Analytical Solutions to Eddy-Current Probe-Coil Problems

Abstract

LEGA L NOT ICE lo(Governmen t sponsored work. Neither the UnJted This repart was prepared as an accoun Ung n behalf of the CommJeeto n: States, nor tbe Commissio n, nor any person ac o ed o implied with respect to the accu-A. Makes any warranty or re~r:~~: ::~=~::s con~ed tn th.ts rePort, or that the use racy, completene ss, or useful nee, dJ 1 ed tn this report may not tnCrtnge of any tnformaUon , apparatus, method, or process sc oe privately owned rights; or t to th use of or for damages resulting from the B. Assumes any UablUUes with r=c or prO:ess di~closed in thJs report. use of any tnformaUon , apparatus, me ' behalf f the CommtSsio n" includes any em-As used in the above, "perso:ea~: :u~::m('lln yP.: of lll\lCh contractor , to the extent that ployee or contractor of the Cu@mi 1 • t t or employee of eucb contractor prepares, sucb ewiJ\uyee or contract"'" nf the Comm ee on, uant to biB empluywcl1 t or oontrlM:t dtesem.lne. tee, or provides e.ccees to, any tnformatto~ pure wt th the Comm!eeto n, or bis employmen t with such contractor .

Eddy Current Testing of Carbon-Carbon Composites

“…The results are shown in Fig.8, where the square markers indicate values observed during heating and the solid circles correspond to cooling. Ouring the heating we observed two regions: the first was from room temperature to 80°C with constant resistivity, and a second region above 80° with temperature coefficient a = -0.00077/ o C, where the coefficient is defined by P = Po (1 + a"T) , (6) with Po the extrapolated value at T=O. On cooling, a hysteresis was observed of about 7.5%, but at room temperature the resistivity returned to its original value.…”

Prediction of Eddy-Current Probe Impedance Due to Surface Cracks in Ferromagnetic Steels

“…In parallel with (9), the y-component of the scattered part of the magnetic field at the crack mouth, H~")(rm), can be written where…”

Prediction and analysis of transient eddy-current probe signals

“…Br denotes the Bromwitch contour taking the path of integration with respect to s in the complex plane to the right of any poles. (1) enables us to derive a transient solution from a corresponding time-harmonic solution.…”

“…Br denotes the Bromwitch contour taking the path of integration with respect to s in the complex plane to the right of any poles. Perhaps the most well known time harmonic fields in the theory of eddycurrent NDE are those determined by Dodd and Deeds for normal rectangular section coils above multi-layered infinite conducting slabs [1]. To take initially a slightly more general case, suppose we consider a normal axially symmetric coil of arbitrary cross section carrying a current whose density has the form…”