COLLEGE HOUSE ENTERPRISES, LLC

EXPERIMENTAL

SOLID

MECHANICS

Arun Shukla University of Rhode Island

James W Dally, University of Maryland @ College Park

　Arun Shukla, University of Rhode Island

Experimental Solid Mechanics has evolved from the 4^th edition of Experimental Stress Analysis.  The title change reflects the fact that the field today is much broader than it was in 1965 when the first edition of Experimental Stress Analysis was published.  Experimental Solid Mechanics describes methods used to measure forces, pressure, displacements, stresses, strains and fracture mechanics parameters.  Measurements described include electrical and optical methods.

The text is intended for upper-division undergraduate students or graduate students beginning to study experimental methods.  Extensive revisions have been incorporated, which reflects many of the changes in experimental mechanics that have occurred during the past decade.  A significant amount of new content has been added by expanding existing chapters and by introducing new chapters.  Some material covering outdated methods have been removed.  The organization of the textbook includes five parts, which are briefly described below:

 Part I:  Elementary Elasticity and Fracture Mechanics contains three chapters on elasticity and an introductory chapter on elementary fracture mechanics.  A section has been added to Chapter 2 to provide the stress-strain relations for composite materials.

 Part II:  Displacement and Strain Measurement Methods contains four chapters describing up to date techniques for measuring these quantities.  Chapter 5 defines the properties of strain-gage systems.  It provides descriptions of several strain-gage systems as well as an introduction to five different types of sensors that are used in measuring mechanical quantities.  Chapter 6 describes electrical resistance strain gages in considerable detail.  Strain-gage circuits and parameters affecting their performance are covered in Chapter 7.  Chapter 8 describes analysis methods and illustrates techniques for determining principal stresses from rosettes.  The chapter also describes torque and stress gages, and covers techniques for measuring stress intensity factors, crack initiation toughness and residual stresses.

 Part III:  Optical-Methods of Stress, Strain and Displacement Analysis, the core of this textbook, includes eight chapters.  Chapter 9 covers basic optics that serves as a foundation for subsequent chapters.  The coverage of photoelasticity is divided into two chapters.  Chapter 10 provides the theoretical basis for the method.  Chapter 11 provides practical information on the application of photoelasticity including two- and three-dimensional methods and birefringent coatings.  Chapter 12 introduces interferometric methods which serve as a basis for describing techniques used in holographic interferometery.  Chapter 13 covers both classical moiré methods, the more modern procedures of moiré interferometry and e beam moiré.  Chapter 14 describes speckle methods including speckle interferometry and electronic speckle pattern interferometry.  Chapter 15 describes digital image correlation methods, which have surged in their applications during the past decade.  Chapter 16 covers methods for determining fracture parameters and extends the textbook’s coverage to include fracture analysis.

 Part IV:  Measurements under High Strain Rates and Small Length Scales consists of two chapters that are new and they reflect the growing interest in high-rate loading in the measurement of material properties and in the behavior of nanoscale materials.  Chapter 17 describes seven different loading methods used today to provide a wide range of strain-rates to relatively small specimens.  Techniques are also introduced to measure stress and strain during these dynamic experiments.  Chapter 18 describes nanoscale measurement, which includes description of three different microscopes that enable observation of the substructures so important in the understanding of material behavior at these scales.

 Part V:  Measurement and Analysis Methods contains two chapters.  Chapter 19 describes digital recording systems covering the important topic of analog to digital conversion and aliasing.  Data logging systems and well as PC based data acquisition systems are covered.  Chapter 20 deals with the application of statistics in enhancing experimental accuracy and in improving the method of reporting experimental results that show variation.

 Each part of the book is essentially independent so that instructors can be quite flexible in selecting course content.  For instance, a two- or three-credit course on strain gages can be offered by using three chapters of Part I and all of Part II.  Parts I and III can be combined to provide a thorough three- or four-credit course on optical methods of experimental analysis.  Selected chapters from the first four parts can be organized to introduce the broader field of experimental stress analysis.  Chapters selected from Part II, Part III and PartIV can be combined to teach an experimental measurements course.  Part IV provides the basis for an advanced course on modern methods in Experimental Mechanics.  A complete detailed treatment of the subject matter covered in the text and supplemented with laboratory exercises on strain gages, photoelasticity, moiré interferometry, speckle methods and digital image correlation will require six- to eight-credit hours.

The essential feature of the text is its completeness in introducing the entire range of experimental methods to the student.  A reasonably deep coverage is presented of the theory required to understand experimental stress analysis and of the five primary methods employed: strain gages, photoelasticity, moiré, interferometry (including holography, coherent gradient sensing and speckle) and digital image correlation.  While primary emphasis is placed on the theory of experimental stress analysis, the important experimental techniques associated with each of the four major methods are covered in sufficient detail to permit the student to begin laboratory work with a firm understanding of experimental procedures.  Exercises designed to support and extend the treatment and to show the application of the theory have been placed at the end of all of the chapters.

Laboratory exercises have not been included, because laboratory work will depend strongly on local conditions such as the equipment and supplies available, the instructor’s interests, the number of students in the class and research activities of current interest.  It is believed that the instructor is best qualified to specify the associated laboratory exercises on the basis of interest, equipment, supplies, and time available for this important supplement to the course.

A significant amount of new material has been added to edition; however, space limitations did not permit coverage of the many modern research topics such as, bio-mechanics, smart structures, MEMs, etc.  It is anticipated that the instructor will, in certain instances, treat these topics by using his or her lecture notes or by using recent papers published in the technical journals.  The authors hope that most instructors will find the fundamental material required to present a complete and practical course on the theory of experimental solid mechanics in this text.

The material presented here has been assembled by both authors.  Courses have been developed on Experimental Stress Analysis, Photoelasticity, and Photomechanics at Illinois Institute of Technology, Cornell University, The U. S. Air Force Academy, University of Rhode Island and the University of Maryland.  The material has been shown to be interesting by the students participating in these courses.  The mathematics employed in this treatment can easily be understood by senior undergraduates.  Cartesian notation and/or vector notation has been used to enhance the student’s understanding of the field equations.  A great deal of effort was devoted to the selection and preparation of the illustrations employed.  These illustrations complement the text and should aid appreciably in presenting the material to the student.