Accession Number : ADD009875

Title :   A Strain Sensitive Ultrasonic Surface Wave Detector.

Descriptive Note : Patent Application,


Personal Author(s) : Gerhart,Grant R ; Rose,Douglas N

Report Date : 29 Sep 1982

Pagination or Media Count : 19

Abstract : A novel transducer is described for detecting ultrasonic surface waves over a wide frequency band. The transducer is essentially a grid or series of bars connected in parallel or series. The sensitivity of the transducer increases proportionally with frequency for constant surface wave amplitude. The transducer detects surface waves by providing a resistance change across the transducer output terminal proportional to the surface wave strain. The output voltage can be calibrated to give a direct reading of the surface wave amplitude. The coupling problems which are inherent in most transducer configurations are drastically reduced for this strain sensitive detector. The modulation of the grid excitation voltage provides a means for mixing two signals by giving the direct product of the signals in time. Complicated filtering functions can be built into the grid detector by varying the bar spacing in a manner analogous to the piezoelectric interdigital grid transducer. The novel transducer hereof also lends itself to performing a novel method of detecting ultrasonic surface waves, i.e., particularly Rayleigh waves.

Descriptors :   *Patent applications, *Strain gages, *Ultrasonics, *Detectors, *Transducers, Surface waves, Coupling(Interaction), Configurations, Functions, Output, Signals, Voltage, Reading, Amplitude, Parallel orientation, Broadband, Rayleigh waves, Resistance, Strain(Mechanics), Amplitude, Frequency bands, Sequences, Modulation, Filters, Mixing, Excitation, Grids, Constants

Subject Categories : Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE