Muravin physical principals of acoustic emission

Seminar on Fundamentals of Acoustic Emission לשכת המהנדסים , האדריכלים והאקדמאים במקצועות הטכנולוגיים בישראל אגודת מהנדסי מכונות - ענף בדיקות לא הורסות Dr. Boris Muravin Chairman of Israeli Acoustic Emission Group Feb 24, 2011 יום עיון השנתי בנושא פליטה אקוסטית This presentation for acoustic emission education purposes only More in www.muravin.com

סיכום פעילות התא לפליטה אקוסטית בשנת 2010. ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Seminar Outline ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

History of AE More in www.muravin.com

Who was the First? ,[object Object],He was the First who used AE as a forecasting tool More in www.muravin.com

Early History of AE ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

History of First AE Experiments ,[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

History of First AE Experiments ,[object Object],[object Object],[object Object],More in www.muravin.com

Start of Industrial Application of AE ,[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Physical Principals of Acoustic Emission More in www.muravin.com

Definition of Acoustic Emission Phenomenon ,[object Object],[object Object],[object Object],More in www.muravin.com

Classification of AE More in www.muravin.com

Classes and Mechanisms of Acoustic Emission Mechanical acoustic emission - acoustic emission generated by a leakage, friction, impact or other sources of mechanical origin. Material acoustic emission - acoustic emission generated by a local dynamic change in a material structure due to fracture development and/or deformation processes. More in www.muravin.com

Source Mechanisms of AE in Metals More then 80% of energy expended on fracture in common industrial metals goes to development of plastic deformation. More in www.muravin.com

Source Mechanisms in Composites ,[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Primary vs. Secondary AE More in www.muravin.com Secondary AE Primary AE Crack surface friction Crack jump Inclusion breakage in the process zones Plastic deformation Corrosion layer fracture in corrosion fatigue cases Crack growth

AE Types: Burst and Continuous AE Signals More in www.muravin.com

Some Mechanisms of Burt and Cont. AE More in www.muravin.com

Acoustic Emission is Flaw-Type-Material Specific Tree Falls Paper tear ICE CRACK Glass Ice Crack Brake Identification of distinctive flaw-type-material specific AE characteristics of different flaws in high energy equipment is a necessary condition for reliable diagnostics. Glass Brake More in www.muravin.com

AE in Metals More in www.muravin.com

Metals More in www.muravin.com

Factors that Tend to Increase or Decrease the Amplitude of AE Nondestructive Testing Handbook, Volume 6 “Acoustic Emission Testing”, Third Edition, ASNT. More in www.muravin.com

“ Friendly” Metals for Traditional AE Inspections ,[object Object],[object Object],More in www.muravin.com

Detectability by AE Depends on Failure Mechanism ,[object Object],[object Object],More in www.muravin.com

Plastic Deformation as a Major Source of AE More in www.muravin.com

Plastic Zone at the Crack Tip ,[object Object],[object Object],[object Object],[object Object],Fracture Mechanics Fundamentals and Applications, Second Edition, T.L. Anderson. More in www.muravin.com

Comparison of Plastic Deformation around Crack Tips Mode I and II 1 2 3 Mode II 0.5 mm 1 Mode I ,[object Object],[object Object],Our experimental results J. F. Kalthoff, Failure Methodology of Mode-II Loaded Cracks, Mechanics, Automatic Control and Robotics Vol.3, No 13, 2003, pp. 533 - 552 More in www.muravin.com Plastic Strain Plastic Stress Mode I Mode II

Ellipses of Dispersion Energy vs. Average Frequency of Single Fatigue Crack under Mode I and Mode II Loading (1200kgf) 1– Plastic Deformation 2 – Micro Cracking More in www.muravin.com Released Energy, r.u. Amount of Data Flaw Type 0.33 99 Plastic Deformation 0.5 16 Micro-Cracks Released Energy, r.u. Amount of Data Flaw Type 1 228 Plastic Deformation 1 23 Micro-Cracks

Models of AE in Metals ,[object Object],[object Object],[object Object],[object Object],(3) Strains at the crack tip vary at where r is the radial distance from the crack tip. (4) The assumptions lead to development of the following equations for the model ( ) More in www.muravin.com

AE Effects ,[object Object],[object Object],[object Object],ASTM E1316: 2010 Kaiser effect —the absence of detectable acoustic emission at a fixed sensitivity level, until previously applied stress levels are exceeded. Discussion—Whether or not the effect is observed is material specific. The effect usually is not observed in materials containing developing flaws. Kaiser effect (BCB) Felicity effect (DEF) More in www.muravin.com

Kaiser Effect ,[object Object],[object Object],[object Object],[object Object],Example of the Kaiser Effect in a cyclically loaded concrete specimen. Thick black lines represents AE activity, thin lines the loads and dashed lines the Kaiser Effect. http://www.ndt.net/ndtaz/content.php?id=476 More in www.muravin.com

AE Waves More in www.muravin.com

Types of Acoustic Emission Waves ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Modes of Elastic Waves Propagation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Longitudinal, Shear, Rayleigh and Love Waves Reference: http://web.ics.purdue.edu/~braile/edumod/slinky/slinky.htm More in www.muravin.com

Wave Modes in Different Geometries ,[object Object],[object Object],[object Object],In thinnest plates only Lamb wave arrivals are visible. Symmetric Antisymmetric More in www.muravin.com t = 10 mm t = 5 mm

Example of AE Signal More in www.muravin.com

Wave Speed in Different Materials Wave speeds derivation: λ and μ – Lame constants ν – Poisson’s ratio ρ – material density More in www.muravin.com

Properties of Elastic Waves in Semi-Infinite Media ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Reference: “Dynamic Behavior of Materials” by M. Meyers More in www.muravin.com

Wave Propagation Effects ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Group and Phase Velocity ,[object Object],[object Object],[object Object],Reference: http://www.owrc.com/waves/waveSpeed/waveSpeed.html More in www.muravin.com

Dispersion Curves Example calculated for steel 347 plate (10mm thick) Triple point Non-dispersive part of A 0 mode More in www.muravin.com

Use of Dispersion Curves ,[object Object],[object Object],[object Object],More in www.muravin.com

AE Source Location More in www.muravin.com

Principals of Acoustic Emission Source Location ,[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Time of Arrival Evaluation ,[object Object],[object Object],More in www.muravin.com

Effective Velocity ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Linear Location ,[object Object],[object Object],More in www.muravin.com

One Sensor Linear Location ,[object Object],[object Object],[object Object],More in www.muravin.com

Two Dimensional Source Location Sensor 1 Sensor 2 Sensor 1 Z D R2 R1 R1 R2 R3 Sensor 2 Sensor 3 For location of AE sources on a plane minimum three sensors are used. The source is situated on intersection of two hyperbolas calculated for the first and the second sensors detected AE signal and the first and the third sensor. More in www.muravin.com R3

Over-determined Source Location ,[object Object],[object Object],Chi Squared error function that minimized in over-determined source location. More in www.muravin.com

2D Location on Cylinder Minimization on χ 2 : (x o ,y o )– location of source (x i ,y i )– location of sensor i t i – arrival time to sensor i t 1 - arrival time to sensor 1 The time delay between the signal arrival to two sensors: ,[object Object],[object Object],More in www.muravin.com

X o – location of source X i – location of sensor i E o – energy at source E i – energy at sensor i β - the decay constant Energy attenuation in line: * 3 sensors are required for location for unknown β (for known β 2 sensors are required for location) Energy Attenuation Location More in www.muravin.com Source ( ( ( ( * ) ) ) ) x I

Location in Anisotropic Materials ,[object Object],[object Object],More in www.muravin.com

Cross-correlation based Location Ch 1 Ch 2 Cross-correlation method is typically applied for location of continuous AE signals. Cross-correlation is another method for location of AE sources based on estimation of time shifts between AE signals detected by different sensors. It is usually applied for continuous AE signals when it is impractical to estimate the time of wave arrival but possible to estimate time shifts between sensors. More in www.muravin.com Δ t Normalized cross-correlation function Δ t Cross-correlation function

Zone Location ,[object Object],[object Object],[object Object],[object Object],More in www.muravin.com

Geodesic Location ,[object Object],[object Object],Reference: G. PRASANNA, M. R. BHAT and C. R. L. MURTHY, “ACOUSTIC EMISSION SOURCE LOCATION ON AN ARBITRARY SURFACE BY GEODESIC CURVE EVOLUTION”, Advances in Acoustic Emission - 2007 More in www.muravin.com

Other Location Methods ,[object Object],[object Object],[object Object],More in www.muravin.com

The End More in www.muravin.com

Muravin physical principals of acoustic emission

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Muravin physical principals of acoustic emission