Display - A data presentation method in which signal amplitude is
plotted along the y-axis versus time on the x-axis. The horizontal distance
between any two signals represents the material distance between the two conditions
causing the signals. In a linear system, the vertical excursion is proportional
to the amplitude of the signal.
Measurement - A Measurement made without a direct reference to a second
signal or measurement.
- The amount of energy, imparted to matter by an ionizing particle per unit
mass of irradiated material at the place of interest. It is expressed in rads.
- The taking up of energy from the medium through which it passes.
Coefficient - The ratio of energy absorbed by a medium or material to
the energy incident on the surface. If a flux through a material decreases
with distance x in proportion to e-ax,
then a is called the absorption coefficient. Also known
as the absorption factor; absorption ratio; coefficient of absorption.
Coefficient, Linear - The fractional decrease in transmitted intensity
per unit of absorber thickness. It is usually designated by the symbol µ
and expressed in units of (cm-1.2).
- A device that accelerates charged atomic particles to high energies. An
x-ray machine or a betatron is an accelerator.
Standard - A controlled specimen containing natural or artificial
discontinuities that are well defined and similar to the maximum acceptable
discontinuity, in size and extent, in the product.
- Also may refer to the document defining acceptable discontinuity size limits.
Emission Testing (AE) -
A nondestructive testing method that "listens" for transient elastic-waves
generated due to a rapid release of strain energy caused by a structural alteration
in a solid material.
Impedance (Z)- The resistance of a material to the passage of sound
waves. The value of this material property is the product of the material
density and sound velocity. The acoustic impedance of a material determines
how much sound will be transmitted and reflected when the wave encounters
a boundary with another material. The larger the difference in acoustic impedance
between two materials, the larger the amount of reflected energy will be.
Microscopy - A general term referring to the use of high resolution,
high frequency ultrasonic techniques to produce images of surface or near
Plane Wave - A disturbance of molecular matter (sound
energy) for which the wave disturbance is distributed uniformly over a planar
surface (same phase / same amplitude)
Properties - Intrinsic characteristics of any particular material that
describe how sound travels through it. Such characteristics include the density,
acoustic impedance, and sound velocity
Reflectivity - The relative reflectivity of a specific
material, that is, the tendency to deflect sound energy in a specific medium
rather than absorb it.
- Acronym for Alternating Current
- The process by which neutron bombard is used to make normally stable atoms
- A measure of the radioactivity of a particular radioisotope. Activity is
calculated by the number of atoms disintegrating per unit of time. Its unit
of measurement is the curie.
- That portion of a gear tooth between the pitch line and the tip of the tooth.
Plural is "addenda."
- The free space that the magnetic flux must cross when a magnetic circuit
contains a break. Cracks produce small air gaps on the surface of a part.
- Algorithm - A set of steps for solving a specific problem. Algorithms can be expressed in many ways but are commonly expressed as one or more mathmatical equations.
Particle - A positively charged particle emitted by certain radioactive
material. It is made up of two neutrons and two protons; hence it is identical
with the nucleus of a helium atom.
Radiation: A stream of fast-moving helium nuclei. This is a strongly
ionizing radiation with very weak penetration (e.g. cannot penetrate a piece
Current (AC) - Electric current that reverses direction periodically (usually
many times per second).
- Surrounding or background level. Usually used in relation to temperature,
light or sound.
- An instrument for measuring the magnitude of electric current in a circuit.
- A term used to describe the strength of electric current. The number
of electrons moving past a fixed point in a conductor in one second. Measured
in amperes. The term amps is often used for short.
- A standard unit of measure for electric current or the flow of electrons.
The amount of current sent by one volt through a resistance of one ohm.
Turns - A measure of the magnetizing or demagnetizing strength of
the coil, which is the product of the number of turns in a coil and the number
of amperes of current flowing through it. For example: 500 amperes in a 6
turn coil = 500 x 6 = 3000 ampere turns.
- A device to increase or amplify electric impulses.
- (1) The maximum absolute value obtained by the disturbance of a wave or
any quantity that varies periodically. (2) The vertical height of a received
signal on an A-scan. It is measured from peak to peak for an RF presentation
or from base to peak for a video presentation.
- Angle Beam
Testing - An ultrasound testing technique that uses an incidence wave
angle other than 90 degrees to the test surface. The refracted angle of the
sound energy is calculated using Snell's law.
- Angle Beam
Transducers - A device used generated sound energy, send the energy into
a material at angle other than 90 degrees to the surface, and receive reflected
energy and convert it to electrical pulses.
of Incidence - The angle between the direction
of propagation of an electromagnetic or acoustic wave (or ray) incident on
a body and the local normal to that body.
of Reflection - The angle between the direction of propagation of
an electromagnetic or acoustic wave (or ray) reflected by a body and the local
normal to that body.
of Refraction - The angle between the direction of propagation of
an electromagnetic or acoustic wave (or ray) refracted by an optically homogeneous
body and the local normal to that body.
- A unit of length equal to 0.0000000001 or (1 x 10-10) meter.
- Angular Frequency
- For any oscillation, the number of vibrations per unit time, multiplied
by 2π. Also known as
angular velocity and radian frequency.
- The characteristic of a substance for which a physical property, such
as the elastic properties, varies with the direction along which the measurement
- Any treatment of metal at an elevated temperature for the purpose of softening,
removing residual stresses, recrystallization and other purposes.
- (1) The positive terminal or the collector of electrons
in an electrical system (i.e. the positive terminal of a battery)
(2) The electrode
at which oxidation or corrosion occurs. It is the opposite of cathode.
electrochemical process that thickens and toughens the naturally occurring
protective oxide forming a surface coating for corrosion protection
or aesthetic purposes on metal surfaces. It is Commonly used to produce an
aluminum oxide coating on aluminum parts.
- A point in a standing wave where certain characteristics of the wave field
have maximum amplitude.
Stress - The stress applied to a part or assembly as a result of
external forces or loads.
Strike - The location where a welding electrode has contacted a metal
surface, melting a small volume of metal.
Blocks - Calibration
blocks in which there are a series of flat-bottomed holes of varying diameter.
Transducer - A transducer made up of several individually piezoelectric
elements connected so that the signals they transmit or receive may be treated
separately or combined as desired.
- In nondestructive inspection, and indication that may be interpreted.
Discontinuity - A feature, such as a notch, hole or crack, that is
manufactured to closely resemble a natural defect.
- A term used in wear technology or tribology to describe a peak or projection
from a surface.
- The smallest
particle of any element that still retains the characteristics of that element.
All matter such as solids, liquids, and gases, is composed of atoms.
- Atomic Number
- A number representing the positive charge or number of protons in the
nucleus of an atom.
- The reduction in the level of a quantity, such as the intensity of a
wave or radiation.
Coefficient - A factor which is determined by the degree of
reduction in sound wave energy per unit distance traveled. It is composed
of two parts, one (absorption) proportional to frequency, the other (scattering)
dependent on the ratio of grain size or particle size to wavelength.
- A device for causing or measuring attenuation. Usually calibrated in decibels.
- A nonmagnetic solid solution of ferric carbide or
carbon in iron. An elevated-temperture parent phase in ferrous metals from
which all other low-temperature structures are derived. The normal structures
are derived. The normal condition of certain types of stainless steels.
- A special type of single coil transformer in which the output voltage can
be easily varied. The autotransformer is thus employed to adjust the primary
voltage applied to the stepup transformer which produces the high voltage
applied to the x-ray tube.
- Longitudinal or parallel to the axis or centerline of a part.