture Parameters.- 8.10 Closure.- Exercises.- References.- 9 Stress Separation Techniques.- 9.1 Introduction.- 9.2 Oblique Incidence Method.- 9.2.1 Secondary Principal Stresses.- 9.2.2 The Methodology.- 9.3 Shear Difference Technique.- 9.3.1 Conventional Method.- 9.3.2 Improvement by Tesar.- 9.4 Survey of Numerical Methods.- 9.4.1 Integration of Compatibility Condition.- Finite difference approach.- 9.4.2 Integration of Stress Difference Equations.- 9.4.3 Least Squares Method.- 9.4.4 Hybrid Techniques.- 9.4.5 Methods Using Only Isochromatic Data.- 9.5 Stress Separation by Combined Phase Shifting and FEM.- 9.5.1 Finite Element Formulation.- 9.5.2 Meaningful Discretization of the Domain.- 9.5.3 Plotting of Fringe Contours from FE Results.- 9.5.4 Influence of Error in Fringe Data.- 9.5.5 Application of the Technique to the Problem of Plate with a Hole.- 9.6 Use of Integrated Photoelasticity Concepts for Stress Separation.- 9.6.1 Least Squares Algorithm.- 9.6.2 Design of the Loading Frame.- 9.6.3 Application to the Problem of Disc under Diametral Compression.- 9.7 Stress Separation in Three-Dimensional Photoelasticity.- 9.8 Stress Separation in Reflection Photoelasticity.- 9.8 Closure.- Exercises.- References.- 10 Fusion of Digital Photoelasticity, Rapid Prototyping and Rapid Tooling Technologies.- 10.1 Introduction.- 10.2 Difficulties in Conventional Three-Dimensional Photoelasticity.- 10.3 Rapid Prototyping in Model Making.- 10.3.1 Software Issues in RP.- 10.3.2 Stereolithography Process.- 10.3.3 Solid Ground Curing.- 10.3.4 Fused Deposition Modelling.- 10.4 Direct Analysis of RP Models by Photoelastic Coatings.- 10.4.1 Experimental Results.- 10.4.2 Analysis of the Results.- Evaluation of Young’s modulus by tensile test.- Study on the seepage of the adhesive.- Numerical simulation of fringe patterns.- 10.4.3 Recommendations.- 10.5 Direct Use of RP Models for Transmission Photoelastic Analysis.- 10.6 Rapid Tooling for Model Making.- 10.6.1 Basic Steps in Rapid Tooling.- 10.6.2 Digital Photoelastic Characterisation of the Process.- 10.7 Closure.- Exercises.- References.- 11 Recent Developments and Future Trends.- 11.1 Introduction.- 11.2 Evaluation of Characteristic Parameters.- 11.2.1 Srinath and Keshavan’s Method.- 11.2.2 Whole Field Determination of Characteristic Parameters by Phase Shifting.- Development of relevant equations.- Experimental evaluation of characteristic parameters.- Whole field theoretical evaluation of characteristic parameters.- 11.3 Tensorial Tomography.- 11.4 Developments in DIP Hardware.- 11.5 Developments in DIP Software.- 11.5.1 Development of a Device Independent Software.- Selection of software features.- FRN_DAT software.- An application.- 11.5.2 Future Possibility.- 11.6 Digital Dynamic Photoelasticity.- 11.6.1 Classification of High, Very-high and Ultra-high-speed Photography.- 11.6.2 Classical Methods for High-speed Photography.- 11.6.3 Digital Dynamic Recording.- 11.7 Application to Composites.- 11.7.1 Photo-Orthotropic Elasticity Theories.- Stress-Optic law.- Strain-Optic law.- 11.7.2 Calibration of Photo-Orthotropic Composites.- 11.7.3 Influence of Residual Birefringence.- 11.7.4 Separation of Stresses in Photo-Orthotropic Elasticity.- 11.7.5 Application of Digital Photoelasticity to Composites.- 11.8 Closure.- Exercises.- References.

Blurb

The principal objectives of the book are to provide an introduction to basic concepts and methodologies for digital photoelasticity and to develop a foundation on which the future researcher and student can develop his on ideas and promote research in formulation of problems in digital photoelasticity and application of these techniques to industries. Particular care has been taken to give a clear, straightforward, and simple presentation of various topics. In one volume it provides data acquisition by DIP techniques, data analysis by statistical techniques, data presentation by computer graphics and the use of Rapid Prototyping technologies to enhance the speed of the entire process. The book not only presents the various techniques but also provides time-tested software codes for important techniques. Exercises designed to support and extend the treatment have been placed at the end of each chapter.