Patent ID: 6502463
Filing Date: 2003-01-07
Classification: G01L,G01N

Abstract:
An ultrasonic strain gauge comprising:a computer; an instrument for generating a signal; an oscilloscope; an electromagnetic acoustic transducer (EMAT); a digital gate; a counter; a diplexer; said computer controlling said instrument, oscilloscope, EMAT, digital gate, counter and diplexer; said instrument connected to said diplexer and to said digital gate and to said oscilloscope, whereby a signal generated by said instrument is transmitted and received by said instrument; said instrument connected to said counter and to a switch; said digital gate connected to said switch and to said oscilloscope and to said counter whereby a signal is captured from said EMAT for analysis; said counter connected to said digital gate and to said instrument whereby a zero crossing for a signal is identified; said diplexer connected to said EMAT for selecting signals transmitted to and from said EMAT; wherein said computer compares a first time of flight (TOF) and a second TOF and determines an orientation of pure mode polarization directions &PHgr; of a specimen in a stressed state, where &PHgr; is an angle of rotation from pure mode polarization directions; wherein said first TOF is measured from a signal transmitted to and from said EMAT to select a zero crossing in the signal; and wherein said second TOF is measured from a second signal transmitted to and from said EMAT to select a zero crossing in said second signal.