Accession Number : ADD006328

Title :   Non-Destructive Technique for Surface Wave Velocity Measurement.

Descriptive Note : Patent,


Personal Author(s) : Gerhart,Grant R

Report Date : 24 Oct 1978

Pagination or Media Count : 7

Abstract : It is often desirable to measure absolute and relative USW velocities in a specimen. One example is a specimen which is to be tested for residual surface stresses. The specimen is provided with two scratches which are parallel and a known distance apart. An ultrasonic surface wave (USW) transducer is attached to the surface of the specimen in such a way as to efficiently transfer USW energy to the specimen. During testing, the incident pulse from the transducer is partially reflected at each scratch. The same transducer generates and detects both reflections. The transducer output goes through a clipping circuit which clips the large incident voltage spikes in the output and passes the smaller, echo voltages through to an oscilloscope. The oscilloscope horizontal sweep is driven at a frequency which is the reciprocal of the difference in arrival times between the two reflected pulses. A dual pulse delay generator is detailed as a double strobe delay generator having a plurality (herein six) of integrated circuits (IC's) interconnected as described below to provide the Z-axis input to the oscilloscope.

Descriptors :   *Patents, *Surface waves, *Ultrasonic tests, *Wave propagation, Nondestructive testing, *Residual stress, *Strength(Mechanics), Velocity, Ultrasonic radiation, Measurement, Transducers, Circuits, Gates(Circuits)

Subject Categories : Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE