UT Testing-Section 2 Physics of Ultrasound

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Note that the applet defaults to compressional velocity in the second material. The refracted compressional wave angle will be generated for given materials and angles. To find the angle of incidence required to generate a shear wave at a given angle complete the following: 1. Set V1 to the longitudinal wave velocity of material 1. This material could be the transducer wedge or the immersion liquid. 2. Set V2 to the shear wave velocity (approximately one-half its compressional velocity) of the material to be inspected. 3. Set Q2 to the desired shear wave angle. 4. Read Q1, the correct angle of incidence.
Transverse wave can be introduced into the test material by various methods: 1. Inclining the incident L-wave at an angle beyond the first critical angle, yet short of second critical angle using a wedge. 2. In immersion method, changing the angle of the normal search unit manipulator, 3. Off-setting the normal transducer from the center-line for round bar or pipe. for 45° refracted transverse wave, the rule of thumb is the offset d= 1/6 of rod diameter
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Section 2: Physics of Ultrasound
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2.0: Ultrasound Formula http://www.
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Ultrasonic Formula
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2.1: Wave Propagation Ultrasonic te
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Acoustic Spectrum
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Acoustic Wave - Node and Anti-Node
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http://hyperphysics.phy-astr.gsu.ed
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2.2: Modes of Sound Wave Propagatio
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Longitudinal and shear waves
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Longitudinal and shear waves
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2.2.3 Longitudinal Wave Also Knows
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Longitudinal wave: Longitudinal wav
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2.2.4 Shear waves (S-Waves) In air,
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Shear waves
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Q10: For a shear wave travelling fr
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Rayleigh waves are a type of surfac
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Q29: The longitudinal wave incident
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The major axis of the ellipse is pe
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Surface wave
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Surface wave has the ability to fol
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Surface wave - One wavelength deep
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Love Wave http://web.ics.purdue.edu
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Other Reading: Rayleigh Waves Surfa
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Q110: What kind of wave mode travel
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2.2.6 Lamb Wave: Lamb waves propaga
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Types of Wave New! • Plate wave-
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Plate or Lamb waves are similar to
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With Lamb waves, a number of modes
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Symmetrical = extensional mode Asym
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Symmetrical = extensional mode
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The form is determined by whether t
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Q1: The wave mode that has multiple
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Dispersion refers to the fact that
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Thickness Limitation: One can not g
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Spring model- A mass on a spring ha
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In terms of the spring model, Hooke
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Elastic Model / Longitudinal Wave
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Elastic Model / Shear Wave
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The Speed of Sound Hooke's Law, whe
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What properties of material affect
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Where V is the speed of sound, C is
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Q50: The principle attributes that
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E/N/G
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Examples of approximate compression
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Shear Wave Velocity: V S The veloci
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The applet below shows a longitudin
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http://www.ndt-ed.org/EducationReso
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Java don’t work? http://jingyan.b
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Java don’t work? http://jingyan.b
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As can be noted by the equation, a
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The two velocities of sound are lin
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Sensitivity and resolution are two
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2.5.2 Grain Size & Frequency Select
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Since more things in a material are
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Detectability variable: • pulse l
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Q7: When a material grain size is o
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Pulse Length: A sound pulse traveli
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Determining cross sectional area us
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Pulse volume rule-of-thumb: Competi
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When sound travels through a medium
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Scattering: Grain Size and Wave Fre
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Spreading/ Scattering / adsorption
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The units of the attenuation value
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Attenuation can be determined by ev
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A o Ut A
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2.6.3 Frequency selection There is
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Q94: In general, which of the follo
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Q7: When the material grain size is
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Transmission & Reflection Animation
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The following applet can be used to
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Reflection/Transmission Energy as a
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2.8: Reflection and Transmission Co
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Since the amount of reflected energ
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Note that the reflection and transm
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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 210 and 211: Offset of Normal probe above circul
Page 212 and 213: Refraction and mode conversion at n
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
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Near field (near zone) or Fresnel z
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Near/ Far Fields
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where D is the diameter of the tran
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Fresnel & Fraunhofer Zone 10dB, K-0
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Fresnel & Fraunhofer Zone
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Q: Where does beam divergence occur
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Q160 Beam divergence is a function
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Dead Zone - The interval following
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Dead Zone -The initial pulse is a t
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Dead Zone http://www.ni.com/white-p
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Q36: To eliminate the decrease in s
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Large Reflector Inverse Rule
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Small Reflector Inverse Square Rule
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Fundamental Frequency The lowest re
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Transducers Piezoelectric Thickness
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Application Case#1: The specimen's
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Application Case#2: Electromagnetic
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Q7: The resonance frequency of 2cm
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dB is a measures of ratio of 2 valu
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The Decibel The equation used to de
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Why is the dB unit used? Use of dB
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Use of the dB in Sound Measurements
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Since transducers and microphones p
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Sound Levels- Relative
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Practice:
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“Absolute" Sound Levels Whenever
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Absolute: The standard reference so
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Exercise: ANSWER Find the absolute
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Relative dB: Example Calculation 1
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Example Calculation 3 Consider the
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2.16 Practice Makes Perfect
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Q104: If an ultrasonic wave is tran
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学习总是开心事
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UT Testing-Section 2 Physics of Ultrasound

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