Low-frequency reciprocatory-rotary motion is imparted to a conventional axially vibrated ultrasonic cutter (18 kHz) that is impregnated with diamond grit of average size 0.003 in. The rotary motion is in a plane normal to the cutter axis. Cutting rates in rock materials of 10 ft/h are exceeded for 1-in. diam circular holes drilled to depths greater than 1 ft. Peak axial amplitude was 1.6 mil and the rotary motion was less than three to-and-fro oscillations per minute. Specific energy of the cutting process was measured to be less than 100 J/cm3 or less than that involved in the rotary cutters used for oil well drilling. Pulsed excitation at a 50% duty cycle leads to an 8%–10% increase in drilling rate for the same power input. Self pumping of the abraded material is obtained through subharmonic vibration of the cutter on pulse excitation. Static pressure, peak amplitudes, and rotary motion are optimized.

An ultrasonic image-converter system is described which provides two-dimensional visual images of incident-sound fields. The system is based on an electronically operated image-converter tube, similar to a television-camera tube, except that the photosensitive surface is replaced by a slab of piezoelectric x-cut quartz. The spatial distribution of sound pressure produces a similar distribution of piezoelectric potential at the ungrounded quartz surface which is scanned by a 500-v electron beam. The output of the converter, dependent upon secondary emission from the quartz, is used to generate a cathode-ray tube display of the sound field. Constructional details of the continuously pumped converter tube are described, including electrode configurations, crystal bonding, and vacuum techniques. With the water-immersed converter face irradiated by a pulsed 7-Mc/sec collimated sound beam directed normally to the face, a 12-mm-diam metallic wire intercepting the sound beam is easily discernable on the cathode-ray tube display. Laminar-type defects measuring 0.75 mm diam and 0.01 mm thick, simulated in a steel plate and oriented normal to the sound beam, are resolved by suitable electronic processing of the converter output pulses. Applications to flaw detection and medical diagnostics are discussed.

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The dynamic strain amplitude of sapphire whisker reinforced and nonwhisker reinforced types I, II, and III piezoelectric ceramics was measured as a function of increasing electric field until fracture occurred. The 1-in.-diam by 0.2-in.-thick disk specimens were poled in their [33] direction and excited at their planar resonance. The direct measurement of radial displacement amplitude allows accurate assessment of the nonlinear behavior of piezoelectric and elastic constants from low to very high excitation fields. Test results show that previous determinations of peak dynamic tensile strengths, based on calculations which assume linear d constants, can result in large error. In addition, the investigations show the whisker-reinforced ceramics exhibit linearity and excellent performance to excitation levels unattainable by their nonwhisker-reinforced counterparts. [This work sponsored in part by ONR Code 468.]

The investigation detailed here was carried out on a ring magnetostrictor vibrating in radial mode and exposed to hydrostatic pressures ranging from ambient to 5000 psi. The hydrostatic environment was produced in an oil-filled annular pressure cavity dimensioned so that the radiating surfaces of the ring were separated by less than 110 of a sound wavelength from the cavity walls. Pressure-induced changes in the oil radiation impedance were thereby minimized and amounted to less than 5%. Analysis of electrical-impedance diagrams obtained at polarization levels up to 25.2 Oe showed that the magnetic permeability μr, changed by less than 1% between ambient pressure and 5000 psi while the magnetostriction constant λr changed by 4% over the same pressure range. The transducer mechanical “Q” was constant to within 5% over the 5000 psi pressure range even though the laminations were “soit” bonded. Quasistatic measurements of λr, and μr confirmed the previous findings to within the experimental-error limits (5%). These results are compared with measurements previously reported for axial, compressive, bonding of a bar magnetostrictor. [Work was supported by the U. S. Office of Naval Research.]