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E
- Echo - A signal indicating
reflected acoustic energy.
- Echoes - A sound wave that continues to
bounce around a room or off other barriers, or reverberate, until
it has lost all its energy.
- Eddy Current - Circular induced
currents that are generated by an alternating current in the nearby
coil.
- Eddy Current Inspection - An electromagnetic technique used on conductive materials
for crack detection or the rapid sorting of small components for
either flaws, size variations, or material variation, as well as
other applications.
- Eddy Current Method - An
electromagnetic NDT Method based on the process of inducing
electrical currents into a conductive material and observing the
interaction between the currents and the
material.
- Eddy Current Scope - A scope that uses
little electrical currents call "eddy currents" to find defects in
different materials.
- Eddy Current Testing (EC) -
An electromagnetic technique used on conductive
materials for crack detection or the rapid sorting of small
components for either flaws, size variations, or material
variation, as well as other applications.
- EDGE Effect
- Signal obtained when a surface prove approaches
the sample’s edge.
- Effective Depth of
Penetration -Depth at which eddy current density drops off
to 5% of the surface density.
- Elastic - Able to return immediately to
the original size and shape after being stretched or squeezed;
springy.
- Elastic Constants - The factors of
proportionality that relate elastic displacement of a material to
applied forces.
- Elastic Deformation - Change
of dimensions accompanying stress in the elastic range, original
dimensions being restored upon release of stress.
- Elastic Limit - The maximum
stress to which a material may be subjected with no permanent
deformation after release of the applied load.
- Elastic Modulus - The
ratio of the stress applied to an elastic body to the change in its
shape.
- Elastic-Plastic Fracture
Mechanics - A design approach used
for materials that fracture or behave in a “plastic” manner, such
as lower strength, high-toughness steels.
- Elastic Properties of Solids
- Properties of a solid material defining how it
will react to stress and strain.
- Elasticity - A term that describes how
quickly molecules return to their original
positions.
- Elastomer - A material with
rubber-like properties-that is, quite elastic, returning to its
original size and shape after being deformed.
- Electric Motor - A motor that converts
electric energy into mechanical energy that can be used to do
work.
- Electrical Contact -
Contact of two conductors allowing current to
pass.
- Electrical Current - The movement of
electrons or holes (missing electrons) in an electrical conductor
- Electrical Impedance - The total
opposition that a circuit presents to an alternating
current.
- Electrical Noise - Extraneous
signals caused by externally radiated signals or electrical
interferences within an ultrasonic instrument. A component of
background noise.
- Electricity - A naturally occurring
force that exists all around us.
- Electrochemical - Pertaining
to combined electrical and chemical action. Deterioration
(corrosion) of a metal occurs when an electrical current flows
between cathodic and anodic areas on metal
surfaces.
- Electrochemical Corrosion -
Corrosion which occurs when current flows between cathodic and
anodic areas on metallic surfaces.
- Electrode - An electrical
conductor, usually of metal or graphite, that leads current into or
out of a solution (electrolyte).
- Electrolyte - A material,
usually a liquid or paste, that will conduct an electric
current.
- Electromagnetic Acoustic
Transducer - A device using the magneto effect to generate
and receive acoustic signals for ultrasonic nondestructive
tests.
- Electromagnet - Wrapping a wire into a
coil creates an electromagnet, which behaves just like a regular
permanent bar magnet when the current is flowing.
- Electromagnetic Acoustic Transducers
(EMATS) - A scanning device which transmits
and receives ultrasonic waves.
- Electromagnetic Field - A field that is
created when energy from a power source such as a battery is
applied to a circuit, making the electrons flow through a
conductor, a new type of field is developed around the
wire.
- Electromagnetic Induction - A process
by which electrical current is induced in an electrical conductor
by a changing magnetic field that acts upon the
conductor.
- Electromagnetic Radiation - Energy in a
wave form that possesses both electrical and magnetic
characteristics. EMR radiates in the form
of a wave which can accelerate charged particles. Electromagnetic
radiation can travel through a vacuum and its energy varies
greatly; radio waves have the longest wavelengths and the lowest
frequency and energy, while X-rays and gamma rays have the shortest
wavelengths and highest frequencies and
energies.
- Electromagnetic Spectrum - The entire range of wavelengths or frequencies of
electromagnetic radiation extending from gamma rays to the longest
radio waves.
- Electromagnetic Testing - A nondestructive way to test materials by using
electromagnetic energy.
- Electromagnetism - The production of a
magnetic field by current flowing in a
conductor.
- Electromagnets - An iron bar placed
through the center of the coiled wire would become a temporary
magnet, as long as the electric current is flowing through the
wire.
- Electromotive Force - The
work or energy which causes the flow of an electric current.
Expressed as volts. It should be noted that the term "force" is a
misnomer. However, the term is so well established that its use
continues in spite of its being incorrect.
- Electromotor Force
- A force that causes electrons to move in a particular
direction.
- Electron Volt - An amount of energy
equal to the energy gained by one electron when it is accelerated
by one volt,
- Electron - A negatively charged
particle that is in constant motion and generally orbits the
nucleus of an atom. The electron is the lightest known particle
that possesses a charge.
- Electroscope - A fairly simple device
comprised of a metal rod with two thin leaves attached to one end.
If the electroscope is given a negative charge, the metal leaves
will separate from each other. The rate of discharge of the
electroscope is a measure of ions in the air and can be used as a
basis of measurement and detection.
- Electrostatic Field - Electrons are
said to have a negative charge, which means that they seem to be
surrounded by a kind of invisible force field. This is called an
electrostatic field.
- Electrostatic Generator - This device
accelerates electrons to produce high energy radiation.
- Elements - Any material composed of
only one kind of atom.
- Elementary Particle -
Originally a term applied to any particle that could not be further
subdivided; now applied only to protons, electrons, neutrons,
antiparticles and strange particles, but not to alpha particles and
deuterons.
- Ellipse - When a parabola is closed off
by another curved surface an ellipse is
produced.
- Elliptical Void Formula - A formula used to calculate the amount of time it takes for a
viscous fluid to fill an elliptical defect in a
material.
- Elongation - In tensile
testing, the increase in the gage length, measured after fracture
of the specimen within the gage length, usually expressed as a
percentage of the original gage length.
- EMATs - Electromagnetic Acoustic Transducers
- Embrittlement - Reduction in
the normal ductility of a metal due to a physical or chemical
change.
- Emissivity - The energy
emission rate usually expressed as r/c/hr @ 1ft or mr/mc/hr @ 1
ft.
- Emulsification Time - The
period of time during which the emulsifier is permitted to combine
with the liquid penetrant. Emulsification action begins when the
emulsifying agents come in contact with the penetrant and ends with
the removal of this agent, by water rinsing.
- Emulsifier - An agent,
usually in liquid form which, when combined with a liquid penetrant
that is insoluble in water, renders such a penetrant "soluble"
thereby facilitating its removal by a water wash.
- Emulsifier Bath - The
bath used to soak a part in a penetrate fluid to test for
defects.
- Emulsifier Concentration and Contact
Time - The time the material needs to be
soaked in and the concentration of penetrate in the bath depends on
the type of penetrate used and the desired
results.
- Emulsifiers - An
additive that promotes the formation of a stable mixture between
two liquids like oil and water.
- Emulsion Penetrant - A
mixture of water and oil produced by the addition of a third
material, the liquid penetrant emulsifier.
- Emulsion Radiographic - A
gelatin and silver bromide crystal mixture coated onto a
transparent film base.
- Encapsulation - The process
of sealing radioactive materials to prevent
contamination.
- END Effect - Signal obtained
when an internal or encircling probe approaches the end of a tube
or rod (Similar to edge effect).
- Equiaxed Grain
Structure - A structure in which
the grains have approximately the same dimensions in all
directions.
- Earing - The amount of wasted,
irregular material (usually snipped or cut off) as part of the
stamping or deep drawing process.
- Erosion
- Destruction of metals or other materials by the
abrasive action of moving fluids, usually accelerated by the
presence of solid particles of matter in suspension. When corrosion
occurs simultaneously, the term erosion-corrosion is often
used.
- Error Analysis - The
process used to evaluate the total error throughout an experiment.
This can be due to bias error, precision error as well as
others.
- Erythema Dose - The
amount of radiation needed, when applied to the skin, to make it
turn temporarily red.
- Etchants - A chemical
used to etch a metal to reveal the structural
details.
- Etch cracks - Shallow cracks
in hardened steel, containing high residual surface stresses,
produced on etching in an embrittling acid.
- Etching - Subjecting the
surface of a metal to preferential chemical or electrolytic attack
in order to reveal structural details.
- Eutectic Alloy
- The composition in a binary alloy system which
melts at minimum temperature. More than one eutectic composition
may occur in a given alloy system.
- Evaluation - The process of
deciding the severity of a condition after an indication has been
interpreted. Evaluation determines if the test object should be
rejected, repaired or accepted. See indication and
interpretation.
- Evanescent Wave - A
disappearing wave.
- Exfoliation - A type of
corrsion that progresses approximately parallel to the outer
surface of the metal, causing layers of the metal to be elevated by
the formation of corrosion product.
- Expanded Sweep - A short
duration horizontal sweep positioned to provide close examination
of a particular signal.
- Exposure - The time
which radiation is being exposed to
something
- Exposure Film - Radiation
intensity multiplied by time.
- Exposure Vaults and Cabinets
- Exposure vaults and cabinets are areas that
allow personnel to work safely in the vicinity while exposures are
taking place
- External Discontinuities -
Surface irregularities which cause density variations on a
radiograph. These are observable with the naked eye.