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Questions and Answers
What occurs when the incident angle equals or exceeds the second critical angle?
What occurs when the incident angle equals or exceeds the second critical angle?
In typical angle beam inspections where only shear waves are desired, what range do most useful incident angles fall within?
In typical angle beam inspections where only shear waves are desired, what range do most useful incident angles fall within?
Why is it important for field NDI inspectors to understand how the correct refracted beam angle is obtained, even when the specific procedure details this angle?
Why is it important for field NDI inspectors to understand how the correct refracted beam angle is obtained, even when the specific procedure details this angle?
What is the primary effect of using higher frequency ultrasonic waves in contact method flaw detection?
What is the primary effect of using higher frequency ultrasonic waves in contact method flaw detection?
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What is a potential drawback of using higher frequency ultrasonic waves for flaw detection?
What is a potential drawback of using higher frequency ultrasonic waves for flaw detection?
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What is the approximate range of incident angles useful for shear-wave inspection NDI, operating in plastic for steel?
What is the approximate range of incident angles useful for shear-wave inspection NDI, operating in plastic for steel?
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Which of the following is most influenced by the variables of an ultrasonic inspection system?
Which of the following is most influenced by the variables of an ultrasonic inspection system?
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What is a primary advantage of using scanning equipment over manual scanning in ultrasonic inspection?
What is a primary advantage of using scanning equipment over manual scanning in ultrasonic inspection?
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Which of the following best describes the capability of large gantry-based immersion systems in ultrasonic scanning?
Which of the following best describes the capability of large gantry-based immersion systems in ultrasonic scanning?
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In older ultrasonic instruments, what type of controls were typically used for fine adjustments?
In older ultrasonic instruments, what type of controls were typically used for fine adjustments?
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What is the primary function of the 'smart' knob found on some menu-driven ultrasonic instruments?
What is the primary function of the 'smart' knob found on some menu-driven ultrasonic instruments?
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Which of the following factors enhances the ability of an inspection system to detect small discontinuities, although it may compromise penetrating power?
Which of the following factors enhances the ability of an inspection system to detect small discontinuities, although it may compromise penetrating power?
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Which type of waveform display is considered traditional in ultrasonic instruments?
Which type of waveform display is considered traditional in ultrasonic instruments?
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What characteristic of a transducer affects the duration it 'rings' after excitation, influencing the width and amplitude of the front surface signal?
What characteristic of a transducer affects the duration it 'rings' after excitation, influencing the width and amplitude of the front surface signal?
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What is a potential risk if the intensity of a CRT display is set too high for extended periods?
What is a potential risk if the intensity of a CRT display is set too high for extended periods?
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How is the horizontal scale typically illuminated on older ultrasonic instruments with a CRT display?
How is the horizontal scale typically illuminated on older ultrasonic instruments with a CRT display?
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What is the primary application for dual transducers noted in the provided text?
What is the primary application for dual transducers noted in the provided text?
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In ultrasonic inspection displays, what does the sweep or baseline represent?
In ultrasonic inspection displays, what does the sweep or baseline represent?
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What effect does high "ringing" in a transducer have on resolution?
What effect does high "ringing" in a transducer have on resolution?
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How is sensitivity generally rated in an inspection system?
How is sensitivity generally rated in an inspection system?
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On which type of flaw detectors are baseline alignment adjustments typically unnecessary?
On which type of flaw detectors are baseline alignment adjustments typically unnecessary?
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In dual transducers, what is the function of the plastic material filling the spaces under the transducer elements?
In dual transducers, what is the function of the plastic material filling the spaces under the transducer elements?
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Which characteristic of a transducer most directly influences its resolution?
Which characteristic of a transducer most directly influences its resolution?
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If an inspection requires improved differentiation between signals from closely spaced interfaces, which adjustment would likely be most effective regarding the transducer?
If an inspection requires improved differentiation between signals from closely spaced interfaces, which adjustment would likely be most effective regarding the transducer?
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Why are dual transducers often preferred in ultrasonic thickness measurement?
Why are dual transducers often preferred in ultrasonic thickness measurement?
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What is a significant trade-off when using higher frequency transducers to increase sensitivity?
What is a significant trade-off when using higher frequency transducers to increase sensitivity?
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What diameter hole does the block marked 5-0300 have?
What diameter hole does the block marked 5-0300 have?
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What is the significance of the blocks with 3-inch metal travel distances having different diameters?
What is the significance of the blocks with 3-inch metal travel distances having different diameters?
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Which of the following is NOT a typical ultrasonic standard manufacturing requirement?
Which of the following is NOT a typical ultrasonic standard manufacturing requirement?
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For what purpose are the IIW Type 2 blocks primarily used?
For what purpose are the IIW Type 2 blocks primarily used?
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What characteristic distinguishes the miniature angle beam block from the Type 2 IIW block?
What characteristic distinguishes the miniature angle beam block from the Type 2 IIW block?
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What is the purpose of using a couplant material between the transducer and any wedge?
What is the purpose of using a couplant material between the transducer and any wedge?
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Which material is commonly used to fabricate shoes for curved surfaces?
Which material is commonly used to fabricate shoes for curved surfaces?
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What should be done to achieve a proper fit when the radius of curvature of the shoe does not match the test part?
What should be done to achieve a proper fit when the radius of curvature of the shoe does not match the test part?
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Why is it not advisable to adapt the shoe too closely to the test part when using large angles for inspection?
Why is it not advisable to adapt the shoe too closely to the test part when using large angles for inspection?
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What is a recommended modification for the shoe to mitigate unwanted surface wave propagation?
What is a recommended modification for the shoe to mitigate unwanted surface wave propagation?
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How should major shaping of a shoe be performed?
How should major shaping of a shoe be performed?
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What effect does decreasing the radius of curvature on the shoe have during inspection?
What effect does decreasing the radius of curvature on the shoe have during inspection?
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Which approach can be used when the same material as the test part is utilized for shoe fabrication?
Which approach can be used when the same material as the test part is utilized for shoe fabrication?
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What properties characterize the sound beam when using plastic shoes for angle beam inspection on curved surfaces?
What properties characterize the sound beam when using plastic shoes for angle beam inspection on curved surfaces?
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Why might dimensions of shoes used for curved surfaces need to change?
Why might dimensions of shoes used for curved surfaces need to change?
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Study Notes
Ultrasonic Inspection Methods
- Ultrasonic inspection uses sound waves with frequencies greater than 20,000 Hz to detect internal flaws like cracks or disbonds.
- Transducers generate and receive ultrasonic vibrations.
- The ultrasonic energy travels through a coupling medium.
- Common vibration modes are longitudinal, transverse and surface (Rayleigh) modes.
- Knowledge of a part's internal geometry is critical for interpreting defect signals.
Ultrasonic Energy Characteristics
- Sound waves propagate through materials by vibrating molecules.
- Period: The time for a complete cycle of vibration.
- Velocity: The distance sound travels per unit time.
- Frequency: The number of cycles per second (measured in Hertz).
- Wavelength: The distance a wave travels in one cycle.
Ultrasonic Inspection Equipment
- Instruments Generate, receive, and display ultrasonic pulses of electrical energy converted to and from sound.
- Transducers Convert electrical energy to acoustic energy, then back to electrical energy.
- Scanning Equipment Computer-controlled systems for complete area coverage.
- Controls Examples include rotary knobs, push buttons, and controls for adjusting waveforms, display scale, and positioning.
Ultrasonic Inspection Variables
- Frequency: Affects signal detection and penetration, with higher frequencies offering finer detail but less penetration. Values range from 2.25 MHz to 10 MHz.
- Frequency Bandwidth: The range of frequencies produced by the instrument. Inspection results are sensitive to bandwidth variations.
- Beam Spread: The sound beam widens in the far field from the transducer.
- Beam Intensity: Sound wave energy transmitted through a unit cross-sectional area.
- Acoustic Impedance: The resistance to sound wave propagation, affected by material density and sound velocity. The higher the difference between materials acoustic impedance results in greater reflection.
Ultrasonic Inspection Methods
- Contact Inspection: The transducer is in direct contact with the part using a couplant (liquid).
- Immersion Inspection: The transducer and test part are submerged in a fluid (usually water) coupling sound waves.
Ultrasonic Inspection Data Presentation
- A-Scan: Displays amplitude versus time, useful for thickness and flaw detection.
- B-Scan: Displays cross-sectional view of the part, showing the location of subsurface defects.
- C-Scan: Displays a plan view of the part indicating the location of defects in two dimensions.
Ultrasonic Inspection Limitations
- Dead Zone: A region near the transducer where accurate evaluation of flaws is difficult.
- High Attenuation: Thick materials may reduce the amplitude of sound to a level making flaw detection more difficult.
Ultrasonic Inspection of Bonded Structures
- Bonded Structure Reference Standards: Reference standards similar to the parts, with controlled areas of unbonds.
- Defect Types: Discontinuities are classified into five types for different bonded structures.
- Fabrication of Bonded Reference Standards: Different techniques for creating the controlled unbonds, including using Teflon sheets.
Ultrasonic Inspection Process Controls
- Reference Standards: Verification of instrument function using reference standards.
- Equipment Checks: Regular verification and calibration of all equipment to ensure stable performance.
- System Linearity and Sensitivity: Verification of sensor resolution to ensure consistent measurement across the scan area.
Ultrasonic Inspection Equations
- Snell's Law: Used to determine refracted wave angles (important for angle beam inspections).
- Near Field Calculation: The formula to determine distance for the region where the amplitude variations are very high.
- Beam Spread Calculation: Calculation for the half-angle of the sound beam spread.
- Acoustic Impedance calculation: The calculation needed to determine the ratio of the sound energy that will be reflected or transmitted when sound waves strike a boundary.
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Description
Test your understanding of key concepts in ultrasonic inspection techniques used in Non-Destructive Testing (NDI). This quiz covers critical angles, shear-wave inspections, and the effects of frequency on flaw detection. Perfect for NDI professionals looking to reinforce their knowledge.
