Contents

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Symbols

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Introduction

Many of the definitions in this glossary are adapted from the second and third edition of the ASNT Nondestructive Testing Handbook. The definitions have been modified to satisfy peer review and editorial style. For this reason, references at the end of this glossary should be considered not attributions but acknowledgments and suggestions for further reading.
The definitions provided here should not be referenced for tests performed according to standards, specifications or contracts. Written procedures should refer to definitions in standards.
This glossary is provided for my own personal instructional purposes. No other use is intended.

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A

acceptance standard

Document defining acceptable discontinuity size limits. See also standard.

acoustic emission

Transient elastic waves resulting from local internal microdisplacements in a material. By extension, the term also describes the technical discipline and measurement technique relating to this phenomenon.

acoustic impedance

Material property defined as the product of sound velocity and density of the material. The relative transmission and reflection at an interface are governed in part by the acoustic impedances of the materials on each side of the interface. See also characteristic acoustic impedance; specific acoustic impedance.

acoustic microscopy

General term referring to the use of high resolution, high frequency ultrasonic techniques to produce images of features beneath the surface of a test object.

AE

Acoustic emission method of nondestructive testing.

amplitude linearity

See linearity, amplitude, amplitude, echo: Vertical height of a received signal on an A-scan, measured from base to peak for a video presentation or from peak to peak for a radio frequency presentation.

analog-to-digital converter

Circuit whose input is analog and whose output is digital.

angle beam

Ultrasound beam traveling at an acute angle into a medium. The angle of incidence or angle of refraction is measured from the normal to the entry surface.

angle of incidence

Included angle between the beam axis of the incident wave and the normal to the surface at the point of incidence.

angle of reflection

Included angle between the beam axis of the reflected wave and the normal to the reflecting surface at the point of reflection.

angle of refraction

Angle between the beam axis of a refracted wave and the normal to the refracting interface.

angle beam testing

Technique of ultrasonic testing in which transmission of ultrasound is at an acute angle to the entry surface.

angle beam transducer

Transducer that transmits or receives ultrasonic energy at an acute angle to the surface. This may be done to achieve special effects such as setting up transverse or surface waves by mode conversion at an interface.

anisotropy

Condition in which properties of a medium (velocity, for example) depend on direction in the medium.

anomaly

Variation from normal material or product quality

antinode

Point in a standing wave where certain characteristics of the wave field have maximum amplitude.

area linearity

See linearity, area.

array

Group of transducers used for source location.

array transducer

Transducer made up of several piezoelectric elements individually connected so that the signals they transmit or receive may be treated separately or combined as desired. See also phased array.

artificial discontinuity standard

See acceptance standard.

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Symbols

c	speed of sound in air (meter per second)
D	diameter (meter)
dB	decibel
E	Young's modulus of elasticity
f	frequency (hertz)
R, r	reflection coefficient
T	transmission coefficient
t	time (second)
V	volt
v	velocity (meter per second)
Z	impedance (pascal second per meter)
α	attenuation
ε	strain
λ	wavelength (meter)
XXX	angle (radian)
p	density (kilogram per cubic meter)
σ	Poisson's ratio; stress (pascal)

Cement-bonded Wood Fiber

Mineralized wood chips cast in cement. Known for its insulating and acoustic properties.

Learn more: https://en.wikipedia.org/wiki/Cement-bonded_wood_fiber

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Professional Disclosure

At time of writing, I am serving as the Sales Director for Dolphitech. If you wish to learn more, please get in touch with me!

Last Updated: 2023-08-29

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