Study on the Doppler Method to Detect Metal Fault

Study on the Doppler Method to Detect Metal Fault

The study deals with the interaction of ultrasound with metals discovered an unusual phenomenon. Microwave  sensor  indicates  fluctuations  of  electric  surface  conductivity  when  exposed  to  elastic ultrasonic vibrations in metal objects. The defective area is by a content of microdefects of the type “the mouth of the cracks”. They are known as the field of “acoustic activity” the method of Acoustic Emission (AE). The high coefficient of phase modulation of the reflected field allows you to indicate the  Doppler signal  is  useful  for  6-30  dB  over  the  noise  from  a  distance  of  70-180  mm.  The phenomenon is called “of Gorbunov effect”. It has been successfully used as remote non-destructive testing method is ultrasonic methods of flaw detection, acoustic emission. A semiconductor detector responds  to  the  amount  of  incident  and  reflected  waves,  registering  the  change  in  reflection coefficient. When injected into the area of the surface that differ in conductivity from the previous one can identify cracks the size of a quarter wavelength. It has been successfully used as remote non-destructive testing method that replaces the ultrasonic methods of flaw detection, acoustic emission. While testing a fragment of the  steam-pipe destroyed during  operation due to  flooding,  our device allowed to indicate these defects when the external surface of the steam pipe is excited by ultrasound. The microwave sensor at this time irradiated the outside surface of the steam. Rrevealing that the new device is able to reconsider the defectoscopy of the inne-surface of the steam pipe by chemical etching method of the inner-surface with scrutinizing by a contrast agent, a microscope, an x-ray flaw detector.

Another version of the test of the new device relates to the indication of the quality ofzirconium tubes (used for heat Emitting Elements (TVEL) in thermal nuclear power plants).  Result revealed that the manufactured tubes should be rejected due to the appearance of “punctures”, “sticking”, scratches, micro-cracks. All these defects can be determined by optical methods using special microscopes with electronic  video  recording,  software.  The  time  taken  for  this  study  takes  up  to  ten  minutes.    The device, reveals the defects in 2-3 seconds.

Research work on the new device continues. The new results are significantly different (in a positive way)  from  the  results  of  ultrasonic  flaw  detection,  acoustic  emission  method,  which  use  contact sensors, immersion lubrication.  Noticing the contact of the generators of the ultrasound in the new device to the laser generators will let you create a fully remote device.

Read full article: http://bp.bookpi.org/index.php/bpi/catalog/view/25/62/150-1

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