| 摘要 |
<p>A method and apparatus for the excitation and spectral calibration of acoustic emission systems in which a helium or other gas jet is used as a calibration source which makes no mechanical contact with the specimen or structure under examination. The gas jet which simulates an acoustic emission event, is sprayed on a reference material which is acoustically coupled to either an acoustic emission transducer or to a transducer having a flat frequency response up to 1 MHz. The transducer spectra are measured in decibels and subtracted from each other thereby obtaining a "transducer calibration". The "calibrated" transducers are then coupled to a specimen under test, the gas jet is applied and a "gas jet system spectrum" is measured. The spectrum of acoustic emission activity is then measured and corrected by subtracting, in decibels, the "gas jet system spectrum", thereby obtaining system independent acoustic emission spectral information which can be used to compare results in other systems.</p> |
