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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 18 23 February 2009 2 Contact Information Alten F. (Skip) Grandt, Jr. Email: email@example.com 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 18 23 February 2009 Last Time: Start radiography Today: Continue radiography 4 Assignment Please read Textbook : Chapter 11 Webpage powerpoint references Radiographic Testing collaboration for NDT education Paper #1 Due Session 21 (2 March 2009) Exam #1 Session 29 (Friday, 27 March 2009) 5 Chapter 11: Radiography Use penetrating power of x-rays or gamma rays to locate internal anomalies 6 Chapter 11: Radiography Topics Overview Absorption/Scatter Radiation sources Image formation Image quality Examples Computed Tomography Safety issues Summary AAE 552 Spring 2009 A. F. Grandt 2 Overview 7 8 Electro-magnetic Spectrum Fig 11.1 1.E-14 1.E-12 1.E-10 1.E-08 1.E-06 1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06 Wave length (m) Gamma ray X-ray Visible Ultra-violet Infrared Microwave Radio 1.E +20 1.E +18 1.E +16 1.E +14 1.E +4 1.E +22 1.E +6 1.E +8 1.E +10 1.E +12 Frequency (Hz) Energy (electron volts) 1.E +5 1.E +7 1.E -11 1.E +1 1.E +3 1.E -9 1.E -7 1.E -5 1.E -3 1.E -1 9 Electromagnetic Spectrum Relations c = f Eq. 11.1 E = hf = hc/ Eq. 11.2 = the wave length of radiation (m) f = frequency of radiation (Hz) E = photon energy (joule) c = speed of light = 3 x 10 8 m/sec h = Plancks constant = 6.624 x 10-34 joule-sec Short wavelength allows penetration of materials that are opaque to visible light Penetration power of x-rays discovered in 1895 by Roentgen 10 Radiography Radiation absorbed differentially by test piece Transmitted energy indicates density variation Note flaw orientation Issue: Crack parallel to x-ray beam for best detection Radiation Film Test piece Exposed film General Principles of Radiography The energy of the radiation affects its penetrating power. Higher energy radiation can penetrate thicker and more dense materials. The radiation energy and/or exposure time must be controlled to properly image the region of interest. Thin Walled Area Low Energy Radiation High Energy Radiation IDL 2001 Radiography has sensitivity limitations when detecting cracks. X-rays see a crack as a thickness variation and the larger the variation, the easier the crack is to detect....
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This note was uploaded on 11/04/2010 for the course AAE 552 taught by Professor Longuski during the Spring '10 term at IUPUI.
- Spring '10