Understanding Acoustic Emission Testing- Reading 1 Part B-A

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Martensitic Transformation: Mysterious Properties Explained The difference between austenite and martensite is, in some ways, quite small: while the unit cell of austenite is a perfect cube, in the transformation to martensite this cube is distorted so that it's slightly longer than before in one dimension and shorter in the other two. The mathematical description of the two structures is quite different, for reasons of symmetry, but the chemical bonding remains very similar. Unlike cementite, which has bonding reminiscent of ceramic materials, the hardness of martensite is difficult to explain in chemical terms. The explanation hinges on the crystal's subtle change in dimension, and the speed of the martensitic transformation. Austenite is transformed to martensite on quenching at approximately the speed of sound - too fast for the carbon atoms to come out of solution in the crystal lattice. The resulting distortion of the unit cell results in countless lattice dislocations in each crystal, which consists of millions of unit cells. These dislocations make the crystal structure extremely resistant to shear stress - which means, simply that it can't be easily dented and scratched. Picture the difference between shearing a deck of cards (no dislocations, perfect layers of atoms) and shearing a brick wall (even without the mortar). Charlie Chong/ Fion Zhang http://www.threeplanes.net/martensite.html
Keywords: Hexagonal & BCC Martensite The reason for twinning is that the alloy elements make two martensitic transformations possible – first a change from austenite to hexagonal martensite, and then from the hexagonal structure to the body-centered cubic martensite. Charlie Chong/ Fion Zhang http://www.threeplanes.net/martensite.html
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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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Charlie Chong/ Fion Zhang
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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
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16.6.3 Signal Attenuation The elast
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16.6.4 Specimen Geometry It has bee
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16.6.6 Concrete Strength It has bee
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16.7.1 Fracture Mechanics Studies A
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16.7.2 Type of Cracks A number of a
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They found that, while the number o
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Sadowska-Boczar et al. tried to qua
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FIGURE 16.7 Within-batch variabilit
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16.7.6 Fiber Reinforced Cements and
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Fiber Reinforced Cements and Concre
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Perhaps the most extensive series o
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16.7.8 Thermal Cracking Relatively
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They found that acoustic emissions
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Corrosion of Reinforcing Steel in C
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16.8 Field Studies of Acoustic Emis
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16.9 Conclusions From the discussio
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Concrete Structures Charlie Chong/
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Concrete Structures Charlie Chong/
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Concrete Structures- The Troll A pl
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Concrete Structures- The Troll A pl
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End of Reading 2 Charlie Chong/ Fio
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1.0 Introduction Acoustic Emission
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Twinning Charlie Chong/ Fion Zhang
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Acoustic Emission is unlike most ot
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2.0 A Brief History of AE Testing A
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3.0 Theory - AE Sources As mentione
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The amount of energy released by an
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Activity of AE Sources in Structura
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Kaiser/Felicity effects Felicity ef
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Dunegan corollary states that if ac
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Comments: Emissions are observed pr
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Pseudo Sources In addition to the A
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Wave Propagation A primitive wave r
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Waves radiates from the source in a
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Angular dependence of acoustic emis
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The signal that is detected by a se
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highly damped, nonmetallic material
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Attenuation: 1. Spread (30% for 2D,
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Teflon shoe http://www.ndt.net/ndta
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Lamb waves in acoustic emission tes
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2.2.5 Rayleigh Characteristics Rayl
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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 Charlie Chong/ Fion Zh
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Surface wave has the ability to fol
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Surface wave - One wavelength deep
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Rayleigh Wave Charlie Chong/ Fion Z
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Love Wave Charlie Chong/ Fion Zhang
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Other Reading: Rayleigh Waves Surfa
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Q110: What kind of wave mode travel
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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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Page 315 and 316: examination area- that portion of a
Page 317 and 318: Kaiser effect- the absence of detec
Page 319 and 320: Linear, Planar, 3D Linear 3D Planar
Page 321 and 322: location, continuous AE signal, n-
Page 323 and 324: Methods of Location • Hit method
Page 325 and 326: logarithmic (acoustic emission) amp
Page 327 and 328: signal overload level- that level a
Page 329 and 330: stimulation- the application of a s
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Page 333 and 334: Q1. The most common range of acoust
Page 335 and 336: Q5. The felicity effect is useful i
Page 337 and 338: Q9. Threshold settings are determin
Page 339 and 340: Q12. What is the Felicity Effect? A
Page 341 and 342: Q15. A Hsu-Nielson Source: A. measu
Page 343 and 344: Q19. The term ""rise time"" refers
Page 345 and 346: Q23. Four types of AE Source Locati
Page 347 and 348: Study Note 6: High Strength Steel-
Page 349 and 350: The properties of different steels
Page 351 and 352: Keywords: • DP (dual phase), •
Page 353 and 354: Figure 1: Ductility-strength relati
Page 355 and 356: However, with conventional TRIP ste
Page 357: Back to Basic: Martensite Martensit
Page 361 and 362: Figure 2: The stress-strain diagram
Page 363 and 364: Also, the TRIP steel is particularl
Page 365 and 366: Figure 3: The diagram shows the ver
Page 367 and 368: Table 1: Effect of alloying element
Page 369 and 370: ■ B, Ti, Zr Adding small amounts
Page 371 and 372: Acoustic Emission Technique the opt
Page 373 and 374: ASM introduction Since 1908, ASM is
Page 375 and 376: Active approach to leak detection T
Page 377 and 378: Leak detection and location The mod
Page 379 and 380: ■ Method of testing (Linear) The
Page 381 and 382: Fig 2: Cross-correlation function p
Page 383 and 384: The figure 1 shows how the position
Page 385 and 386: Area surveys using acoustic loggers
Page 387 and 388: The reading of an area meter could
Page 389 and 390: CONCLUSIONS In the last fifteen yea
Page 391 and 392: ■ ωσμ∙Ωπ∆ ∇ º≠δ≤
Page 393 and 394: Charlie Chong/ Fion Zhang
Page 395 and 396: Peach - 我爱桃子 Charlie Cho
Page 397 and 398: Good Luck Charlie Chong/ Fion Zhang
Page 399: Charlie Chong/ Fion Zhang
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Understanding Acoustic Emission Testing- Reading 1 Part B-A

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