METHODOS Flashcards
NDT (126 cards)
AE Review Questions
1. The most common range of AE is:
a. 10 to 15 kHz
b. 100 to 300 kHz
c. 500 to 750 kHz
d. 1 to 5 MHz
b. 100 to 300 kHz
- Discontinuities that are not readily detectable by AE are:
a. leaks.
b. plastic deformation.
c. growing cracks.
d. rounded inclusions.
d. rounded inclusions.
- The total energy loss of a propagating wave is called:
a. scatter.
b. dispersion.
c. diffraction.
d. attenuation.
d. attenuation.
- The Kaiser effect refers to:
a. velocity changes due to temperature changes.
b. low amplitude emissions from aluminum structures.
c. the behavior where emission from a source will not occur until the previous load is exceeded.
d. emissions from dissimilar material interfaces.
c. the behavior where emission from a source will not occur until the previous load is exceeded.
- The Felicity effect is useful in evaluating:
a. fiber-reinforced plastic components.
b. high-alloy castings.
c. large structural steel members.
d. ceramics.
a. fiber-reinforced plastic components.
- The Kaiser effect is useful in distinguishing:
a. electrical noise from mechanical noise.
b. electrical noise from growing discontinuities.
c. mechanical noise from growing discontinuities.
d. electrical noise from continuous emissions.
c. mechanical noise from growing discontinuities.
- The term “counts” refers to the:
a. number of times a signal crosses a preset threshold.
b. number of events from a source.
c. number of transducers required to perform a test.
d. duration of hold periods.
a. number of times a signal crosses a preset threshold.
- The acoustic emission signal amplitude is related to:
a. the preset threshold.
b. the intensity of the source.
c. the bandpass filters.
d. background noises.
b. the intensity of the source.
- Threshold settings are determined by the:
a. graininess of the material.
b. attenuation of the material.
c. test duration.
d. background noise level.
d. background noise level.
- Background noise can be reduced by:
a. electronic filtering.
b. using flat response amplifiers.
c. using in-line amplifiers.
d. using heavier gauge coaxial cable.
a. electronic filtering.
ET Review Questions
1. Eddy currents are circulating electrical currents induced in conductive materials by:
a. continuous direct current.
b. gamma rays.
c. an alternating magnetic field.
d. a piezoelectric force.
c. an alternating magnetic field.
- The method used to generate eddy currents in a test specimen by means of a coil can most closely be compared with the action of a:
a. transformer.
b. capacitor.
c. storage battery.
d. generator.
a. transformer.
- ET relies on the principle of:
a. magnetostriction.
b. electromagnetic induction.
c. piezoelectric energy conversion.
d. magnetomotive force.
b. electromagnetic induction.
- When the electrical current in an eddy current coil reverses direction, the:
a. direction of the eddy currents in the test part remains the same.
b. eddy currents in the test part will change phase by 45°.
c. direction of the eddy currents in the test part also reverses.
d. eddy currents in the test part will change phase by 90°.
c. direction of the eddy currents in the test part also reverses.
- In order to generate measurable eddy currents in a test specimen, the specimen must be:
a. an electrical conductor.
b. an electrical insulator.
c. a ferromagnetic material.
d. a nonmagnetic material.
a. an electrical conductor.
- The magnetic field generated by eddy currents induced in a test specimen:
a. reinforces the magnetic field that induced the eddy currents.
b. cancels the magnetic field that induced the eddy currents.
c. opposes the magnetic field that induced the eddy currents.
d. has no effect on the magnetic field that induced the eddy currents.
c. opposes the magnetic field that induced the eddy currents.
- In ET, IACS is a recognized abbreviation for:
a. Induced Alternating Current System.
b. Inductively Activated Comparison System.
c. Internal Applied Current System.
d. International Annealed Copper Standard.
d. International Annealed Copper Standard.
- In ET, the specimen is coupled to the test coil by:
a. core coupling.
b. magnetic saturation.
c. the coil’s electromagnetic fields.
d. magnetic domains.
c. the coil’s electromagnetic fields.
- The penetration of eddy currents in a conductive material is decreased when the:
a. test frequency or conductivity of the specimen is decreased.
b. test frequency is decreased or conductivity of the specimen is increased.
c. test frequency, conductivity of the specimen, or permeability of the specimen is increased.
d. permeability of the specimen is decreased.
c. test frequency, conductivity of the specimen, or permeability of the specimen is increased.
- At a fixed test frequency, in which of the following materials will the eddy current penetration be greatest?
a. Aluminum (35% IACS conductivity).
b. Brass (15% IACS conductivity).
c. Copper (95% IACS conductivity).
d. Lead (7% IACS conductivity).
d. Lead (7% IACS conductivity).
- A term used to describe the effect observed due to a change in the coupling between a test specimen and a flat probe coil when the distance of separation between them is varied is:
a. liftoff.
b. fill factor.
c. edge effect.
d. end effect.
a. liftoff.
- When testing with eddy currents, discontinuities will be most easily detected when the eddy currents are:
a. coplanar with the major dimension of the discontinuity.
b. perpendicular to the major plane of the discontinuity.
c. parallel to the major dimension of the discontinuity.
d. 90° out of phase with the current in the coil.
b. perpendicular to the major plane of the discontinuity.
- Which of the following discontinuities is easiest to detect with an electromagnetic test? (Assume that the area of the discontinuity is equal in all four choices listed.)
a. A subsurface crack which lies parallel to the direction of the eddy current.
b. A discontinuity located in the center of a 51 mm (2 in.) diameter bar.
c. A radial crack that extends to the outer surface of a 51 mm (2 in.) diameter bar.
d. A subsurface radial crack located at a depth of 13 mm (0.5 in.) in a 51 mm (2 in.) diameter bar.
c. A radial crack that extends to the outer surface of a 51 mm (2 in.) diameter bar.
- A term used to define the timing relationships involved in alternating current signals is:
a. magnitude.
b. phase.
c. impedance.
d. time-gain correction.
b. phase.