Nondestructive Ultrasonic Characterization of the Orientation Distribution of Short-Fiber Composites

The ease of fabrication and relatively low cost of composites containing short glass or ceramic fibers embedded in a polymer or metal matrix has made them attractive candidates for a wide range of applications. The preferential alignment, or misalignment depending on one’s view, of the short fibers results in an overall texture of the composite and strongly influences its mechanical and physical response, for example, stiffness, conductivity, strength, and so on. The orientation of the short fibers depends strongly on the processing conditions. From a process-control viewpoint, it is imperative to determine if a composite component has adequate strength, stiffness, and so on, and it is preferable to obtain this information nondestructively. In short-fiber reinforced composites, the orientation distribution of the short fibers is the most significant variable that determines these overall properties. Thus its determination is essential

Profil sinhrontronske rengenske difrakcijske linije

We analyse diffraction line profiles obtained at the X3B1 National Synchrotron Light Source powder-diffraction beamline. Calculated diffraction-line widths are compared to the measurements of a National Institute of Science and Technology Standard Reference Material, LaB6. The discrepancy at high Bragg angles is probably caused by the inadequate Gaussian approximation for the Darwin width of monochromator Bragg reflection. The equatorial-slit width has a major influence not only on vertical (equatorial) divergence but also on the character of diffraction-line profiles at high angles. The least-squares fits of instrument-function deconvoluted tungsten-line profiles show that a Voigt function satisfactorily models physically broadened line profiles.Analizirali smo difrakcijske profile linija dobivenih na snopu X3B1 Nacionalnog sinhrotronskog izvora svjetlosti u Brookhavenu. Načinili smo usporedbe za razne uvjete i s više prilagodbenih funkcija. Prilagodbe primjenom najmanjih kvadrata za profile volframovih linija, koje su bile dekonvoluirane instrumentalnom funkcijom, pokazuju da Voigtova funkcija dobro opisuje fizičko proširenje profila linija

Profil sinhrontronske rengenske difrakcijske linije

We analyse diffraction line profiles obtained at the X3B1 National Synchrotron Light Source powder-diffraction beamline. Calculated diffraction-line widths are compared to the measurements of a National Institute of Science and Technology Standard Reference Material, LaB6. The discrepancy at high Bragg angles is probably caused by the inadequate Gaussian approximation for the Darwin width of monochromator Bragg reflection. The equatorial-slit width has a major influence not only on vertical (equatorial) divergence but also on the character of diffraction-line profiles at high angles. The least-squares fits of instrument-function deconvoluted tungsten-line profiles show that a Voigt function satisfactorily models physically broadened line profiles.Analizirali smo difrakcijske profile linija dobivenih na snopu X3B1 Nacionalnog sinhrotronskog izvora svjetlosti u Brookhavenu. Načinili smo usporedbe za razne uvjete i s više prilagodbenih funkcija. Prilagodbe primjenom najmanjih kvadrata za profile volframovih linija, koje su bile dekonvoluirane instrumentalnom funkcijom, pokazuju da Voigtova funkcija dobro opisuje fizičko proširenje profila linija

Artificial Crack in Steel: An Ultrasonic-Resonance-Spectrscopy and Modeling Study

The problem of detecting and characterizing cracks in solids is a major research area involving contributions from mathematics, physics, mechanics, and materials science

Nondestructive Ultrasonic Characterization of the Orientation Distribution of Short-Fiber Composites

The ease of fabrication and relatively low cost of composites containing short glass or ceramic fibers embedded in a polymer or metal matrix has made them attractive candidates for a wide range of applications. The preferential alignment, or misalignment depending on one’s view, of the short fibers results in an overall texture of the composite and strongly influences its mechanical and physical response, for example, stiffness, conductivity, strength, and so on. The orientation of the short fibers depends strongly on the processing conditions. From a process-control viewpoint, it is imperative to determine if a composite component has adequate strength, stiffness, and so on, and it is preferable to obtain this information nondestructively. In short-fiber reinforced composites, the orientation distribution of the short fibers is the most significant variable that determines these overall properties. Thus its determination is essential.</p

Acoustic spectroscopy of lithium niobate: Elastic and piezoelectric coefficients

Ogi H., Kawasaki Y., Hirao M., et al. "Acoustic spectroscopy of lithium niobate: Elastic and piezoelectric coefficients" Journal of Applied Physics, 92(5), 2451-2426 (2002) https://doi.org/10.1063/1.1497702

Contactless mode-selective resonance ultrasound spectroscopy : Electromagnetic acoustic resonance

A noncontacting resonant-ultrasound-spectroscopy (RUS) method for measuring elastic constants and internal friction of conducting materials is described, and applied to monocrystalline copper. This method is called electromagnetic acoustic resonance (EMAR). Contactless acoustic coupling is achieved by energy transduction between the electromagnetic field and the ultrasonic vibrations. A solenoidal coil and static magnetic field induce Lorentz forces on specimen surfaces without using a coupling agent. By changing the field direction, a particular set of vibration modes can be selectively excited and detected, an advantage in identifying the vibration modes of the observed resonance peaks. Contactless coupling allows the measure of intrinsic internal friction free from energy loss associated with contact coupling. The elastic constants and internal friction measured by EMAR are compared with those by the usual RUS method for a rectangular- parallelepiped copper monocrystal. Both methods yielded the same elastic constants despite fewer resonant peaks in the EMAR case. The two methods gave essentially the same shear-mode internal friction, but the RUS method gave higher volume-mode internal friction.Hirotsugu Ogi, Hassel Ledbetter, Sudook KimLedbetter, Masahiko Hirao. Contactless mode-selective resonance ultrasound spectroscopy: Electromagnetic acoustic resonance. Journal of the Acoustical Society of America, 1999, 106(2), 660. https://doi.org/10.1121/1.427607