Chapter Eleven Quiz Flashcards
Sound wave is a mechanical vibration.
Yes, it is vibration that has characteristic frequency that is a number of vibrations per second
In most codes and standards the acceptance or rejection of a discontinuity is based on whether it is shown that it will cause failure.
false
Distance calibration using an IIW block for a normal (longitudinal mode) probe requires the probe to be placed on the:
Side to reflect off the backwall.
The frequency of a sound passing through a material with an ultrasonic velocity of 4 .65 × 103 m/s and a wavelength of 1.8 mm is:
2.6MHz
Difficulties with UT can arise when welds have backing bars due to reflections from corners, internal reflections in the bars, etc.
True
Fill in the blank: In what unit is the gain control (or attenuator) marked? The abbreviated form of this unit is written as ______.
dB
Acoustic emission relies on detecting very small amounts of mechanical energy released from such things as growing cracks or structural discontinuities under load.
True
Do transverse waves in a solid travel faster or slower than longitudinal waves?
Slower
When working to CSA W59, to what must the ultrasonic operator be certified?
CAN/CGSB 48.9712
To reduce the height of an indication on the screen by 50%, you would turn the gain control (or attenuator) through:
6dB
Fill in the blank: If the amplitude of a wave is reduced to 25%, what is the corresponding drop in dB? (Hint: you can figure it out from the information in Section 2.5, but you could also use logarithm tables or a calculator). The drop in is _____ dB.
12
Quartz and lead metaniobate are examples of piezoelectric material.
True
Fill in the blanks: What two features of an angle probe can be calibrated or checked using the IIW block?
Exit point and angle
Can shear waves operate in similar ways to longitudinal waves in the water?
No because not enough force of attraction between the atoms of water.
Why should most ultrasonic examinations of welds begin with a search of the plate with a normal probe?
To locate conditions that could interfere with finding defects.
Can we say that the action of a hammer pounding onto the surface of a metal is just about the same as the action exerted by ultrasonic probe?
Yes
The amplifier in the ultrasonic testing circuit performs the following task:
regulates the vertical beam deflection
For imperfections interpreted as incomplete fusion, the maximum acceptable length according to ASME Section VIII, Div. 1 is:
Incomplete fusion imperfections are unacceptable regardless of length
Fill in the blank: For the transverse mode, what reflector in the IIW block is used to calibrate sensitivity according to CSA W59? _____ mm side hole.
1.5
Is it possible to use acoustic emission method for global monitoring of the structure service life?
yes
As the direction of approach of the beam is changed, the amplitude of the wave reflected from a spherical pore can be expected to:
not vary significantly
If you are examining a groove weld in a plate from one surface with an angle probe, you would examine the upper portion of the weld by:
Move probe away from the weld so the beam bounces off the lower surface to strike the upper portion of the weld.
Why is good acoustic contact between the transducer and the test specimen needed? Select the most correct response:
Ultrasonic waves do not travel far in air. Need good coupling.
Fill in the blank: If an ultrasonic wave in a block of steel has a wavelength of 1.3 mm and travels at a velocity of 5.85 x 103 m/s, what is the frequency? The frequency is ______ MHz
4.5
