Theory Flashcards
The wave mode that has multiple or varying wave velocities is:
a. longitudinal waves
b. shear waves
c. transverse waves
d. Lamb waves
d. Lamb waves
Which of the following would be considered application(s) of ultrasonic techniques?
a. Determination of a material’s elastic modulus.
b. Study of a material’s metallurgical structure.
c. Measurement of a material’s thickness.
d. All of the above.
d. All of the above.
The only significant sound wave mode that travels through a liquid is a:
a. shear wave
b. longitudinal wave
c. surface wave
d. Rayleigh wave
b. longitudinal wave
The acoustic impedance of a material is used to determine the:
a. angle of refraction at an interface
b attenuation within a material
c. relative amount of sound energy coupled through and reflected at an interface
d. beam spread within the material
c. relative amount of sound energy coupled through and reflected at an interface
When angle beam contact testing a test piece, increasing the incident angle until the second critical angle is reached results in:
a. total reflection of a surface wave
b. 45 degree refraction of the shear wave
c. production of a surface wave
d. none of the above
c. production of a surface wave
Acoustic energy propagates in different modes. Which of the following represent a mode?
a. A longitudinal wave
b. A shear wave
c. A surface wave
d. All of the above
d. All of the above
The simple experiment where a stick in a glass of water appears disjointed at the water surface illustrates the phenomenon of:
a. reflection
b. magnification
c. refraction
d. diffraction
d. diffraction
The crystal thickness and transducer frequency are related. The thinner the crystal:
a. the lower the frequency
b. the higher the frequency
c. there is no appreciable effect
d. none of the above
b. the higher the frequency
The random distribution of crystallographic direction in alloys with large crystalline structures in factor in determining:
a. acoustic noise levels
b. selection of test frequency
c. scattering of sound
d. all of the above
d. all of the above
The length of the zone adjacent to a transducer in which fluctuations in sound pressure occur is mostly affected by:
a. the frequency of the transducer
b. the diameter of the transducer
c. the length of the transducer cable
d. both a and b
d. both a and b
The differences in signals received from identical reflectors at different materials distances from a transducer may be caused by:
a. material attenuation
b. beam divergence
c. near field effects
d. all of the above
d. all of the above
In immersion testing, the near field effects of a transducer may be eliminated by:
a. increasing transducer frequency
b. using a larger diameter transducer
c. using appropriate water path
d. using a focused transducer
c. using appropriate water path
Which of the following may result in a long narrow rod if the beam divergence results in a reflection from a side of the test piece before the sound wave reaches the back surface?
a. Multiple indications before the first back refection.
b. Indication from multiple surface reflections
c. Conversion from the longitudinal mode to shear mode.
d. loss from the surface indications
c. Conversion from the longitudinal mode to shear mode.
Where does beam divergence occur?
a. near field
b. far field
c. at the crystal
d. none of the above
b. far field
As frequency increases in ultrasonic testing, the angle of beam divergence if a given diameter crystal:
a. decreases
b. remains unchanged
c. increases
d. varies uniformly through each wavelength
a. decreases
As the radius of curvature of a curved lens is increased, the focal length of the lens:
a. increases
b. decreases
c. remains the same
d. cannot be determined unless the frequency is known
a. increases
When examining materials for planar flaws orientated parallel to the part surface, what testing method is most often used?
a. angle beam
b. through-transmission
c. straight beam
d. dual crystal
c. straight beam
If a contact angle beam transducer produces a 45 degrees shear wave in steel, the angle produced by the same transducer in an aluminum specimen would be: (VS=0.323 cm/us; V=0.310 cm/us)
a. less than 45 degrees
b. greater than 45 degrees
c. 45 degrees
d. unknown: more information is required
a. less than 45 degrees
Rayleigh waves are influenced most by defects located:
a. close to or on the surface
b. 1 wavelength below the surface
c. 3 wavelength below the surface
d. 6 wavelength below the surface
a. close to or on the surface
The ultrasonic testing technique in which finger dampening is most effective in locating a discontinuity is the:
a. shear wave technique
b. Longitudinal wave technique
c. surface wave technique
d. compressional wave technique
c. surface wave technique
Lamb waves can be used to detected:
a. laminar-type defects near the surface of a thin material
b. lack of fusion in the center of a thick weldment
c. internal voids in diffusional bonds
d. thickness changes in heavy plate material
a. laminar-type defects near the surface of a thin material
The ratio of velocity of sound in water compared to that for aluminum of steel is approximately:
a. 1:8
b. 1:4
c. 1:3
d. 1:2
b. 1:4
In an immersion test piece of steel or aluminum, the water distance appears on the display as a fairly wide space between the initial pulse and the front surface reflection because of:
a. reduced velocity of sound in water as compared to the test specimen
b. increased velocity if sound in water as compared to test specimen
c. temperature of the water
d. all of the above
a. reduced velocity of sound in water as compared to the test specimen
Using the immersion method, a distance amplitute curve (DAC) for a 19mm (0.75 in.) diameter, 5 MHz transducer shows the high point of the DAC at the B/51 mm (2 in.) block. One day later, the high point
of the DAC for the same transducer is at the J/102 mm (4 in.) block. Assuming that the calibration has not changed, this would indicate the transducer:
a. is improving in resolution
b. is becoming defective
c. has the beam of a smaller transducer
d. both b and C
d. both b and C
