Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

More documents

Recommendations

Info

The two coils are at the same location, so that the windings cross each other, like the equator and a circle through north and south poles on the earth. Although different manufacturers produce probes with a variety of shapes, one of the more common type of probes for testing welds has a semicylindrical tip, and is intended to be operated with the axis of the semicylinder parallel to the weld Whatever the shape, weld testing probes should be operated with the plane of one coil parallel to the weld, and the plane of the other transverse to the weld. Charlie Chong/ Fion Zhang
Since the eddy currents produced at the surface under tangential coils flow along the surface in the direction of the windings, the eddy currents produced by the coil wound parallel to the weld are also parallel to the weld and will therefore detect transverse cracks but not longitudinal cracks. Likewise, the eddy currents produced by the coil wound transverse to the weld are also transverse to the weld and will therefore detect longitudinal cracks but not transverse cracks. Therefore, when these two coils are connected differentially, they will give a signal for either a transverse or a longitudinal crack. If a crack was present at 45° to the weld, which, fortunately, is extremely unlikely, it would not be detected because the eddy currents of both coils would be distorted equally by it. The differing sensitivities of the two coils also explains why crack signals from weld scan probes do not have the typical differential signal shape. Since only one coil detects the crack, the spot simply diverts as the probe approaches the crack, then returns to the balance position after the probe passes it. Test frequencies of approximately 100 kHz have been found satisfactory for testing ferromagnetic structures for surface cracks, although higher frequencies can be used. Charlie Chong/ Fion Zhang
Page 1 and 2:
Electromagnetic Testing - Eddy Curr
Page 3 and 4:
http://igor113.livejournal.com/5121
Page 5 and 6:
Charlie Chong/ Fion Zhang
Page 7 and 8:
同桌的你 Charlie Chong/ Fion
Page 9 and 10:
Fion Zhang at Shanghai 2014/Novembe
Page 11 and 12:
5.0 APPLICATIONS 5.1. Surface testi
Page 13 and 14:
FIG. 5.1. Schematic diagram showing
Page 15 and 16:
Eddy current field extends laterall
Page 17 and 18:
Depth of Penetration & Current Dens
Page 19 and 20:
Please also comment on this illustr
Page 21 and 22:
FIG. 5.2 Directional properties of
Page 23 and 24:
The depth of surface flaws (the dis
Page 25 and 26:
Case Discussion: The corresponding
Page 27 and 28:
5.1.2.2 Types of standard surface t
Page 29 and 30:
(b) Spot probes Spot probes are pro
Page 31 and 32:
FIG. 5.6. A spring loaded probe. Ch
Page 33 and 34:
FIG. 5.5. (a) The core and coil of
Page 35 and 36:
Although it is usually evident by i
Page 37 and 38:
FIG. 5.7. Effects of cores and shie
Page 39 and 40:
5.1.2.3 Other types of surface prob
Page 41 and 42: FIG. 5.8. A tangential probe showin
Page 43 and 44: Compare vertical probe with the FIG
Page 45 and 46: Discussion Topic- Why in the tangen
Page 47 and 48: FIG. 5.9. A gap (horseshoe) probe.
Page 49 and 50: Horseshoe probe - maximum sensitivi
Page 51 and 52: A gap (horseshoe) probe - Magnetic
Page 53 and 54: 5.1.3 Testing for surface-breaking
Page 55 and 56: Eddy Current Testing over painted s
Page 57 and 58: Testing Frequency: • 200 kHz to 5
Page 59 and 60: If the fastener is not removed, cra
Page 61 and 62: Following are some examples of spec
Page 63 and 64: Threaded Probe Charlie Chong/ Fion
Page 65 and 66: Eddy Current Testing- Hole fatigue
Page 67 and 68: Hand operated or manual hole probes
Page 69 and 70: If motor driven probes are to be us
Page 71 and 72: FIG. 5.12. Typical rotating hole pr
Page 73 and 74: Bolt hole probes Charlie Chong/ Fio
Page 75 and 76: (c) Aircraft wheels: Aircraft wheel
Page 77 and 78: Aircraft wheels Charlie Chong/ Fion
Page 79 and 80: Automated equipment which will perf
Page 81 and 82: Tangential probe - used in electron
Page 83 and 84: FIG. 5.3 Charlie Chong/ Fion Zhang
Page 85 and 86: Although these blocks can be used f
Page 87 and 88: (f) Scan over the appropriate disco
Page 89 and 90: 4.1.3.5 Testing in-service welds in
Page 91: FIG. 5.14 a. Typical weld testing p
Page 95 and 96: For testing, the instrument should
Page 97 and 98: Charlie Chong/ Fion Zhang
Page 101 and 102: Keywords: Typically, the magnetic f
Page 103 and 104: Multilayer structures - of flaws in
Page 105 and 106: 5.1.4.2 Probe and frequency selecti
Page 107 and 108: An acceptable compromise which give
Page 109 and 110: FIG. 5.15. Eddy current signals fro
Page 111 and 112: FIG. 5.16. Spot probes testing a la
Page 113 and 114: ) Sliding probes Sliding probes are
Page 115 and 116: 5.1.4.4 Reference samples Reference
Page 117 and 118: 5.1.5 Conductivity testing and mate
Page 119 and 120: 5.1.5.3 Factors which affect conduc
Page 121 and 122: (b) Alloying. Dissolving any elemen
Page 123 and 124: (d) Cold work Plastic deformation o
Page 125 and 126: (b) Test part thickness The conduct
Page 127 and 128: (c) Edge effect Probes dedicated to
Page 129 and 130: 5.1.5.6 Frequency selection The fre
Page 131 and 132: FIG. 5.19. Impedance diagrams and t
Page 135 and 136: The Characteristic Parameter (PC) i
Page 137 and 138: Example: Calculate the optimum freq
Page 139 and 140: When eddy current conductivity mete
Page 141 and 142: (d) Perform conductivity measuremen
Page 143 and 144:
5.1.5.9 Heat treatment of aluminium
Page 145 and 146:
5.1.5.10 Sorting materials by magne
Page 147 and 148:
5.1.6 Thickness measurement of non-
Page 149 and 150:
FIG. 5.22. Methods of obtaining sta
Page 151 and 152:
Non-conducting coating thickness me
Page 153 and 154:
A typical operating frequency to me
Page 155 and 156:
5.1.6.4 Measurement procedure (a) C
Page 157 and 158:
(k) (l) Alternatively, if the measu
Page 159 and 160:
5.1.7 Thickness measurement of cond
Page 161 and 162:
5.1.7.2 Probe and frequency selecti
Page 163 and 164:
5.1.7.3 Signals from variations in
Page 165 and 166:
FIG. 5.26. Part of the display show
Page 167 and 168:
5.1.7.5 Measurement procedure (a) C
Page 169 and 170:
(j) (k) Alternatively, if the measu
Page 171 and 172:
5.1.8 Thickness measurement of cond
Page 173 and 174:
FIG. 5.28 shows the impedance curve
Page 175 and 176:
5.2.1.1 Tube testing probes and the
Page 177 and 178:
The coil(s) in bobbin probes produc
Page 179 and 180:
Bobbin probe eddy current the orien
Page 181 and 182:
To obtain adequate sensitivity to f
Page 183 and 184:
As for surface testing, the test se
Page 185 and 186:
5.2.1.2 Selection of test frequency
Page 187 and 188:
The basis for the selection of test
Page 189 and 190:
FIG. 5.32. Impedance diagram showin
Page 191 and 192:
5.2.1.4 Flaw signals from absolute
Page 193 and 194:
At f 90 , all flaw signals appear i
Page 195 and 196:
5.2.1.5 Absolute probe signals from
Page 197 and 198:
Wobble - A-go-go Charlie Chong/ Fio
Page 199 and 200:
Discussion Topic- Discuss on the fo
Page 201 and 202:
(c) Ferromagnetic conditions at the
Page 203 and 204:
A signal from a ferromagnetic condi
Page 205 and 206:
FIG. 5.36 shows the signal from a f
Page 207 and 208:
Tube Sheet: Baffle Plate Charlie Ch
Page 209 and 210:
Tube Sheet: Baffle Plate Charlie Ch
Page 211 and 212:
(e) Non-ferromagnetic support or ba
Page 213 and 214:
This signal will be modified by any
Page 215 and 216:
(f) Ferromagnetic support or baffle
Page 217 and 218:
FIG. 5.37. The signals from a carbo
Page 219 and 220:
FIG. 5.38. Absolute and differentia
Page 221 and 222:
5.2.1.7 Correlating flaw depth and
Page 223 and 224:
FIG. 5.39. Graph showing the correl
Page 225 and 226:
5.2.1.8 Correlating flaw depth and
Page 227 and 228:
5.2.2 Bar and tube testing using en
Page 229 and 230:
Discussion Topic: This means that p
Page 231 and 232:
FIG. 5.41. The eddy current intensi
Page 233 and 234:
5.2.2.2 Selection of frequency For
Page 235 and 236:
Associated with the f/f g concept i
Page 237 and 238:
The optimum operating point depends
Page 239 and 240:
5.2.2.3 Specific test applications
Page 241 and 242:
(c) Flaw detection Surface flaw ind
Page 243 and 244:
5.2.2.4 Testing ferromagnetic bars
Page 245 and 246:
Ferromagnetic material can be teste
Page 247 and 248:
5.3.2 Equipment Most modern eddy cu
Page 249 and 250:
These standards cover such topics a
Page 251 and 252:
The following example is taken from
Page 253 and 254:
The content of written procedures d
Page 255 and 256:
Charlie Chong/ Fion Zhang
Page 257 and 258:
6.5. Records and reports 6.5.1 Test
Page 259 and 260:
6.5.2 Test reports A formal test re
Page 261 and 262:
Records Charlie Chong/ Fion Zhang
Page 263 and 264:
Calibration Standard A test standar
Page 265 and 266:
Coil, probe A small coil or coil as
Page 267 and 268:
Discontinuity Artificial Reference
Page 269 and 270:
Electromagnetic Testing That non de
Page 271 and 272:
IACS σ IACS . International Anneal
Page 273 and 274:
Material, Diamagnetic A material ha
Page 275 and 276:
Parameter A material property or in
Page 277 and 278:
Phase Lag β (beta), radians or deg
Page 279 and 280:
Resistivity ρ (ro), microhm centim
Page 281 and 282:
Signal A change in eddy current ins
Page 283 and 284:
Space Station Charlie Chong/ Fion Z
Page 285 and 286:
Charlie https://www.yumpu.com/en/br
Page 287:
Good Luck! Charlie Chong/ Fion Zhan
show all

Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

Create successful ePaper yourself

Delete template?

Save as template?