09.09.2014 Views

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

5.0 Attenuation<br />

The amplitude change of a decaying plane wave can be expressed as:<br />

In this expression A o is the unattenuated amplitude of the propagating wave<br />

at some location. The amplitude A is the reduced amplitude after the wave<br />

has traveled a distance z from that initial location. The quantity α is the<br />

attenuation coefficient of the wave traveling in the z-direction. The α<br />

dimensions of are nepers/length, where a neper is a dimensionless<br />

quantity. The term e is the exponential (or Napier's constant) which is equal<br />

to approximately 2.71828.<br />

http://www.ndt.net/article/v04n06/gin_ut2/gin_ut2.htm

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!