Level 1 Flashcards
Waves used in ultrasonic testing of materials are ___________ in nature.
a) mechanical
b) magnetic
c) electromagnetic
d) harmonious
A
In a longitudinal wave, zones of compression alternate with________ zones.
a) dead
b) rarified
c) subduction
d) anticline
B
Elastic waves can be transmitted in
a) air
b) water
c) solids
d) all of the above
D
The smallest distance between two points on an elastic wave where the particles are in the same state of motion is the a) period b) wavelength c) frequency d) hypotenuse
B
The maximum displacement of a particle from its point of rest in a sound wave is its a) velocity b) amplitude of movement c) frequency d) wavelength
B
Particle motion in a longitudinal wave is a) parallel to the direction of wave propagation b) at right angles to the direction of wave propagation c) retrograde d) in counterclockwise ellipses
A
In transverse waves, particle motion is a) parallel to the direction of wave propagation b) right angles to the direction of wave propagation c) retrograde d) in counterclockwise ellipses
B
Rayleigh waves are a phenomenon associated with a) solid to liquid boundaries b) solid to air boundaries c) solid to solid boundaries d) all of the above
D
Surface waves limited on two surfaces are also called a) long. waves b) lamb waves c) shear waves d) P waves
B
Rayleigh, shear and longitudinal describe a) wave forms b) wave modes c) wave lengths d) wave guides
B
In general, the result of two waves interacting on each other can be found by a) strobe lighting b) vector addition c) cross-multiplying d) linear summation
B
The point where no particle displacement occurs on a standing wave is called a) an anticline b) an antidnode c) a node d) a dead zone
C
The point where maximum particle displacement occurs on a standing wave is called a) an anticline b) an antinode c) a node d) a peak detector
B
Wavelength of sound is determined by a) (velocity) / (frequency) b) (frequency) / (velocity) c) (frequency) X (velocity) d) none of the above
A
Compared to water, the acoustic impedance of steel is a) higher b) lower c) about the same d) higher or lower depending on the wave mode
A
2,500,000 cycles per second (cps) is also expressed as a) 25 kHz b) 2.5 MHz c) 2.5 mHz d) 25 GHz
B
The product of acoustic velocity times the density of a material gives a) power intensity b) frequency c) wavelength d) acoustic impedance
D
In steel, shear wave velocity as compared to longitudinal wave velocity is about a) twice as fast b) the same c) one half as fast d) one quarter as fast
C
The usual form of denoting acoustic impedance is a) Z b) A c) I d) R
A
If a material borders on empty space the interface is called a) a vacuum b) infinity c) a free boundary d) none of the above
C
In determining the coefficient of reflection, a negative value indicates a) reduced amplitude b) loss of sound pressure c) phase reversal relative to the incident wave d) none of the above
C
Phase reversal of an ultrasound wave upon reflection from a sonically softer material is indicated by a) a zero R value b) a negative R value c) an R value greater than 1 d) increased resonance
B
Incidence of a sound wave from a solid to a gas is considered a free boundary condition because a) there are no particles in a gas b) all sound is lost in transmission c) the acoustic impedance of a gas is essentially zero d) none of the above
C
Bending of a sound wave upon entering a new medium is explained by a) Krautkramer’s law b) Snells’s law c) Boyle’s law d) Hooke’s law
B
If a sound beam is incident on steel from water at 20 degrees, the refracted transverse wave will have an angle a) greater than 20 degrees b) less than 20 degrees c) about 20 degrees d) that cannot be determined
A
The change from longitudinal to transverse waves (and visa versa) at a boundary is called a) Snell’s law b) mode conversion c) reciprocity d) reversal
B
The incident angle at which the transmitted longitudinal wave first ceases to exist in the defracting medium is called the a) longitudinal angle b) short angle c) first critical angle d) second critical angle
C
The incident angle at which the transmitted transverse wave first ceases to exist in the refracting medium is called the a) long angle b) short angle c) first critical angle d) second critical angle
D
The critical angle for the longitudinal wave is also called the a) right angle b) snell angle c) first critical angle d) second critical angle
C
The critical angle for the transverse wave is also called the a) right angle b) Snell angle c) first critical angle d) second critical angle
D
Mode conversion in ultrasonics occurs at a) defects b) corner reflectors c) only free boundaries d) all boundaries
D
For a longitudinal wave entering a medium of lower acoustic velocity, the refracted longitudinal wave angle in the new
material will be
a) totally internally reflected
b) the same
c) less than incidence angle
d) greater than incidence angle
C
The law of reflection requires that
a) the angle of reflection equals the angle of incidence
b) the normal to the reflecting surface, the reflected ray and incident ray lie in the same plane
c) both a and b
d) none of the above
C
The “bending” of sound waves at gaps and openings is accounted for by
a) reflection
b) diffraction
c) density
d) acoustic pressure
B
According to geometric-optic treatment of sound, acoustic pressure
a) increases with distance from source
b) decreases with distance from source
c) varies unpredictably with distance from source
d) none of the above
B
Reflection and refraction phenomenon are illustrated in geometric-optic treatment of ultrasound by means of
a) mirrors
b) equations
c) rays and straight lines
d) none of the above
C
In practical ultrasonic testing, mirror surfaces can be used with
sound beams to
a) image flaws
b) reach points of difficult access
c) reduce scatter
d) reduce short wave dispersion effects
B
The interference pattern produced in front of a transducer face
is a result of
a) rarefaction
b) dispersion
c) diffraction
d) refraction
C
The distance from the probe face to the last main maximum on the
beam axis is called the
a) near field
b) far field
c) dead zone
d) ozone
A
Acoustic pressure fluctuates in the near zone due to
a) diffraction interference
b) dispersion
c) refraction
d) density fluctuations
A
A longitudinal wave generating transducer will have a given near
field in steel. If in water the near field for this probe will
be
a) the same distance
b) about half as long
c) about 1/4 as long
d) about 4 times as long
D
Acoustic pressure along the beam axis moving away from the probe
has various maxma and minima due to interference. At the end of
the near field pressure is
a) a maximum
b) a minimum
c) the average of all maxima and minima
d) none of the above
A
Beyond the near zone of an ultrasound beam from a probe is the
a) dead zone
b) Fresnel zone
c) far field
d) null zone
C
Variations in acoustic pressure at right angles to the probes’
sound beam in the near zone are a result of
a) side lobes
b) overtones
c) sub harmonics
d) divergence
A
The angle of divergence is
a) constant for a given piezoelectric material
b) applicable to the far zone only
c) increases with increasing probe dimensions
d) decreases with increasing wavelength
B
The “main lobe” of a rectangular probe is
a) axially symmetric
b) broader in the small probe dimension
c) narrower in the small probe dimension
d) two dimensional
B
Focusing of ultrasound is accomplished by
a) curved piezoelectric crystals
b) lenses
c) both a and b
d) none of the above
C
Difficulties determining exact lateral location and relative size
of a flat reflector in the near zone result from
a) the dead zone
b) ring down
c) multiple maxima and minima
d) absorption
C
AVG (or DGS in English) diagrams are used for
a) establishing gain settings
b) determining vertical beam spreads
c) estimating flaw size
d) none of the above
C
Flaw detection using the through transmission method can give
accurate information about
a) flaw depth
b) flaw type
c) flaw orientation
d) none of the above
D
In ultrasonic testing, a wave pulse contains
a) a single well defined frequency
b) a range of frequencies
c) two full cycles
d) only positive going waves
B
The main contribution to loss of sound pressure of a beam
incident on a rough surface is provided by
a) scatter
b) mode conversion
c) refraction
d) diffraction
A
More scatter of a sound beam is had when using
a) high PRF
b) short pulse lengths
c) higher frequency probes
d) lucite delay lines
C
For best results detecting a defect that may be irregularly
shaped and slightly off perpendicular to the beam, the wavelength
used should be
a) the size of the defect
b) as small as possible
c) as large as possible to locate the defect
d) 1 MHz
C
In ultrasonic testing by pulse-echo method, the sound waves off
the probe are
a) omni-directional
b) a single frequency
c) a range of frequencies
d) non-existent in the dead zone
C
Higher frequency probes are not preferred for inspection of
castings due to
a) poor directivity
b) higher coefficients of transmission
c) higher coefficients of reflection
d) scatter
D
Sound reduction over a distance can be accounted for by
a) absorption
b) scatter
c) beam spreading
d) all of the above
D
Attenuation of ultrasound by absorption is a result of
a) reflection
b) refraction
c) scatter
d) heating
D
For a plane wave, sound pressure is reduced by attenuation in a
_______ fashion.
a) linear
b) exponential
c) random
d) none of the above
B
If a signal on your CRT is 28% FSH and 6 dB gain is added to the
receiver amplifier the signal will be _______ FSH.
a) 34%
b) 42%
c) 56%
d) 70%
C
If a signal is reduced from 84% to 42% FSH, the number of dB
gain removed from the receiver is
a) 2
b) 6
c) 12
d) 42
B
A typical maximum thickness range for inspecting forged steel by
ultrasonics is
a) 0.5 to 1m
b) 1 to 2 m
c) 1 to 10 m
d) 10 to 100 m
C
As temperature of a solid increases the attenuation of sound in
that object tend to
a) increase
b) decrease
c) remain constant
d) vary sinusoidally
A
Scatter is more likely to be a problem if
a) grain size is small
b) grain size is large
c) a material is isotropic
d) grain crystals are cubic
D
Scatter of ultrasound at grain boundaries is a result of
a) frequency
b) in-homogenous inclusions
c) angulation
d) differences in elastic properties
D
Scatter generally increases with
a) increasing grain size
b) decreasing wavelength
c) increasing frequency
d) all of the above
D
In ultrasonic testing a piezoelectric material is used to
a) convert electric energy to mechanical energy
b) convert mechanical energy to electrical energy
c) both a and b
d) none of the above
C
The piezoelectric material first used for ultrasonic transducers
is
a) PZT
b) SiO2 (quartz)
c) Na Cl
d) PVDF
B
X-cut quartz crystal transducers are cut with active element face
at right angles to the
a) X-axis
b) Y1-axis
c) Y2-axis
d) Z-axis
A
Shifts of the positive charge on the silicon and negative charge
on the oxygen in a quartz crystals account for
a) twin crystals
b) the piezoelectric effect
c) polymorphs
d) none of the above
B
In order to generate mechanical displacements (ultrasound waves)
in a X-cut piezoelectric crystal we must
a) squeeze the crystal
b) heat the crystal
c) apply an alternating voltage
d) none of the above
C
Applied voltage on a piezoelectric crystal used in a transducer
requires ________ to cause mechanical displacement
a) electrodes
b) vibration
c) heat
d) all of the above
A
The fundamental frequency of a piezoelectric crystal used in
ultrasonics is a function of
a) its thickness
b) the velocity of sound in the crystal material
c) both a and b
d) none of the above
C
The ratio of vibration amplitude at resonance frequency to the
amplitude of static thickness change is called
a) fo
b) fr
c) the modulus of resonance
d) Q factor
D
A large Q factor indicates
a) high damping
b) narrow bandwidth
c) wide bandwidth
d) low permeability
B
Resonance peaks at frequencies of odd numbered multiples of the
resonance frequency are called
a) harmonics
b) PRF
c) multiple frequencies
d) sub-harmonics
A
In pulse-echo testing there is an advantage to using short pulses
to excite the transducer because
a) the dead zone is decreased
b) the frequency spectrum is broadened
c) both a and b
d) none of the above
C
Of the various materials used for transducer crystals, lithium
sulphate hydrate is the most critical because it
a) looses its water of crystallization above 130 degrees C
b) breaks down at excitation voltages over 500 V
c) cannot be used in immersion testing
d) all of the above
A
A PZT transucer will loose its piezoelectric property if
a) immersed in water
b) used on a forging that has not been de-magnetized
c) used on a surface whose temperature is 140 degrees C
d) heated above its curie point
D
In addition to a low critical temperature, lithium sulphate
hydrate
a) is soluble in water so must be water proofed
b) is a poor impedance match to water
c) has the lowest coupling coefficient
d) none of the above
A
Methods of generating and receiving ultrasound by deformation of
ferromagnetic materials in a magnetic field utilize the
phenomenon called
a) magnetics
b) electrodynamics
c) magnetostriction
d) eddy currents
C
Magnetostrictive principles can be used
a) for transmitting ultrasound
b) for receiving ultrasound
c) both a and b
d) none of the above
C
Mechanical methods of ultrasound generation
a) utilize electro-mechanical hammers
b) utiltize rotating wire brushes
c) require no coupling liquids
d) all of the above
D
The method whereby sound is transmitted through a plate from a
transmitter on one side to a receiver on the other
a) is used to characterize flaws
b) is called an intensity method
c) is used to determine flaw depth
d) all of the above
B
Pulse-echo ultrasonic testing is used for
a) thickness testing
b) flaw detection
c) acoustic velocity determinations
d) all of the above
D
Using the pulse echo method with a 0 degrees probe (single
crystal) on a flat steel plate 50mm thick, the pattern on the CRT
would appear as
a) evenly spaced multiples
b) randomly spaace multiples
c) multiples with increasing spacing between them
d) none of the above
A
When testing thick specimens, it may be advisable to
a) decrease the pulse repetition frequency
b) add reject
c) change to a higher frequency
d) use a delay line probe
A
In immersion testing you would normally position the
a) main bang on the left edge of the CRT
b) entrance echo on the left of the CRT
c) first bacwall on the right edge of the CRT
d) none of the above
B
Transmitter voltage pulse is triggered by the
a) probe resonance
b) control pulse of the sweep generator
c) sweep delay control
d) vertical deflector plates in the CRT
B
For flaws immediately below the surface the best option is
a) TR or twin crystal probes
b) single crystal probes
c) multi probe configurations
d) through wall testing
A
The normal presentation of ultrasonic signals on an ultrasonic
machine used in NDT is
a) rectified form
b) RF form
c) b-scan
d) c-scan
A
If not equipped with a frequency selecter for the reciever
amplifier an ultrasonic machine would probably use a (an)
a) broadband receiver
b) wide receiver
c) ineligible receiver
d) tight end
A
Threshold adjustment is applied to
a) RF display of signals
b) “clean up” the noise on the baseline
c) both a and b
d) none of the above
B
Electrode material on the piezoelectric crystal faces, typically
evaporated to about 1000 angstroms thick, is made of
a) gold
b) silver
c) chrome/gold
d) all of the above can be used
D
Boron, aluminum oxide and sapphire are often used in transducers
as
a) tuning transformers
b) electrodes
c) wear faces
d) none of the above
C
In contact testing using angle beam probes with removable wedges,
the purpose of groves in the front of the wedge is
a) to prevent couplant buildup
b) increase resolution
c) absorb internally reflected sound
d) all of the above
C
The most commonly used wave mode for angle beam testing is
a) longitudinal
b) transverse
c) Rayleigh
d) Lamb
B
Unless otherwise noted, the refracted beam angle on a perspex
wedge is the refracted angle in
a) aluminum
b) brass
c) plastic
d) steel
D
Angle beam wedges can be used to generate surface waves only if
a) the refracted shear wave is 90ø
b) the test piece is steel
c) the test peice is cylindrically shaped
d) none of the above
A
A property of the receiver amplifier that is periodically
verified is
a) horizontal linearity
b) vertical linearity
c) beam spread
d) near zone
B
The purpose of the IIW block is to determine
a) probe exit point
b) refracted angle
c) range (or depth scale)
d) all of the above
D
Information obtained about the exit point and refracted angle of
an angle beam probe
a) is qualitative only
b) must be check periodically since the probe is subject to wear
c) is fixed by the manufacture
d) none of the above
B
The IIW block is used primarily
a) for contact probes
b) for angle beam probes
c) for immersion work
d) in place of the IOW block
A
A system that electronically monitors an echo signal in a gate
such that an alarm is triggered if the signal exceeds a
predetermined amplitude is called a / an
a) B-scan
b) go / no-go system
c) early warning system
d) sweep generator
B
The preferred presentation method for determining the amplitude
of a echo signal is the
a) A-scan
b) B-scan
c) C-scan
d) D-scan
A
Resonance testing methods are used for
a) determining Poisson’s ratio
b) flaw detection
c) thickness testing
d) all of the above
C
Thickness readings from ultrasonic testing can be indicated by
a) reading the position of pips on a CRT screen
b) meter or digital readout
c) graphing by a pen on strip chart paper
d) all of the above
D
For immersion testing, surface scale and rust can be removed by
a) steel brushes and scrapping
b) sand blasting and grinding
c) both a and b
d) none of the above, cleaning is not needed for immersion
testing
C
In contact testing best probe contact is made on ________
surfaces.
a) flat
b) convex
c) concave
d) 250 RMS surfaces
A
Uniformity of coupling is verified by the operator monitoring
a) backwall amplitude
b) “grass” level
c) a and b
d) calibration
C
For normal ultrasonic contact testing of forged carbon steel and
aluminum the optimum frequency range of transducers is
a) 100 to 500 kHz
b) 0.5 to 1 MHz
c) 2 to 5 MHz
d) 10 to 15 MHz
C
High frequency transducers, over 10 MHz, have
a) little use in contact testing
b) very thin crystals
c) good sensitivity to minute defects
d) all of the above
D
When a longitudinal wave is directed along the length of a large
solid shaft from an end of the shaft, sensitivity to defects
fluctuates as the probe is moved from the centre to the outside
edge of the shaft. This is accounted for by
a) interfering edge effects
b) the near zone
c) mode conversion
d) none of the above
A
When performing contact angle beam testing interferring surface
waves can be distinguished from flaws by
a) triangulation
b) testing from the opposite side
c) touching the work surface with an oily finger
d) none of the above
C
When inspecting a thin flat plate with a 60ø shear wave probe it
is possible to see both top and bottom corners of the plate when
the beam is aimed at the plate edge. This is due to
a) ghosting
b) splitting
c) beam spread
d) none of the above
C
When scanning a test plate with angle beam probes, the operator
can often determine the front and backwall position on the screen
from
a) “grass mounds”
b) gates
c) the distance amplitude correction curve
d) none of the above
A
In plate testing with angle beams, the full skip distance refers
to
a) the sound path to the opposite wall
b) twice the sound path to the opposite wall
c) the plate thickness
d) twice the plate thickness
B
For an ultrasound beam to skip in the circumferential direction
of a tubular product
a) the ratio of inside to outside diameter must be right
b) the incident angle must be sufficiently steep
c) both a and b
d) none of the above
C
The delta technique uses
a) a single pulse echo probe
b) a transmitting probe and receiving probe on the same side of
the test piece
c) a transmitting probe and receiving probe on opposite sides of
the test piece
d) there is no such technique
B
Surface wave ultrasonic testing is superior to penetrant testing
because it
a) is cheaper
b) is faster
c) can find sub-surface defects
d) can be used on ferro-magnetic materials
C
Flaw size is often determined by
a) comparison of probe movement with change in amplitude
b) amplitude of maximum reflection
c) both a and b
d) none of the above
C
If the sound beam strikes a flaw at right angles and the flaw has
a greater area than the beam it will
a) cause resonance
b) absorb most of the beam energy
c) cause destructive interference
d) at like a backwall
D
Although ingots of metal are often difficult to test by
ultrasonics due to large dimensions and scatter due to grain
size, it is useful to locate
a) laminations
b) bursts
c) gross piping
d) cold shots
C
Which of the following plate defects would not be a result of
inservice use?
a) stress-corrosion cracking
b) laminations
c) fatigue cracking
d) pitting
B
Production line testing of high pressure ribbed tubing would use
which ultrasonic technique?
a) contact testing
b) immersion testing from the outside diameter
c) immersion testing from the inside diameter
d) the bubbler technique
C
The common metric term Hertz (abb.Hz) is used to indicate
a) wavelength
b) velocity of sound
c) cycles per second
d) acoustic impedance
C
With a sound velocity of 1.5mm/æs in water, the wavelength of the
ultrasonic disturbance in water provided by an ultrasonic
cleaning machines’ 40 kHz transducer is
a) 26mm
b) 26cm
c) 3.7mm
d) 37mm
D
The 3 essential elements common to all systems that use
ultrasonic devices are
a) transducers, cables, couplant
b) transducers, scopes, testpiece
c) power source, transducer, convertor
d) none of the above
C
The incident angle at which the longitudinal mode is refracted at
90ø is
a) 27 degrees
b) the first critical angle
c) the second critical angle
d) not used in NDT
B
The number of nanoseconds in 2 milliseconds is
a) 0.002
b) 2000
c) 2 X 10^6
d) 2 X 10^9
C
When a piezoelectric material has a voltage applied to it
a) eddy currents are generated
b) flux leakage can be used for testing
c) mechnanical deformation occurs
d) all of the above
C
To a degree, the mechanical deformation of a piezoelectric
material is directly proportional to the
a) acoustic impedance of the backing
b) acoustic impedance of the piezo material
c) applied voltage
d) none of the above
C