Explain how eddy current inspection works.
What will be an ideal response?
This method is based upon magnetic induction in which a magnetic field induces eddy currents within the material being tested. An eddy current is an induced electric current circulating wholly within a mass of metal. This method is effective in testing nonferrous and ferrous materials for internal and external cracks, slag inclusions, porosity, and lack of fusion that are on or very near the surface. Eddy current cannot locate flaws that are not near the surface.
A coil carrying high-frequency alternating current is brought close to the metal to be tested. A current is produced in the metal by induction. The part is placed in or near high-frequency, alternating current coils. The magnitude and phase difference of these currents is, in turn, indicated in the actual impedance value of the pick-up coil. Careful measurement of this impedance is the revealing factor in detecting defects in the weld.
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Identify the ten troubleshooting models used in this text.
What will be an ideal response?
Creep deformation occurs in
A) aluminum members. B) concrete members. C) steel members. D) all of the above.
Which if the following rules must be followed if all of the cables in a tray are smaller than 4/0?
a. The cables must be installed in a single layer. b. The sum of all the diameters of all cables shall not exceed the cable tray width. c. The sum of the cross-sectional area of all cables must not exceed the maximum allowable cable fill area. d. The diameter of the cables shall not exceed ?D2/4.
It is expected that a parallel RLC resonant circuit has a midband admittance of 25 x 10^–3 S, quality factor of 120, and a resonant frequency of 200 krad/s. Calculate the values of R, L, and C. Find the bandwidth and the half-power frequencies.
What will be an ideal response?