Ut Lavender Question

1. Identify from Figure One below, which of the four materials exhibits the greatest attenuaton in the far zone?

1

2

3

4 2. Identify from Figure One below, which of the four materials exhibits the least attenuation in the far zone?

1

2

3

4 3. Identify from Figure One below, which of the four materials is the near zone shortest?

1

2

3

4 4. In antisotropic materials linear elastics waves may propagate along a given direction. These are not pure modes. The waves with large parallel components are called?

Lamb waves

Quailongitudinal waves

Quasishear waves

Anistropic 5. A non linear transverse wave propagating in a solid that is free of discontinuities?

Distorts

Propagates without an accompanying longitudinal wave

Does not distort

Propagates without attenuation 6. Ultrasonic nondestructive test create stresses in the test component which are?

Below the yield stress and do not cause permanent deformation

Above the yield stress but do not cause permanent deformation

High compared to mechanical testing

Permanently affecting the internal structure without affecting the surface 7. In contact testing of material with known and constant acoustic velocities the time taken for sound energy to reach a reflector is ??? the distance from the contact surface to the reflector?

Exponentially proportional to

Inversely proportional to

Directly proportional to

Not proportional to

8. Which of the following wave modes would be chosen for an application that required an ability of a wave to follow the contours of irregular shaped surfaces?

Longitudinal wave

Lamb wave

Shear wave

Rayleigh wave 9. What angle of incidence would produce only a shear wave method in steel when transmitted from a probe with a perspex shoe? VI perspex=2.7 x 106 mm / sec, VL steel=6.0 x 106 mm / sec, VS steel=3.2 x 106 mm / sec

18.5

26.7

36.6

57.5 10. To which of the following techniques does this description refer? 'The time represented on the screen is indicative of a single traverse through the material'

Pulse echo

A scan

Through transmission

B scan 11. In the far field of an ultrasonic beam the beam has a?

Spherical wave front

Plane wave front

Wave front with constant acoustic pressure

Both plane wave front and wave front with constant acoustic pressure 12. The region of an ultrasonic beam characterised as a collection of symmetrical high and low pressure regions caused by interfering wave fronts is called the?

Near or Fraunhofer zone

Near or Fresnel zone

Far or Fraunhofer zone

Far or Fresnel zone 13. An increase in the pulse repetition rate is likely to ??? the brightness of the indication on the CRT screen?

Increase

Decrease

Have no effect on

Either increase or decrease depending on the actual pulse repetition rate 14. The critical angle for the interface of two media with dissimilar acoustic wave velocities is the incident angle at which the refracted angle equals?

Zero degrees

35 degrees

90 degrees

120 degrees 15. The application of Snells Law to ultrasonic waves at an acoustic interface is dependent on the wave mode velocity in the second medium?

Being greater than the wave velocity in the incident medium

Being less than the wave velocity in the incident medium

Being equal to the wave velocity in the incident medium

Either greater or lesser to the wave velocity in the incident medium 16. At a water to steel interface approximately 88% of the sound is reflected back into the water. If the sound was travelling through steel to a steel to water interface approximately ??? of the sound would be transmitted across the interface?

12%

88%

50%

To calculate would require the relative acoustic impedances 17. Water will support?

Longitudinal waves

Shear waves

Rayleigh waves - surface waves

Both longitudinal and rayleigh waves 18. Ultrasonic frequencies are above?

200 Hz

2000 Hz

20000 Hz

200000 Hz 19. Sound energy can be formed into beams, similar to that of light, at frequencies above?

10 KHz

100 KHz

1000 KHz

10000 KHz 20. Wavelength is?

Equal to the product of velocity and frequency

Inversely proportional to velocity and directly proportional to frequency

Directly proportional to velocity and inversely proportional to frequency

Both Equal to the product of velocity and frequency and Directly proportional to velocity and inversely proportional to frequency 21. The velocity of lamb - plate - waves is dependent upon?

Sample thickness

Elasticity modules

Frequency

All the above 22. Which of the following modes of ultrasonic wave may be used to volumetrically inspect material that is too thin to alow resolution of the first back wall reflection from the initial pulse?

Rayleigh

Compression

Lamb

Shear 23. Rayleigh waves can be effectively sustained only when the medium on one side of the interface?

Is a liquid

Is a gas

Is a solid

Has a sound velocity value similar to the test material 24. At an aluminium / water interface peak transmission of acoustic pressure for a returning transverse wave echo occur at beam angles between?

0-90 degrees

0-10 degrees

35-51 degrees

All angles transmit the same acoutsic pressure across an interface 25. Two components with different acoustic impedances are couples by a material having an acoustic impedance equal to the mean of the component's acoustic impedances. The thickness of the coupling layer is a quarter wavelength. What percentage of sound energy is transmitted at zero degree incidence across the coupling layer into the second component: First component Z1=17, Second component Z2=45, Coupling layer Zc=31?

100%

80%

50%

4% 26. The degree to which sound energy is reflected at an interface is dependent upon the?

Wave length of the sound wave

The frequency of the sound wave

The velocity of the sound wave

The amplitude of the sound wave 27. Sound propagates well through most liquids particularly those with?

Low viscosity

High viscosity

Elastic properties

Plastic properties

Figure One (click image to enlarge)

Answer

1. 1 2. 2 3. 3 4. Quailongitudinal waves 5. Does not distort 6. Below the yield stress and do not cause permanent deformation 7. Directly proportional to 8. Rayleigh wave 9. 36.6 10. Through transmission 11. Spherical wave front 12. Near or Fresnel zone 13. Increase 14. 90 degrees 15. Either greater or lesser to the wave velocity in the incident medium 16. 12% 17. Longitudinal waves 18. 20000 Hz 19. 100 KHz

20. Directly proportional to velocity and inversely proportional to frequency 21. All the above 22. Lamb 23. Is a gas 24. 35-51 degrees 25. 100% 26. The velocity of the sound wave 27. Low viscosity

1. Block E in Figure One below, is being used to?

Check beam angle

Calibrate the time base

Measure material thickness

Measure the probe dead zone 2. Block B in Figure One below, is being used to?

Measue beam angle

Position the beam exit point

Set sensitivity

Calibrate the time base for an angle probe 3. Block F in Figure One below, is being used to?

Check probe resolution


Measure the probe dead zone

Construct a distance amplitude correction curve 4. Block D in Figure One below, is being used to?


Calibrate the time base for an angle probe

Check probe resolution for an angle probe

Set sensitivity 5. Block G in Figure One below, is being used to?


Measure beam angle for a zero degree probe

Set sensitivity

Calibrate the time base 6. Block A in Figure One below, is being used to?

Set sensitivity


Measure beam angle

Check probe resolution 7. Block C in Figure One below, is being used to?


Set sensitivity


Check probe near surface resolution 8. Reference reflectors giving an omnidirectional response are used most often in?

Immersion testing

Contact testing

Normal beam testing

Angle beam testing 9. If a flaw echo amplitude is equal of the calibration reflector it is assumed that the flaw is

Smaller than the calibration reflector

Larger than the calibration reflector

At least as large as the calibration reflector

The same shape as the calibration refelctor 10. An increase in pulse length - less transducer damping - will?

Lower the probe frequency

Improve penetration

Improve resolution

Both lower the probe frequency and improve frequency 11. A change in amplitude of 14dBs is equivalent to a ratio of?

2:1

3.5:1

5:1

8:1 12. The use of a focusing lens on a transducer will?

Increase side lobe energy, reducing the effects of rough surfaces

Decreased side lobe energy, increasing the effects of rough surfaces

Increase side lobe energy, increasing the effects of rough surfaces

Decrease side lobe energy, decreasing the effects of rough surfaces 13. What is the diameter of the flat bottomed hole in Number 8 ASTM area amplitude block?

8.0mm

4.8mm

3.2mm

0.8mm 14. The time base has been claibrated using a steel block. Four repeat echoes are shown at 2.5, 5.0, 7.5 and 10.0 on the screen graticule. What signals would be displayed if the probe was placed on a copper test block of the same dimensions with no change to the calibration settings? VL steel 5.9 x 106mm/sec. VL copper 4.7 x 106mm/sec.

2.0, 4.0, 6.0, 8.0

1.5, 3.0, 4.5, 6.0

3.1, 6.3, 9.4

4.3, 8.6 15. The plastic insert in the 50mm diameter hole in the IIW standard calibration block A2 - V1 - calibration block is specified to have the absorption characteristics of ??? of steel?

25mm

50mm

75mm

100mm 16. To determine the scan index for an immersion system it is necessary to use the effective beam diamater at each metal distance. The effective beam diamater is considered to be at a point which is ??? dBs less than the intensity at the beam axis?

20 dB

12 dB

6 dB

2 dB 17. The depth of penetration of Rayleigh waves is?

Approximately three wavelengths

Dependent on energy which distributes in a linear way with depth

Frequency dependent

All of the above 18. A block used to establish reproducible test conditions is referred to as?

A reference block

A calibration block

A sizing block

A test block 19. If the amplitude of an indication from a flaw in a component is equal to that from a 3mm diameter flat bottomed hole at the same depth. Is the flaw?

Larger than the 3mm diameter FBH

The same size as the 3mm diameter FBH

No smaller than the 3mm diameter FBH

Smaller than the 3mm diameter FBH 20. When an ultrasonic wave encounters a point reflector the reflected wave is re-radiated as a?

Spherical wave front

Plane wave front

Either of them

Neither of them


Answer

1. Calibrate the time base 2. Measue beam angle 3. Check probe resolution 4. Set sensitivity 5. Set sensitivity 6. Position the beam exit point 7. Calibrate the time base 8. Immersion testing 9. At least as large as the calibration reflector 10. Improve penetration 11. 5:1 12. Decrease side lobe energy, decreasing the effects of rough surfaces 13. 3.2mm 14. 3.1, 6.3, 9.4 15. 50mm 16. 6 dB 17. Frequency dependent 18. A calibration block 19. No smaller than the 3mm diameter FBH 20. Spherical wave front

1. Which of the following parameters is controlled by the operator using ultrasonic equipment?

Material velocity

Material attenuation

Pulse length

SUrface geometry 2. The pulse repetition rate on a pulse echo system is adjusted so that reverberations within the test object?

Interact and cancel out

Decay completely between pulses

Match the natural frequency of the transducer

Both decay and completely between pulses and match the natural frequency of the transducer 3. What should the minimum water path be for an immersion set up testing a 40mm thick steel plate with a zero degree beam?

8mm

10mm

16mm

20mm 4. A butt weld prep in a 30mm thick plate is a single vee with an included angle of 60 degrees. What probe angle shall be used for the beam to be normal to the weld fusion face in the second half skip?

30 degree

38 degree

50 degree

60 degree 5. A butt weld prep in 10mm thick plate is a single vee with an included angle of 45 degrees, what probe angle shall be used for the ebam to be normal to the weld fusion face in the second half skip?

45 degrees

54.3 degrees

67.5 degrees

70 degrees 6. In the squirter or bubbler system using a column of flowing water, to ensure satisfactort coupling it is essential that the?

Probe emits a sound wave radially through the water stream

Water stream velocity is constant

Water stream is free of turbulence causing air bubbles

All of the above are essential 7. To which of the following testing techniques does this statement refer? 'Test items of many different configurations can be examined with little difficulty'

Manual contact testing

Immersion testing

Automated testing

C scan testing 8. Which of the following arrangements would be most suitabel for the detection of a vertical planar defect at mid depth in a double vee plate butt weld?

Twin crystal probe system

Immersion probe system

Tandem probe system

Angle probe system 9. Laminations in plate are detected and sized using?

A straight beam technique

An angle beam technique

An A scan technique

A pulse echo technique 10. An ultrasonic operator should be aware that the use of reject circuitry may?

Reject components that are acceptable

Alter the linearity of the time base

Increase sensitivity to low level signals

Alter the linearity of the amplifier 11. For maximum detection reliability the sound wave should strike a reflector at?

Normal incidence

Zero degree incidence

90 degree incidence

Either normal incidence or 90 degree incidence 12. Couplants used for ultrasonic inspection of stainless steels and high nickel alloys susceptible to stress corrosion cracking should be free from traces of?

Water

Cellulose

Oil

Sulphur 13. Ultrasonic signal to noise ratio may be improved by use of?

Broad band instrument

Narrow band instrument

Low pass filters

Both narrow band instrument and low pass filters 14. In fine grained, homogenous and isotropic materials which of the following beams will travel the greater distance?

Wide beam spread

Narrow beam spread

Beam spread will not affect distance travelled

Polarised beam 15. Using lower frequency probes to decrease attenuation losses will usually result in?

Increased sensitivity and decreased resolution

Decreased sensitivity and increased resolution

Increased sensitivity and increased resolution

Decreased sensitivity and decreased resolution 16. An ultrasonic method was used to check the oil level in a steel tank. Multiple backwall echoes were displayed on the screen from the tank above the oil level. Below the oil level these multiple echoes?

Decreased in amplitude

Increased in amplitude

Were spaced wider apart

Were spaced closer together 17. When using ultrasound to determine microstructural differences which of the following factors is likely to be measured?

Grain boundary echo amplitude

Attenuation

Velocity

Attenuation and velocity 18. One reason that angle beam inspection of weld is used is that?

The ultrasonic beam angle can be chosen to be parallel to major defect directions

The transducer does not have to be placed on the weld surface

The wavelength of an angle beam is shorter and will give a higher sensitivity

Zero degree probes are only used for inspecting plate material 19. During ultrasonic inspection of bonding between bearing metal and a steel backing three echoes are seen on the screen: The initial pulse, the interface echo and the back wall echo. The interface echo increases at one point during scanning. The indicates that the bonding?

Has improved in that area

Has deteriorated in that area

The steel backing is thinner in that area

The bearing metal is thinner in that area 20. Angle beam testing may be carried out using which of the following modes?

Surface waves

Longitudinal waves

Shear waves

All the above modes may be used 21. The linear distance between two successive nodes on the same surface when using angle beam testing is called the?

Skip distance

Resonance length

Wave length

Cycle length 22. Which of the following flaws is most likely to have been detected? Swivelling the search unit to either side away from the direction of maximum echo amplitude causes the peak to fall rapidly accompanied by a slight shift to the right on the time base. Traversing the search unit in an arc causes the echo signal to broaden slightly and fall rapidly with no change in position.

Gas pore

Crack

Slag

Clustered porosity 23. 30mm thick steel plates 1.5m wide are stacked 20 high. Preliminary screening for laminations could be carried out by?

Scanning from the edge at right angles to the direction of rolling

Scanning with a low frequency probe from the top surface of the stack

Removing each plate from the stack and scanning a grid system from the top surface

Scanning with a probe array from the top surface of the stack 24. Which of the following ultrasonic methods involves only the measurement of signal attenuation?

Immersion

Puls echo


Spectral analysis 25. Which of the following techniques requires only one transducer type regardless of the incident angle?


Pulse echo

Immersion

Crack tip diffraction 26. In straight beam immersion inspection the water path is generally adjusted to require a ??? than the depth of scan?

Longer transit time

Longer beam path

Shorter transit time

Shorter beam path 27. Acoustic lenses are used for contour correction such that in the straight beam inspection of tubing where the transducer is inside the tube the preferred beam is?

Narrow and converging

Narrow and parallel

Narrow and diverging

Wide and parallel 28. Materials exhibiting a columnar grain structure are more likley to?

Show isotropic elastic behaviour

Show better ultrasound propagation in certain preferred directions

Show both isotropic elastic behaviour and show better ultrasound propagation in certain preferred directions

Have less attenuation characteristics than similar homogenous materials

Answer

1. Pulse length 2. Decay completely between pulses 3. 16mm 4. 60 degree 5. 67.5 degrees 6. Water stream is free of turbulence causing air bubbles 7. Manual contact testing 8. Tandem probe system 9. A straight beam technique 10. Alter the linearity of the amplifier 11. Either normal incidence or 90 degree incidence 12. Sulphur 13. Both narrow band instrument and low pass filters 14. Narrow beam spread 15. Decreased sensitivity and decreased resolution 16. Decreased in amplitude 17. Attenuation and velocity 18. The transducer does not have to be placed on the weld surface 19. Has deteriorated in that area 20. All the above modes may be used 21. Skip distance 22. Crack 23. Scanning from the edge at right angles to the direction of rolling 24. Through transmission 25. Immersion 26. Longer transit time 27. Narrow and diverging 28. Show better ultrasound propagation in certain preferred directions

1. The temporal resolution of a transducer is directly proportional to?

Frequency

Its crystal diameter

Its crystal thickness

Its bandwith 2. Cylindrical acoustic lenses make it possible to fouc the ultrasonic beam?

At a point

Along a line

To a disc the diamater of the cylinder

Without loss of axial resolution 3. Short duration pulses from well damped transducers should significantly improve?

Near surface resolution

Far field penetration

Near zone length

All of the above 4. Lateral resolution is prinicipally a function of?

Wavelength

Probe diamater

Material velocity

Beam width 5. Higher frequency probes producing increased sensitivity levels are able to be used in?

Manual contact testing

Immersion testing

Automated testing

C scan testing 6. Which of the following is a principal advanatge of focused transducers?

The energy at the focal spot decreases

The sensitivity at the focal spot increased

The axial resolution is increased

Both the sensitibity at the focal spot increases and the axial resolution increases 7. With reference to Figure One below, which of the following pulses first exhibits phase reversal?

0.5 microsecs

1.6 microsecs

2.6 microsecs

3.7 microsecs 8. The bandwidth of a tranducer is measured at points 70% of the resonance frequency intensity. These points represent a drop in intensity of?

2 dBs

3 dBs

4 dBs

5 dBs 9. Which of the following couplants would be considered to be most suitable for use on hot aluminium surfaces?

Water

Wall paper paste

Grease

Glycerine 10. Which type of probe can be described as containing an acoustical barrier seperating the transmitter element from the receiver?

Twin crystal

Damped wide bandwidth

Damped narrow bandwidth

Damped low resolution 11. Paintbush transducers are designed to?

Pinpoint the location and size of a flaw

Allow smooth scanning with less couplant than a conventional transducer

Be survey devices

Have a narrow parallel beam pattern for uniform scanning 12. Given the following information regarding the relation between Pulse Repetition Rate -PRR- and Scanning Speed -SS- what scanning speed shall be used for a PSR of 900PPS? 500PPS & 101.6SS, 750PPS & 152.4SS, 1000PPS & 203.2SS

160.4

173.6

182.9

198.4 13. Which of the following is a monohydrate piezoelectric crystal that is highly sensitive to minute quantities of water?

Quartz

Lithium suplphate

Barium titanate

Lead zirconate 14. When evaluating the Damping Factor of an ultrasonic transducer it shall be based on the number of cycles in the pulse envelope greater than?

70% of the initial pulse amplitude



20% of the initial pulse amplitude 15. Bond imperfections between the transducer and the damping element cause?

Increased beam symmetry

Decreased Damping Factor

Increased transducer operating frequency

All of the above 16. One of the factors that are primarily responsible for the loss in beam intensity is transmission losses. Transmission losses include?

Diffraction

Scattering

Beam spreading

Frequency shift 17. Near field and far field effects in the ultrasonic beam occur due to the transudcer crystal not vibrating under the influence of an impressed electrical voltage. Near and far fields can occur due to?

A pulsed instead of constant output signal

A refelction of the ultrasonic beam at interfaces

Disturbances in the water couplant used in immersion testing

Gradual changes in acoustic velocities within a material 18. For a non-focused zero degree 10mm diameter probe calculate the 6 dB beam diameter at the near zone length?

2.5mm

10mm

5mm

6.5mm 19. Which of the following piezoelectric materials tend to depolarise with age?

Lithium sulphate

Lead zirconate titanate

Lead metaniobate

Barium titanate 20. A nickel rod placed in a coil carrying a current experiences a change in length as a function of the current through coil. This fact explains the basic principle of?

Thickness measurement

Magnetostriction transducers

Lamb wave testing

Resonance testing 21. Material noise consists of low amplitude, random signals from numerous small reflectors irregularly distributed throughout the test piece. This noise may be reduced by the use of?

Focused probes

Parallel beam probes

High frequency probes

Twin crystal probes 22. The predominant central frequency of an ultrasonic beam is closely related to?

The diamater of the transducer

The transducers natural thickness resonance

The velocity of sund in the test material

The grain size of the test material


1. Its bandwith 2. Along a line 3. Near surface resolution 4. Beam width 5. Immersion testing 6. The sensitivity at the focal spot increased 7. 1.6 microsecs 8. 3 dBs 9. Grease 10. Twin crystal 11. Be survey devices 12. 182.9 13. Lithium suplphate 14. 50% of the initial pulse amplitude 15. Increased transducer operating frequency 16. Scattering 17. A refelction of the ultrasonic beam at interfaces 18. 2.5mm 19. Barium titanate 20. Magnetostriction transducers 21. Focused probes 22. The transducers natural thickness resonance

1. Ultrasound travels through a test block 20mm thick at a velocity of 3.4 x 106 mm/sec. How long does it take froom pulse transmission for refelected sound to reach the probe?

11.8 microsec

5.9 microsec

118 microsec

59 microsec 2. A 60 degree shear wave is used to inspect a 100mm diameter steel bar in a circumferential direction. An indication is located from a point defect at a beam path of 40mm. What is the depth of this defect below the bar surface? [Cosine rule a2=b2+c2-2 bc cos A]

1.5mm

3.2mm

4.2mm

6.0mm 3. What probe angle is required to meet the requirements shown in Figure One below?

40 degree

45 degree

50 degree

55 degree 4. The next six questions are based on the information in Table One at the bottom of the page. What screen height response will be given by a 2.5mm dia FBH under the same conditions?

20%

18%

16%

10% 5. What screen height response will be given by a 4.0mm dia FBH under the same conditions?

43%

39%

35%

30% 6. What screen height response will be given by a 5.0mm dia FBH under the same conditions?

70%

65%

61%

57% 7. What diameter of FBH will give a screen response of 65% under the same conditions?

5.4

5.2

4.8

4.0 8. What diameter of FBH will give a screen response of 35% under the same conditions?

3.2

3.5

3.8

4.2 9. What diameter of FBH will give a screen response of 90% under the same conditions?

6.3

6.1

5.8

5.6 10. Calculate the focal length in water of an ultrasonic probe fitted with an epoxy lens having a radius of curvature of 56mm? VLepoxy = 2.7 x 106 mm/sec, VL water = 1.5 x 106 mm/sec

28mm

112mm

127mm

168mm 11. Calculate the offset required for an immersion probe to create a 45 degree shear wave in a steel bar having a radius of 21mm?

3.5mm

5.0mm

7.0mm

10.5mm

12. Calculate the offset required for an immersion probe to create a 60 degree shear wave in a steel bar having a radius of 21mm? VL water = 1.5 x 106 mm/sec, Vs steel = 3.2 x 106 mm/sec

5.5

8.5

10.5

12.5 13. Using Figure Two below, how much energy will be transmitted through water to aluminium interface by a longitudinal angle beam created by an 11 degree angle of incidence?

5%

20%

48%

72% 14. Calculate the apparent attenuation from teh following information? Amplitude of second back wall echo = 84% FSH, Amplitude of sixth back wall echo = 15% FSH, Thickness of Material = 20mm

0.09 dB/mm

14.9 dB/mm

1.49 dB/mm

0.90 dB/mm 15. Calculate the dB differece between 5/64 inch FBH and 3/64 inch FBH?

4 dB

6 dB

9 dB

12 dB 16. It is possible to approximately calculate the elastic modulus of material by determination of the longitudinal and transverse velocities of sound in that material. Calculate Youngs Modulus of Elasticity from the information in Table Two below?

7068 x 104 dynes/cm2

146 x 106 dynes/cm2

53 x 104 dynes/cm2

5074 x 105 dynes/cm2 17. Calculate the incident angle required to produce Rayleigh waves in aluminium? VL 6.35 x 106 mm/sec, Vp 2.7 x 106 mm/sec, VL3.1 x 106 mm/sec

30.4 degrees

45.8 degrees

57.5 degrees

60.6 degrees 18. A 6 MHz longitudinal pulse of ultrasound is transmitted at a pulse repetition rate of 800 pulses per second. To what theoretical depth in steel can this pulse travel and return before the next pulse is initiated? Longitudibal velocity in steel VL x 6.0 x 106 mm/sec

15mm

1.5mm

7.5mm

3.75mm 19. Calculate the attenuation of a test material where the gain differene between the second and fourth back wall echoes is 20sBs. The material thickness is 40mm and take into consideration the natural loss of 6dB between double distance back wall echoes?

0.087 dBs per mm

0.125 dBs per mm

0.175 dBs per mm

0.25 dBs per mm 20. Calculate the hald beam spread angle when considering beam extremities that are 1/10 of the intensity of the axis. The 10mm diameter transducer is producing ultrasound at 5MHz into steel at zero degrees? VL steel 6 x 106 mm/sec, Vs steel 3.2 x 106 mm/sec

12 degrees

7.4 degrees

6 degrees

4.8 degrees 21. Calculate the total beam spread angle when considering beam extremities that are one half of the intensity at the axis. The 25mm diameter transducer is producing ultrasound at 2 MHz into steel at zero degrees? VL steel 6 x 106 mm/sec, Vs steel 3.2 x 106mm/sec

4.8 degrees

8.4 degrees

9.6 degrees

16.8 degrees 22. Calculate the near field length for a zero degree 2.5MHz, 25mm diameter single crystal transducer transmitting ultrasound into a steel forging using a polycell couplant? VL steel 6 x 106 mm/sec, Vs steel 3.2 x 106 mm/sec

2.6mm

26mm

65mm

130mm

Figure One (click image to enlarge) Figure Two (click image to enlarge)

Table One:

Using area amplitude flat bottomed reference holes and a zero degree probe at a constant gain setting the following was recorded:

mm dia FBH Screen Height Resolution 6.4 100% 5.5 74% 4.5 49% 3.2 25% 1.6 6.5% 0.8

1.5%

Table Two:

E = [dvs2 (3vI

2 - 4Vs2)]

VI2 - Vs

2

Answer

1. 11.8 microsec 2. 4.2mm 3. 50 degree 4. 16% 5. 39% 6. 61% 7. 5.2 8. 3.8 9. 6.1

10. 127mm 11. 7.0mm 12. 8.5 13. 20% 14. 0.09 dB/mm 15. 9 dB 16. 7068 x 104 dynes/cm2 17. 60.6 degrees 18. 3.75mm 19. 0.087 dBs per mm 20. 7.4 degrees 21. 9.6 degrees 22. 65mm

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