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Department of Nuclear Engineering
Nondestructive Testing (NE 462)
Fall 2014 Final Exam
Ultrasonic Testing
Q-I Circle the best choice in the following questions:
1. Reflection indications from a weld area that inspected by the angle-beam technique may represent:
- Weld bead. D. Only B and C.
- B.Cracks. E. All of the before
- Porosity
2. The resonance technique of thickness measurement demonstrated by:
- Single sideband anti-resonance techniques D. Linear time base pulse-echo techniques.
- Acoustic emission monitoring. E. Pitch and catch shear wave techniques.
C. Through transmission longitudinal wave techniques.
3. The UT technique that uses two search units is the:
- Pulse-echo technique. C. Resonance technique.
- Through-transmission technique. D. Angle beam technique
4. The area at the front of a test object where discontinuities may be present but cannot be detected is called the:
- Front zone C. Dead zone
- Far field D. Close field
5. The gradual loss of energy as ultrasonic vibrations travel through material is referred as:
- A.Refraction. D. Reflection.
- B.Reproducibility. E. Attenuation
6. Ultrasound energy for immersion testing is transmitted to the test object as a compressional wave because:
- The higher intensity Compressional waves is necessary to overcome high attenuation in liquids.
- Compressional waves travel faster, and will therefore reduce the distance of the interface signal.
- Liquids will only sustain compressional waves.
- Compressional waves are used with immersion testing only.
7. In a basic pulse-echo ultrasonic instrument, the component that produces the voltage the activates the search unit is called:
- A.Receiver. C. Synchronizer
- B.Pulser. D. Amplifier.
8. Snell’s law is used to determine the relationship of:
A. The angle of incidence and the angle of refraction C. Frequency and attenuation
B. Longitudinal velocity and contact angle. D. Frequency and velocity
9. The depth that surface waves can penetrate a material:
A. Is one tenth of the material thickness. C. Is one wavelength
B. Depends on acoustic attenuation. D. Is half the material thickness
10. The general use of distance-amplitude calibration is to compensate for:
- Vertical non-linearity in the ultrasound instrument.
- Amplitude of noise signals. D. Transducer size
- Velocity changes E. Attenuation, distance and beam spread.
11. The technique commonly used to detect lamination located parallel to the surface of the test object is the:
A. Lamb wave technique C. Through-transmission technique
B. Straight beam technique D. Angle beam technique
12. The primary difference between the contact and immersion testing techniques is the use of:
A. oil couplant in immersion testing C. water couplant in immersion testing
B. low frequency search units in immersion testing D. two search units in immersion testing
13. The amount of energy reflected from a discontinuity is dependent on:
- The orientation of the discontinuity. D. Only A and C.
- The type of the discontinuity E. All of the before.
- The size of discontinuity.
14. Lack of parallelism between the entry surface and the back surface:
- Usually indicates a porous condition existing in the metal.
- Will decrease the penetrating power of the test.
- May result in a screen pattern that does not contain back reflection indications.
- Make it difficult to locate discontinuities that lie parallel to the entry indications.
15. Generally, the best ultrasonic testing techniques for detecting discontinuities oriented along the fusion zone in a welded plate is:
- A resonance technique. D. A contact test using a straight longitudinal wave.
- An angle-beam method using shear waves. E. A contact test using a straight longitudinal wave.
- An angle-beam contact method employing surface waves.
16. Ultrasonic inspection of casting is occasionally impractical because of :
- Random orientation of discontinuities. C. Coarse grain structure
- Extremely small grain structure typical in castings D. Uniform flow lines.
17. Ultrasonic techniques are frequently used in on-line automatic process control applications to measure and control:
- Chemical activity in chemical etching processes. D. Moisture content in food
- The density of forgings. E. Surface roughness of turbine blade castings.
- The thickness of cold-rolled strip, sheets and plates.
18. Another name of Rayleigh waves is:
A. Shear waves C. Surface wave
B. Longitudinal waves D. Transverse waves
19. Most UT inspections of industrial metallic components use frequencies of:
A. 10 - 200000 Hz C. 1-20 million Hz
B. 200000 – 1 million Hz. D. 20-100 million Hz
20. An advantage of the contact technique over the immersion technique is:
A. The ability to scan irregularly-shaped objects. C. Deeper penetration power of sonic energy.
B. Better near surface resolution of discontinuities. D. That higher frequencies can be used for faster scanning
21. The use of lower test frequencies is required for:
A. Forgings. C. Rolled shapes
B. Castings D. Weldments
22. In immersion testing, the angle formed by the ultrasound beam and a line perpendicular to the component surface:
A. Decreases when it penetrates the component and increases when it leaves the component.
B. Increases when it penetrates the component and decreases when it leaves the component.
C. Decreases when it penetrates the component and decreases when it leaves the component.
D. Increases when it penetrates the component and increases when it leaves the component.
23. UT of castings is not a common practice due to their:
- Small grain boundaries C. Irregular surface conditions.
- Considerable amount of porosity D. Large grain boundaries
24. The mode of vibration in steel that has the greatest sound velocity is the:
- Shear wave. C. Longitudinal wave.
- Surface wave D. Lamb wave.
25. In, general, shear waves are more sensitive to small discontinuities than longitudinal waves for a given frequency and in a given material because:
- The wavelength of shear waves is shorter than the wavelength of longitudinal waves.
- The direction of particle vibration for shear waves is more sensitive to discontinuities.
- The wavelength of shear waves is longer than the wavelength of longitudinal waves.
- Shear waves are not as easily dispersed in the material.
26. Which of the following will create a resonance condition in a specimen?
- Pulsed shear waves D. Continuous longitudinal waves
- Pulsed longitudinal waves E. All of the before
- Continuous shear waves
27. The A-scan displays information of a discontinuity’s depth and its:
A. Relative location to the back surface only C. Shape
B. Orientation D. Relative size
28. A B-scan presentation displays:
A. Plane view of an object. C. Cross-sectional view of an object.
B. Amplitude of a discontinuity. D. The depth of the discontinuity from the back surface.
29. In contact testing, shear waves can be induced in the test material by:
A. Using two transducers on opposite sides of the test specimen.
B Placing a spherical acoustic lens on the face of the transducer.
C. Using an “angle-beam transducer” with the transducer mounted on a plastic wedge so that sound eneters the part at an angle.
D. Placing an X-cut quartz crystal directly on the surface of the materials, and coupling through a film of oil.
30. In immersion testing, proof that the search unit is normal to a flat entry surface is induced by:
- Maximum amplitude from a discontinuity indication D. Elimination of water multiples
- Maximum reflection amplitude from the entry surface E. Maximum amplitude of the initial pulse.
- Maximum reflection amplitude from the back surface
31. Ultrasonic waves propagate through the test material in the form of:
A. Mechanical vibrations D. Discontinuous radio waves
B. Electromagnetic waves E. Radiation
C. Low voltage electrical field
32. Ultrasonic velocities are different for different materials. These differences are primarily caused by differences in materials:
A. Chemistry permeability C. Thickness and travel time
B. Elasticity sand density D. Frequency and wavelength
33. When inspecting coarse-grained materials, which of the following frequency will generate a sound wave that will be most easily scattered by the grain structure?
A. 5 MHz C. 1 MHz
B. 10 MHz D. 2.25 MHz
34. The ability of transducers to detect echoes from small discontinuities is a definition for:
A. Selectivity D. Sensitivity
B. Gain E. Definition
C. Resolution
35. The display on most basic pulse-echo ultrasonic instruments consists of:
A. C-scan presentation C. A-scan presentation
B. B-scan presentation D. Automatic read-out equipment
36. The primary purpose of reference blocks is to:
A. Establish the size and orientation of a discontinuity D. Aid the operator in obtaining maximum back reflections
B. Enable testing of non-metals E. Obtain the greatest sensitivity possible from an instrument
C. Obtain a common reproducible reference standard
37. The presence of a discontinuity will not produced a specific discontinuity indication on the CRT screen when which of the following technique is being used?
A. Pulse-echo technique D. Surface wave testing
B. Through-transmission testing E. Angle beam testing
C. Straight beam testing
38. Significant errors in ultrasonic thickness measurement can occur if:
A. Longitudinal waves are used
B. Water is employed as a couplant between the transducer and the part being measured
- The velocity of propagation deviates substantially from an assumed constant value for a given material
- Test velocity is varied
39. The most commonly used method of producing shear waves in a test part when inspecting immersion method by:
- Angulating the search tube to the proper angle with respect to the entry surface of the test part
- Using a low frequency transducer
- Using two crystals vibrating at deferent frequencies
- Transmitting longitudinal waves into a part in a direction perpendicular to its font surface
40. In immersion testing, the water distance between the search unite and the test piece:
A. Should be as great as possible C. Will have no effect on the test
B. Should be the same as the water distance used during calibration D. Should be as small as possible
41. The sheet may be inspected for laminar discontinuity with the ultrasonic wave direct normal to the surface by observing:
A. Signals that “walk” or move along the time base as the transducer is Scand over the sheet
B. The amplitude of the initial pulse
C. The multiple reflection pattern D. The amplitude of the front surface reflection
42. Angle beam testing of plate will often miss:
A. A series of small discontinuities C. Inclusions that are randomly oriented
B. Laminations that are parallel to the front surface D. Cracks that are perpendicular to the sound wave
43. Ultrasonic testing technique are useful in testing laminate and sandwich construction test object for:
A. Electrical conductivity D. Paint thickness
B. Surface roughness E. Leakage
C. Bond integrity
44. The a large acoustic impedance mismatch at an interface will result in:
A. A high amount of transmitted sound energy C. A small degree of refraction
B. A large critical angle D. A high amount of reflected sound energy
45. Which of the following could influence the behavior of a transducer?
A. Electrical construction C. Mechanical construction
B. Material construction D. All of the before
46. Immersion transducers have:
A. An acoustical impedance matching layer C. A large angle of refraction
B. A small angle of refraction D. A large angle of reflection
47. The active element of most acoustic transducers used today is:
A. Lithium C. Quartz
B. Piezoelectric ceramic D. Sulfide
48. The material of the reference standard used to setup for a flaw inspection:
A. Can be made from similar material as long as the velocity is the same
B. Should be the same material being inspected
C. Must have the same impedance values as the base material
D. Can only be used once
49. The sound that emanates from a piezoelectric transducer originates:
A. From a point on the active surface C. From most of the active surface
B. From a small area in the center of the active surface D. From the edges of the active surface
50. Beam spread is greater when using:
A. High frequency transducers C. Larger diameter transducers
B. Low frequency transducers D. Angle beam transducers
51. Which of the following waves is able to follow a surface around a curve?
A. A longitudinal wave C. A Lamb wave
B. A surface wave D. A shear wave
52. Within a given material, the speed of sound:
A. Is constant C. Decreases with distance from the transducer
B. Increases with distance from the transducer D. None of the before
53. The ability to locate discontinuities that are close together within the material is called:
A. Resolution C. Sensitivity
B. Effectiveness D. Phase delay
- In the transverse of shear wave, the particles:
- Move in an elliptical pattern C. Oscillate parallel to the direction of wave propagation
- Do not actually move D. Oscillate at a right angle to the direction of wave propagation
55. Resolution generally increases:
- With increase depth of a defect C. When the transducer diameter is reduced
- With decrease in the transducer frequency D. With increase in the transducer frequency
56. Longitudinal waves are also called:
- Surface waves C. Compressional waves
- Pressure waves D. Both B and C
- Angle beam transducers and wedges are typically used to introduce a:
A. Reflected shear wave into the part C. Share wave into the part
B. Longitudinal wave into the part D. Compression wave into the part
- Which type of screen presentation displays the amount of received ultrasonic energy as a function of time?
- A-scan C. C-scan
- B-scan D. All of the before
59. The terms used to describe a technique's ability to locate flaws are:
- Sensitivity and penetration C. Sensitivity and resolution
- Space and time D. Frequency and size
- IN order to have a reasonable chance at detecting a discontinuity, the reflective surface of the discontinuity must have dimension that is at least as long as ___________ wavelength.
A. One-half C. Two
B. One D. One-quarter
- The sound energy or ultrasonic beam is more uniform in the:
- Far field zone C. Interface between the transducer and plastic wedge
- Near field zone D. Band along the central axis
- The total resistance that the cable presents to the electrical current passing through it is called:
- Attenuation C. Shielding
- Impedance D. Resistance
- Which type of screen presentation displays a profile or cross-sectional view of the test specimen?
A. A-scan C. C-scan
B. B-scan D. All of the before
64. When sound travels through a medium:
A. Its intensity diminishes with distance C. Its speed remains constant
B. It speeds perpendicular to the primary direction of the wave travel D. All of the before
- Which type of transducer can be used to scan wide areas when high sensitivity is not required?
A. Mosaic transducer C. Composite transducer
B. Single crystal transducer of small diameter D. Paint brush transducer
- What part of ultrasonic machine generates short, large-amplitude pulses of controlled energy?
- Pulser C. Transducer
- Amplifier D. Scanner
67. The act of evaluating and adjusting the precision and accuracy of the measurement equipment is called:
A. Standardization C. Accuracy
B. Calibration D Tuning
- As frequency increases, sound tends to:
- When a longitudinal wave encounters an interface between two matrial with different acoustic impedances, what occurs when the angle of incidence is 90 degree?
- Become more compressed C. Convert to a different wave mode
- Scatter more from large or course grain structure D. Become more penetratin
- Reflection C. Mode conversion
- Refraction D. Reflection and refraction
70. A decibel is:
A. A unit of measure used only for sound measurements
B. A logarithmic unit that describes a ratio of two measurements
- A logarithmic unit that describes the product of two measurements
- None of the before
72. What type of transducer contains two independently operating elements in a single housing?
- Crystal mosaic transducer C. Liquid crystal transducer
- Dual element transducer D. Bi-polar transducer
73. Which of the following would make a good couplant?
- Water C. Glycerin
- Oil D. All of the before
74. The first critical angle describes the condition where the:
A. The angle of the refracted longitudinal wave is less than 90 degree
B. The angle of the refracted longitudinal wave is exactly 90 degree
C. The angle of the refracted longitudinal wave is greater than 90 degree
D. The angle of the refracted shear wave is exactly 90 degree
75. The ability to locate a small discontinuity is called:
A. Resolution C. Wavelength
B. Sensitivity D. Frequency
76. Which of the following waves is only able to travel through a thin section of material?
A. A longitudinal wave C. A surface wave
B. A shear wave D. A lamb wave
77. Share waves do not propagate in:
A. Solids C. Liquids
B. Gases D. Both B and C are correct
78. Surface or Raleigh waves traveling along the surface of relative thick solid material, penetrate to a depth of approximately:
A. One wavelength C. Three wavelength
B. Two wavelength D. Infinite wavelengths
79. Which type of screen presentation displays a plan-type view of the location and size of the test specimen features?
A. A-scan C. C-scan
B. B-scan D. All of the before
80. What type of set-up can provide information about both the size of the flaw and distance between the flaw and the transducer?
- C.A. Through transmission C. Pulse echo
B. Pitch/catch with two transducers D. Both B and C
Q-II. Write the difference between the following:
A. Compression and Share Waves
B. Back Echo and Initial pulse on CRT
C. First and second Critical Angles of Incident Beam
D. Near and Far Fields of Ultrasonic Transducer
E. Sound Propagation and Mode Conversion
F. Creep and Rayleigh Waves
G. Beam Spread and Beam Divergence.
H. Reflected and Refracted Angles
I. Sensitivity and Resolution of Ultrasonic Inspection
J. Ultrasonic Attenuation and Acoustic Impedance
Q-III Calculate the angle of incident compression wave in water that gives 20o an angle of refraction shear wave in steel, where the shear wave velocity in steel is 3240 m/s, the compression wave velocity of sound in steel is 5960 m/s, and 1480 m/s in water.
Q-IV Draw the setup of the transducer with the calibration block showing the direction of the propagate wave and the pulse echo from the CRT for the following Ultrasonic calibrations:
1. Range of calibration is 100 mm, first echo back pulse comes from 50 mm distance on V1 block using normal single transducer.
2. Range of calibration is 200 mm, first echo back pulse comes from 25 mm distance on V1 block using normal single transducer.
3. Range of calibration is 150 mm, first echo back pulse comes from 50 mm distance on V2 block using normal single transducer.
4. Range of calibration is 250 mm, first echo back pulse comes from 25 mm distance on V2 block and 45o angular transducer.
Q-V Sketch the dual crystal probe (TR-probe) construction including all layers and materials.
Q-VI Calculate the percentage energy reflected at water to steel interface, given that the acoustic impedance for steel is 46.7, and 1.48 for water.
Q-VII Calculate the beam spread angle for a 2.25 MHz compression wave in steel when using 2 cm diameter transducer.
Q-VIII Calculate the far field distance in steel for 2.25 MHz compression wave when using transducer that is 1.5 cm diameter
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