AAE552-Session23

AAE552-Session23 - AAE 552 Spring 2009 A. F. Grandt AAE...

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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 23 – 6 March 2009 2 Contact Information Alten F. (Skip) Grandt, Jr. Email: aae552@ecn.purdue.edu 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 23 64 March 2009 Last Time: Wrap up radiography X-ray diffraction Start Ultrasonics Today: Ultrasonics 4 Assignment Please read Textbook : Chapter 12 – Ultrasonics Webpage powerpoint references “Ultrasonic Testing, ” collaboration for NDT education Exam #1 – Session 29 (Friday, 27 March 2009) 5 Chapter 12 Ultrasonic Inspection Goal: Describe NDE use of high frequency (0.2 – 25 MHz) sound waves A B C 6 Overview Test piece interrogated with high frequency sound waves Versatile method Can find internal and external flaws and other types of anomalies Safe, applicable to many materials Various strategies to send/receive signal Test piece
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AAE 552 Spring 2009 – A. F. Grandt 2 Properties of Sound Waves 7 8 Sound Waves Mechanical Vibrations – not electromagnetic Velocity V = λ λλ f V = velocity = constant for given material depends on density and elastic properties λ = wave length f = frequency ~ 200 kHz – 25 MHz Given material, select f for desired λ For comparison NDE ultrasound λ ~ 1 mm (with f ~ 10 MHz) Infrared λ ~ 10 – 1 - 10 -5 mm Visible light λ ~ 10 - 3 mm X-rays λ λλ ~ 10 - 6 – 10 - 9 mm 9 Properties of Sound Waves General Classification Bulk Waves – propagate in large bodies – don’t require boundaries for support Guided or interface waves – depend on a boundary for existence NDE Types Compression (longitudinal) Shear (transverse) Surface waves Lamb waves Standing waves 10 Table 12.1 Wave Speeds for Various Materials V E c = - + - ( ) ( )( ) / 1 1 1 2 1 2 ν ρ ρ = υ + ρ = G ) 1 ( 2 E V 2 / 1 s Compression Wave Speed Shear Wave Speed Surface Wave Speed Material Density (gm/cm 3 ) inch/sec m/sec inch/sec m/sec inch/sec m/sec Aluminum 2.7 248,000 6300 122,000 3100 114,000 2900 Copper 8.9 185, 000 4700 89,000 2260 76,000 1930 Magnesium 1.75 226,000 5750 122,000 3090 113,000 2870 Mild Steel 7.85 232,000 5900 127,000 3230 118,000 3000 Titanium 4.5 240,000 6100 123,000 3120 110,000 2790 Boundary Interactions 11 12 Boundary Interactions Understanding wave/boundary interaction key to NDE applications Normal incidence Transmitted vs reflected energy Characterize with impedance Oblique incidence Angles of reflection/refraction Mode changes Snell’s law Can control type of waves inputted to test piece
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AAE 552 Spring 2009 – A. F. Grandt
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AAE552-Session23 - AAE 552 Spring 2009 A. F. Grandt AAE...

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