FLEXURAL-VIBRATION ULTRASONIC TRANSDUCER FOR GASEOUS ATMOSPHERES

摘要

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, , where lambdan - 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 , respectively, where lambdanFn is wavelength of resonant flexural vibrations on nth pair of opposite segments of bimorph at frequency Fn, where n = 2, 3, 4 ... . Metal screens are installed on effective and rear sides of bimorph at distance , where lambdaó - is wavelength of ultrasonic vibrations in gaseous atmosphere; axisymmetric matching structure of n/2. in diameter is arranged in screen on effective side of bimorph. Piezoelectric rings are made either of adjacent ring zones, in width, with opposing polarization vectors, or of ring-wise sectionalized external electrodes with even-numbered ele