Ultrasonic Measurement of Phase and Group Velocity Using Continuous Wave Transmission Techniques.
Final rept. 24 May-4 Nov 72,
PANAMETRICS INC WALTHAM MASS
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AMMRCCTR-73-2composite materials, nondestructive testing, halocarbon plastics, ultrasonic radiation, test methods, test equipment, propagation, velocity, attenuationphase, velocity, group velocity, tetrafluoroethylene resins, ultrasonic testsPhase and group velocities V and U, respectively, were measured in the 1001 frequency range 50 kHz to 5 MHz using longitudinal and shear ultra-sonic continuous waves in teflon and in a dispersive three-dimensional reinforced composite. A new transmission approach was developed which utilized broadband transducers and a pair of wedges to obtain V BY A DIFFERENTIAL PATH, FIXED FREQUENCY TECHNIQUE, AND TO OBTAIN U by fixed-path, differential frequency technique. The path or frequency was incremented to fit additional whole wavelengths in the path, as indicated by 2 pi phase shifts in a Lissajous pattern. Cross-checks between U AND V confirmed the validity of the approach at least for the two materials investigated. Author-PL
- Laminates and Composite Materials
- Test Facilities, Equipment and Methods