Understanding Acoustic Emission Testing- Reading 1 Part B-A

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Crack: When cracks exist in a metal, the stress levels present in front of the crack tip can be several times higher than the surrounding area. Therefore, AE activity will also be observed when the material ahead of the crack tip undergoes plastic deformation (micro-yielding). Fatigue Crack: Two sources of fatigue cracks also cause AE’s. ■ The first source is emissive particles (e.g. nonmetallic inclusions) at the origin of the crack tip. Since these particles are less ductile than the surrounding material, they tend to break more easily when the metal is strained, resulting in an AE signal. ■ The second source is the propagation of the crack tip that occurs through the movement of dislocations and small-scale cleavage produced by triaxial stresses. Charlie Chong/ Fion Zhang
The amount of energy released by an acoustic emission and the amplitude of the waveform are related to the magnitude and velocity of the source event. AE Amplitude: The amplitude of the emission is proportional (∝) to the (a) velocity of crack propagation and the (b) amount of surface area created. Large, discrete crack jumps will produce larger AE signals than cracks that propagate slowly over the same distance. Detection and conversion of these elastic waves to electrical signals is the basis of AE testing. Analysis of these signals yield valuable information regarding the origin and importance of a discontinuity in a material. As discussed in the following section, specialized equipment is necessary to detect the wave energy and decipher which signals are meaningful. Charlie Chong/ Fion Zhang
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Understanding Acoustic Emission Tes
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Concrete Offshore structure Charlie
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Refinery Applications Charlie Chong
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Charlie Chong/ Fion Zhang
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The Magical Book of Acoustic Emissi
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ASNT Certification Guide NDT Level
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3 Techniques • Equipment calibrat
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Fion Zhang at Shanghai 3rd Septembe
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Charlie Chong/ Fion Zhang http://gr
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Video on - Leak Detection on Buried
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ASME V Article Numbers: Gen Article
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ASTM Standards E976 - 05 Standard G
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ASTM Standards E1781 - 08 Standard
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Typical AET Signal https://dspace.l
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Study Note 1: AET http://www.geocit
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Until about 1973, acoustic emission
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Charlie Chong/ Fion Zhang http://ww
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AE Technique The AE technique (AET)
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What is Normal (Gaussian) distribut
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Probability density function for th
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Cumulative distribution function of
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Crystal Twinning Crystal twinning o
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What is Crystal Twinning Crystal tw
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Crystal Twinning Charlie Chong/ Fio
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Crystal Twinning- Diagram of twinne
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AET Set-up Charlie Chong/ Fion Zhan
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Continuous type Charlie Chong/ Fion
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Discussion Subject: explains on the
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Kaiser Effect Plastic deformation i
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Felicity effect is an effect in aco
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Activity of AE Sources in Structura
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Felicity Effect - the applied load
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AE Parameters Various parameters us
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AET Advantages AE testing is a powe
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A Few Typical Applications • Dete
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Acoustic Emission Testing Advantage
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End of Reading 1 Charlie Chong/ Fio
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16 Acoustic Emission Methods Charli
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Foreword: Acoustic emission refers
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Acoustic emissions, which occur in
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At about the same time, but indepen
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Figure 1: A cube with sides of leng
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Green also noted the Kaiser effect,
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16.3 Theoretical Considerations Whe
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FIGURE 16.1 The two basic types of
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FIGURE 16.2 A typical acoustic emis
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FIGURE 16.3 Typical view of an acou
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1. The total number of counts (e.g.
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■ Rise time — This is the inter
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Energy analysis — This is an indi
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FIGURE 16.5 The main elements of a
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Fourier-Transform (FT) The Fourier
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Signal Evaluation: Analysis of the
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Signal Evaluation: Raise Time/ Even
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Signal Evaluation: Amplitude Distri
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Signal Evaluation: Energy analysis-
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Signal Evaluation: Raise Time/ Even
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FIGURE 16.5 The main elements of a
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A brief description of the most imp
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PZT:- If the p.d or the stress is c
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AET Transducer In 0.1KHz~2.0KHz Cha
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2. Preamplifier: Because of the low
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There are generally two (or more) c
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Spooner and Dougill confirmed that
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Spooner and Dougill conclusion on K
Page 133 and 134: 16.6.3 Signal Attenuation The elast
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Page 141 and 142: 16.7.2 Type of Cracks A number of a
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Page 149 and 150: 16.7.6 Fiber Reinforced Cements and
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Page 155 and 156: 16.7.8 Thermal Cracking Relatively
Page 157 and 158: They found that acoustic emissions
Page 159 and 160: Corrosion of Reinforcing Steel in C
Page 161 and 162: 16.8 Field Studies of Acoustic Emis
Page 163 and 164: 16.9 Conclusions From the discussio
Page 165 and 166: Concrete Structures Charlie Chong/
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Page 169 and 170: Concrete Structures- The Troll A pl
Page 171 and 172: Concrete Structures- The Troll A pl
Page 173 and 174: End of Reading 2 Charlie Chong/ Fio
Page 175 and 176: 1.0 Introduction Acoustic Emission
Page 177 and 178: Twinning Charlie Chong/ Fion Zhang
Page 179 and 180: Acoustic Emission is unlike most ot
Page 181 and 182: 2.0 A Brief History of AE Testing A
Page 183: 3.0 Theory - AE Sources As mentione
Page 187 and 188: Activity of AE Sources in Structura
Page 189 and 190: Kaiser/Felicity effects Felicity ef
Page 191 and 192: Dunegan corollary states that if ac
Page 193 and 194: Comments: Emissions are observed pr
Page 195 and 196: Pseudo Sources In addition to the A
Page 197 and 198: Wave Propagation A primitive wave r
Page 199 and 200: Waves radiates from the source in a
Page 201 and 202: Angular dependence of acoustic emis
Page 203 and 204: The signal that is detected by a se
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Page 207 and 208: Attenuation: 1. Spread (30% for 2D,
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Page 211 and 212: Lamb waves in acoustic emission tes
Page 213 and 214: 2.2.5 Rayleigh Characteristics Rayl
Page 215 and 216: Q29: The longitudinal wave incident
Page 217 and 218: The major axis of the ellipse is pe
Page 219 and 220: Surface wave Charlie Chong/ Fion Zh
Page 221 and 222: Surface wave has the ability to fol
Page 223 and 224: Surface wave - One wavelength deep
Page 225 and 226: Rayleigh Wave Charlie Chong/ Fion Z
Page 227 and 228: Love Wave Charlie Chong/ Fion Zhang
Page 229 and 230: Other Reading: Rayleigh Waves Surfa
Page 231 and 232: Q110: What kind of wave mode travel
Page 233 and 234: Q192: Surface waves are reduced to
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Since the 1990s, the understanding
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Plate or Lamb waves are the most co
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Plate wave or Lamb wave are formed
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When guided in layers they are refe
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Symmetrical = extensional mode Asym
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Other Reading: Lamb Wave Lamb waves
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Fig. 4 Diagram of the basic pattern
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2.2.7 Dispersive Wave: Wave modes s
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Discussion Subject: Wave Mode and V
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Key Points: • Two classes: resona
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Q. The most common range of acousti
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Equipment- Probe Charlie Chong/ Fio
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Schematic Diagram of a Basic Four-c
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After passing the AE system mainfra
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AET Charlie Chong/ Fion Zhang
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6.0 AE Signal Features With the equ
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Amplitude, A, is the greatest measu
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7.0 Data Display Software-based AE
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Intensity displays are used to give
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Amplitude/counts Signal Analysis Th
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Source location techniques assume t
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Because the above scenario implicit
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When additional sensors are applied
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9.0 AE Barkhausen Techniques The Ba
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Hysterisis Loop- magnetization or d
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■ Bucket Truck (Cherry Pickers) I
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■ Gas Trailer Tubes Acoustic emis
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■ Aerospace Structures Most aeros
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Others • Fiber-reinforced polymer
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Study Note 4: ASTM E1316 Term & Def
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• acoustic emission (AE)- the cla
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• acoustic emission signature (si
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• array, n- a group of two or mor
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• continuous emission- see emissi
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• dB AE - a logarithmic measure o
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AE signal amplitude measured as a r
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• distribution, differential (aco
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effective velocity, n- velocity cal
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FIG. 1 Burst Emission on a Continuo
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FIG. 3 Continuous Emission. (Sweep
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examination area- that portion of a
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Kaiser effect- the absence of detec
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Linear, Planar, 3D Linear 3D Planar
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location, continuous AE signal, n-
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Methods of Location • Hit method
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logarithmic (acoustic emission) amp
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signal overload level- that level a
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stimulation- the application of a s
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End of Reading 4 Charlie Chong/ Fio
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Q1. The most common range of acoust
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Q5. The felicity effect is useful i
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Q9. Threshold settings are determin
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Q12. What is the Felicity Effect? A
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Q15. A Hsu-Nielson Source: A. measu
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Q19. The term ""rise time"" refers
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Q23. Four types of AE Source Locati
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Study Note 6: High Strength Steel-
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The properties of different steels
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Keywords: • DP (dual phase), •
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Figure 1: Ductility-strength relati
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However, with conventional TRIP ste
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Back to Basic: Martensite Martensit
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Keywords: Hexagonal & BCC Martensit
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Figure 2: The stress-strain diagram
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Also, the TRIP steel is particularl
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Figure 3: The diagram shows the ver
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Table 1: Effect of alloying element
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■ B, Ti, Zr Adding small amounts
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Acoustic Emission Technique the opt
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ASM introduction Since 1908, ASM is
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Active approach to leak detection T
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Leak detection and location The mod
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■ Method of testing (Linear) The
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Fig 2: Cross-correlation function p
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The figure 1 shows how the position
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Area surveys using acoustic loggers
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The reading of an area meter could
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CONCLUSIONS In the last fifteen yea
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■ ωσμ∙Ωπ∆ ∇ º≠δ≤
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Peach - 我爱桃子 Charlie Cho
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Good Luck Charlie Chong/ Fion Zhang
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Understanding Acoustic Emission Testing- Reading 1 Part B-A

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