Salesforce Miami User Group Event - 1st Quarter 2024
Muravin physical principals of acoustic emission
1. 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
13. 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
14. 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
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16. 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
17. AE Types: Burst and Continuous AE Signals More in www.muravin.com
19. 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
22. 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
28. 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
38. 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
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42. Dispersion Curves Example calculated for steel 347 plate (10mm thick) Triple point Non-dispersive part of A 0 mode More in www.muravin.com
50. 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
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53. 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
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55. 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