Flaw detection system using acoustic doppler effect

• US 6,324,912 B1
• Filed: 01/26/2001
• Issued: 12/04/2001
• Est. Priority Date: 02/24/1998
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Wooh, Shi-Chang
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/770,323
• Publication Number:
  US 20010045130A1
• Time in Patent Office: 312 Days
• Field of Search: 73/596, 73/618, 73/620, 73/624, 73/627, 73/629, 73/643
• US Class Current: 73/629
• CPC Class Codes: B61K 9/10 for detecting cracks in rails or welds thereof
• CPC Class Codes: G01N 2291/017 Doppler techniques
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 2291/2623 Rails; Railroads
• CPC Class Codes: G01N 29/2412 using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G01N 29/265 by moving the sensor relative to a stationary material
• CPC Class Codes: G01N 29/40 by amplitude filtering, e.g. by applying a threshold or by gain control
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency

Abstract

A flaw detection system using acoustic Doppler effect for detecting flaws in a medium wherein there is relative motion between the medium and system includes a transducer, spaced from the medium to be inspected, for introducing to and sensing from the medium an acoustic signal that propagates in the medium at a predetermined frequency; and a detector, responsive to the sensed propagating acoustic signal, for detecting in the sensed acoustic signal the Doppler shifted frequency representative of a flaw in the medium.

Claims

1. A flaw detection system for detecting flaws in a medium using acoustic Doppler effect resulting from relative motion between the medium and the system comprising:

transducer means, spaced from the medium to be inspected, for introducing to and sensing from the medium an acoustic signal that propagates in said medium at a predetermined frequency, said transducer means including an electromagnetic acoustic transmitter and receiver for inducing an acoustic signal into said medium and sensing the Doppler shifted acoustic signal; and

means, responsive to the sensed propagating acoustic signal, for detecting in the sensed acoustic signal the Doppler shifted frequency representative of a flaw in the medium.

2. A flaw detection system for detecting flaws in a medium using acoustic Doppler effect resulting from relative motion between the medium and the system comprising:

transducer means, spaced from the medium to be inspected, for inducing an acoustic signal to propagate in the medium at a predetermined frequency and sensing the propagating acoustic signal in the medium, said transducer means including an electromagnetic acoustic transducer for inducing and sensing the acoustic signal; and

means, responsive to the sensed propagating acoustic signal, for distinguishing the Doppler shifted frequency representative of a flaw in the medium.