UT Testing-Section 2 Physics of Ultrasound

More documents

Recommendations

Info

Sound travels through materials under the influence of sound pressure. Because molecules or atoms of a solid are bound elastically to one another, the excess pressure results in a wave propagating through the solid. The acoustic impedance (Z) of a material is defined as the product of its density (p) and acoustic velocity (V). Z = pV Acoustic impedance is important in: 1. the determination of acoustic transmission and reflection at the boundary of two materials having different acoustic impedances. 2. the design of ultrasonic transducers. 3. assessing absorption of sound in a medium.
The following applet can be used to calculate the acoustic impedance for any material, so long as its density (p) and acoustic velocity (V) are known. The applet also shows how a change in the impedance affects the amount of acoustic energy that is reflected and transmitted. The values of the reflected and transmitted energy are the fractional amounts of the total energy incident on the interface. Note that the fractional amount of transmitted sound energy plus the fractional amount of reflected sound energy equals one. The calculation used to arrive at these values will be discussed on the next page. http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Physics/applet_2_6/applet_2_6.htm
Page 1:
Section 2: Physics of Ultrasound
Page 4 and 5:
2.0: Ultrasound Formula http://www.
Page 6 and 7:
Ultrasonic Formula
Page 9 and 10:
2.1: Wave Propagation Ultrasonic te
Page 11 and 12:
Acoustic Spectrum
Page 13 and 14:
Acoustic Wave - Node and Anti-Node
Page 15 and 16:
http://hyperphysics.phy-astr.gsu.ed
Page 17 and 18:
2.2: Modes of Sound Wave Propagatio
Page 19 and 20:
Longitudinal and shear waves
Page 21 and 22:
Longitudinal and shear waves
Page 23 and 24:
2.2.3 Longitudinal Wave Also Knows
Page 25 and 26:
Longitudinal wave: Longitudinal wav
Page 28 and 29:
2.2.4 Shear waves (S-Waves) In air,
Page 30 and 31:
Shear waves
Page 33 and 34:
Q10: For a shear wave travelling fr
Page 35 and 36:
Rayleigh waves are a type of surfac
Page 37 and 38:
Q29: The longitudinal wave incident
Page 39 and 40:
The major axis of the ellipse is pe
Page 41 and 42:
Surface wave
Page 43 and 44:
Surface wave has the ability to fol
Page 45 and 46:
Surface wave - One wavelength deep
Page 47 and 48:
Love Wave http://web.ics.purdue.edu
Page 49 and 50:
Other Reading: Rayleigh Waves Surfa
Page 51 and 52:
Q110: What kind of wave mode travel
Page 53 and 54:
2.2.6 Lamb Wave: Lamb waves propaga
Page 55 and 56:
Types of Wave New! • Plate wave-
Page 57 and 58:
Plate or Lamb waves are similar to
Page 59 and 60:
With Lamb waves, a number of modes
Page 61 and 62:
Symmetrical = extensional mode Asym
Page 63 and 64:
Symmetrical = extensional mode
Page 65 and 66:
The form is determined by whether t
Page 67 and 68:
Q1: The wave mode that has multiple
Page 69 and 70:
Dispersion refers to the fact that
Page 71 and 72:
Thickness Limitation: One can not g
Page 73 and 74:
Spring model- A mass on a spring ha
Page 75 and 76:
In terms of the spring model, Hooke
Page 77 and 78:
Elastic Model / Longitudinal Wave
Page 79 and 80:
Elastic Model / Shear Wave
Page 81 and 82:
The Speed of Sound Hooke's Law, whe
Page 83 and 84:
What properties of material affect
Page 85 and 86:
Where V is the speed of sound, C is
Page 87 and 88:
Q50: The principle attributes that
Page 89 and 90:
E/N/G
Page 91 and 92:
Examples of approximate compression
Page 93 and 94: Shear Wave Velocity: V S The veloci
Page 95 and 96: The applet below shows a longitudin
Page 97 and 98: http://www.ndt-ed.org/EducationReso
Page 99 and 100: Java don’t work? http://jingyan.b
Page 101 and 102: Java don’t work? http://jingyan.b
Page 103 and 104: As can be noted by the equation, a
Page 105 and 106: The two velocities of sound are lin
Page 107 and 108: Sensitivity and resolution are two
Page 109 and 110: 2.5.2 Grain Size & Frequency Select
Page 111 and 112: Since more things in a material are
Page 113 and 114: Detectability variable: • pulse l
Page 115 and 116: Q7: When a material grain size is o
Page 117: Pulse Length: A sound pulse traveli
Page 120 and 121: Determining cross sectional area us
Page 122 and 123: Pulse volume rule-of-thumb: Competi
Page 124 and 125: When sound travels through a medium
Page 126 and 127: Scattering: Grain Size and Wave Fre
Page 128 and 129: Spreading/ Scattering / adsorption
Page 130 and 131: The units of the attenuation value
Page 132 and 133: Attenuation can be determined by ev
Page 134 and 135: A o Ut A
Page 137 and 138: 2.6.3 Frequency selection There is
Page 139 and 140: Q94: In general, which of the follo
Page 141 and 142: Q7: When the material grain size is
Page 143: Transmission & Reflection Animation
Page 147 and 148: Reflection/Transmission Energy as a
Page 149 and 150: 2.8: Reflection and Transmission Co
Page 151 and 152: Since the amount of reflected energ
Page 153 and 154: Note that the reflection and transm
Page 155 and 156: If reflection and transmission at i
Page 157 and 158: Incident Wave other than Normal? -
Page 159 and 160: Further Reading (Olympus Technical
Page 161 and 162: Further Reading: Reflection & Trans
Page 163 and 164: 2.9: Refraction and Snell's Law
Page 165: V s1 Only If this medium support sh
Page 168 and 169: http://www.ni.com/white-paper/3368/
Page 172 and 173: Note that in the diagram, there is
Page 174 and 175: Snell Law
Page 176 and 177: Snell Law
Page 178 and 179: Example: Snell’s Law L-wave and S
Page 180 and 181: Snell Law: First critical angle
Page 182 and 183: Q155 Which of the following can occ
Page 184: Q: When angle beam contact testing
Page 192 and 193: Snell Law: http://techcorr.com/serv
Page 194 and 195:
More on Snell Law Like light, when
Page 196 and 197:
http://www.ndtcalc.com/calculators.
Page 198 and 199:
Mode Conversion http://www.ndt-ed.o
Page 200 and 201:
Snell's Law holds true for shear wa
Page 202 and 203:
In the applet below, the shear (tra
Page 204 and 205:
Creep wave
Page 206 and 207:
Beyond the first critical angle, on
Page 208 and 209:
Note that the applet defaults to co
Page 210 and 211:
Offset of Normal probe above circul
Page 212 and 213:
Refraction and mode conversion at n
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Q118: At the water-steel interface,
Page 220 and 221:
Q72. In a water immersion test, ult
Page 222 and 223:
Q53. The term used to determined th
Page 224 and 225:
The absolute noise level and the ab
Page 226 and 227:
Sound Volume: Area x pulse length M
Page 228:
Acoustic Volume: w x w y ∆t
Page 231 and 232:
Determining cross sectional area us
Page 233 and 234:
4. Decreases in materials with high
Page 235 and 236:
Pulse Length Affect Resolution
Page 237 and 238:
Transducer cut-out http://ichun-che
Page 239 and 240:
UT Transducer
Page 241 and 242:
UT Transducer- Surface creep wave t
Page 243 and 244:
UT Transducer
Page 245 and 246:
When the origins of the two interac
Page 247 and 248:
However, as stated previously, soun
Page 249 and 250:
Q5: Acoustic pressure along the bea
Page 251 and 252:
Of course, there are more than two
Page 253 and 254:
2.12.3 Fresnel & Fraunhofer Zone Fr
Page 255 and 256:
The Near Field (Fresnel)- Wave Inte
Page 257 and 258:
Fresnel / Fraunhofer Zone
Page 259 and 260:
Near field (near zone) or Fresnel z
Page 261 and 262:
Near/ Far Fields
Page 263 and 264:
where D is the diameter of the tran
Page 265 and 266:
Fresnel & Fraunhofer Zone 10dB, K-0
Page 267 and 268:
Fresnel & Fraunhofer Zone
Page 269 and 270:
Q: Where does beam divergence occur
Page 271 and 272:
Q160 Beam divergence is a function
Page 273 and 274:
Dead Zone - The interval following
Page 275 and 276:
Dead Zone -The initial pulse is a t
Page 277 and 278:
Dead Zone http://www.ni.com/white-p
Page 279 and 280:
Q36: To eliminate the decrease in s
Page 281 and 282:
Large Reflector Inverse Rule
Page 283:
Small Reflector Inverse Square Rule
Page 287 and 288:
Fundamental Frequency The lowest re
Page 289 and 290:
Transducers Piezoelectric Thickness
Page 291 and 292:
Application Case#1: The specimen's
Page 293 and 294:
Application Case#2: Electromagnetic
Page 295 and 296:
Q7: The resonance frequency of 2cm
Page 297 and 298:
dB is a measures of ratio of 2 valu
Page 299 and 300:
The Decibel The equation used to de
Page 301 and 302:
Why is the dB unit used? Use of dB
Page 303 and 304:
Use of the dB in Sound Measurements
Page 305 and 306:
Since transducers and microphones p
Page 307 and 308:
Sound Levels- Relative
Page 309 and 310:
Practice:
Page 311:
“Absolute" Sound Levels Whenever
Page 314 and 315:
Absolute: The standard reference so
Page 316 and 317:
Exercise: ANSWER Find the absolute
Page 318 and 319:
Relative dB: Example Calculation 1
Page 320 and 321:
Example Calculation 3 Consider the
Page 322 and 323:
2.16 Practice Makes Perfect
Page 324 and 325:
Q104: If an ultrasonic wave is tran
Page 326 and 327:
学习总是开心事
Page 328 and 329:
Page 330 and 331:
Page 332 and 333:
show all

UT Testing-Section 2 Physics of Ultrasound

Create successful ePaper yourself

Delete template?

Save as template?