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AAE552-Session28

AAE552-Session28 - AAE 552 Spring 2009 – A F Grandt 1 1...

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Unformatted text preview: AAE 552 Spring 2009 – A. F. Grandt 1 1 AAE 552: Nondestructive Evaluation of Structures and Materials A. F. Grandt, Jr. Professor of Aeronautics and Astronautics Purdue University W. Lafayette, IN 47907 Session 28 – 25 March 2009 2 Contact Information Alten F. (Skip) Grandt, Jr. Email: [email protected] Telephone: • Office: 765-494-5141 • Home: 765-463-4276 FAX: 765-494-0307 Course webpage accessed at: http://www.itap.purdue.edu/tlt/blackboard 3 AAE 552 Session 28 25 March 2009 Last Time: • Chapter 11 & 12 problems • Start eddy current Today: • Eddy current parameters • Depth of penetration • Impedance testing 4 Assignment • Please read: • Chapter 13 in textbook: Eddy Current Testing • Exam #1 – Session 29 • Cover material thru ultrasonic inspection (Ch 12 in text) • See topic list and sample exam on webpage • Term paper #2 – Monday, 6 April (session 33) 5 Midterm Exam - Session 29 • 25% of final grade • Final exam – 30% (comprehensive) • Paper 1 – 20% • Paper 2 – 25% • Closed book • 1 page review sheet (both side of 8.5 x 11 inch sheet) • Short answer, fill in blank, true/false, numerical calculations, etc. • Chapters 1, 4, 10, 11, 12 • Exam description and example exams on web page 6 Chapter 13: Eddy Current NDE • ac coil induces electrical currents in test piece • Versatile method to detect • Cracks, anomalies • Thickness • Material properties – microstructure – conductivity – magnetic permeability • Residual stresses • Etc. • Limited to electrical conductors AAE 552 Spring 2009 – A. F. Grandt 2 7 Eddy Current Inspection Alternating current in coil generates “eddy” currents in test piece that are disturbed by anomalies Eddy Currents Primary magnetic field Indicator Secondary Magnetic Field Test piece (conductor) 8 Test Measures Impedance of Coil and Coupled Test Object Test Object Opposing magnetic field Eddy currents Coil circuit impedance modified by coupling with induced eddy current field in test part – varies with anomalies in component Ammeter A V V X V R X L R AC Source Coil 9 External Coil Test piece Surface Coil Test piece Internal Coil Test piece Test piece Schematic Representation of Eddy Current Coils (Fig. 13.2) 10 Factors that Influence Eddy Current Development • Anomalies • Conductivity • Composition, temperature, heat treatment, hardness, microstructure, residual stress • Magnetic permeability • Lift-off and fill-factors • Edge effects • Depth of penetration • Operating frequency • Coil current 11 Conductivity of Metals and Alloys (Table 13.1) Metal or Alloy Conductivity % IACS* Silver 105 Copper, Annealed 100 Gold 70 Aluminum 61 Magnesium 37 70-30 Brass 28 Phosphor Bronzes 11 Monel 3.6 *IACS – International Annealed Copper Standard (Copper = 100 %) 12 Conductivity of Metals and Alloys (Table 13.1) Continued Metal or Alloy Conductivity % IACS* Monel 3.6 Zirconium 3.4 Zircaloy-2 2.4 Titanium 3.1 Ti-6Al-4V Alloy 1.0 304 Stainless Steel...
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AAE552-Session28 - AAE 552 Spring 2009 – A F Grandt 1 1...

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