Electromagnetic Acoustic Transducers

This second edition provides comprehensive information on electromagnetic acoustic transducers (EMATs), from the theory and physical principles of EMATs to the construction of systems and their applications to scientific and industrial ultrasonic measurements on materials. The original version has been complemented with selected ideas on ultrasonic measurement that have emerged since the first edition was released.

The book is divided into four parts:

PART I offers a self-contained description of the basic elements of coupling mechanisms along with the practical designing of EMATs for various purposes. Several implementations to compensate for EMATs' low transfer efficiency are provided, along with useful tips on how to make an EMAT.

PART II describes the principle of electromagnetic acoustic resonance (EMAR), which makes the most of EMATs' contactless nature and is the most successful amplification mechanism for precise measurements of velocity and attenuation.

PART III applies EMAR to studying physical acoustics. New measurements have emerged with regard to four major subjects: in situ monitoring of dislocation behavior, determination of anisotropic elastic constants, pointwise elasticity mapping (RUM), and acoustic nonlinearity evolution.

PART IV deals with a variety of individual issues encountered in industrial applications, for which the EMATs are believed to be the best solutions. This is proven by a number of field applications.

Describes the physical principle of EMATs stemming from electromagnetics and elasticity mechanics, providing useful clues about the application of EMATs for individual purposes Provides many new studies of physical acoustic measurements that only EMATs can realize, including electromagnetic acoustic resonance and resonance ultrasound microscopy Summarizes successful industrial applications of EMATs for materials characterization and nondestructive inspection Includes supplementary material: sn.pub/extras

Inhalt
Introduction.- Coupling mechanism.- Available EMATS.- Brief instruction to build EMATS.- Principles of EMAR for spectral response.- Free-Decay measurement for attenuation and internal friction.- In-SITU monitoring of dislocation mobility.- Elastic constants and internal friction of advances materials.- Resonance Ultrasound microscopy.- Nonlinear acoustics for Microstractural evolution.- On-line texturer monitoring of steel sheets.- Acoustoelastic stress measurements.- Measurement of induction-hardening depth.- Detection of flaw and corrosion.- Average grain size of steel.- Remaining-life assessment of fatigued metals.- Creep damage detection.- Field applications of EMATS.