Preface Acknowledgments 1. Introduction 2. Dispersion principles 3. Unbounded isotropic and anisotropic media 4. Reflection and refraction 5. Oblique incidence 6. Waves in plates 7. Surface and subsurface waves 8. Finite element method for guided wave mechanics 9. The semi-analytical finite element method (SAFE) 10. Guided waves in hollow cylinders 11. Circumferential guided waves 12. Guided waves in layered structures 13. Source influence on guided wave excitation 14. Horizontal shear 15. Guided waves in anisotropic media 16. Guided wave phased arrays in piping 17. Guided waves in viscoelastic media 18. Ultrasonic vibrations 19. Guided wave array transducers 20. Introduction to guided wave nonlinear methods 21. Guided wave imaging methods Appendix A: ultrasonic nondestructive testing principles, analysis and display technology Appendix B: basic formulas and concepts in the theory of elasticity Appendix C: physically based signal processing concepts for guided waves Appendix D: guided wave mode and frequency selection tips.

Ultrasonic Guided Waves in Solid Media

Ultrasonic guided wave inspection is expanding rapidly to many different areas of manufacturing and in-service inspection. The purpose of this paper is to provide a vision of ultrasonic guided wave inspection potential aswe move forward into the new millennium. An increased understanding of the basic physics and wave mechanics associated with guided wave inspection has led to an increase in practical nondestructive evaluation and inspection problems. Some fundamental concepts and a number of different applications that are currently being considered will be presented in the paper along with a brief description of the sensor and software technology that will make ultrasonic guided wave inspection commonplace in the next century.

A Baseline and Vision of Ultrasonic Guided Wave Inspection Potential

Piezoelectric wafer active sensors may be applied on aging aircraft structures to monitor the onset and progress of structural damage such as fatigue cracks and corrosion. The state of the art in piezoelectric-wafer active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) the Electro–Mechanical (E/M) impedance technique are cited and briefly discussed. For health monitoring of aging aircraft structures, two main detection strategies are considered: the E/M impedance method for near field damage detection, and wave propagation methods for far-field damage detection. These methods are developed and verified on simple-geometry specimens and on realistic aging aircraft panels with seeded cracks and corrosion. The experimental methods, signal processing, and damage detection algorithms are tuned to the specific method used for structural interrogation. In the E/M impedance method approach, the high-frequency spectrum, representative of the structural resonances, is recorded. Then, overallstatistics damage metrics can be used to compare the impedance signatures and correlate the change in these signatures with the damage progression and intensity. In our experiments, the (1 � R 2 ) 3 damage metric was found to best fit the results in the 300–450 kHz band. In the wave propagation approach, the pulse-echo and acousto-ultrasonic methods can be utilized to identify the additional reflections generated from crack damage and the changes in transmission phase and velocity associated with corrosion damage. The paper ends with a conceptual design of a structural health monitoring system and suggestions for aging aircraft installation utilizing active-sensor arrays, data concentrators, wireless transmission, and a health monitoring and processing unit.

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Piezoelectric Wafer Embedded Active Sensors for Aging Aircraft Structural Health Monitoring

Quantitative ultrasound (QUS) methods have been introduced in recent years for the assessment of skeletal status in osteoporosis. The performance of QUS techniques has been evaluated in a large number of studies. Reviewing existing knowledge, an international expert panel formulated the following consensus regarding the current status of this technology. To date, evidence supports the use of QUS techniques for the assessment of fracture risk in elderly women. This has been best established for water-based calcaneal QUS systems. Future studies should include the predictive validity of other QUS systems. Additional clinical applications of QUS, specifically the assessment of rates of change for monitoring disease progression or response to treatment, require further investigation. Its low cost and portability make QUS an attractive technology for assessing risk of fractures in larger populations than may be suitable or feasible for bone densitometry. Additional investigations that assess innovative QUS techniques in well defined research settings are important to determine and utilize the full potential of this technology for the benefit of early detection and monitoring of osteoporosis.

Quantitative ultrasound techniques for the assessment of osteoporosis : Expert agreement on current status

http://www.mkckorea.com/catalog/qseeman/hc-200_ref8.pdf

Corrosion Monitoring of Reinforced Concrete Structures - A Review

Nondestructive testing of solid material using ultrasonic waves, for defects such as cavities, nonbonding, and strength variations, is treated in this book from the physical fundamentals of ultrasonics and materials up to the most sophisticated methods. The book is written at a level which should make it accessible to readers with some knowledge of technical mathematics. Physical laws are explained in elementary terms, and more sophisticated treatments are also indicated. After the fundamentals, instrumentation and its application is extensively reported. Tricks and observations from thirty years of experience in the field are included. The third part of the book presents test problems related to special materials or ranges of modern heavy industry, including recent applications such as those in nuclear power plants. This fourth edition features improved presentation of certain fundamental physical facts, updated reports on electronic instrumentation, and new applications in the nuclear and space industries.

Ultrasonic Testing of Materials

Werkstoffprüfung mit Ultraschall

This Chapter deals with the measurement of material properties and of elastic constants, as far as they are of interest for materials testing in general and where they can be carried out by using commercial testing instruments. This excludes therefore many purely scientific problems and measuring methods or permits only their brief mention. For further and more detailed studies the textbook of Tietz [41] is strongly recommended.

Ultrasonic Testing by Determination of Material Properties

Ultrasonic testing of materials utilises mechanical waves in contrast, for instance, to X-ray techniques which use electromagnetic waves. Any mechanical wave is composed of oscillations of discrete particles of material. The motion carried out by a small mass attached to a spring as shown in Fig. 1.1 if pulled down once and released, is called an oscillation. Left to itself, the mass oscillates about the equilibrium position. The nature of this oscillation is of particular importance inasmuch as it is sinusoidal, the path recorded as a function of time being a sine curve. It is obtained only if the driving force, in this case supplied by the spring, increases proportionately to the displacement. It is then also referred to as an elastic oscillation. Furthermore, one can imagine the body to consist of individual particles kept in position by elastic forces. Very much simplified, the model of an elastic body can be visualised as shown in Fig. 1.2, but three-dimensionally. Provided such a body is not stressed by compression or tension beyond its elastic limit, it behaves like this spring model. In it, the particles can perform elastic oscillations. How then does a wave arise from an oscillation?

Ultrasonic Waves in Free Space

Table 9.1 lists all current methods of ultrasonic testing of materials. They are categorized by reference to three basic criteria: namely the type of primary measured quantity, the form of radiated ultrasound used (continuous wave or pulses) and the effect of an anomaly within the material under test or on its surface. Based on the presentation in the Table, each method will be discussed to an extent depending on its practical importance.

Josef Krautkrämer

Papers

Ultrasonic Testing of Materials

Werkstoffprüfung mit Ultraschall

Ultrasonic Testing by Determination of Material Properties

Ultrasonic Waves in Free Space

Historical Survey of Developments