FLAW CHARACTERIZATION BY ULTRASONIC FREQUENCY ANALYSIS

A NEW METHOD WAS DEVELOPED FOR THE CHARACTERIZATION (DETERMINATION OF THE SIZE AND ORIENTATION) OF A REFLECTOR BY ULTRASONIC SPECTRAL ANALYSIS. THIS TECHNIQUE CAN BE USED TO DETERMINE NONDESTRUCTIVELY THE NATURE OF FLAWS DETECTED IN A MATERIAL BY MEANS OF ULTRASONIC EXAMINATION. IT IS SHOWN THAT IT IS FEASIBLE TO CHARACTERIZE A FLAW BY THIS TECHNIQUE IN SPITE OF ITS COMPOSITION (I.E., CRACK, VOID, OR INCLUSION) OR SHAPE AND WITHOUT THE NEED FOR A CALIBRATION STANDARD. THIS TECHNIQUE IS FREE OF SEVERAL LIMITATIONS INHERENT IN TECHNIQUES BASED ON AMPLITUDE. THE RESULTS PRESENTED HERE ARE BASED ON A SERIES OF REFLECTION EXPERIMENTS IN WHICH THE ENDS OF SOLID RODS IMMERSED IN WATER AND MACHINED DISCONTINUITIES IN METAL SAMPLES WERE USED AS REFLECTORS. BROAD-BAND ULTRASONIC PULSES WERE ANALYZED AFTER REFLECTION FROM THE INTERFACE OF INTEREST. A PHYSICAL AND ANALYTICAL MODEL WAS DEVELOPED BASED ON AN INTERFERENCE MECHANISM THAT RESULTS FROM THE SUPERPOSITION OF SPHERICAL WAVELETS EMITTED FROM OPPOSING EXTREMES OF THE REFLECTOR. THIS MODEL EXPLAINS VERY WELL THE EXPERIMENTALLY OBSERVED SPECTRA VARIATIONS IN TERMS OF SIZE AND THREE-DIMENSIONAL ANGULAR ORIENTATION OF THE REFLECTOR, DISTANCE BETWEEN THE TRANSDUCER AND REFLECTOR, AND DISPLACEMENT OF THE REFLECTOR FROM THE AXIS OF THE TRANSDUCER FOR A FLAT REFLECTOR OF ANY COMPOSITION. BASED ON THIS TECHNIQUE, A DETAILED PROCEDURE CAN BE OUTLINED FOR CHARACTERIZING A RANDOMLY ORIENTED NATURAL FLAW IN A PLATE. THE FEASIBILITY AND PRACTICALITY OF USING THIS TECHNIQUE TO TEST VARIOUS MATERIALS AND IN AUTOMATED TESTING SYSTEMS WERE CONSIDERED. /ME/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00255327
• Supplemental Notes:
  • Vol 29, No 8, PP 182-188, 192, 7 FIG, 5 TAB, 1 REF
• Authors:
  • Whaley, H L
  • Adler, L
• Publication Date: 1971-8

Media Info

• Serial:
  • Materials Evaluation
  • Publisher: American Society for Nondestructive Testing
  • ISSN: 0025-5327

Subject/Index Terms

• TRT Terms: Audio frequency; Defects; Frequency analyzers; Nondestructive tests; Reflection; Reflectorized materials; Ultrasonic tests; Ultrasonic waves
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00217151
• Record Type: Publication
• Files: TRIS
• Created Date: Sep 19 1971 12:00AM