The excitation and spectral calibration of acoustic emission systems using a helium gas jet is shown to produce system independent acoustic emission spectral information. The calibration source makes no mechanical contact with the specimen or structure under investigation and can be conveniently used for specimen or structural response mapping.
The transient pressure fields of ideal planar ultrasonic transducers may be described in terms of plane and edge wave contributions. Based on this concept, a technique is developed which allows characterization of wideband unfocused transducers by a single measurement close to the transducer face. This method is examined experimentally for both polyvinylidene difluoride and commercial PZT transducers. Also investigated is the effective radiated frequency of these devices.
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