FLEXURAL-VIBRATION ULTRASONIC TRANSDUCER FOR GASEOUS ATMOSPHERES Russian patent published in 1999 - IPC

FIELD: measurement technology; contactless ultrasonic inspections of materials and parts. SUBSTANCE: transducer can be made as single-frequency or broad- band device and provides for emission of extremely high-intensity ultrasonic vibrations. It has case accommodating bimorph in the form of thin metal disk arranged axisymmetrically or stepwise axisymmetrically over its perimeter that carries on one or both ends axisymmetric piezoelectric ring or several axisymmetric parts of piezoelectric rings. Bimorph diameter is , where is wavelength of resonant flexural vibrations of bimorph at its low frequency; n = 3, 5, 7 .... . Inner and outer diameters of piezoelectric ring are, respectively, ≥kλ_n/2,≤kλ_n/2+λ_n,, where λ_n - is wavelength of resonant flexural vibrations of bimorph; k = 1, 3, 5 ... . Bimorph is provided with radial slits made along lines of stepwise variations in its fixation from its side surface to diameter , where is wavelength of flexural vibrations of bimorph at its high frequency; each pair of opposite segments of bimorph formed by radial slits mounts parts of piezoelectric rings of inner and outer diameters ≥kλ_nFn/2,≤kλ_nFn/2+λ_nFn,, respectively, where λ_nFn is wavelength of resonant flexural vibrations on nth pair of opposite segments of bimorph at frequency F_n, where n = 2, 3, 4 ... . Metal screens are installed on effective and rear sides of bimorph at distance ≪λ_в/2,, where λ_в - is wavelength of ultrasonic vibrations in gaseous atmosphere; axisymmetric matching structure of <λ_n/2. in diameter is arranged in screen on effective side of bimorph. Piezoelectric rings are made either of adjacent ring zones, ≤λ_n/2, in width, with opposing polarization vectors, or of ring-wise sectionalized external electrodes with even-numbered electrode sections being interconnected as well as odd-numbered ones. Piezoelectric rings of bimorph with radial slits are made in the same way. EFFECT: enlarged functional capabilities. 6 cl, 1 dwg